Eindhoven University of Technology

MASTER

Inventory of water pollution caused by industrial activities in and around Colombo, SriLanka

Creemers, H.J.F.

Award date:1991

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lnventory of Water Pollulion Caused by lndustrial Activities

in and around Colombo, Sri Lanka.

Flnal Report of the M.Sc. Research Eric Cteemers, May 1991

Summary of Final M.Sc. Research Report Eric Creemers, may 1991

SUMMARY lnventory of water Pollution Causec:l by lndustrial Actlvities

in and around Colombo, Sri lanka

Since Sri L.anka is industrialising rapidly, the authorities are increasingly concerned about the environmental consequences of this industrial development. Environmental organisations receive extensive assistance trom foreign donor organisations. From one of these organisations, United Nations lndustrial Development Organisation (UNIDO), the project proposal originated to transfer modern technologies for treatment of industrial wastewater in South Asian countries, including Sri L.anka. The research presently under consideration is serving as a tactfinding mission or an exploratory survey supporting to this UNIDO project.

The general alm of this research has been to make an inventory of industrial water polJution in the greater Colombo area. The objectives consist of two parts:

(1) Assess the state of the art of environmental polJution in Sri L.anka and particularly water pollution caused by industrial activities.

(2) Assess the performance of these industries with respect to wastewater treatment and Inplant waste reducing technology.

(1) Environmental pollution problems The assessment of environmental problems is again divided lnto two parts: Environmental orga­nisation and legis/ation (a), and Water polfution caused by industrial activities (b).

(a) Being a side aspect throughout the survey, the environmental situation of Sri tanka and the functioning and effectiveness of the relevant environmental organisations were studied. In order to obtain a general picture of the actlvities and constraints of the relevant environmental organisations, experts trom these organisations were interviewed. The following was found:

Although most organisations are provided with the required powers and legislative instru­ments, still no results of polJution reduction can be seen as a consequence of actions by these organisations. Effective abatement of the environmental pollution is prevented by constraints including: lack of financlal resources, understaffing, lack of qualified personnel, lack of expertise with waste reducing technology, undercapacity of laboratories, transport and communication problems, disproportionate emphasis on buroeratic activities. The research actlvities for the development of suitable wastewater treatment systems are insufficient.

(b) For the assessment of industrial water polfution three industrial sectors which cause significant water pollution were selected: the textile industry, the leather tanning industry and the natural rubber industry. These selections were made on basis of literature studies. Factorles with extremely high water polJution were selected for further analysis. Data were collected by means of personal interview and observation during vislts tothese factories. In total 8 textile, 5 leather and 6 rubber companies were visited. The findings are the following:

The awareness of the pollutional consequences of the production processes on the side of the industrialists is not satisfactory. Mostly the heavily polluting industries are concentrated in industrial zones, which in the course of time also became partly residentlaL All visited factorles are producing a wastewater with characteristics which are expected to exceed the toleranee limits largely. The wastes trom the textile, leather and rubber industries are mainly organic and biodegradable. Dangerous situations are caused by toxic constituents of the wastewater (dyes in the textile industry, chromium in the leather industry) and because this wastewater is discharged into public waterbodles and paddy fields. The processes mostly take place on old and badly maintained machinery. The insuftielent housekeeping causes spilis of chemieals and hazards to the factory werkers.

(2) Waste reducing technology Both end-of-pipe wastewater treatment (a) and inplant waste reduclng measures (b) were investiga­ted for the visited factories in the three industrial sectors.

(a) In order to assess the end-of-pipe wastewater treatment applied at the visited factories, an extensive literature study of existing wastewater treatment methods was carried out. Within the three foregoing sectors all companies, which are eperating a system to purify their wastewater, were selected. Interviews and observation were the methods of data collection. The following was found:

Wastewater treatment in Sri Lanka is rather an exception than commonly practised. Pilot plants which have been set up with foreign assistance are not achieving their goal of being an example for ether industrialists. In the three sectors totally nine attempts of wastewater traat­ment were observed, of which only three systems can be called effective. All systems are confronteet with operational problems, due to bad design or due to inaccurate operation. Lack of expertise with wastewater treatment is the underlying factor. Generally the limiting factors for construction of a treatment plant are: lack of space, lack of financial resources and lack of expertise. In most cases the initiative of installing a treatment plant is left to the Central Environmental Authority of Sri Lanka.

The common wastewater treatment plants in the Export Processing Zones (Biyagarna and Katunayake) seem to be effective. The treatment infrastructure in the zones could serve as an example for the rest of the country.

(b) Inplant pol/ution control also was assessed by means of interview and observation during factory visits. Prior to these visits a list was composed of optional waste reducing measures which can be praeticeet within the processas of textile, leather and rubber factories. The results are:

Inplant waste reducing measures are not pracised with a few exceptions. In a few cases it is done for resources minimization or profit maximisation. Housekeeping is generally insufficient and the knowledge of the polluting character of the chemieals used is poer. No need is feit for recycling of process water or by-products.

Recommendations Organisations should be more action oriented instead of legislation oriented. For this purpose a

streng professional cadre of environmental experts should be built. A coherent philosophy should be developed in the field of pollution abatement by the organisations involved. lndustrial zones and residential areas should be separated in order to avoid direct health hazards and to be able to construct central treatment facilities. The research capacity which is actually used tor the development of suitable wastewater treatment systems should be increased.

Commonly used treatment systems are more economical than one system for each individual factory. lndustrialists should be made aware of the environmental consequences of their industrial activities. This can be done by means of training programmes or seminars. In this way also skilis should be developed on how to operate a wastewater purification plant. Pilot treatment plants should be developed which serve as a realistic example for ether companies. The incentives for instanation of treatment facilities should be made more effective.

Labour circumstances and housekeeping should be improved by the companies. Incentives should be introduced by the authorities for inplant waste reducing measures. Research and development of recycling techniques should be encouraged.

1.

2.

3.

4.

5.

SUMMARY OF CONTENTS

Introduetion

General environmental situation in Sri lanka

Theoretica! framewerk 3.1. General description of the rubber, leather and rubber sectors 3.2. Overview of wastewater treatment methods

The environmental aspects of the production of leather, rubber and textile 4.1. Introduetion 4.2. Qualitative description of the visited factorles 4.3. Estimated characteristlcs of the wastewater of visited factorles 4.4. Present status of low waste technology applied in the visited factorles

Conclusions and Recommendations 5.1. Conclusions 5.2. Recommendations

2

5

12 12 21

39 39 39 55 60

69 69 75

ACKNOWLEDGEMENTS

1. INTRODUCTION Background of the study Objectives of the study Research area

DETAILED CONTENTS

Selection of industrial sectors and factorles Research methodology

2. GENERAL ENVIRONMENTAL SITUATION IN SRI LANKA 2.1. Actual water quality and urgent water pollution problems 2.2. lndustrial polJution 2.3. Overview of environmental organisatlons

3. THEORETICAL FRAMEWORK

3.1. GENERAL DESCRIPTION OF THE LEATHER, RUBBER AND TEXTILE INDUSTRIES.

3.1.1. Introduetion 3.1.2. PolJution parameters ...-d polJution loads 3.1.3. The textile industry

processas summary of wastes arising In textile factorles in plant waste reducing measures recommended treatment

3.1.4. The leather industry processas summary of wastes arising in laather tanneries in plant waste reducing measures recommended treatment

3.1.5. The rubber industry processas summary of wastes arising in rubber factorles in plant waste reducing measures recommended treatment

3.2. WASTEWATER TREATMENT METHOOS • AN OVERVIEW

3.2.1. Physical treatment systems screening grit and sand removal oil & grease removal equalization I balanclng tank I homogenisation gravity settling (sedimentationlclarification) flotation

1

2 2 2 2 3 3

5 5 7 7

12

12 12 13 14 14 15 15 16 16 16 17 17 18 18 18 19 19 20

21 21 22 22 22 22 23 23

3.2.2. Chemica! treatment systems neutralization coagulation-precipitation

3.2.3. Biologica! treatment systems AEROBIC SUSPENDEO GROWTH SYSTEMS

conventienel actlvated sludge aerated lagcon oxidation dltch

AEROBIC ATIACHED GROWTH SYSTEMS trickling filter rotating biological centactor

LAGOONS (STABILIZATION PONDS) aerobic lagcon facultatlve lagcon anaerobic lagcon

ANAEROBIC SUSPENDEO GROWTH SYSTEMS

anaerobic digestion upflow anaerobic sludge blanket

ANAEROBIC ATIACHED GROWTH SYSTEMS anaerobic filter

LAND TREATMENT overland flow wetlands application

3.2.4. Sludge treatment & disposal A. sludge thickening B. sludge stabilization

anaerobic sludge digestion aerobic sludge digestion

C. sludge.conditioning 0. disinfection E. Sludge dewatering

drying beds F sludge cornposting G final sludge disposal

land application incineration

3.2.5. Factors which influence the selection of trestment processes

24 24 24 26 26 26 26 27 28 28 29 29 30 30 31 31 31 32 32 32 32 33 33 34 35 35 35 35 35 36 36 36 36 37 37 37 37

4. THE ENVIRONMENTAL ASPECTSOF THE PRODUCTION OF LEATHER, RUBBER AND

4.1.

4.2.

TEXTILE IN SRI LANKA 39

INTRODUCTION

DESCRIPYlON OF THE NATURE OF THE TEXTILE, RUBBER AND LEATHER INDUSTRY

4.2.1. Textile industry general background factory vislts cernparisen of the visited textile factorles

4.2.2. Leather industry general background factory vislts cernparisen of the vislted leather tanneries

4.2.3. Rubber industry general background factory vislts cernparisen of the vislted rubber factorles

39

39 40 40 41 44 45 45 45 47 51 51 51 53

4.3. ESTIMATED CHARACTERISTICS OF THE WASTEWATER OF THE VISITED FACTORlES 4.3.1. Introduetion 4.3.2. Results

Textile industry Leather industry Rubber industry General remarks Summary

55 55 56 56 56 57 58 59

4.4. PRESENT STATUS OF WASTE REDUCING TECHNOLOGY APPLIED IN THE VISITED FACTORlES 60 4.4.1. Research and development 60 4.4.2. Present status of low waste technology 60

Textile industry 61 Leather industry 61 Rubber industry 62

4.4.3. present status of wastewater trestment 62 General 62 Textile industry 62 Leather industry 63 Rubber industry 64 Export Processing Zones 65 Factors which have been lnfluencing the selection of applied treatment method6 63

5. CONCLUSIONS AND RECOMMENDATIONS 69 .. 5. 1. CONCLUSIONS 69

Part one - Environments! problems 69 General environmental problems 69 Environmental organisation and leglslation 69 Water pollution caused by textile, leather and rubber factorles 70

Part two- Waste reducing technologyIn textile, lesther and rubber factorles 73 Wastewater treatment 73 Inplant pollution control 74

5.2. RECOMMENDATIONS 75 Organisations 75 lndustrial water pollution 75 Wastewater treatment 75 In-plant pollution control 76 Suggestions for further research 76

APPENDICES

APPENDIX I

APPENDIX 11

APPENDIX 111

APPENDIX IV

APPENDIX V

APPENDIX VI

APPENDIX VIl

REGOMMENDEO LOW WASTE TECHNOLOGY FOR THE TEXTILE AND LEATHER INDUSTRY

(AD 3.1.)

ADVANTAGES AND DISADVANTAGES OF THE DISCUSSEC TREATMENT METHOOS (AD 3.2.)

DETAILED DESCRIPTION OF PRODUCTION PROCESSES IN TEXTILE, LEATHER & RUBBER INDUSTRY (AD 4.2.)

CALCULATION OF THE ESTIMATED WASTEWATER CHARACTERISTICS (AD 4.3)

INFORMATION QUESTIONNAIRE, USED FOR FACTORY VISlTS

CHEMICALS USED IN THE VISITED FACTORlES

REFERENCES

ACKNOWLEDGEMENTS

The M.Sc. research on industrial polution in Sri Lanka was carried out during the period May 1990 to november 1990. The initial preparatien of the research took place in Vienna at the United Nations lndustrial Development Organisation in march 1990. In Vienna I was supervized by S. Maltezou, Phd, whowas in fact the proposer of the M.Sc.research. She assisted me with the constitution of the research proposal. My official supervisor in Sri Lanka was Padmini de Alwis of the National Aquatic Resources Agency. She provided me with the narnes of relevant environmental organisations and experts and she gave advice during the research period. My word of thanks goes out to Mrs S. Maltazou and Mrs P. de Alwis.

In the framewerk of this research many environmental experts trom various organisations were contacted. These experts contributed significantly to the research. My special word of gratitude goes out to Mr Wijesooriya and MrT. Hewawasam (Central Environmental Authority), Dr Mathes (Ceylon lnstitute tor Scientific and lndustrial Research), Mr P. lllangovan (National Building Resources Organisation) and Dr E.D.I.H. Perera (Rubber Research lnstitute), Dr. S.P. Amarakone and mr. G.L. Perera (Greater Colombo Economie Commission).

I also want to express my gratitude to Drs. P. van Tilburg and ProfS. Ottengraf, who supervised me during the preparatien and terminatien of the research in the Netherlands.

I am thankful to Rohan Peiris for allowing me and lssanka to stay in his house in Mount Lavinia; to Sir Willy van Diest for borrowing his personal computer. I want to thank the persons who inspired and motivated me with their support: the Gunawardenas (my neighbours in Sri Lanka), Shantha and Sanath. And tinally my gratitude goes out to my parents, my girltriend lssanka and her parents, trom whom I received extensive moral support.

Eric Creemers, May 1991

1

1

INTRODUCTION

1

INTRODUCTION

Background of the study

During the period June 1990 to November 1990 a research has been carried out in Sri L.anka titled lnventory of Water Pol/ution caused by lndustrial Actlvities In and around Colombo, Sri Lanka. The study has been executed as a final research in the framewerk of the M.Sc. course "Technological Development Sciences" at the Eindhoven Univarsity of Technology, The Netherlands. The South Asian Co-operative Environment Programme (SACEP), an intergovernmental organisation of ten South Asian countries including Sri L.anka, has taken initiatives and contacted the UNI DO Technology Promotion Division in Vienna, Austria. This resulted into a project proposal trom Mrs S. Maltezau Phd. called "Modern technologies tor the treatment of industrial wastewaters in South Asian countries. • The survey, carried out under ausplces of the UNIDO, serves as a preliminary phase or a general tactfinding mission to this UNIDO-project The survey has consequently an explorative nature.

Vienna At the UNI DO in Vienna the research has been prepared in consultatien with my supervisorS. Maltezou, Phd. I modified my research proposall'fi'order to maximize the usefulness of my survey tor UNI DO, while at the sametime meeting the requirements of a M.Sc. graduation at the E.U.T. Furthermore relevant intermation has been studled which is available in the UN library in order to prepare the theoretica! framework. The research preparatien in Vienna took month.

Objectives of the study

The general alm of the survey is firstly to assess the state of the art of water polJution caused by the most polluting industries in Sri lanka and secondly to give an assessment of the performance of these industries with respect to wastewater treatment and lew waste technology.

Research area

For several reasans the radius of my research activities was llmited geographically. The first two reasans are limited time and limited budget. Transport takes a considerable time in Sri L.anka because of the condition of the roads, condition of the vehlcles and traffic jams. Hence, daily travelling long dlstances would be relatively costly and time-consumlng. I declded to limit my survey to an area with a radius of 50 kilometers from the place of residence. Thirdly, 80% of the entire industrial production in Sri L.anka is concentrated in the Gampaha and Colombo Dlstricts. The extent of these districts is roughly equiva­lent to a radius of 30 to 40 kilometers trom Colombo City.

Concludingly Colombo was selected as the place of rasielenee and the two above mentioned districts as the research area.

2

• Selection of lndustrial sectors

Based on a CEA report and discussJon wlth experts (Oxley and others) 7 industrial sectors wlth significant water pollution were selected. These sectors are: Textile rnanufacturing, laather tanning, rubber processing, soapand detergents production, metal plating, paper and pulp production, petroleum refining. From these sectors the textile, rubber and leather were selected for further analysis in the course of this research. The motlvation of the choice Is glven below.

The paper and pulp lndustry was not selected, because only one factory is operatlonalln Srl Lanka. Thls factory Is located in the south of Sri Lanka, too far outside the research area. An environmental study has been carried out recently. There Is also only one petrol refinery in Sri Lanka. This factory is more notorious for lts air polJution (sulphur) than tor its water pollution. The wastewater Is characterized by a high organic waste concentratien and the presence of oil. The oil is separated and re-refined.

The metal sector (electroplating, metal faundries and metal products) is causing very high pollution. This is mainly done In small scale units and in srnall wastewater volumes. Cyanides are forming the taxie constituent of the electro-plating effluent. Because of the small scale character and the complexlty of the metal sector I decided not to select this sector. However further lnvestigation of the sector Is very much recommended, because of possible envlronmental dangers.

The number of factorles producing soap and detergents is srnall: Four campanles are eperating on medium/large scale, of which two in the Colombo district. (Lever Brathers and BCC = Brltish Ceylonase Co-operation). Lever Brathers is recycling lts cooling water, whlle at BCC this is dlscharged. The wastewater contalns organlc material: oils and fats. This sector was not selected for three reasons: firstly only two campanles are operative in the greater Colombo area. Secondly the fabrication of soaps and detergents has a complex nature, which makes this sector difficult to analyse. Thirdly, the four medium/large scale campanles in Sri Lanka are all using advsneed high technology. They can solve the wastewater problem with their own expertise, without external support, on condition that the Sri Lankan is providing incentives.

The rubber producing industry has a considerable share in the total industrial production and is Sri Lanka's third export product after tea and coconut. The number of production units exceeds thousand. About 234 medium scale units are producing natura! rubber. The lndustry Is predomlnantly small and medium scale and is scattered over the south west of Sri Lanka. Most units can be found wlthin a radius of 75 km from Colombo. Water pollution which is characterized by high organic loads is causing environmental hazards in bath urban and rural areas.

The leather sector is relatively small. Only 14 tanneries are significant polluters. However, the pollutional hazards are considerable because of large effluent volumes containing high organic wastes and high discharges of toxic chromium. All tanneries are located in or very near urban areas.

The textile industry deserves the first place when water polJution is concerned. Large volumes of effluent are containing organic waste as well as toxic chemieals from the dying of all types of fibres. About 30 to 40 factorles are located in the urban areas In and around Colombo. Consequently the Textile, Leather and Natura! Rubber lndustry have been selected for further research.

• Research methodology

Firstly the research can be divided into two parts: a theoretica! part and a part which rnainly consists of field work. The theoretica! part serves as a preparatien for the field work. lt contains a detailed study of the three selected sectors textile, leather and rubber. Also an overview has been made of existing wastewater trestment methods in order to enable myself to judge properly the treatment systems applied in sri Lanka.

3

The field work consisted of visiting the export processing zones, environmental orgaPiisations, ministries and industries. lnterviewing environmental experts of several organlsations provicled me information on environmental management and legislation. Visiting industries formed the major part of the field work. I visited 19 factorles of which 8 textile, 5 laather and 6 rubber factories, In order to make an lnventory of the lndustrial water pollution and pollution abatement in the three sectors. Appolntments were made by telephone and the Interviews wlth the factory managers of each company were done by means of an lnformation questionnaire wlth open questions. (see Appendix V). lt was planned to visit campanles lnside the Export Processing Zones of the GCEC (Greater Colombo Economie Commlssion), but unfortunately access was refused by the lndustrlallsts.

During the period of field work, a general inventory has been made of the major environmental problems which are recognized in Sri Lanka. Generally data were obtained by studying reports and through personal interviews. During the factory vislts also observation played a role. The field work took me twelve weeks, the preparatien ten weeks (Vienna included).

Note: lt Is NOT aimed that the factorles which have been visited are glvlng a representative overview of the Sri Lankan textile, leather and rubber industry. After discussion with CEA-experts, it became logica! to visit all factorles within the sector with access to an effluent treatment system. In addltion the factorles which are characterised by an extremely high water pollution were visited.

The environmental study of Sri Lanka (chapter 2) discussas the organisations involved in environmental issues, the environmentallegislation and the major industrial pollution problems in the country. The theoretica! part is presented in chapter 3 and contains the study of the three sectors (3.1.) and the overview of wastewater treatment methods (3.2.). The fieldwork is discussed in chapter 4. Observations during factory vislts are described in 4.2, foliowed by a quantitative description of the water polJution caused by the factorles in 4.3. The inventory of effluent treatment in the three sectors Is presented in 4.4 .

..

4

2 ENVIRONMENTAL STUDY OF SRI LANKA

2 ENVIRONMENTAL STUDY OF SRI LANKA

2.1. GENERAL (socio economie)

Sri Lanka is an island, where water is available in excessive amounts. The country can be divided in a wet zone and a dry zone. In the wet zone, the south western part of Sri Lanka, two monsoons per year cause an annual rainfall of saveral meters. The majority of the total popuiatien of about 17 million people lives in this wet zone (see map 3.2). Here no water scarcity exists, but the supply of fresh drinking water is below the required capacity [Daily News, 30-10-1990]. Especially along the south west coast, urbanisation has starled to take excessive proportions along the main roads (ribbon development). In these urban areas half of the people live in slums where poverty is high, resulting in unhygienic circumstance and malnutrition. These people are economlcally almost non-existant. Intheir attempts to survive, they become victlms as wellas contributors to envlronmental degradation.

The majority of the Sri Lankans is buddhist, but there is also a minority of christians, muslims and hindus. In its origin, Buddhism is very respecttul towards nature and life in generaL lt is thought, that hlstorical events during colonlal rule.cbanged the attitudes of people living previously in harmony to nature into new attitudes. These new attitudes were characterised by increasing individualism, distinct from the traditional community life and profit maximization. Old values were ignored and a more avaricious attitude towards nature was developed. Many environmental problems have their origins in certain basic attitudes conditioned by the cultural heritage of the past. Therefore legislative, technica! and economie solutions alone cannot solve environmental issues entirely. A proper understanding of the dangers of the present attitude towards the environment is primarily required.

The public awareness IS 1ncreasing and the

.·.·.. .·. .... .

One quarter of theSri Laf,l<an populati~n llves >Jn urban areas,· ot which 50%)11. the Colornoo ....

. area (2 mil/ion inhabltants). fialf of this · .. ·.pop. . ulatiqn lilles in slumsJ · W11efe one ·toilet is

used per 36 persons .and orie water tap pei < 128 . persons. Çolornbó is a heavily compacted •·. area: . whl/e . . the. a~erage .... ·. populationdef!sift.·is· 240 pe:t~q. k.m,. t/Je•····• density lnCoi0/11Pó êJJstrlctJs 28()0 resident$ • ..

persq.km.> >········••••·.•••····· ·.····· )•·· . • ••The•····income••···dlstribution.•.•··in··••••$r/ .•.•• 1f1,nka••·•••áncl···•···· •

pàrticûlarl}'.Jn tirban areasis llety uneqiJal. ·•••·• .•. . ·.·. The .top 10%, spencJs. 43% óf the. total exp~nclitures. T/le poOieSt 40% .. Of thif .

· popi.Jiation has only 13% tq. $Penëf. i •···•• • •.. ·•• • •·•·••··• .·.···· f'O'(ert)i Is significant: 23% oft!Jê Srll.,ankarr

. . . popu/ation Jives below the p()~rt)i Jine öf 80 •· Ijs ~nnonth ($ 2.-). · · · .. · · · · .. ·.·.· ·. .·. · ·· ·.·. · ·. · ·

government is becoming more committed to the envlronmental conservation. In 1990 even two ministrles of environment were established! Some of the governmental institutions however still see environmental considerations as unnecessary obstacles In achlaving lndustrial development.

Sri Lanka knows a high unemployment, which Is still rising. About 2 miJlion people out of a werkforce of 7 million is unemployed at the moment - among others - because lndustry failed to grow at a rate that could absorb the increasing Iabour force. Liberalisatlon of Sri Lanka starled in 1977 but did not result in a dynamic industry with the expected export earnings. In addition the country started to build a large foreign debt and high rates of inflation.

5

0 ....... 50 100

Map 3. 1 - Sri Lanka: Provinces and major cities Map 3.2 - Sri Lanka: Popu/ation distribution

The high unemployment and under-employment of rural educated youth resulted (among ether causes) In seclal unrests and civil war in 1971, 1983 and 1989. Therefore the rural economy is functioning below lts capacity at the moment.

When counting the total number of industrial establishments with less than 25 employees, 43% is located within the GCEC area of authority. Another 40% is located between Galle and Ratmalana (Southern coast). 36% Is located in Ratmalana, Moratuwa and Panadura only. So 79% of the small scale lndustry is located along the west coast between Negombo and Panadura. Medium and large scale Industries are mainly located around Colombo, except for some state companles, whlch were establlshed In rural areas tor promotion of rural development (employment).

Environment At the natlonallevel, many environmental problems exlst. The torest cover dimlnlshed from one half to one quarter of the island over the last 40 years due to popuiatien growth, expansion of plantations, extenslve agriculture and irrigation schemes. The deforestation caused land degradation In the form of soli erosion, coastal eroslon, land slldes, etc. In agrlculture excesslve irrlgation results in siltation of the soli. Excesslve use of fertilizer and pestieldes are causing damages to aquatic ecosystems. Coastal habitats are in danger due to uncontrolled sewage discharge and tourlsm. In the urban areas, water Is polluted with excess chemieals from industries and contamlnated wlth faecal bacteria trom househeld wastes In such a way, that public health is In danger. Canals and drainage systems are improper1y maintained. The water quality of all water bodles in Colombo city Is endangered but they are still used for washing and bathing purposes.

6

In addition the air polJution In theseareasIs unbearable, In the sense that most transport vehicles are exhausting black smoke. This finds its cause in badly maintaineet englnes and an interlor petrol quality.

2.2. INDUSTRIAL POLLUTION

lndustrial and dornestic effluents are dischargeet lnto sea and rivers and small streams, causlng depletion of oxygen, unhygienic somatimes dangerous clrcumstances to human belngs and flsh kill. Some of the beaches around Colombo are black, especlally near sewage discharge points. 011 spilis can be found here trom oft tankers rinsing their tanks near the coast. A real problem is the location of industries. Very often these are establisheet in the mlddie of residentlal areas; or somatimes residentlal dwellings are not kept out trom approveet industrial zones. Due to high urbanisation industries which were once locateet at the border of the city, are now surroundeet by residentlal areas. Rapid industralisation causes an increasing polJution which will also extend to rural areas.

lndustrial polJution is often eauseet by bad planning and poor management in combination with Jack of environmental awareness. There are no effectlve incentives for industrialists to lnstall clean technologles and wastewater treatment. Although lndustrial polJution Is serieus, at the moment it is still manageable because industrialisation is still in its early stage. Adequate monitoring is very important since a significant expanslon of industry Is expecteet In the near future. In the field of solid waste disposal a lot has to be done. At the moment no proper dump sites have been allocateet. Solid wastes are useet for land fill to build houses on or dumpeet onto abandoneet paddy fields.

Responsibility for industrial growth Is shareet by the ministries of Industries, Rurallndustrlal development and textiles industries, Higer eetucation, Science and Technology and of Flnance as well as by the Greater Colombo Economie Commlssion, which promotes lndustrial investment In its export processing zones Katunayake and Biyagama.

Among the public sector corporation&:"the following enterprises are eperating in Sri Lanka: petroleum refinery, cement, steel, tyres, ceramics, paper, leather, milk, beverages, mineral processing. In the private sector, where the number of companies is growing fast, the following sectors have a significant share in the country's production: engineering goods, textiles, garments, asbestos, cement products, lead accumulators, rubber and rubber products, leather, food and beverage, tobacco. Significant polJution is eauseet mainly by pulp & paper mills, teather tanneries, processing of asbestos fibres, textile mills, natural rubber processing, metalplating and the manufacturing of soap and detergents. These sectors neeet extra high priority. High priority is also needeet for those areas where polluting industries and residentlal dwellings are mixeet.[NORAD, 1989]

2.3. OVERVIEW OF ENVIRONMENTAL ORGANISATIONS

Paradoxically it can be said, that too many organlsatlons are lnvolveet In the environmental monitoring and management. These organisations have overlapping responsibllities and actlvities. Consequence of the dispersal of environmental actlvities Is communication problems. Transport through Colombo city between two organisations is time consumlng. People are very difficult to reach, because they can be anywhere. Making telephone calls however Is also very time consuming In Srl Lanka because of long waiting times, especially for organlsations with one telephone line. Some organisations are eenstraineet In their wastewater sampling actlvities because of transport problems. There are not enough company vehicles available.

Administration is a mess in most organisations. Libraries are inaccessible. Pil es of paper are filling desks making it difficult finding information to answer even the simplest questions. For instanee it is impossible to get a complete list of the companies in a certain sector, except at the Ministry of Industries, where they have only a few sectors registereet in a computer data bank. All this paperwerk attracts the attention from the real polJution abatement: no action is taken. No visible signs from CEA of reetucing

7

pollution anywhere in the country. Most organisations are cumbrous and burocratic.

There is not enough expertise to take the necessary amount of samples and to design effluent treatment plants. Though at universities environmental knowledge is present, this knowledge is unfortunatlely not directly applicable, not adapted to the practical need. Also equipment somatimeslacks the required capacity. In most cases however the capacity is sufficient, but not fully utilized. All these constraints are preventing the organisations from effective abatement of the environmental pollution, which of course is or should be the ultimata goal of these organisations.

Formally CEA is the governmental coordinating agency with the overall responsibility on environmental Issues. However many individual governmental agencles are undertaking actlvities and thus lnvolved in the pollution abatement. Among these organisatlons the most active are:

NBRO = National Building Research Organisation CISIR = Ceylon lnstitute of Scientific and lndustrial Research NARA = National Aquatic Resources Agency RRI = Rubber Research lnstitute GCEC = Greater Colombo Economie Commission NWS&DB = National Water Supply and Drainage Board

Based on personal interviews of experts trom these organisations the environmental avctivitles and some constraints are outlined in the following paragraphs. For an overview of the persons intervlawed Is referred to Appendix VIl.

Central Environmental Authority

In 1980 the Central Environmental Authority (CEA) was created in the "National Environmental Act" with the objectives of protection, management, regulation and quality control of the environment as well as the prevention, abatement and control of pollution. In short the CEA was made responsible of all matters concerning environment in the country.

Also District Environmental Agencies (DEAs) were established tor decentralised environmental management and conservation. These agencies are manned by 3 to 10 people.

The first Export Processing Zone (EPZ) was established in 1978 under responsibility of the Greater Colombo Economie Commission (GCEC). Because of its lack of expertise, CEA copied the environmental standards which the GCEC were uslng. Furthermore the CEA handed over its authority over the GCEC area to the GCEC. Because the GCEC developed an lnfrastructure for the collection and treatment of lndustrial wastewaters prior to the establishment of the factorles in the EPZ, the polJution Is much more effectively abated than outslde the EPZ.

During its flrst 8 years of existence, the CEA played a role of monitoring and coordinatlng agency, rather than an action oriented authority with emphasls on implementation. There was growlng critlclsm, that CEA was hardly effective In pollution control. This lack of executive authority resulted in the National Environmental Act of 1988 in which the required powers were provided. CEA was made responsible tor licencing allindustries from the point of view of environmental pollution. lt received the right to draw up standards and to take companies to court In order to make them to cease polluting the environment. CEA may delegate its authority to other organisations as it is doing now to the GCEC for the Greater Colombo area. lt received the right to let other organisations do work tor them in the form of studies and monitoring. lt was assisted in setting up its organisation and Iabaratory by the Norvegian and the Dutch

8

governments. The CEA received tromthem Iaberatory equipment, personal computers, a telephone communication system and training of personnel. Assistsnee was also obtsined trom ether donors including UNOP, USAID and ADB (Asian Oevelopment Bank), mainly in the form of environmentsl studies and tinance. [Oxley 1990; CEA, 1990]

.. The CEA has a stsff of 70 people and was organised in 6 divisions:

- environmentsl management division, - environmental proteetion division, - planning division, - environmentsl promotion divlsion, - administration division and - finance division.

The environmental proteetion division deals wlth industrial pollution. Until recently the posltion of chairman was a parttime one fitled by prestigieus civil servants. In september 1990 a distinguishecl zoolegist and marine blolegist wlth wide knowledge of environmental problems became fulltime chairman. He saw lt as his task to breath new llfe into the organlsation. Untortunately he left early 1991 trom his post tor unknown reasons. Probably because the cumbrous CEA organlsation was not susceptible for the changes and activlties proposed by the new chairman.

In 1990 two Ministries of Environment were established. Consequently the Planning Oivision of the CEA shitteel to one of the two mlnistries. Activlties of the CEA and the mlnistrles were interrelatecl In the following period and responslbillties were unclear.

In splte of extensive assistsnee and 1 0 years experience, still some deficiencies exist:

• There is the problem to reeruitand keep quallfiecl personnel, faiture to bulld professional cadre. People are often teaving after having received usetul training courses (especislly when these training courses were abroad).

9

• The CEA has not been blessed with adequate govemment funding.

• The CEA lacks a coherent philosophy and a general direction. Efforts by initiative takers are disappointed by lack of support from other govemmental agencies (including mlnistries). The quick changes in the top positions cause very Inconsequent and thus Inadequate leadership.

• At the moment registration of documents and actlvities Is lnsufficient. Data are often not up to date but still in use. An accessible library and a database are requlred. At the moment there is no data retrieval system. Simple intermation is difficult to locate between the plles of papers.

• CEA Is easny accepting assistance from all sorts of donor organisations. Many studies have been carried out on the environment, but the expected subsequent action fails to appear. The CEA Is burocratic, not enough action oriented and leaves much of the lnitiatlves to the foreign donor organisations. Still no practical achievements in reduction of pollution can be seen.

• The Iaberatory withall its equipment is only rarely used. [Schoort, Wiggers, 1988]

National Building Research Organlsation

The Environment Department of the NBRO consists of 8 scientists, 2 technicians and a Iaberatory capable of doing simple analysis necessary tor water pollution. No spectrophotometers and chromatographs are available.

The actlvities of the NBRO are in principle conneeteet with the environmental aspects of urban development and include:

• Air pollution monitoring in Colombo city • Tap water quality surveillance programme • Monitoring the quality of water at the city water Intake on the Keiani river, together with the study of the composition of effluents entering the Keiani river. • They have taken the initiative of publishing two beoklets In order to contribute to the reduction of industrial pollution. The beoklets contain useful information on environmental aspects of the textile and leather industry in Sri Lanka.

Ceylon lnstitute for Scientific and lndustrial Research

The Environmental Science and Technology Sectien of the CISIR has 13 staff members. The Iaberatory is wen equipped with those instruments to determine all critica! pollutlon parameters In a wastewater. With this staff and equipment the sectien is capable of doing about 5 simple analyses per day. Generally 3 to 4 effluent analysis are done per week. However, if auto-analysers would be available anywhere In the country and if some innovations would take place In the Iaberatory and H extra staff members would be attracted, then 30 to 40 analysis could be done weekly, according to Dr. Mathes.

The actlvities of the environmental sectien of the CISIR mainly consist of developing cheap ways of purifying locally produced wastewaters. Research Is done to reduce growth of algae in eutrified water. Cl SIR is also investigating the use of anaerobic puriflcation technlques, because with aerobic treatment there is a tendency tor industrialists to turn off the aeration In order to save money.

The Cl SIR has a very extensive library which is even surprisingly up to date. However its usefullness can be improved by developing a database on the mlni-computer whlch is already available.

10

National Aquatic Resources Agency

NARA is equipped with a Iaberatory to analyse polluted water. Analysis is done only for the common wastewater trestment systems of the two GCEC export processing zones and for one leather tannery outside these zones. NARA is mainly occupied with conservation of aquatic resources like beaches, aquatic vegetation and fish. lndustrial water pollution is only a side aspect.

Rubber Research lnstitute of Sri Lanka

This institute is mainly investigating ways of increaslng the productivity of the rubber production. lt is also developing different types of rubber, meeting special requirements. They have an own Iaberatory near Colombo (Moratuwa) as wellas one near their plantation in Agalawatte (rural area). A few chemists are doing useful research on the rubber effluent. Experiments are taken with a trestment system, which is yet net functioning properly. Expertise on effluent trestment is net available. Some rubber chemlsts are thinking of land application, letting the effluent flow in between the rubber trees. However no expertise on required soil conditions is readily available.

The institute is lacking money for suftielent transport vehicles. Vislts to rubber factorles for inspeetion are dependent on the availability of the vehicle.

Greater Colombo Economie Commission

The first Export Processing Zone (Katunayake) was established in 1978 in order to attract foreign investors. Prior to construction the GCEC carried out an Environmentallmpact Assessment (EIA), which was the first in Sri Lanka. lnside the GCEC area which includes the two Export Processing Zones, the GCEC received the full authority of environmental conservation and monitoring from the CEA. The industries inside this area are now subjected to GCEC-Iaw.

The GCEC has an environmental division equipped with a Iaberatory and 9 people of which 3 chemists. This small amount of officers manages to monitor the environmental pollution in the two export processing zones. Because the GCEC developed an infrastructure for the colleetien and trestment of industrial wastewaters prior to the establishment of the factorles in the EPZ, the polJution is much more effectively abated than outside the EPZ.

National Water Supply and Drainage Boarel

The board is responsible for all water supply and drainage In the country. They have a staff of 200 engineers. Their actlvities include design of drlnking water trestment plants (they have also designed the effluent trestment plant at Katunayake, one of the GCEC export processing zones. Their capabilities are not suftielent for designing industrial effluent trestment plants. A proper library is lacking. They have a simple Iaberatory with ene chemist and three technicians for doing routine water purity analysis (60 per day). CEA approved this Iaberatory for doing analysis on their behalf, but it is doubtful if the extra capacity exists which is needed for additional analysis. [Oxley, 1990]

11

3

THEORETICAL FRAMEWORK

3

THEORETICAL FRAMEWORK

This theoretica! framework has been wrltten in order to enable myself to give useful comments on the water polJution and wastewater treatment in the selected Sri Lankan industry and in order to provide the reader the necessary background knowledge. In part one of the framework the method is explained which is used to make estimations of certain wastewater characteristics. Then some general information of the Textile, leather and rubber industry will be given. First the production processas applied in each industry are briefly described. This is foliowed by a qualitative summary of the expected pollution. Finally a list is provided of recommen­ded pollution abating measures proposed for the textile, leather and rubber industry respectively. The goal of this pollution abatement is to reduce the flow, strength and toxicity of the final wastewa­ter to acceptable levels. Waste can be minimized either by means of low waste technology or by wastewater treatment. Low waste technology reduces the pollution load within the process. Waste­water treatment brings down the polJution load at the end of the pipe.

In part two of this chapter a summary is provided of the most important methods of wastewater treatment, which have opportunities of application in Sri Lanka. A more extensive description including the advantages and disadvantages can be found in Appendix 11.

3.1. GENERAL DESCRIPTION OF THE LEATHER, RUBBER AND TEXTILE INDUSTRIES AND THEIR WASTEWATER.

3.1.1. INTRODUCTION

Before the textile, leather and rubber industry are described each in a separate paragraph, it is necessary to explaio the meaning and the selection of pollution parameters, which are found relevant in the framework of this research.

A method will be explained, that is used for the estimation of wastewater characteristics from textile, leather and rubber manufacturing industries in developing countries, based on literature [Economo­poulos, 1981]. In the course of this research this method has been used in order to make rough estimations of the wastewater characteristics trom the vlsited factories. The wastewater characterls­tics are expressed in the chosen polJution parameters. This is elaborated in the subsequent paragraph, 3.1.2.

In order to obtain a clear view of the textile, leather and rubber industry In general, first the production processas will briefly be desrcibed. Then the wastes will be indicated, which are typlcal tor each particular sector and which are the major cause of environmental hazards. Finally a summary is provided of wastewater treatment methods which are recommended tor each sector in genera!, on basis of the literature consulted.

12

3.1.2. POLLUTION PARAMETERS AND ESTIMATION METHOD

Pol/ution parameters Pollution of wastewater Is measured with certain worldwide recognised parameters. From these, I have chosen for the blochemlcal oxygen demand (BOD), Suspended Solids (SS) and the wastewater flowrata (WF). Definitions are given In the cadre below. For the laather lndustry In particular the Chromium (Cr)-concentration In the wastewater Is also taken into consideration because this heavy metal is disposeet in large amounts and is taxie In very small concentrations. Reasans for the cholce of BOD, SS and WF as relevant parameters are twofold:

1) With these parameters lt Is posslble to give a reliable estlmate of the pollutlon hazard. 2) In Sri Lanka the opportunity exlsts (equipment is avallable) to maasure these parameters in a laboratory. In wastewaster sampling generally the BOD and Suspended Solids are measured in Sri Lanka, which makes camparisen possible of these data wlth the estimated values.

The expected BOD and Suspended Solids can be expressed in two ways: as a concentration of the wastewater (mgfl] and as a daily Joad in (kgfday].

Generally lt can be said, that a medium strength wastewater like damestic wastewater Is characteri­zed by BOD-concentrations of about 500 mgjl. When wastewater contains over 2000 mg/1 BOD it is called strong or concentrated, which is typlcal for industrial wastewaters.

Although COD is a better parameter than BOD (easier, COD can be measured within 3 hours, while BOD takes 5 days) for the maasurement of the polJution laad, the BOD has been selecteet because this parameter Is used more aften in the literature and by the laboratorles in Sri lanka. This makes camparisen easier. Furthermore about the COD no relativa laads are known (kg COD/kg product). Roughly the COD is related to the BOD according to the relation: COD = 2.4 * BOD

Methoei to estimate the pol/ution Here an explanation will be given of the methad to estimate the expected characteristics of wastewa­ter from textile, laather and rubber manufacturing industries in developing countries. When the production level of a certain factory is known (in kgfday), then the daily amount of BOD, the daily amount of suspended solids and the flowrata or daily volume of the wastewater can be estimated. With this methad lt is easy to estimate characteristics of the wastewater from a certain factory without taking any samples of that wastewater. lf samples have been taken, than the results can be campareet to the estimated values. And lf those samples were reliable, than the reliability of the estimation can be checked.

In order to make these estimations, information is needed on the expected degree of pollution per kg product. This intermation is contalneet in the relativa BOD-laad, the relativa SS-laad and the relativa wastewater flowrata (see cadre). These figures are called •relativa pollution Jaads• and they are speelfled tor lndividual lndustrial sectors in developing countries [Economopoulos, 1981 and WH0,1982]. The relativa pollution laads are multiplied with the production level of the partJeular factory, rasuiting in the expected BOD [kgfday], the expected suspended soliels [kgfday] and the expected wastewater flowrata [m3 jday].

Of course the discussed characteristics of a wastewater can be examlned more accurate by analysing samples in a laboratory. In the course of this research this methad was too time consu­ming. The Interesteet reader is referred to •standard methods for the examinatien of water and Wastewater: [M.A.H. Fransen, 1981]

13

In the Appendix IV the calculations are made and explained. The re­sults of these calculations are discussed in chapter 4.3. The polJution loads expected to be produced in the textile, leather and rubber sector respectively, are also provided in Appendix IV.

In this chapter the processes which are used in the textle, leat­her and rubber industry are descri­bed as well as the waste origins and the types of waste expected (constituents of the wastewater). Also general recommendations on waste reducing measures in the three sectors will be provided !n chapter 3.1.

3. 1.3. TEXTILE INDUSTRY

Processas

The processes of textile manufac­turing will be explained first. Two types are discussed: cotton and polyester textile manufacturing, since in Sri Lanka mainly cotton and polyester textile is produced. A more detailed description of the processes can be found in Appen­dix 11.

Cotton

-.":-. .:.:":-·· ··.· .. · .. ·-:-:--.-.::····... : ·-.. - .. :-.---:·.·:-:-:- · .. ·. ··.·-:··

. the non-puk,Hictliqu~ contiin;t1fl ~ie rnaterials~ <.

·····tf)s····pu~····l~qkf···being••··the····~uá ··~·······•·.va..=•··········· ., tntátlijent I)Tánt. · · · ·

BÖO ~ ~JielnMai ~efi Hetn~d .. /71eas~~ for ~rada1. · p~panic imltériitfin j ifl;!t$~watei. The tJxygen used. by rTH- . ·

•· êiOOrganiSms fo(tJ/ó&grarlätlon Of fhl!$ m~rlal Js ITJéasuf8(j. . . . . · · *As a BOlJ.c()rffienfration: tr(fmg J3()p/f W;a$te~J; < · .·.· · ·.· .. · ·

>~A$ f1 ~Jiia;àfJ# (kri 8()/)Jday{ · · · · · · · · · · · · · · · ·

·coo···'"··········(;he~iear~i-~;·•••~·······17J6;1•••1b;··~···~·ó'l1~ie········· .) ? •·· ···•···•·•·1niit~BriaJ .in • ll/astewatëf. Thê oxfgën used fQi i;IJBtrlical/ · ··· // -öiictaiio~lde9i'adatic>l'(p{fhë örgánic r(l/#!ria(is; rfiiJ~u~, · · · · i:(:>:]:[~:?(/)

•••••······$§·••;·•·· ···········~uspelldecf··~~s···j···stnétlf••lnsot(lbfe•·~Jes···ln···~··-~nt.·•·········· ·•·•··· · ·· ·•· i · ii ffi.Jthët fk>at/ng Ol) t/Jë<surf8ce nor81nking to tfftj. bottó11J. < • U $U.pendfld SOlkis ar. exp~ssecl as~ ~iqht()fdryirljJttflf. >

C;i!;r;liil.: ~~;~::4f'SSA~ ;········· WF·.·~· ··········~~!~~~~~·····=·····~···w>tu~.··(Jf·••wa8fewater •• pmd~········

Je~~ ~57 meaJs ~idic; pH-=t•iÏHHlfls ietJtraf; ~>1 ... . ·.· ~atls ~skf · · ·· · · ··· · · · ·· ····· · · · · · ·

..... B()l)R;~••••R.,afivé····~k)ad••••=••••~•·•~~~••öf••!JOC)•••which •is·••.w~o/ · · - < .pröduçed pet lf§ piodupt 111 fl ~pecific $6Ctor. Unit llf§ BOD I . kfl product] ........... · . . ·.· · .. ·

·•Flefati~···Ss-toad···~····the···~~M·~ sus~ndect··S<),ids··~ich• ·~ •··.· .. ·· avërágeo/ prr:xJUC«f per kg pioduetin (J specifJC seCtor. t1n1t · lkfiSS/Iirfproëluë.t] > · · ·· .... ·.·.... · · · .. ·· ·

~ati\'e efll&lent flowratê = .IK)/ume of 'Wastewa~r. which is ·• .llVftragëty pfOdÜCSd per kg prödiJCt in ·~ sfJ6ÇI(JC s~r.< Unit .•. iirJ~ was~wa1er/kg pioduet]. · · · · · · · · · · ·

Definitions of pol/ution parameters

Raw Cotton is carded, spun, spooled and warped, slashed (filled wlth starch), drawn, and woven or knitted into cloth before being sent to the finishing mill. No water borne polJution originates in this sequence of operations, since they are all mechanica! processes, except slashing. In slashing, the thread is sized with starch to give it the strength and smoothness necessary for subsequent weaving. The sized cloth ("grey goods") contains 8-15% slashing compound which must be removed in the finishing operation. The grey goods are desized to allow further wet processing, kiered to remove natural impurities, bleached to render them white, mercerized to give the fabric luster, strength and dye affinlty, printed or dyed, finally tilled or sized again, to make them more resistant to wear and smoother to touch. [Nemerow, 1978)

Polyester and other synthetic fibres Synthetic fibers are essentially composed of pure chemica! compounds and have no natural impurities. Because of this, only light scouring and bleaching are necessary to prepare the cloth tor dyeing. lt Is the dying proces where the major water polJution is produced in the form of toxic dyes and chemicals. The wastewater flow is lower than in cotton processing, but the BOD-Ioad is higher. Processing of the fibers and cloth is readily done on the conventional machinery used for cotton. In Sri Lanka, polyester is the most widely used synthetic fibre. All the polJution trom the processing of these fibers originates in the various scouring and dyeing chemieals used to process them.

14

In Sri Lanka the distinction between polyester and eetton manufacturing is not very strict for two reasons. Firstly the production processas of cotton, polyester-eetton and polyester cloth manufactu­ring are essentially ldentical. Secondly, in most textile factorles in Sri Lanka eetton and polyester fibres are both processed on the same machines. However, there Is one difference: for polyester cloth manufacturlng different chemieals are used, such as toxic dyes, antistats, lubricants, carriers etc. [Nemerow, 1978]

Summary of wastes arising in the textile industry

Generally the following pollution is caused by the textile lndustry:

Liguid wastes: Wastewaters from the subprocessas contain excess dyes, soaps and detergents and ether chemicals. Only 20 to 50% of chemieals like dyes Is really attached to cloth, the rest is discharged. Substances which are used in large quantities are salt, eaustic soda, hydrogen peroxide, sulphites, sulphates, acetates, carbonates, organic aclds, organic dyes and urea. These constituents cause an alkaline pH, high suspended solids, high BOD and a strongly coloured high tempersture wastewater. This water pollution is mainly blodegradable. Dyes and inorganic suspended solids have to be removed otherwise.

Gaseous waste: Chimneys trom steam boilers which are not provided with filters cause black polluting smoke containing soot and sulphur.

Solid wastes: Cloth cuttings are not causing real environmental hazards.

Noise pollution: Weaving and knitting departments generally cause unbearable noises, darnaging the hearing of the numerous labourers.

In plant waste reducing measures

Reduction of the pollution load within the production process can be performed by several measures: [NBRO, 1989]

• improved process control, like for instanee application of correct quantities of chemicals.

• process modification andjor chemica! substitution. Technology can be used with a lower water consumption (example: jiggers instead of winch dyers). Chemieals with low BOD­production should have higher priority

• recovery of chemicals. Chemieals like eaustic soda and certaln dyes can be reecvered and reused

• water conservation by process modificatlon and reuse. Countercurrent washing systems and reuse of dyebaths can reduce the wastewater volume and pollution load.

• clean housekeeping practices can prevent the wastage of chemieals

• segregation of waste streams. In order to reduce the required capscity of a treatment system the lew waste streams should be segregated from the high waste wastewater. The washing wastewater containing low waste can pass the pretraatment

In Appendix I some more examples are given of waste reducing measures in the textile industry.

15

A suggestion for further reading can be "Techniques for lndustrial Poltution Prevention" [M.R. Overcash, 1987].

Reeommendeel wastewater trestment

The following wastewater trestment actlvities are recommended for a textile factory wastewater: Pretraatment is recommended in the form of screening, addition of nutrients, equalization and neutralization. This pretraatment serves as prevention of darnage to the subsequent traat­ment operations. Colour caused by excess dyes should be remo­ved through chemica! precipltation The biodegradable material Is biodegraded with biologica! treatment. Options are the trickling filter, the activaled sludge system, the aerated lagoon or the oxidation pond. Sludge can be dried and disposed onto con­trolled dump sites. lt can also be lagooned lf space is available. Sludge digestion is a more expensive solution. [Nemerow 1978)

The treatment components which are really indispensable are the colour removal by preclpitation and the organic waste reduction by biologica! treatment. These treatment methods wilt be discussed and analysed in chapter 3.2 In order-to provide the reader the background knowledge fo(á proper understanding of this report.

3.1.4. LEATHER TANNERIES

The poltution is caused by an wastewater contalnlng high organic waste and toxic chromium(lll). In this chapter I wilt briefly explain the theoretica! background of teather tanning, starting with the processes. Hence I will give a qualilalive summary of the waste generally arislng from tanneries, foliowed by a quantitative description in the form of relativa poltution loads.

The processes

Tannery wastes originate from the wet processas in the beamhouse and the tanyard. In the beam­house, curing, fleshing, washing, soaking, dehairing, lime splitting, bating, pielding and degreasing operations are carried out. In the tanyard, the final teather is prepared by saveral processes. These include vegetabla or chrome tanning, shaving and finishing. The finishlng oparation includes bleaching, stutting, fat-tiquoring and coloring.

Curing involves dehydration of the hide by drying it with salt or air. Fleshing removes the fatty tissues from the skin by mechanica! means. Washing and soaking remove the dirt, salts, blood, manure and nonfibreus proteins and restere the moisture lost during preservalion and storage. Unhairing is accomplished by the use of time, with or without sodium sulfide; this makes the skins more attractive and more amenable to the removal of trace protein impurities. Lime splitting

16

separates the skin into two layers: one is the more valuable grain layer; the other, the lower or flesh side, is called the "split". Bating prepares the hicle for tanning by reducing the pH, reducing the swelling, peptizing the fibers, and removing the protein-degradation products. Bating is generally accomplished with ammonium salts and a mixture of commercially prepared enzymes. The bating bath renders the grain silky, slippery, smoother and more porous, incresses its width, and diminishes its wrinkles. Pickling generally precedes chrome tanning and involves trestment of the skin wlth salt and acid to prevent precipitation of the chromium salts on the skin fibers. Degreasing removes natural gresse, thus preventing formation of metallic soaps and allowing the skin to be more evenly penetrateel by tanning liquors.

Chrome tanning Is used prlmarlly for light lesther, while vegetable tanning is still preterred for most heavy-leather products. The process of chrome tanning is of shorter duration and produces a more resistant lesther. Vegetabla tanning produces lesthers which are fuller, plumper, more essily tooled and embossed and less affected by body perspiratlon or changes in humiclity.

Bleaching with dilute sodium carbonate foliowed by sulphuric acid, gives the lesther a lighter and more uniform color before dyeing. The process of incorporating oils and gresses into the tanned skins is called stutting and fat-liquoring and makes the hides soft, pliable and resistant to tesring. Dyeing to produce the final colored leather product is usually done with basic dyestuffs. < ref 3 > (for a more detailed description of the processes, see Appendix 111.

Summary of wastes arising in the leather industry

Wastewater trom lesther tanneries generally contains dirt, blood, flesh pieces, fats and gresses, polluting chemieals due to the putrefaction of blood and flesh pieces, chromium in the case of chrome tanning. Solid waste consists of rests of raw hides (hair, trimmings,etc) and rests of tanned leather (cuttings). Gaseous emmissions of ammonia, thinner and formaldehyde cause unheslthy werking conditions and nuisance to neighbours.

Hair, tails, flesh pieces and hydrogen sulfide (due to putrefaction) are produced while trimming the hides. Fleshing and unhairing result in hair shavlngs and fat tissues. The wastewater trom the washing of hides with salt water contains dirt and blood with high salinity. Wastewater from liming is highly alkaline and contains nitrogen and ammonia (due to decomposltion of proteins). Vegetabla tannlng causes a hlghly coloured wastewater which is acldic if oxalic acid Is used. Bark extract residues which accumulate In the baths form the major component. In chrome tannlng pale green wastewater is produced, containing chromium ions and a high BOD.

In plant waste reducing measures

In the laather industry, pollution can be reduced with the following in plant messures: • improved process control, like for instanee the application of the correct quantity of chemicals.

• process modification/ chemica! substitution. Example: improved chromium flxation lesves less chromium in the wastewater.

• recovery and reuse of chemieals like chromium.

• recovery and reuse of by-products such as hairs, splittings, shavings, lime sludge, etc.

• water conservation for instanee by batch washing lnstesd of continuous washing. Recycling in the llming, bating, deliming and tanning processas can also save water.

17

• clean housekeeping practices in order to avoid wastage of chemicals.

• segregation of waste streams in order to reduce the required capacity of a treatment system.

In Appendix I some more examples are given of waste reducing measures within the process. [NBRO, 1989]. For further reading Is referred to "Technlques for lndustrial Pollution Preventlon• [M.R. Overcash, 1987].

Reeommendeel wastewater trestment

A generally accepted procedure for tannery wastewater treatment is the following:

For pretraatment the wastewater has to scree­ned, equalized and subjected to sedimentation. Then the chromium should be removed in or­der to prevent the killing of microorganisms In the subsequent biologica! treatment. Wastewa­ters containing chromium should be segregated for separate treatment. Chromium is removed by chemica! coagulation (soluble hexavalent chromium can be converted into insoluble triva­lent chromium). The biologica! treatment can be done with lagooning, activated sludge, tric­kling fitration or the oxidation ditch. The wastewater sludge from vegetable tanning can be dewatered and incinerated or""ûsed for manure. Sludge from chrome tanning can be spread on land in consultatien with local or national authorities.

Other solid wastes and sludges from the tanne-

i ~~~~i:~;!;l ; ~~~~:ii? iliiji{1 ~:~ ·· <2)Prlmaiy trNtmef'lt: < i i .

> a) plaln St!Kiimentation> >·•······<< / / ... · > . < . . . .·.·.• b) removäJ of c~~romiurn) ................ ·.·············· ············ \ ... . 3) $e(;öndary treatment: ()ptionap. • . . i .. · • ·· · ·

;. Anäëi'Obiç anêl/or aerob}ç ilJgoonlng . •· .·.·. . . . .

... ·~~:::.~~~~~~r:'/7; .. . "'Yegetab!e tannln~sludfle c~ be. dfrNafere(j

. ·.· ·.·· .·.·· .. ärkiirn;tn.iated or used lor man ure. . . ...... .· ... < 'ë ChrOfrJfJ ti#Jning-sl~ge "ëan be sPread . on · • fSrld tn eollsûltation wit/ftf'Je auttiórities~ · · ·

·········~~··~ol~····waste~···and···~~···,Jt)~···the··tahh~iy··;a"··· ·. · IJe asec1 u · ··Sóif. condmorier. r.rlitizflt, • .• Jandfit~ 11JW · ·. •· material for gtue (flesJ71t1gs),fuet(vsg~ t;Jf~l>ark), e~~ i< •·

ry can be used as soli conditioner, fertilizer, landfill, raw material for glue (fleshings) or fuel (veg. tan bark), etc. [J4>rgensen, 1979; Callely, Forster & Stafford, 1977]

All the wastewater treatment methods mentioned above will be discussed in chapter 3.2.

3.1.5. RUBBER INDUSTRY

The industry where tapped latex Is processed into natural rubber is discussed here. Several types of rubber exist, but in Sri Lanka mainly crepe rubber and ribbed smoked sheet rubber are produced. In the following paragraph I will describe the processes of all rubber types, emphasizing on the crepe and RSS manufacturing.

The processes

Basically the process of natural rubber manufacturing comes to the following: Latex is tapped, collected in barrels and brought to the factory. Here it is coagulated in tanks or in small trays by adding coagulation chemicals. Coagulated rubber is taken out of the tank or tray,

18

while the remaining liquid - the serum - flows out as wastewater. In order to give the rubber its typieal properties (strong, flexlble) the "coagulum" Is pressed into sheets by wet roller mllls. The sheets are hanged in a drylng tower for drylng. In mllling, excessive amounts of water are used, but are only polluted with rubber particles. Finally the sheets are pressed tagether and cut lnto pleces of correct size.

Processas are varying with the types of rubber produced: * Crepe rubber: the production of this type of rubber Is following the basic process. Coagulatlon is done in large basins. For sole crepe several sheets or laces are pressed tagether and milled again in order to get the right thickness. * Ribbed srnoked sheet: The basic process is followed: coagulation takes place in small trays. Milling is done on a ribbed roller mill. The rubber sheets are dried by smoking. * Scrap rubber: this type coagulates naturally In the field. cup lumps and tree laces are collected, washed and milled into low grade rubber. * Skim crepe rubber: when latex is centrifuged for production of dipped products like rubber gloves, a by-product of the centrifugation Is skim latex. This skim latex ean be coagulated and milled into skim crepe rubber. wastewater Is formed by skim serum and milling water. * Centrifugated latex: the production simply takes place In centrifuges. The processing of the by product, the skim latex and the cleaning of the centrifuges are the major eauses of water pollutlon.

Summary of wastes arising In the naturel rubber sector

Generally a rubber factory produces an wastewater whlch Is harmful to the environment beeause of the high suspendeel solids, high BOD and some toxic constituents with an acldlc nature. Except a polluted wastewater also a bad odour accompanles the production of natural rubber

Liguid waste: The polluting characteristics of wastewater from a rubber producing factory are: High BOD, bad odour, high suspendeel solids, variabie pH, High chlorldes. The wastewater has generally two different origins: * Washing water,

containing rubber particles, latex and ammonia, process chemieals, uncoagulated latex. * Serum water,

containing proteins, earbohydrates, lipids, salts, tormie + oxalic acids, sodium bisulphite, mereaptans. (in the production of concentrateel latex: rubber particles, latex, sulphuric acid)

* Milling water, containing mainly rubber particles.

Gaseaus waste: a strong putrid odour, mainly due to hydragen sulphide arlslng trom the breakdown of proteins in the rubber serum. Other chemieals contrlbuting to the odour are:

- mereaptans (used in crepe rubber manufacture), - formaldehyde (anticoagulant) and -ammonia (latex preservative andjor anticoagulant)

Inplant Pollution Reduction

In the rubber industry the waste ean be reduced by the following in-plant measures:

• Reduction in quantity of process chemieals to reduce the strength of the wastewater

19

• pH control during the process for optimal chemica! use.

• Reduction of the quantity of process water to reduce the wastewater flow: - Serum water can be used to dilute latex - Milling water from smooth mills can be recycled to grooved mills

• Recovery and reuse of waste and by-products: - Quebrachitol (trom serum) can serve as a medicine - Serum water + Phosphorus (nutrlent) can be used as a fertilizer for rubber trees, if transport available

• Practical advlee to reduce bad smell: - proper storage of chemieals to reduce gaseous emissions - a good and well maintained drainage system will improve hygiene in and around the factory - processing of coagulum should be done without delay to reduce gaseous mission

• Good housekeeping practlces will reduce the wastage of chemicals.

• Separation of less contaminated wastewater from the highly polluted wastewaters In order to minimize the treatment costs (the required capacity of treatment will be lower)

Recommended wastewater trestment

The wastewater of units processsing latex into natural rubber can be subjected to the follo-wing methods of treatment: • · Pretraatment consists of screening, equalizati­on, a rubber trap to remove rubber particles, sedimentation and neutralization to correct the acicidity (pH). Also nutrients (nitrogen and phosphor) should be added for subsequent biologica! treatment. Optlons for biologica! treatment are the ponding system, activated sludge, rotating biologica! contactors, the oxi­dation ditch or a combination of anaerobic and aerobic treatment. The biologica! treatment has to be foliowed by sedimentation.

An alternative end-of-pipa solution for rubber wastewater can be "overland flow". For this purpose an extended flat land area and ade-

Tl8lllment of ellluents flom 1he rubber lndustry 1)f~treatment •········ .. . . . ... ·· .· · · · . . . < a) EquaJJiatïoii . . . . ..

.· ··. ·•·•·•··· •· b) Rilbberirap 10 .ntmoW, I?Jbbet Part;ëlfls / . . c) SediiTientation . . . . . . . . . . . . . .. .... · · · ... · d) Chëinicat dosing 10• cOmict the pH and fO

. add nutrient$ (N & Pj>forbio/Ogicál ~atment 2) 8/o/oglca/.freatment ~ options: ·······•••··· ·•·•.···•• •. ····•··•·······••··•····•·•••··· .·•·• ·

· · · · • · • · .. · * Pond s~m. anaerobic, fticu~ve ándjor mechanicaJ.Iy aerätecf <

•...••....••. • · Activáted slûdge · i · < < · . <· • Rötating biOlogica/ C(>ntacfóis < · · · · ·

· · • AriaëfO/JiC, · fol/owe(J bY äftrb},ic tfë~tmei1t . . . . * OxkJatiOn dltch

. 3) Aitër~tieatiTieilfi.~fJclimeiitatîon •·••••••·· •

Ànemauve so1utioh < .• > / \ • / • ······•·•·•·• Overland floW system: · Thë fina/ iîJbbel' !fi~Uent car{pe • i ustKI as a fertlllzer lor rubber tl8es 0r coconfit tiWs. < • • •

quate soil conditlens are requlred. When this method Is functionlng properly, the wastewater can serve as fertilizer for rubber or coconut trees. Experience with this method exists In Malaysla. The end-of-pipa treatment methods are dlscussed In the next chapter 3.2

20

3.2. WASTEWATER TREATMENT METHOOS • an overview

3.2.0. INTRODUCTION

In this chapter I will provide an overview of the numerous treatment methods which are available to treat an lndustrial wastewater. Different systems are recommended for the treatment of textile, rubber and leather wastewater; different systems are In operatien In Sri Lanka. In order to provide the necessary information to the readerfora general understanding, I will glve this overview. Treatment methods which are not interesting for Srl lanka in anticipation will not be discussed (reasons can be high capital costs, high rnaintance costs, required expertise/complex technology).

~--------~~-----------, :~ :~: :;~~~i:~7 ~~~;'~e;a:l~ ~~e~~~: f~~~:~~~ea~~: \t'=~~~~ < > The advantages and disadvantages of each system are . <ANOit'ERIIIEWt:Fms~ < ·.

glven.

The discussion of the treatment systems is only very brief and not too technica!, because an adequate technica! analysis requires high specialisation in this field. The content of this chapter cannot be a basis for the final selection of a system, because exact calculations are necessary by tech­nica! experts. However when these experts make their calculations, they should also take lnto consideration some factors which are relevant for the adequate selection of a wastewater treatment system (see paragraph 3.2.5.).

Wastewater treatment systems can be dlvided into physical, chemica!, biologica! and sludge treatment. Physical traat­ment is a form of treatment where physical properties Qike size) of the waste material are used for separation from the wastewater. The principle of chemica! treatment is the separation of waste constituents trom the wastewater by means of chemica! reaction. In biologica! treatment the organic material in the wastewater is blodegraded by mi­croorganisms. In the cadre on the right the complete overview is provided of the treatment methods discussed in this chapter.

3.2.1. PHYSICAL TREATMENT SYSTEMS (PRE·TREATMENT)

::·>>>:-:::-:::-:::::::: .::: . .:>:-:::-:-.·.. :.: :: :::}:::) .· :::-::-:::::}:': <<·> ·::··.<<·::::::: :.::::::::::::·. .

.PIJySic:al~~ <

.. ············•·•·••••••••• ~rit•"anS:'::J:~"!fTIOvar·••••••••••••••••••··········. ····· < o;1 & glhse rëmowil· .•.•. · •·· ·•············ • . .. . Equalization ••.•••. · / · •. • Gravlty ssttling

Flotàtiön < ··.·.-:·:-:-.· . :.· .. ·.·.··:-:- :.:-:-:···:-.····· ·· .. (;hemîcalflvati7Jent S)'Si9tnS · ...

... ·. Neutralizatjon ·.· ...

. •··· .··•••·•·· .·. . . Addition O(nutrlents . · · · ÇoagulatioiJ..ptecipitätion

. . .

~&wJtment systsms çonwntional ac;tivatJH:I sludge

· ox/t:JätfOn ditch ·. ·. · äerated lagoon

.. · •..•..• ··•• • ·····.·.·. trickling filter rgtat~ng biolOgica/ contactor. · · · · · seraled tagoon · ·

.. ·.•. . aerob/(:.lagoon · · •· ••·•• ••••· •• •. ··• Jacuftatilie ·lagooll.• • ·

anaeroblc 11Jgool7 ••....•. • .. ·. . änaerobic digestiofl .

.. îi;>flo'N anaeroblc slüdge blanket . • änaeiT)blc fitter . ·

.cwet1anii floW ······· ···.-: . ·.· . ·:· .. ··-:··:::::··· -:· / :::::::

. Sluclge ~f& dlspósal.

·•· · · .··•• •··••·• •.· •·· ."aerobic $ïl.ldgë digestior( .•··.· .....• . · i aerobiC ïktdgedigestion········· ............. .

~ct~:~>

Physical treatment or mechanica! treatment consists of operations, where no chemica! reactions or biodegradation are involved. General principle of this kind of treatment is the separation of certain compounds from the wastewater on basis of the difference in physlcal properties such as size, density. lt is often used as pretraatment of biologica! or chemica! systems. Pretraatment is most widely used in industrial inplant treatment. lt is important for:

- reduction of effluent charges or costs, - downstraam treatment efficiency, - recovery of valuable materials. - prevention of damages to downstraam equipment.

21

The most important unit operations are screening, equalisatlon, grit and sand remaval and oil and grease removal. These will be discussed below.

Screening

Screening is the most camman pretraatment Screens, used to remave the coarse solids from the wastewater, can be installed in the factory or as first unit operatien of a wastewater treatment plant. Fineness of screening is determined by the dimensions of the solids and by the treatment envisaged ulteriorly.

Sereens are necessary if subsequent treatment Is planned, In order to prevent damages to the system. lnstallation casts are very low and, lf properly designed, also the operatien casts can be negligible (especially in cheap Iabour countrles).

Equalization (or Flow and load balancing or Homogenisation)

The purpose of equalization is to adjust varlatlans in waste volume and loads. Homogenisation takes place in a homogenisation basin or balancing tank, which is designed to deliver water with practically constant characteristics.

A balancing tank is especially required for small industries with highly polluting batch discharges (tanneries, cocanut oil, electroplating). The installation of a balancing tank reduces the operatien casts of a subsequent biologica! treatment system as well as the risk of damages due to shock loads. However, because of the relatively high casts, the small scale treatment plants may be unable to afford a completely equipped equalization tank. In that case campromises have to be taken, like using the force of gravity instead of pumps.

Grit and sand remaval

Gravel, sand and other large particles are removed to avoid deposits in channels and pipes, to proteet pumps and to avoid overloading. This methad is only applied to specific production processes, mainly in the food industry.

Oil and grease remaval 1 fat traps

Oil and grease remaval is widely used in the food lndustry (slaughterhouses, meatcanning, oil mills) for remaval of fats and oil prior to discharge into sewer or blological treatment. Recovery of valuable oils is possible. This methad Is a relatively cheap methad when it is compared to biologica! treatment.

Sedimentation and flotation are two camman methods to remave small particles trom the wastewa­ter. Sedimentation is aften used after blologtcal treatment to remave the sludge. Flotation can be used for treatment of low strength wastewater.

22

Gravity settling (clarification 1 seclimentatlon)

The purpose of gravity settling Is to remove suspenelect settiesbie solids as well as floating material trom the wastewater, using the force of gravity.

Clarification is normally used prior to subsequent trestment processes, particularly blological treatment. Physical sizings of a sedimentation tank or a clarifier are highly dependent upon the quantity and composition of the wastewater flow to be trested. The wastewater with its suspended solids Is admltted to the trestment unit through the inlet zone. Separation of these solids trom the wastewater occurs In the relatively quiescent clarificatlon zone. From here, ciarifled wastewater Is removed trom the unit vla the outlet zone. Separated sollds are allowed to accumulate and compact In the sludge zone and are then removed by mechanical mesns trom the bottorn of the tank. Sludge is then pumped to the "resldual management system" (e.g. sludge drying beds). Also any scum and floatlng material which is accumulated on the surface Is skimmed off.

The residual sludge mass may be dense, gelatineus, stringy, slimy, oily etc. (dependent on previous pretrestment system). In addition it will contain the majority of suspended matter that was In the wastewater but in more concentrated form.

Through clarification, suspended solids are removed trom the wastewater to reduce BOD and to prevent clogging. A settling tank is generally a necessary part of a biologica! trestment system or a coagulation - precipitation system. The clariflcation process Is chesp and slmple in operatlon, but the construction costs are high.

Flotation

Flotation separates suspended partic~ by reducing their density by the introduetion of air into the system. Fine bubbles either adhere to · or are adsorbed by the solids, which are then lifted to the surface. Possible means are:

air flotation. Flotation is applied to wastewaters trom tanneries, slaughterhouses, canneries, oil refineries and soap mills. An example of air flotation is Dissolved air flotation. electroflotation, which has the disadvantage of high energy use.

Dissolved air flotation The objective is to remove or separate suspended matter which has a low specific gravity. The basic principles are:

- add air under pressure to the waste stresm, - pass this mixture of liquor containing dissolved gas into the flotation tank, - gases dissolved in the tank are relessed (atm. pressure) as finely dlspersed bubbles, becoming attached to oil, gresse etc, bringing them rapidly to the surface, - recycled effluent Is used for dissolving the air.

Dissoved air flotation is only a suitable option for Industries with access to expensive and complex technology and highly skilied personnel. With this methoef particles with a low specific gravity such as finely divided suspended solids, olls and gresses can effectively be removed trom the waste stream. The application is very specific. The capital costs are lower than a fat trap, however eperation costs are higher.

23

3.2.2. CHEMICAL TREATMENT SYSTEMS

The principle of chemical treatment is the separation of certain components from the wastewater by means of chemical reaction. Chemica! treatment methods are generally used for pretraatment as in the case of neutralisation and addition of nutrients. The coagulation-precipitation method removes speelfled toxic chemieals from the wastewater. Thls can be done prior to or after blological treatment.

Neutralisation

The purpose of neutralisation is to adjust the pH of excesslvely acldic or alkaline wastewater. For acid waste streams lime, soda ash and eaustic soda are the most common base chemieals used in neutralisation. In the case of alkaline wastestreams, sulfuric, hydrochloric and nitric acid are generally used.

lf the wastewater is strongly basic or acldic, neutralisation is recommended in order to prevent eerrosion of the pipes and the subsequent treatment units. However, the use of chemieals for this purpose should be reduced as much as possible for instance:

a) by treating only the most acidie/basic portion of the wastewater, b) by exact dosing and c) by equalisation.

Coagulation - precipitation

Coagulation-precipitation is done according to the following mechanism: Coagulation chemieals are added and the liquid is rapidly mixed for dispersion. Then flocculation takes place, teading to the agglomeration of small particles lnto flocs of a size large enough for removal. In a sedimentation tank these flocs are either settie down or float to the surface and are removed.

The nature of an industrial wastewater is often such that conventional physical treatment methods wilt not provide an adequate level of treatment. Particularly, ordinary settling or flotation processas wilt not remove ultrafine colloldal particles and metal ions. In these instances coagulation-precipitati­on may be warranted. Biodegradable and non-biodegradable waste and suspended solids are removed by coagulation-precipitation. In addition phosphorous, nitrogen compounds, metals etc. can be removed.

With relatively simple treatment technology and the addition of coagulating chemieals certain pollutants can be removed (metal ions, ultrafine colloldal particles). This is a low cost treatment method, as far as equipment and instanation costs are concemed. The continuous addition of chemieals wilt be pricely. This type of treatment is sametimes necessary, but not always capable of solving the waste problem completely, because a water polfution problem can be replaced by a solld waste problem (sludge).

24

3.2.3. BIOLOGICAL TREATMENT SYSTEMS

The essential role of biologica! treatment Is eliminatien of the organic matter present In a water in the form of a fine colleid or in solution. Application of these processas requires placing the water to be treated in contact with a dispersed actlve biologica! medium. Such contact can be obtained using: • Attached growth: accumulated inert materials are serving as a support tor the microorganlsms which are responsible tor the biodegradation of the organic waste. • Suspended growth: a bacterial culture in the farm of flocs dispersed in the liquid (this is known as the activated sludge) is responsible tor the breakdown of organic material. The biomass-sludge is generally separated by sedimentation, and a portion of the sludge can then be recirculated.

Apart trom the dlvision into suspended and attached growth, biologica! treatment can be dlvicled into aerobic and anaerobic treatment. Aerobic means that durîng the process oxygen is available. Anaerobic means that the biodegradation takes place without oxygen. When in the case of an aerobic treatment system the oxygen is supplied mechanically, the system is called aerated.

In the aerobic treatrnent process the organic waste is biodegraded into mineral substances by microorganisms. Part of the energy produced throughout this breakdown process is used tor formation of new cells. Because in aerobic treatment the breakdown process is total, high amounts of energy are produced, which means a high level of cell formation. This results in large volumes of sludge. When aerobic treatment is applied to a wastewater, generally 50% of the organic waste materials end up in the sludge.

In anaerobic treatrnent the microorganisms are biodegrading the organic waste not completely into mineral substances, but into intermediate products. By-products are formed like methane. Because the biodegradation is not complete, less energy is produced tor cell formation of microorganisms. Consequently the sludge volume trom anaerobic treatment lower than tor aerobic treatment. The intermediate products trom anaerobic vaatment can still be oxidized lnto mineral substances. When the wastewater has to meet high requirements, this oxidation can be performed by subsequent aerobic treatment. However, the extra waste reduction with subsequent aerobic treatment must be to such an extent, that it is worth to InstaU an extra aerobic system after an anaerobic system.

Consequently one can determine tour main categories of biologica! treatment systems: 1 aerobic, attached growth (examples: trickling filter, RBC) 2 aerobic, suspended growth (examples: act. sludge, oxidation ditch, aerated lagoon) 3 anaerobic, attached growth (examples: anaerobic filter) 4 anaerobic, suspended growth (examples: anaerobic digestion, UASB)

In addition, there are two categories, which can better be separated trom the first tour: 5 the ponding systems (examples: aerated, aerobic, facultatlve and anaerobic pond) 6 land treatment methods (examples: overland flow)

Note: Biologica! wastewater treatment requires a ratio of BOD5/N/P close to 100/5/1, because a shortage of phosphorus or nitrogen can lead to the formation of difficultly settleable filamentous bacteria, especially with activated sludge. For this reason nutrients in the form of Nitrates and Phosphates are added previously.

25

• AEROBIC SUSPENDEO GROWTH SYSTEMS

In aerobic suspendeel growth processas biodegradation takes place wlth presence of oxygen and is done by microorganisms whlch are dispersed in the wastewater. The energy produced during the process of biodegradation is partly used for the growth of new microorganisms, leading to the production of sludge. Some process variations are: conventional activateel sludge process, oxidation dltch, step aeration, extended aeration, aerated lagoon, deep tank aeration, contact stabilization. In the course of thls research only conventional activateel sludge, the oxidation dltch and the aerated lagoon are discussed below, because these systems are most likely to be applied in Sri Lanka. The other systems are too specific.

Conventional activated sludge Pretreateel wastewater is led into an aeration tank where lt is mixed wlth flocs of aerobic micro­

organisms (activated sludge). The mixture of activateel sludge and wastewater is aerated vigorously. Organic substances in the wastewater are absorbed by the active micro-organisms, which biodegrade the organic matter, utillzing the breakdown products for growth and formation of new cells. As a result the sludge quantity in the aeration tank is increased.

Suspendeel solids in the waste water are also absorbed by the activateel sludge flocs. The mixture is led from the aeration tank into a sedimentation tank where the flocs settie into a sludge. Part of this sludge is returned to the aeration tank in order to maintain a constant concentration of activateel sludge. Usually a concentration of dry solids of 4 kgjm3 is maintained in the aeration tank. The remalnder of wet sludge has to be removed. This surplus sludge is often treated in a sludge drylng bed, which decreasas its volume. The controlled dlsposal of the wet sludge on land is also possible.

The activateel sludge system is a technologically complex and expensive system, which is characteri­zed by a high degree of purification, especially for low strength wastewater Oow BOD). Thls treatment method can be an interesting alternative but has some constraints:

• Skilied Iabour is required for proper rnaintenance; • High technology means that difficulties rnay aise in obtaining spares. • The construction and oparation costs are relatively high. • A reliable power souree has to be available.

Aerated lagoon In tact aerated lagoons evolved from facultative stabilization ponds (as dlscussed before) by

installing surface aerators to overcoma odour problems. Essentially the aerated lagoon process is the same as the conventional (extended aeration) activated-sludge process, except that a basin which has been dug in the ground, is now used forthereactor and the oxygen required is supplied by surface or diffused aerators. Power supply is necessary for thls purpose.

Aerated lagoons can be operateel without recycle of blornass (sludge) which Is foliowed by large settling tanksjponds. However, recycling In combination with settling facilities can lmprove the final effluent. [Metcalf & Eddy, 1979, p.438].

Generally it can be said, that aerated lagoons use a smaller surface area and have a superior effluent compared to ponds. The surface area of the aerated lagoon Is large compared to the activateel sludge process.

Aerated lagoons are applied in different forms: a. the completely mixed (fully suspended) lagoon b. the aerated stabilization pond c. the facultative aerated lagoon

26

The three types differ in mixing level. Consequently the system with the high mixing level is foully aerobic, the system with the lowest mixing has the largest anaerobic zone.

a. Completely mixed aerated lagoon (high mixing level) The fully suspended, completely mixed aerated lagoon Is entirely aerobic and is generally used tor strong industrial wastewater. The lagoons are essentially activated sludge units and a number of them can be operated in serles or parallel. Oxygen Is supplled by mechanica! aeration. There is no reclrculatlon of sludge.

b. Aerated stabllization pond (medium mixing level) This type of aerated lagoon is an intermediate form of the completely mixed and the facultativ aerated lagoons. Mechanlcal mixing of contents of facultative stabilization pond results In organic matter contacting oxygen at the surface.

c. Facultative aerated lagoon (low mixing level) Oxygen is supplied by mechanica! aerators. Senlesbie solids settie on the anoxic bottorn of the lagoon, foliowed by anaerobic digestlon. In the top layer aerobic biodegradation takes place, which is accelerated by the aeration. Except the aeration, the system works the same as the facultative lagoonjstabilisation pond

The aerated lagoon Is a suitable trestment system tor strong lndustrlal wastes (high BOD, no toxlc substances). The oparation is slmple, no skilied persennel needed. The capita! costs are low and the reliability is high. However there are some constralnts: a large land area Is needed for this type of trestment and electric power has to be supplied to the aerators. The effluent is not entirely clean. lt

. still contains some suspended soliels and algae. Generally the effluent has to be posttreated in a sedimentation unit. Compared to ponds, the aerated lagoon Is uslng less land area and delivers a superior effluent against a little higher oparation costs. Compared to the activated sludge system, the·surface area of an aerated lagoon is larger, but the ca"plial costs are lower.

Oxidation ditch The oxidation ditch is a race course shaped aeratlon tank and functlons as an activated sludge system with extended aeration. Generally the process Is intermiltent if it Is operatlng on small scale and continuous on large scale.

The interminent proccess is explalned

Waste sludge

lnfluent

rotor

as follows: The wastewater Is aerated for a tew hours. Then the aeratlon stops and the activated sludge Is allowed to settle. New screened was­tewater is added to one end of the ditch. Treated effluent overspilis to the other end. When the content of the tank is renewed, the addition of was­tewater stops and the aeration Is restarted. Subsequently the process The principle ofthe oxidation ditch

repeats itself. In the continuous pro-cess the wastewater inflow, the aeration, sludge settling and effluent overspiU take place at the same time.

A sludge trap may be recommended to bleed off the surplus of activated sludge. Orlginally the ditch is designed without sedimentation and sludge return, but generally the system is foliowed by a

27

sedimentation tank and sludge drying beds. The oxidation ditch functions as an activateel sludge system with extended aeration and intermittent operation. The oxidation ditch is useful for small plants with malnly blodegradable organic wastes (like rubber wastewater). lt requlres a large area, but less space than ponding systems. The capital and construction costs are high. Process control of the ditch Is less ditticuit than control and operatien of a conventienat activateel sludge system. The required operaticnat skilis are consequent­ly lower.

• AEROBIC ATTACHED GROWTH SYSTEMS

In aerobic attached growth processas blodegradation takes place In a sludge consisting of microorganisms which are attachee! to the surface of a medium (biorotor in the case of ABC; poreus pumice stone or lava or plastic support particles in the case of trickling filtration). The sludge absorbs aerobically biodegradable organic matter in the process of celi-formation of the microorga­nisms. Suspended solids are also absorbed by the sludge film on the contact surface. The excess sludge film on the contact surface is automatically washeel off by the flow of water through the system. Residuals generateel contain less sludge mass per unit of pollutant removed, compared to suspen­ded growth processes. Aerobic attachee! growth processas (In particular the trickling filter) are also used tor nitrification ( = conversion of ammoniacal nitrogen into nitrate)

Some reactor types are the conventlonal trlckllng filter, the rotatlng biologica! contactor, the roughing filter and the percolating filter. The trickling filter and the rotating biologica! contacters will be discussed below because of its most common application.

Trickling filter A trickling filter consists of a bed of highly permeable media to which microorganisms are attachee! and through which wastewater is percolateel or trickled. The organic material in the watewater Is degraded by the microorganisms attachee! to the filter media. Usually these media or support materials consist of pumice stones, lava or plastic. The rock filter beds are usually circular and the liquid wastewater Is distributed over the top of the bed by a rotary distributor. An underdrain system collects treated wastewater and biomass whlch is detached trom the media. Oxygen is supplied by natural conveetien of air through the spaces in the filter media and partially trom the dissolved oxygen in the wastewater.

The trickling filters can be divided into two types: • low rate filters, which are simpte filters wlth a relatlvely low toading rate • high rate filters, which are capable of treatlng higher organic loadings because the filter effluent

is recirculated.

A low rate filter is a relatively simpte, highly reliable treatment facillty, that produces an effluent of a consistent quality even if the lnfluent has a varying strength. Biodegradation takes place mainly in the top layer. Below about one meter, bacteria are responsible for nitriflcation. Low rate filters are widely used tor dornestic wastes. Problems with lndustrlal waste are the low loading rate and large land area required. (see Photo 3.1.)

28

High rate filters are having a higher capacity, but are very expensive in construction and rnaintenace costs. The typical plastic media with which the tank Is tilled is expensive and the high technology used requires skUied personnel. Continuous effluent recycling has to take place tor dilution of the filter input. Strong industrial wastes from for instanee the food industry and breweries can be treated with high rate trickling filters. When lndustrial wastes are treated, problems rnay arise due to excessive growth of microorganisms and algae at the surface preventing the flow of liquid. Also odour problems may occur.

Rotating biologica! contactor The RBC system consists of one or more biorotors, a blorotor being a horizontal shaft to which

the contact surface is attached and which generally consist of polyvinyl chloride or polystyrene. lt Is fitted into a tank into which wastewaw Is led. A film of sludge containing aerobic micro-organisms develops on the rotating biorotor-surfaèe. Rotatien of the blorotor causes Intensive contact between wastewater, micro-organisms and oxygen. The system finels lts application rnainly in small communi­ties, like tor instanee hotels.

The RBC system requires very little space and energy. The eperation costs are low, but the capita! costs are high. The RBC effluent has to be settled in a sedimentation tank. The system can be recommended for upgrading an existing treatment facility, because it's easy to install. The system is capable to treat industrial wastewater trom srnall units. (see Photo 3.2)

• LAGOONS (STABILIZATION PONDS)

Intheir simplest form, stabilisation ponds are large basins dug In the ground, whlch are used for the treatment of wastewater by natural processes. A pond is a shallow lagoon with a large land area. Generally no mechanica! equipment is needed. The principle of this form of wastewater treatment Is natura! self-purification.

29

Aerobic lagoon (stabilization pond) Aerobic lagoons use both algae and aerobic bacterla In these natura! processes. The bacterla and The algae are suspended and the conditions are aerobic throughout the pond depth. Algae are the producers of oxygen under lnfluence of light. The oxygen Is used by microorganisms for energy consumption and growth, which results In the breakdown of organlc materlaL This type of ponding is limited in lts depth because the algae are dependent on light. Oxygen also enters the pond through the surface by diffusion. Aeration by surface serators can lmprove the results of treatment. (see Aerated lagoon)

Aerobic lagoons are able to treat weak lndustrlal wastewater wlth negligible amounts of toxic compo­nents andjor non-biodegradable matter. Functlons are the stablllzation of organic matter (reduction of BOD), the reduction of the nltrate and phosphate content and the reduction of suspended sollds. In aerobic and facultative lagoons very small quantlties of sludge are generateef and therefore a clean out every 5 to 1 o years will suffice. Where anaeroblc lagoons are applled, the sludge Is washed out with the effluent.

The costs of this trestment system are minimaL The technology is very slmple and the rellabillty Is high. However a large land area Is needed. lnhabltants surrounding the lagoon may have complalnts about odour (bad smell). Furthermore wastewater can seep lnto the groundwater. The effluent contains suspended solids and algae. Another problem of aerobic lagoons is the fact that algae are consumlng oxygen during the night, lnstead of produclng lt. Therefore somatimes anaeroblc condltlons may arise during the nlght, which can be harmful to the aerobic microorganlsms.

Facultative lagoon (stabilization pond) The pond operatas as anaerobic and aerobic ponds slmultaneously, because the pond Is divlded In the vertical direction lnto three zones: an aerobic, facultative and anaeroblc zone. Thls stratification is the result of water density variatlons caused by temperature difference. Oxygen Inputs take place both by algae and atmosphere. Suspended matter Is deposlted on bottorn and Is subjected to anaerobic digestion. Non-settleable matter Is stabilized aeroblcally In upper layers

30

Facultative lagoons can treat weak industrial wastewaters which have been screened or clarified. The facultative lagoon has sameproperties as the aerobic lagoon Qarge land use, low costs, etc.).

Anaerobic lagoon (stabilization pond) The organic matter in the anaerobic pond is degraded by anaerobic bacteria into gases such as methane, hydrogen sulphide, ammonia and carbon dioxide. Solids settie into a sludge layer at the bottorn of the pond which have to be removed periodically. Once greases form an impervious layer, complete anaerobic condltions develop.

Anaerobic lageons are effective as roughing units prior to aerobic treatment of high strength organic wastewater. The BOD removal is relatively low (70-85%). This type of lagoon has a smaller surface area and a higher depth than the aerobic ponds. The biologica! degradable matter of an industrial wastewater can be treated this way. The strength (BOD) of the wastewater datermlnes the size of the pond. An anaerobic treatment system should not be built within SOOm of dwellings because of the smell.

• ANAEROBIC SUSPENDEO GROWTH SYSTEMS

Anaerobic suspended growth systems stabilize organic material in the wastewater with absence of molecular oxygen, using anaerobic microorganisms. The most important application of anaerobic suspended growth is anaerobic digestion. This method will be discussed in lts simplest form: conventional anaerobic digestion. Also the Upflow Anaerobic Sludge Blanket (UASB) will be discussed, because this system has application opportunities tor developing countires.

Anaerobic digestion The organic material in the wastewater is converted under anaerobic conditions into methane and carbon dioxide in an airtight reactor. From the outgoing effluent the toxic content is greatly reduced. Dilute organic wastewaters can be treated in this way.

Requirements tor anaerobic digestion are: • strict pH control because of the sensibility of micro-organisms to pH variations; neutral ph is optimal; • tempersture of 30 to 3flC; • posttrestment of effluent.

Two types of reactors are in use: standard rate and high rate. The standard-rate type is eperating under unheated and unmixed conditions. The high rate reactor is heated and completely mixed, resulting in lower datention times. A combination of the two basic processas is known as two-stage process.

Anaerobic digestion can be an interesting alternative if skilied Iabour is available and spares can be obtained without difficulties. A reliable power souree must also be available. The system is technologically complex and thus expensive. Posttreatment of the effluent is necessary. Anaerobic digestion is mainly used tor low or medium strength wastewaters discharged by food processing, breweries and sugar factories. Anaerobic digestion is also used tor stabilization of waste sludges. The toxicity of the sludge is reduced in the reactor.

31

Upflow Anaerobic Sludge Blanket (UASB) The UASB system consists of a reactor in which an active sludge blanket is present at the bottom. The active sludge contains the biomass, whlch must have granular characteristics in order to be retained in the blanket. No support media Is needed. The waste flows upward through the sludge blanket fluidizing it. At the top of the reactor the sludge particles flocculate in a qulescent settling zone. The sludge flocs either settie down or are entrapped in a secondary sludge blanket present In the settler campartment At the top of the reactor three-phase separation Is necessary to separate solids, gases and effluent.

The UASB system has been applied to a range of industrial wastewaters. Concentraled lndustrlal wastewater can be treated, especially when it contains large amounts of sugars and starch. Also damestic wastewaters can be treated with the system. Successful applications of this system exist in developing countries. The advantages are low sludge production and low eperation casts when compared toa simpte aerobic pond. The capita! casts of the two systems are not differing significantly. When the waste temperatures are higher, the requlred reactor volume is smaller and thus the capita! casts are lower. This makes the system lnterestlng for tropical countries. [Lettinga, 1978; Stuckey and Hamza, 1981].

• ANAEROBIC ATTACHED GROWTH SYSTEMS

Anaerobic filter The most common anaerobic attached growth process is the anaeroblc filter process used for the treatment of bath damestic and industrial wastes. The filter is a column fitled with media used for the treatment of organic matter in the wastewater. The waste flows upward through the column contacting the medium on which anaerobic bacterla grow and are retained at ambient temperature. The anaerobic filter can be used for the trestment of low-strength wastes. The application of this type of wastewater treatment is not very widespread.

• LAND TREATMENT

Land treatment involves the use of plants, the soli surface and the soil ltself for wastewater trestment Depending on various factors, land trestment systems are capable to remave organics, nitrogen, phosphorus, exchangable cations, trace elements and micro-organisms from the applied wastewater. Three types of land treatment are popular: lrrlgation, rapid fiJtration and overland flow. Overland flow is the simplest and most common methad and wiJl be discussed here. Another methad Is being developed and promises good results: wetlands application.

Overland flow After pretraatment the wastewater is pumped up to a point from where it can flow down slowly, in a thin layer, over a vegetated surface of long gentie slopes. The wastewater Is then adsorbed and filtered by the top soli. Aerobic blodegradation of the organlc matter which rernains takes place in the top soil, while the purified water seeps away.

32

Biological oxidation, sedimentation and grass tiltration are the mechanlsms which remove organics and suspended solids. Nitrogen-removal takes place In the anaerobic-aerobic layer of the soil. Phosphorus and heavy metals are removed by means of adsorption, preclpltation and ion-exchange.

Requirements to vegetation: the plants must have a high water tolerance. Requirements to soil: the surface should net be smooth and net toe steep (2-8% otherwise erosion). Drainability should be limlted (clay is sultable).

Overland flow has two functions: wastewater treatment and, to a minor extent, erop production. The treatment method can be eensidared appllcable lf research has shown, that toxlc components do net advesely affect the vegetation, the soil and groundwater. Also large land area should be available. However, this land should net be toe steep, because of the danger of corrosion. Knowledge of wastewater characterlstics, treatment mechanisms, vegetation and conditlens of the soil as well as public health requirements (bacterlological contamlnation, transmission of diseases, toxic chemicals, danger to erop quallty) is very Important tor a successful appllcation of land treatment.

Screening and grit & grease removal are requlred to prevent clogging of the soli. Lagcon pre­traatment can be recommended. Also pre-disinfection may be advantageous. The system is very simple to run, but a thorough study must preeeed the application of lt.

Wetlands application The application of secondary (biologically, physically or chemically) treated wastewater to existing

_ wetlands, such as marshes, srnall lakes, swamps etc, is being studled extensively. The use of speeltic plants, e.g. water hyacinths, In the ,reatment lagoons" effects the removal of BOD, suspended solids and nutrients. Significant results have been measured in the USA. For efficient removal the plants must be harvesteg_every 5 weeks and may be processed into-teed products, fertilizer, soil conditlener or methane gas. A large surface area is needed tor this type of treatment. Countries with a large land area constltuted by wetlands (like Sri L.anka) have an advantage In this respect. This type of wastewater treatment is net widespread because the dagree of addltional treatment is very lew (after physical, chemica! or blological treatment). [Metcalf & Eddy, 1979).

33

3.2.4. SLUDGE TREATMENT & DISPOSAL

To the subject of sludge treatment and disposal I wlll pay extra attentlon, because the sludge problem is often forgotten or pushed aside as Irrelevant. lt Is relevant, because the waste content of the treated wastewater is almost completely transferred to this sludge.

The solids, removed by the various unit processas at a wastewater treatment plant constitute the most Important by-product of the treatment processes. These solids lnclude grit, screenings and waste sludge. The sludge has a significant volume and Is one of the determining factors for the selection of a wastewater treatment method. The reasans why sludge-dlsposal causes environmental hazards,are:

• Sludge Is offensive, • lt is not stabilized if produced by aerobic biologica! process, • lt has a large volume, • lt may contain toxic components.

The purpose of the major treatment processas Is to reduce the offenslve nature of the sludge and to reduce lts moisture content. Thickening (or concentration), conditioning, dewaterlng and drying are used prirnarily to remove moisture trom sludge. Digestion, inclneration and wet oxidation are used primarily to treat the organic material in the sludge. The sequence of operations of sludge proces­sing and disposal is presented In the cadre below.The cost of a sludge treatment Instanation are considerable and can easily reach 30 to 50% of the total cost of a treatment plant.

·······• prë.Jiminäry operations ..... ] .. : ............. . .···•· thickenif1g ·(A) . ï ..... .

·· stabi/i zation (B) .·.• l ....

conditioning (C) ! · disinfection (D)

· .. ·. J .. ·. .· dewatering (E) l

drying (E)

·.· l ••.••.. C:omposting (F)

. ••••• l .. . ... . .. tiJef7!iaf regucfiön (G)

J. <• . fiflalgispqs~r.(GJ

_:::::::::::::::·::. . .... ::::::::}: .": .. : .· ·::::.·::.< ::· .PROCESS bnloNs.

·:··. ·. ···;.<:::::>.·.·. ·· .. :···.-:-:: .. · .. ;.·.·.·... . .

. ·:- :-.:·.··<· . ·<<·.":-::::.::·::··::< :<-":::::::-:.·>.·:::::::::.::::: .. : .. ·. · .. ·:· .· · • grinding, plj~ding, Stotagë}degritfiqg .·.·.· .··· <-:···.·.-:····-:.·-:·-: .. ··.-:-:··-:.;.· .. -:·· .. <.· .. ···.··-:·.·.· .... ····.·:..·.:.·.· ... ·:··

giavlty 1hlc~llin~. f19tattok ~ntrifu~ticJI) ···<:- -:-:.· ::.: .. :· ·::::.:><<::·\:>:·>>.:·:·:.:::::-::>: :· <:-:·:::..::::::\}:) .. ·::.<<:<::>::: :: ... =::.:<<·:= .:.-·:<::::·:·:·:::::=·=·: · ..

· .. · aerr>biç/anaef{)bic clf9est1on, IH}at tmatl1lfJflt.llirHJ ~liapo", xMctätion ..... . ........ . . . . .. ....... . ......... . ............. .

............. ··.·.·.·.·.·.·.·.·.· .. · .. ···.· ..

desi~Îib~· .·. ·.···· ... . .·· ··.· ... . . ... · .... ·. · ... ··.·.· .. ·.... ... . .... ..... ctrying.bet1 •.. Çëntrifugatic>11 .. •~Jtrati(Jn,·•ta~oon

f&~h qryfng, ~ray drylng, i'otaly drylng, multTpfe. heaifh<drying ... :.: ... :. :·:.::::::::::::::: :.::::::~.:.::: . ._::: :.;::::::::-.... : .... ; ·. ::-:.:-. · ... : : .. ·: . ..: ... ·.: ... : .. · :··:·.: : .· <·:::::. . . ::-:i:::>·:-:::··:·.:: .. ·.·.:-.:::.:-:-:: : ..

.•· • $luifr;i-on!YiQmposting, ccx;()in/Jastjng With $olid :WSstës · · . : >><:·:::·<·. :-:::::::.·:::".>> -:-:: ":"·.·:: .. < >:<:<:::::-· .. .- .. :·::::::::::::.::. ·.:· . ..::·>:·:<·:::·:-.···: <: :-.... -::::::··:··.:.-:·.- :>: :-·>:-:·::::.>: :" .. · .. ::::::::::::<.-:::::.: .. ::::-=:-.: .

••••••••••••·· inbilJêi;tiori,6~6J~6,.J)yrolisi~.~IJirdXidéJtiQrJ,•i.ciamá'tkJA••••·•·.· . .· .. ··.·.·.·.·.·.· .. · .. ····· .. · .. · .. · . ·.··.·.··.·.·.·.·· .. ·.·.·.·.·.·.·.·.··.··.·.· .... ·.·.· .. ·.·.· .. ·.· .. · .. ·.·· .. ·.·.·.·.·.· ... ·.··.···

~11, Îa"d ~.l\9(;tarn~~. ~~~~ i .-:-:-::: = >::=:::::::::::::-_::>>{:.:. ::<>< ·. . >-:=·=<·:-:.:. ::.:.:.>:::=:>::.·=.-:<·= = ·.: ·= ... <=><:::>:=·:::-··=.-··:::r:::::r:::::::::=·===:-.=< ..

l"YP,dt, srudài ~11.fEtfl"~· .· .... ·.··· .. ··.· . .• 1 .•• flotafion·· .. •·anaerob1c .. d~est~6··4··~~tltri~n··4••ChernJc~·concfltkmTng··~·•w••J••disA•·(~·~!~)··················••••·•·•·······• .

···········2.··~11ae~bic•.studge .. d;gestio/l·•• .. •cfHJn#cal··~Jkfo/1/rig•l••r:entrifut;atio/1 ...... cJI~aJ··(of·~J!d·~~udge)········· ................. ·.· •·•·· .· .. ··. >-· :.::::·:.= .. ·.-: .·. : .. · ... ·.::· :=:=:-::. :-."":.: :.:::=::-:=:·.::.-:::::::::·:·:::.:::::::=:::·:::::: .. :.=::=::::: .. -: :-:-:·:.::::::·::-:::·>:····

3. ~Mro'bia digeStion .. sand d~ing iftJd$ j d]S()Ot:J(()f JrilcJ stiJ<igM ···••••••• ..

Sludge processing and disposal flow sheet

34

A. Sludge thickening or concentration

Thickening is the first link in the sludge treatment chain. This is the first and simplest stage in considerable reduction of the sludge's volume. Thickening can be carried out by ordlnary gravlty settling or by flotation (as discussed) Volume reduction by sludge concentratien is beneticlal to the subsequent processes, such as digestion, dewatering, drying and cernbustion because the quantlty of chemicals, reactor volume and heat required by digester can be reduced. The most common thickening application is in a prirnary gravlty settling tank.

B. Sludge stabilization

The three main functions of sludge stabilization techniques are to reduce the toxic character of the sludge, to eliminate offensive odours and to reduce the potentlal for putrefaction.

The following technologies are available for sludge stabilization: • chlorine oxidation (principle: chemica! oxidation of volatile matter by chlorine gas in an

enclosed reactor) • lime stabilization (principle: addition of chemieals to "kill" microorganisms) • heat treatment (principle: appllcation of heat to disinfectjsterilize the sludge under

high pressure) • anaerobic digestion (principle: biological reduction of volatile matter) • aerobic digestion (principle: biological reduction of volatile matter) (see below)

Because of their importance, aerobic and anaerobic digestion are discussed separately.

Anaerobic sludge digestion Anaerobic digestion has been discussëd before under biological treatment methods. This method is also applied for the stabilisation of concentraled sludges produced from the treatment of industrial wastewater. Essentially the processas of anaerobic digestion for the purpose of wastewater purification and for the purpose of sludge stabilization are the same.

Aerobic sludge digestion Aerobic digestion is an alternative process for stabUizing organic sludges produced from various treatment operations. The process is similar to the activated sludge process. As the supply of availabie food is depleted, the microorganisms start to eat their own protoplasm to obtain energy for cell maintenance. Cell tissues are oxidized aerobically into carbon dioxide, ammonia and water. As digestion proceeds, ammonia is oxidized into nitrate. According to this mechanism the microorga­nisms biodegrade themselves.

Aerobic digestion is a sludge stabiJlzing technique to reduce the toxic character, odour nuisance and putrefaction. lt is easier in oparation than anaerobic digestion, but more expensive. However, capita! costs are lower. Both treatment systems are relatively expensive and complex in technology. Aerobic digestion gives better results, but no methane as by-product. lt can be used to treat sludges trom activated sludge treatment and trickling filtration.

C. Sludge conditioning

Sludge is conditioned to improve its dewatering characteristics. Most commonly used are the addition of chemieals and heat treatment. Addition of chemieals results in coagulation of solids and release of absorbed water. The yields of dewatering increase consequently. Economical

35

Heating serves as stabilization and conditioning of the sludge and Is done under pressure. The treatment breaks down structures and reduces the water affinity of sludge solids at high temperatu­res. The equipment casts are very high.

D. Disinfection

Sludge is disinfected to destray pathogenie organisms. Thls is especially Important, when sludge Is applied to the land, in order to proteet publlc health. Many methods can be used for this purpose:

• pasteurization (30 min. at 70°C), • high pH treatment (pH> 12) • long-term starage of digested sludge • complete composting at temperatures above 55°C • addition of chlorine (or other chemicals) • high energy radlation

As the addition of chlorine is a slmple and cheap method, this can easily be practised in Srl lanka.

E. Sludge dewatering I drying

Dewatering techniques are used to reduce the malsture content in the sludge. The result is a drier sludge with a smaller volume. This makes subsequent sludge handling easier and cheaper (trucklng, lncineration, land fill).

Sludge drying can be done by natural means in tropical countrles: using drying bects in combination with solar radiation. However, in cold and humid countries mostly physical (mechanica!) means are used: tiltration or centrifugation. Another -relatively expensive- option Is heat drying. Because Sri Lanka is a tropical elimate with a considerable amount of sun-hours it Is suftielent to discuss only the drying beds option.

Sludge drying beds Drying beds are very cheap to construct but may be Iabour intenseve. All other drying systems are expensive. In the case of Sri Lanka, the drying beds are a suitable option. Centrifugation and tiltration are not suitable because their complexity and capital cast are bath too high. The sludge is placed on beds in a 2-3 cm thick layer. (Loading rates: 100-200 kg dry solids per m2

per year). After drying, the sludge Is removed and can be used for landfilllng or as a fertilizer.

F. Sludge composting

Composting is a process in which organic material undergoes biologica! degradation to a stabie end­product. About 25% of the volatile solids are converled lnto carbon dioxide and water. Prepared wastes are placed in rows In an open field. These rows are tumed every week. After 5 weeks, the composted sludge is removed as a sanitary, nuisance-free and humuslike materiaL The product Is screened, cured, prepared and marketed. lt rnay be used as a soil conditioner. Problem: lack of market for the stabilized end product (in USA).

36

G. Final Sludge disposal

Final disposal of sludge trom treatment facilities usually lnvolve some form of land disposal. The most common methods of land disposal are: spreading on land, lagooning, dumping and landfilling. A second option is reuse of sludge as a soU conditioner or fertilizer, but there's a marketing problem (see F). A third sludge disposal method is thermal reductlon or inclneration. Land application and incineration will be discussed below.

land application Spreading on land Dewatered sludge trom the treatment of dornestic wastewater can be spread onto land to serve as a fertilizer and a soil conditioner. Widespread In rural and noneoastal communities. No option tor lndustrial wastewaters Oimited loadlng rates).

Laqooninq Lagooning is a simple and economical disposal method if the treatment plant is nearby. The lagoen should be a shallow ( < 1.5 m) earth basin into which the sludge is deposited. Organic solids are stabilized in the lagoon. Excess liquid trom the lagoen is returned to the treatment plant. Disadvantage: objectionable odours.

Dumping Dumping tor instanee in abandoned mine quarries can only be done with stabilized sludge so that no decomposition or nuisance will result. Dlgested sludge, clean grit and incinerator residue can be disposed safely.

Landfilling A sanitary landfill can be used tor disposal of sludges, whether stabilized or not. Dewatering tor volume reduction is recommended. This method is most suitable if the landtlil is also used tor ether solid wastes of the community. In selecting a land disposal site, consideration must be given to nuisance and health hazards (toxic substances in the sludge). One should guard against drainage trom the site causing groundwater pollution.

lncineration lncineration converts dewatered sludge into inert ash. The process is complex and needs specially trained operators and the equipment is expensive. Normally only large scale treatment plants are using incineration. This is consequently no suitable option tor Sri Lankan small scale industrial sludges.

3.2.5. FACTORS WHICH INFLUENCE THE SELECTION OF AN APPROPRIATE TREATMENT METHOC

Up to now trestment technologies have been discussed which can be applied in Sri Lanka according to recommendations trom literature (chapter 3.1.). Hence each wastewater treatment method has been discussed in detail (chapter 3.2.). When a eertsin treatment method is recommended tor a certain factory-wastewater, some factors have tobetaken into consideration. These factors influence the choice of an adequate wastewater treatment method. In the course of this survey, it is not aimed to select trestment systems for individual factories, because this is partly a technica! affair. For this activity specific technica! calculations have to be made which are very time consuming. Therefore no selection will be made of the most appropriate treatment system. In the course of this

37

research it will be checked if the factors mentloned below were considered befare a trestment system was selected.(see chapter 4.4) The factors, which play a role in the selection of trestment methods are the following:

A The trestment method must be capable of handling the type of wastewater for which it is applied. This means, that if a factory discharges batch-wise, the system should be capable of handling shock loads.

B The trestment capscity must match the wastewater volume and the poltution load.

C The system with the required capscity must be practicabie withln the available space. Land casts and availability are relevant factors.

D The pollution laad must be reduced significantly. The characteristics of the final effluent must conform to the toleranee limits (the required quallty of the treated effluent).

E The capital and oparation casts should be overseeable ( < 5% of the production casts, ref RAl). Finance should be available for plant construction and operation.

F The level of supervision and rnaintensnee required for the system. The technology must be understood by the local experts (not too complex, not requiring too highly skilied personnel). Is

G The level of pay tor the technicians and operators of the trestment plant. In other words: the Iabour casts.

H The availability of local skilied or semi-skilied personnel.

Spare parts and chemieals for the applied trestment systems should be available within the country against a reasanabie price.

J The reliability of the system (not requiring too much maintenance), especially when skilied personnet is scarce.

K The water pollution problem should not be shifted into a solid wastejsludge problem. The pollution must be reduced adequately. In other words, efforts to obtain a cleaner aquatic system should not shift the problem to another ecosystem, like for instanee the soit or the vegetation.

L Possible social effects should be taken into consideration. Example: the trestment system should try to minimize the nuisance to the neighbourhood, especially when there are many residents in this neighbourhood.

M The trestment system must be able to operate with the available infrastructure (with or without electric power supply; a minimum of space; an interlor transport connection, etc.)

N The understanding of the pollutlonal character of the production process existlng withln the management team. In other words: the awareness of the consequences of environmental pollution. When the understanding is low, only very slmple waste reducing measures are feasible. Then environmental education should have first priorlty.

38

4

THE ENVIRONMENTAL ASPECTS

OF THE PRODUCTION OF LEATHER, RUBBER AND TEXTILE

4

THE ENVIRONMENTAL ASPECTS OF THE PRODUCTION OF LEATHER, TEXTILE AND RUBBER IN SRI LANKA

4.1. INTRODUCTION

During the research perioei several factorles have been visitecl in each sector in order to get an impres­sion of the environmental problems rrelated to the production of textile, leather and rubber. In the textile sector 8 factorles were visited within a radius of 30 km trom Colombo city. 5 leather tanneries were visited all very near Colombo city and 6 rubber processing units with the maximum distance of 50 km trom Colombo. The rubber factorles were locatecl in urban as well as in rural areas.

For the coneetion of data the factory managers or general managers of each company have been intervieweet by means of an intermation questionnaire. This questionnaire can be found in Appendix V. Almast all informatlon needeel has been receivecl, consisting of general information, information about the wastewater and a bout the production processes. The general information and the general imprasslons

· trom observation during the factory vislts are provided in chapter 4.2. For technica! information the managers very aften needeel advlee from technica! staff (lf not they made rough estimations). This technica! information will be analysed in chapter 4.3. in order Jo estimate the pollution level of each factory.

The only information refusecl were the financlal data about sales, incames and profits. Hence some managers were very brief in their answers. Because of a letter trom the CEA I was not refusecl for the interview, butsome managers were obviously not happy to provide me with the requirecl answers. Others treatecl me as a consultantand as keel me tor advlee regarding the wastewater treatment. These managers also gave me complaints about the CEA, because the new regulations were so strict and nobody told them what to do with their wastewater. lt was an exception when taking photographs was allowecl.

4.2. QUALITATIVE DESCRIPTION OF THE NATURE OF THE TEXTILE, RUBBER AND LEATHER SECTORS IN SRI LANKA.

In this chapter the results trom factory vislts and interviews are analyseclln a qualitative way. In the first paragraph a general picture will be given of each sector in its entirety, baseet on interviews and docu­ments. In "Observation in the field" the visitecl factorles in the three sectors textile, leather and rubber are described as observed during the research period.

The factorles which have been visitecl are all ownecl by local enterpreneurs or by the local government. lt was planneef to visit some foreign campanles as well. These foreign investors are locatecl in the Export Processing Zones of the GCEC. No parmission was obtained for visiting the factorles in these zones. Admittance was refused by the campanles themselves.

39

4.2.1. THE TEXTILE INDUSTRY

General background

The textile manufacturing lndustry in Sri Lanka has grown rapidly in the past 10 years and plays a significant role in the country's economy (see cadre below). Exports of textile form a substantial souree of forelgn exchange. I estimate the number of polluting textile industries (i.e. the factorles where wet processing Is performed) in and around Colombo between 30 and 40. [Ceylon textile manufacturers' association, list of members, 1990]

The diversity of needs on the textile market encouraged many different types of medium slze Industries to develop. In addition, a few old large size industries, which have been installed on the basis of soclo­political needs (employment, prestige), continued oparation and increased their production.These large scale factorles are situated In rural areas where they warejare an incentive for rural development. Most textile factorles however are located in urban areas around Colombo. In the RatmalanajMoratuwa area and in Ja-Eia concentrations can be found of saveral factories.

In Sri Lanka, mainly cotton and polyester fibre processing Is carried out. The raw material is imported as yarn. Most factorles have a wet finishing department Only some large scale operations have a weav­ing department as well, rasuiting in a much higher employment: with weaving dept 450 to 3000 workers; without weaving less than 150 workers.

The varying demand in textile material and colours has propagated a large utilization

... ... . ....

. .In 19sJ fe..tile and we';,;ng ~retaccounied for 47;5% C1f the totaUridustrial exports of Sri Lanka. In 1984 this 'percentage amounis 56.2%.

.,he sháte În industriat~~ucfk>n (-vmue) in. 1987. Wils for t8xtile, •·· Wèaring apparel and leather ~Pgether32% (lrt1985: 25% and in

1983: 18%). .· ...... · .. ··.. .· . . ..

fhe textilelndustrypro~sa s~nifK:ant~~u~t of empk>yment: in 1980 the ernployment shiire was 30% of totallndustrial employ-

> mént. · ·· · ·

of dyes and chemicals. These dyes and chemieals used in the wet processing transfarms dirty and unattractive cloth or fibre into marketabie textile products with considerable added value. However, excess dyes and chemieals from these processas cause significant environmental hazards. The chemieals used in the visited factorles are mentioned in Appendix Vl. Commonly used chemicsals are: salts like sulphates and phosphates, soaps and detergents, sulphuric and acetic acid, urea and various dyes. Of the dyes only the tradenames, not the chemica! names, are known to the industrialists.

The characteristics of the wastewater vary because of the large number of unit operatlons and the large number of chemieals used. Special toleranee limits for wastewaters from the textile industry have been specified by the CEA (Appendix N, table 5).

The environmental polJution trom the textile industry is significant. Untreated wastewater generally goes into municipal drains or unused land. There is one exception: one factory is running an wastewater trestment plant: Pugoda. This plant is only partly successful (see 4.4.). The textile industry is concentrated in a few areas. In Ratrnalans the Lady Catherine Estate was originally planned as an industrial estate, but middle class citizens build houses in between the 50 industrial plants. These plants include 8 textile plants which have dyeing and finishing operations. Furthermore 7 plants are dealing with toxic chemieals such as paint and lacquers, glues, resins, pharmaceuticals and pesticides. The wastewater from these plants goes into the Dehiwala canal and flows into the sea at the boundary of the municipality of Colombo, where it bacomes a filthy stream with banks full of solid waste and black tarry substances. Houses are being built near this canal, so that people will soon be living near this refuse.

40

Observation in the field: factory vislts

* Kundanmal The Kundanmal textile factory, a medium scale industry with 600 empoyees, Is located In the industrial zone In Ratmalana and has no access to any wastewater treatment system. The elient agrees that a treatment plant is necessary, but therefore advlee trom CEA is needed in order to recommend a low cost treatment system. Preferrably, the system has to be a central treatment plant, to be used together by several industries.

The factory looks relatively clean, but the wastewater is strongly polluted with excess chemieals mainly from the dyeing of polyester fibres. Th is wastewater Is discharged through a common channellnto a river. The technology dates from 1964 and is mainly Japanese.

Personal impression: The general manager seems only willing to help because he finds it hls obligation not to hinder CEA's efforts. Hls supply of inforrnatlon is marginal and the manager Is rather secretabout the part of lnformation he doesn't show.

* Swastik/Nagindas The Swastik tacotry is located in the mlddie of residentlal areas, less than 1 km trom the place where llived. The weaving section dates trom 1964; the garment section has been built in 1978. Stone washing of jeans was added in 1987. The boundary is berdering a small stream, into which the wastewater is discharged untreated. lt is coloured, hot and containing excess dyes, oil and detergents (foam).

The weaving section causes noise pollution. The workfloor is not extremely dirty; housekeeping Is satisfactory, except torsome dirty corners. Plans have been madefora treatment system, costing about 5 million Ru pees. The acreage availabldior the system is 0.5 acre, however this is the minimum acreage required for blologtcal treatment. "Environmental laboratories" deslgned a small blologtcal treatment system costing 1 milllon Rs. Swastik is awaitlng CEA advlce. Furthermore expanslon is planned in the near future.

* Pugoda The Pugoda factory is located in a rural agriculturaljresidential area, in the little rural town Pugoda. The factory was established in 1972 as a large scale State Company. Underlying politica! motives were creation of employment and prestige. The oldest equipment is rnainly Chinese technology. Modern finishing equipment was installed in 1982. In 1990 the factory was privatized. The complex is a large scale industry, employing over 3000 workers and extending over an area of 18 acres. A giant activated sludge system in combination with three oxidation ponds is treating the wastewater. The results are a reasonable final effluent and a smell from the pondsin the entire area (complalnts). The amount of faecal coliforms Is very high; the other parameters conform to the standards. Some of the final effluent is used as Intake for process water. The system seems to be working well, but overdesigned and consequently too expensive to give a good example to other lndustrialists. The treatment system dief not take into account the special problems of treating wastewater from the dying and finishing department, where also synthetic fibres are dyed. Consequently the final effluent is still coloured and foamy. Samples are taken once In 6 months by NBRO and the treatment plant is rarely maintained. The chief engineer is worried that the lagoons are sllting up. Uttle additional Iabaratory equlpment and some limited expertise can be useful to optimise the operatien of the treatment plant. The final effluent is discharged into a srnall stream which flows into the Keiani river, 44 km trom the rivermouth.

Apart trom the water pollution, some air pollution (contalning sulphur trom furnaces) and a tremendous noise pollution can be observed. This noise is caused by very noisy machines especially in the weaving

41

department All labourers are werking without earprops and will soon end up with impair hearing. Oil is leaking trom boller turnaces and storage tanks lnto drains, making rainwater greasy and brownlsh. Housekeeping can be improved especially in the wet processing zone, where the workfloor is wet and dirty. Insome places the machines are constructed closetoeach other, making it ditticuit to keep the area clean

* MKC Industries MKC Industries Is situated at a very inconvenient location, where no drain system is available and where the limited premises leave very little space for adequate wastewater treatment. The factory is surrounded by residentlal dwellings.

The housekeeplng can be lmproved, much water Is flowing over the workfloor. A treatment system has been constructed and is used, but there's no diffemece in appaerance of the coloured effluent befere and after treatment. The treatment system consists of an aerated pond where the aerator is In repair, a flocculatlon system without a flocculation tank and with negliglble sludge removal, sandfilters which are clogging up and some small sedimentation pits. One chemist Is responsible for maintenance, but lacks essential knowledge about the functioning of the system.

Because no drainage systems are available In the village, the final wastewater is transporled to a factory­owned marshy field of 40 acres, 20 km trom the factory, by means of a tank lorry. The truck makes about 10 trips per day, carrying 13 cublc meters of wastewater each time.

However, during the rainy season or during rainy days, the (only) drain to transport rainwater overflow gets blocked. The consequence is an overflow of all the wastewater treatment tanks. The treated wastewater trom several stages get mixed and flow over the factory premises onto the streets in front of the factory. Neighbouring residents next to the street are confronted with pink and red rivers at places where they expect a road.

The sludge trom the settling tank is taken out every three weeks, dried and buried lnside the premises. The pollution problem is definitely not solved. The treatment system that has been constructed is not reducing the waste load at all. A drain line is planned: MKC has given aproposalto the local authority and Is awaiting approval and allocation. Final discharge point will then be the sea. There are also plans to lmprove the treatment system, but one is awaiting further advlee trom CEA.

The manager is kind and helpful. He sees me as an intermediate between the govemment and the enterpreneurs. l'm objective and in a position to give advlee and Intermation to both CEA and MKC. The willingness to reduce the pollution is present, but the expertise Is missing.

* Duro synthetic textile mills The factory is situated in a residentlal area In Kelaniya. The medium scale factory is eperating mainly with machines trom 1969. 65 Japanase power looms have been added In 1979. The workfloor looks very clean. The factory is experimentlng with a "treatment plant•. Th is means a tew pits In the ground and one propellor used as an aerator. Only half of the wastewater is treated. Wastewater trom the dyeing and printing sectien Is discharged without treatment into a large well, whlch is already overflowing lnto the marshy /paddy fields berdering the factory premises. About 2 acres are available tor treatment. The factory wastewater is not adequately treated, but the first steps have been taken.

Solid waste is dumped inside the premises; noise pollution Is created by the power looms. Everyone is helptul and about 10 people are accompanying me to every place I want to see, even to the toilet.

42

* Velona group of companles Velona accupies a vast area with five buildings, which have been constructed in different periods ranging trom 1948 to 1981. One of them burnt down during the riots last year. The oldest factory is what could be called a textile museum. Adminlstration Is a mess here and the production is negligible. The machines are antiqua and tor sure not effective in chemica! use. Two steam locomotives trom the former century are now serving as boilers, heating water by wood burning. Two factorles were built In 1965, one is responsible for the scourlngjbleachlng process with the orlglnal machines. In the other one is the final flnlshing is done (dry processes). In 1981 a wet textile processing plant started eperation with newer technology and a cleaner workfloor. I was only allowed to take photographs in the newest section. This sectien is located In the building of the weaving sectien c.q. head office. In the weavlng sectien the noise is darnaging the hearing of the labourers who are werking without ear props.

Generally the housekeeping Is very poor, especially in the old factory and In the dying & finishlng department Machines are badly rnalntained and oills spilled trom boilers in the newer factory. There is very little space between the machines in the wet processing area, whlch makes adequate malntenance and cleaning up lmpossible.

There is no form of pollution reduction or wastewater treatment. Everything is discharged into a lagoon berdering the sea. Within the premises there is enough space to construct treatment works. I was introduced to the four production rnanagers of the four sections. Only one of them was really helpful. The others didn't know what they were talklng about or didn't understand what I wanted to know.

* Bakson The factory started oparation In 1967 and was established inslde the approved industrial zone in Ratmalana. However this zone has become more and more residential, because all the gaps were filled with dwellings. The wastewater is dlscharged into an open channel which flows into a river. No treatment of wastewater Is practised. Neither any recycling is taking place (because there is no sultabla infrastruc­ture. Within the premises no space Is available for the construction of a treatment plant (total acreage of the factory: 1.25 acres). The workfloór Is wet and dirty.

According to the directer the government should help by providing treatment facilities, technological know how and space. lt should also investigate the option of a central treatment plant within the area of the 1 mile radius, within which 8 textile industries are situated. Furthermore, to construct treatment systems at the expense of the private companies, low interest loans should be provided.

Personal opinion: nice directer, willing to help and to answer any question, which gives me the feeling of an open discussion. Bakson is a very compact factory. The only salution to the waste problem of this particular factory is to construct a central treatment plant.

* Fairline Fairline has been established in 1978 in Ratmalana In a zone which is mixed residential, commercial and industrial. About 36 Industries are situated within a radius of 2 km. Among these one can flnd about 7 other textile processing factorles (Hybro, Bakson, Kundanrnal, Sigiri, Velona, Cadillac, Colrnan). The factory premisesforma heavily compacted area (1 ~ acre), covered with a boundary wall. No space for any treatment system. Fairline will very much benefit the operatien of a central treatment plant

The wastewater Is discharged into an open channel or drain, which Is also used as a sewer by residents. The water is hot, coloured and strongly polluted. There is also significant air pollution: neighbours are complaining about smoke settling down within their premises. The housekeeping is satisfactory.

43

Comparison of the visited textile factorles

An overview of some typlcal characteristlcs of the visited textile campanles can be found in table below (table 4.1 ). I have to note that the Pugoda factory Is the only state owned company which was visited. This company is large scale, whlle the other seven textile factorles can be called medium scale, when both thelr employment and production are considered. When a weaving section is incorporated in the factory, the employment is significantly higher, but not the production level. Inthls case the employment ranges from 450 to 3000 workers. Without a weaving section about 100 workers are employed. Most of the factorles date from the slxties and early seventies. Water Is in most cases supplied by both tube wells and public supply. Wastewater is dlscharged through open or covered drainsintoa lake (Bolgoda L.ake, near Ratmalana-industrial estate) or into a river.

characteristics MKC Baksons Fairline Swastlk Velona Kundanmal Duro Pugoda

production 8,800 9,700 2,600 4,000 1,100 1,100 1,700 19,200 (kg textjday)

start of oper- 1957 1967 1978 1964 1948 1964 1969 1972 ation

employment 130 100 100 680 1735 600 450 3000 (+w means (+w) (+w) (+w) (+w) (+w) +weaving)

souree of tube public public public public shallow tube Keiani water supply we lis supply supply supply supply we lis wells river

+tube +tube +tube +tube +tube we lis wens we lis we lis we lis

method of tank open open covered open covered open open wastewater lorry drain drain drain drain drain drain drain discharge

Final point of marsh river lake lake lake river marsh lake, discharge river

Table 4.1 - typical characteristics of the visited textile factories

44

4.2.2. THE LEATHER INDUSTRY

General background

The laather industry in Sri Lanka Is relatively small scale and 14 tanneries are significant polluters In the Colombo area. El even of these cernpanles are family concerns which originally started with bark tannlng. Most tanneries shifted to chrome tanning for thelr secend souree of income.

The tanneries are partly located In specially approved industrial zones. Usually the tanneries are located away from residentlal areas. Urban expanslon however has resulted In residentlal areas coming up close to tannerles whlch were originally sited on the outskirts of town. The factorles can mainly be found in three concentra­tlons: Palliyawatta, Rajagiriyaand Kelaniya, all a few miles north and northeast of Colombo city and near the banks of the Keiani river.

In the laather tanning process significant amounts of water are used. Especially the wastewater from chrome tanneries (uslng

. chromium salts) cause a real danger to public health, since no wastewater traat-

......... ",. .. tanneries··~··d~·~ó,di;··~··c~~~·~ri~stmeiJt·br·t/re· .. ······· ~~i~~~=~~;1oo,a&,~s H >

#J>Itäflnvestp!nt; 40 ~ ~ f US$) > -~:;,~=~::;=~OO,oyg·. f i

. S? lalpe scälë (jc;f()rles (~~2,000,00() ~( (;spitS/ JnVê$~nt) · · · · · · · · · · · · · · · · · ·

···········E~veA•tx>nlpan/es··"~·~s~··~BI1···i~·eln~~~:·~·f:Oin})M/es > ha1llt bêfwèe17 .100 atld 500 employees; ()(16 company, ÇeyiÖn t.si!AtherPrOdücts Cojporation, has over 500 iabourers. •· · · ·

::::::: .. :.· .:-:.":"·:::··:::.·.-·::·.::.::·-:-::.·: :·::::::::::.-.:::.-::.:::.:.:.-::::.:.· .. ·-:.:..:. :: ... ·.··· ..... .

Leatnertaf1T1Îng is a I'B{Jici&J~=i~ i~d~stry, m/JCf1 in .1983 ono/ ••····· 9 tiJIIrifJries \Wre in i>~fät/On. coràpa.fed to 15 in 1990. th. pro­<. dllëtion inereased. ft6frl121o 31 metTic 1ons p~~r dll'J In these· 7 y8ärs time. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

ment is practised, except in ene tannery: Tan Lanka. The chemieals which are used by the vlsited tannerles are mentioned In Appendix Vl. T-hese chemieals include chromium salts, sulphites and 'Sülphates, ether salts, formic acid and sulphuric acid.

A recent development: 11 tanneries are forming a company for central tanning. The member-tanneries will cease tannlng. Tan Lanka will continue. The central tannery will probably be allocated at Palliyawatte or in the north-west: Chilaw. The production wlll be approximately 1500-2000 hides per day. Each tanner will have to pay 1 million Rupees for the central tannery. The Export Development Board wlll also be a shareholder and pay this amount. Each member company gets a share of two days production per month ( = 3000-4000 hides). According to Mubarak this is net suftleient (actual production 7000 hides), which means that this factory will continue the tanning process. lt Is planned that the member tanneries will cease tanning except Tan Lanka. I think that after the establishment of the new central tannery, the old tanneries will continue tannlng, because of the expansion opportunitles of the market

Observation in the field: factory vislts

*Ceylon Lesther Products Corporatlon (CLPC) The Ceylon Laather Products Corporatien started eperation in 1941 as a government-owned company and was privatised In 1990. The company owns two tanneries, a factory manufacturlng laather products and some shops. The organlsatlon lnherited a complex bureaueratic structure with many hierarchlc levels and a very high amount of non-productlonal staffmembers. The production line seems lnefficient to me.

CLPC is located in Mattakuliya, a peninsula formed by the Keiani river mouthand the sea. The distance of the tannery to this river, the final wastewater discharge point, Is about 150 meters. The tannery

45

wastewater is discharged almost untreated. There is one sedimentation tank where preclpitated sludge containing chromium hydroxide Is periodically removed. However, the system Is badly functioning and hardly maintained. A larger treatment plant has been designed, but no funds have been allocateet for construction. The wastewater contalns high chromium (av. 42 ppm in 1987, without treatment). The medium scale tannery is located In a zone, whlch Is mainly lndustrial but also partly residentlaL Thls means that certain plants behlnd the tannery are plucked and used for food. According to measures (1987) these plants contain toxlc chromium (26 mgjkg plant! [Amitha, 1987])

The housekeeping within and around the factory Is very inferior. Especially the muddy area between the factory and the river Is almost lnaccesslble. Hldes are lingering around and the final wastewater is flowing everywhere, causing the mud. Hence, the smeU Is unpleasant on the premises.

* Tan Lanka Tan L.anka Is a new and relatively advanced leather tannery. lt is located near the mouthof the Keiani riverIn a mainly lndustrlal area (specially allocateet for leather tanneries). The factory started oparation in 1988 and manufactures chrome tanned leather. With foreign asslstance (TNO, the Nether1ands), a modern treatment plant has been built recently. This plant (aerated lagoon foliowed by coagulation -precipitation) seems to be functioning all right. The construction and oparation costs are high. Without foreign assistance Srl L.ankan tanners would never be able to finance such a treatment plant. There's one drawback to the system: the sludge from the precipitation and sludges from screening and intermediate sedimentation are drled, put in bags and dumped into (deserted) paddy fields. The toxic chromium (VI) Is converted lnto less toxlc chromium (111) by means of the flocculants aluminlumsulphate and polyelectrolyte. Which chemieals are present In the sludge? In the future Tan L.anka wishes to treat the wastewaters of the neighbours as well. Furthermore TNO has written a proposal for recycling of chrome, but funds are not yet available. The factory looks very clean. There are no complalnts about housekeeping, neither about odour. The effluent is also conforming the GCEC-tolerance limits except the BOD, which is somatimes too high (NARA takes samples twice a month). (See also photos 4.1 and 5.1))

* S.A. Perera SA perera Is a small scale tannery in an industrial zone In Kelaniya. SA Perera owns 52% of Tan L.anka and 60% of Ned L.anka (two other tanneries). This smali-scale tannery dates from 1955 and looks wornn out. Some modern machines have been purchased for the leather finishing operations, but the tanning process ltself remained conventional. Chrome tanning is obviously the major cause of water pollution. The wastewater is discharged into abandoneet paddy fields untreated, while the average chromium content is high (peak flows of 33 ppm. [Amitha 1987]) Some form of treatment Is present: sedimentation after neutralization with lime, according to the factory manager. The general manager tells me, that preclpitation with flocculants "Nalco" and MgS04 takes place in 5 sedimentation tanks. The sludge (according to both) Is used for landfill. The sedimentatlon tanks look like ordinary pits, where no controlled process could ever take place or has ever taken place. Some sludge is removed lndeed, but I doubt if the final wastewater Is free of toxlc chromium (111) and other chemicals. Also the sludge can be toxlc.

Chemieals in the soaking pits are recycled, whlch means, that the same contents of the pits are used for more than one batch of hides. Furthermore, the tannery Is trying to lmprove the efficiency of chromium uptake, to reduce the waste chromium. The housekeeplng Is not sufficiently organlzed: Raw salted hides and solld wastes are causing odour problems around the factory. Walking inside the soaklng department is impossible without soaking your feet. There Is very little space between the drums, pits and machines.

SA Perera's future goals are to reduce tanning, to Import processed leather ("wet blue") for final finishing and to expand Tan L.anka by lncreasing their tanning. Furthermore the tannlng processas of S.A.Perera should be lmproved by recycling of chromium and improvement of the chromium absorption (research

46

is carried out). The general manager consiefers a trestment plant at SA Perera as one of the worst alternatives. He fully supports the idea of a central tannery equipped with an adequate trestment system, like Tan Lanka's. (see photos 4.4 and 4.5)

* Mubarak The Mubarak tannery Is a small scale tannery, located In a rural residentlal area 15 km trom Colombo. The factory premises are berdering a wide marsh. Thls water body is used for discharge of the wastewater after sedlmentation in three or four subsequent pits. Sludge is removed, put lnto bags and used as landfill near the factory. All pollutants flow with the wastewater lnto the marshy land. Plans are taken for installation of actlvated sludge trestment (deslgned by NALCO South East Asia). The tannery produces chrome tanned laather for the local market and wet blue for export. This production plant started operatien in 1984. The vegetabla tanning process at Mubarak dates trom 1950. In the near futura, within one year, a production increase of 50% is envisaged.

A new factory building is under construction, which may be the causa of very bad housekseping and a big mess everywhere. Waste laather pieces are being used as landfill to keep the marsh away trom the factory. Sedimentation pits are very close to the factory walls. This area Is muddy and difficult to reach. The marshyland and a small rlver are berdering the sedimentation pits and the buns very closely. The Iabour conditlens are very bad, people are werking with hides in the soaklng pits on barefeet. Within the factory the floer is very wet and dirty, especlally near the drums.

According to Mubarak the idea of a central tannery is good, but its envisaged production will be insufficient, which means that this factory will continue the tanning process. (see photo 4.3)

* Anthony Th is tannery has been summoned by the landlord to cease laather tanning at its existing location. The factory owner has requested forstarting up a plant in Ja-Eia. This plan includes a trestment plant similar to Mubarak's "system". However, no parmission has been glven yet, while the request has been made one year ago. Actually the vegetabla tannlng factory, dating trom 1976, Is owned by Mubaraks. They are also neighbours and discharging into the same marsh. lntolerable smells are emerging from behind the factory walls. The direct neighbours (upper mlddie class residents) are complaining about the situation. lnside the premises the look as wellas the smell are unbearable. Labour circumstances are inhuman. People having wounds, sores and infectlens from werking half naked with hides and chemieals in the soaking pits. (see photo 4.1)

Residentlal areas are surrounding the factory. The marshy land contains black water and smells in a radius of several hundreds of meters around the factory. Many stray dogs and flies cause nuisance within the premises. Wastewater and sollef wastes are spreaded over the entire premises.

Comparison of the visHeel leather tanneries

An overview of some typical characteristics of the visited leather tanneries is provided in table 4.2. Generally it can be concluded, that all tanneries except Tan Lanka are relatively old factories. Tan Lanka and CLPC are having the highest production capacity. The werkforce of the chrome tanners ranges between 50 and 130, which can be classified as smalljmedium scala. All tanneries (except tan Lanka) have their own tube wells. In additlon some tanneries use public water supply. The wastewater is discharged through drains into the Keiani river, paddyfields and marshes.

47

characteristics Tan l.anka CLPC-tannery SA Perera Anthony Mubarak

Production level 6000 9250 2000 712 3160 (kg hides per day)

Commencement of operation 1988 (Cr) 1941 (veg.) 1955 (veg.) 1976 (veg.) 1950 (veg.) (of vegetable and chromium 1957 (Cr) later (Cr) 1984 (Cr) tanning respectively)

Employment 65 130 100 14 52

Souree of water supply public supply public supply public supply tube well tube well + Keiani river +tube wells + shallow

wells

Method of wastewater dis- open+ open drain covered drain open drain open drain charge covered

drains

Final point of wastewater dis- Keiani river Keiani river paddy fields marsh marsh charge

Table 4.2. - Overview of typical characteristics of the visited laather tanneries

Photo 4. 1 - The employees of the Anthony laather tannery

48

Photo 4.2 - The tanning drums at Tan Lanka

49

Photo 4.4- The soal<ing pits of the S.A. Perera tannery

· .. .,· .~--·· ... -

Photo 4.5 - The chemica/ mixing department of S.A. Perera

50

4.2.3. NATURAL RUBBER MANUFACTURING INDUSTRY

Background

The rubber lndustry is widespread over the country, mainly In rural areas. Thousands of small production units - the so-called small-helders - are producing natura! rubber from latex in Sri Lanka. Furthermore 89 private owned and 145 state owned medium scale factorles are operative [RRI, 1990). In addition, CEA counted over 200 industries whlch manufacture products from natural rubber. In the course of this research I will not dlscuss these manufacturers of rubber products, although 3 large scale plants are causing significant water pollution. I will restriet myself to the producers of natural rubber from latex.

All factorles cause water pollution by discharging their wastewater which contalns rubber partiel es, high solids and several chemieals into the nesrest streams or on low-lying land. Chemieals which are used by the visited factorles are mentioned In Appendix Vl. These chemieals lnclude acids like sulphuric, acetic, tormie and oxalic acid, salts, ammonia and organic compounds like mercaptans and phenols. Most chemieals are hazardous to the environment. The polluted water is often used, especially In rural areas, for drinking and washing purposes by the local people.

. Raw rubber processing units have existed In Sri lanka over 75 years. Complaints that wastewaters from these units constitut a nuisance and health hazard have however been made only gyring the

: .. : · .... :·· .. · .. ::_<··: ..... -... -:.:::·:::::::·:::·:-:. . -:"·:-}:::::::·.:: :.":_ ... :::::: ·: ·:· .. ·.-.... · .. · > · ..

. The arrnUIJI natu~r roiJbei prodtÎçtj()tfin Sri Lanka accoi.Jn~ for123,00Q tem {1988} and ïnWIJ/y coi'tsfsts of crepë and RSS rubbei: · • ·. ·• > > < . ·•· ······· ... . . . . . . .·.

~ Ribbed Srri<Jiced Sheet (RSS) . i < > 45%

·•.•·•······ ...• :~.%~ect;:tHJr(TS~)> .·.·······.··········.·~~ ·. •Other ····•.• ··· · · ····· 12% · .. ·· ····.·.·.·.·.· .. ·· ....... ··· .. ....... . . .. .

RSS rubber Is mainly produced by smal/ hofders,. other types of rubbermainly by private Coinpanies.The govem­ment owned faclotif,ts ptodominantly produce crepe rubber. · · ···· · ·

.. .·· ... ·. . .. . ... · ..

· 90% ofthe producticirus eXpbrted, 1llfi çliltivated al8a is at>out 200,000 hectares and the empfoYtrient In the rubber industry has ä shàl'fl of about 5% of the totaJ employment In Srl Lanka (4()(),000 peop1e incl~ smllfl holders).

past decade or two, The reasens for such complalnts are to be found in the following causes:

• Present rubber cicnes produce higher yields of latex than the old seeding varietles and consequently more latex is tapped and has to be processed.

• Medium scale processing centres, set up in recent years to handle small holders' latex, release large quantities of wastewater compared to the srnall and scattered rubber processing units of the earlier period.

• Centrifuging plants, set up to produce latex concentrate, release wastewater with high pollution leads.

• Hurnan settlements have spread into areas close to rubber factorles where no dwelling houses existed previously.

Observatlon In the field: factory vislts

* Ceymac Rubber Company Ltd. The company Is divlded over two factories, both rnanufacturing (pale & sole) crepe rubber. One factory is also producing TSR-block rubber. Raw rnaterials are latex, scrap rubber and RSS rubber. The factorles have both been established in an lndustrial zone near the rural town Horana and started eperation in 1984. One of the factorles discharges into a company owned marshy land. The ether one discharges into a large rlver. No trestment is carried out, because according to the management, the diluted wastewater is not harmful to the river quality. However, samples by RRI (Rubber Research lnstitute)

51

indicate that the Important characteristics are not conformlng to the standards. (BOD and Suspeneled Solids are too high). The flnal wastewater Is white, contains visible rubber particles and flows lnto marshy land, before reachlng the rlver, causing high vegetation growth. Much excess water flows on the factory floor ancl can probably be reduced. Milling water and washing water look very dlrty (brownish), however the major pollution is caused by the serum wastewater. Housekeeping can be improved, especially in the block rubber (TSR) section, where rubber pieces and wastewater is rnaking the floor invislble.

* Matugama Rubber Mllls At Matugarna elther pale crepe or RSS rubber Is rnanufactured from locally tapped latex. The small scale factory with only 15 workers Is located In a rural agrlcultural + resldential area. The wastewater Is discharged lnto a soakage pit ancl finally flows lnto a srnall stream where village people are taklng baths and washing their cloths. The sludge from the soakage pit Is removed once a year. No trestment Is carried out. Because of the insufficient availabllity of space wlthln the premlses, only a srnall trestment system can possibly be constructed. Questlon Is lf the factory owner will be willing to pay for lt.

The factory work floor is dirty and wet. An unpleasant smell can be observed. Behincl the building the continuous wastewater discharge has caused a real marsh.

* Dartonfield Dartonfield Is located In the mlddie of the latex-supplying rubber plantation (500 acres), was established in 1940 and is government owned. Pale and thin crepe rubber are produced. The factory ownes a wastewater trestment plant and a laboratory. The factory serves as an experimental or pilot plant for the Rubber Research lnstitute of Sri Lanka. The trestment at the moment lncludes sedimentation, aeration and sand filtration. The sedimentation works for only one third, because one of the walls collapsed. Prior to sand flitration and after aeration another sedimentation tank should be placed to prevent the final sand filter trom clogging. The system is not werking properly now (BOD still too high)

Research is planned for "overland flow", using the wastewater as fertilizer for rubber trees. There are some pessimistic sounds however, saying that this land application is impossible In Sri Lanka because of the steep slopes of the rubber plantations (which will cause erosion) and because of unsultable soli conditions.

* Sorana State Plantation, Ellakanda factory Ellakanda is established on a hili in an agrlculturaljresidential zone. The factory produces only a small amount of high quality crepe rubber with a Iabour force of 45 werkers. The company was formerly state­owned and inherited a bureaueratic administratlve system. The amount of non-productlve staffmembers is consequently high. Wastewaar is discharged lnto lower paddy fields, which are still in use. Farmers are complaining about the smell ancl the reduction of their rice crops. The factory ltself looks reasonably clean. Hence, a complex trestment plant designed by a toreign assisting agency (BKH, the Netherlands) in 1988 has still not been taken up for construction, because of the slow declsion-taklng processas In the top.

* Glenross Rubber factory Glenross is a neglected rubber factory, establlshed in 1979 in an agricultural + residential area. Centrl­fuged latex, skim rubber ancl sole crepe are produced out of latex trom local srnallholders. The wastewater is dlscharged through a tank and a drain into the neighbouring paddy fields downhill. Regarding wastewater tretment, "land applicatlon" is tried out, which means that wastewater Is pumped uphill. The method is badly practised and doomed to fail:

52

"Land application" Is tried out, 1 00 yards uphill trom the factory, near the managers house. Since two weeks (nov 1990), part of the wastewater (the serum, mainly) is pumped up to the "land

application system", where it ftows into a gutterwith a lengthof approximately 40 meters. when thls gutter overflows, the wastewater will equally be dlstributed onto the land.

The hili has an extremely steep slope. lt is obvious, that the water does not have any time to be absorbed by the soil. The wastewater will form a new drain, which will flow lnto the existing drain nearby the road. After two weeks of experlmenting it is already vlsible, that near the waterflow and because of the waterflow, the grass and other plants have dled. Concludingly, this system is judged as unsuccessfull and a-serlous In handling the wastewater problem.

The housekeeplng In the factory is extremely filthy. Wastewater trom the latex centrifugatioin is ftowing over the work ftoor. There Is an unpleasant smellln and around the factory. The coagulation tanks are very dirty and are probably never cleaned.All thls creates bad clrcumstances tor the workers Some of the mllling water Is recycled. The serum and milling wastewater are ftowing into different drains, but finally come together. This wastewater ftows downward into a common drain, near the road ( residen­tlal area)

* Dippad Products Ltd. Dippad products Ud. Is located in a residential, agricultural and industrial area and has developed advanced technology since it started in 1977. The factory produces rubber gloves trom concentrated latex. Centrifuging of uncoagulated latex also takes place In the factory. The final wastewater contalning high sollds and high COD is treated in an oxldatlon ditch, foliowed by a sedimentation tank. Part of the wastewater (trom the washing dept.) Is only sandfiltrated. The system has been designed by Dippad Products ltself and started oparation in 1985. The company has lts own laboratory. Occaslonally BKH provided technlcal assistance.

The treated effluent is much cleaner, but still contains high dissolved solids (6000 mg/1). Plans are made tor recycling of a part of the washi~wastewater (30% of total wastewater). Sand tiltration is not functioning (clogs up). The company is characterlzed by good and clean housekeeplng, necessary tor complex technology.

Comparison of the visited rubber factorles

An overview of some important characterlstics of the visited factorles in the rubber sector is presented in the table below (table 4.3). lt can be concluded, that tour private factorles are ten to twenty years old, while the two government owned factorles are over 50 years old. Dippad Products Ltd and Ceymac are large scale rubber producers, the other factorles are medium scale, when both production and employ­ment are considered: the two large scale factorles have an employment of over 150; while in the medium scale factorles the work force is less than 70. The large scale factorles are privately owned and the largast producers of natural rubber. Generally the water Is supplied by tube wells and small streams. The wastewater Is dlscharged through drains lnto srnall streams and paddy fields.

53

characterlstic Dipped Ceymac 81akanda Dartonfield Glenross Matugama Products

Production level 5,800 46,000 1,800 1,200 3,000 1,200 (kg rubber per day)

Original ownership private private state state private private

Gommencement of 1977 1984 1940 1940 1979 1970 operation

Total workforce (excl. 350 150 54 30 70 15 latex tappers)

Souree of water sup- tube wens sedimented tube wen tube wen+ tube wen+ tube wen+ ply surface water sman sman stream sman

trom river stream stream

Method of open open+ pipelines covered open drains open drains wastewater discharge drains covered drains

drains

Final point of irrigation marsh (near paddy fields a man paddy fields sman wastewater discharge stream river) stream stream

Table 4.3- overview of typical characteristics of the visited rubber factories

54

4.3. ESTIMATED CHARACTERISTICS OF THE WASTEWATER FROM THE VISITED TEXTILE, LEATHER AND RUBBER FACTORIES.

4.3.1. INTRODUCTION

In chapter 3.1. a method has been explained to estimate the loads and concentrations of certain pollution parameters such as BOD. lt also was explained how to estimate the volume of the wastewater daily produced. The estimations were based on the production level of the factory in particular. In Appendix N the calculations according to 3.1 are carried out and presented In 4 tables. For all factorles vlsited the wastewater flowrates, the BOD-Ioads and BOD concentratlons have been calculated. For the leather tannerles also the chromium loads and -concentratlons In the wastewater have been calculated.

The BOD loads from the industries can be expressed in inhabitant equivalents. The waste load is then consldered as the sewage discharge of a certain amount of citlzens. Figures from Western Europa will be used, because data of the BOD loads produced by a Sri Lankan citizen are not available. In this way it Is possible to give an idea of the organic waste load, being equivalent to the sewage from a certain populatior1 size.

In other words one could say, that for the blologi­cal purification of wastewater from a certain fac­tory, the same treatment capacity Is required as for the puriflcatlon of dornestic wastewater pro­duced by the calculated population size.

The major conclusions from these estimations will be discussed in thls chapter. The estimated polJution loads and concentrations are compared to the toleranee limits valid for Sri Lanka. These toleranee limits can be found in Appendix VIl, table 5. An example of the calculations, which are pres­ented in the appendix In the form of tables, is shown in the cadre below.

· Exampte: Tan Lallka, ~r tannery

• Prodüeti()n of Tän 4flka: 6000 kg leattrerjday. Tlre expected fl()w of t11e wa~tewatet is 52 Vkg *.6000 kgfday = 312,ooolfday ~ '312m

3fday. •············· · .....

· This amount can be compared fO ~ measuted value or · the value obtained by 1fltervîew .. The CEA measuted 275 m3fday at Tan Lanka. .··• ••

.. . . ..

• · Relative ·BOD ·~ fQf}ëäther manuftlcturing: 89 kg BOD jton leather; ttre production was 6000 kgfday. The Expected BOD-Lóad is ëonse(luëntly: 89 * 1if' * 6000 ,., ~34 kg BOD/day. ·. . . ..

··· .... ·.· .. ··.· ... · .... ·.· ... ·

.... . .

The.Expected BOD-ëimcentration is: 534/kg BODjday) f275{rn3jdayJ"' 1.942{kgjm3]=1900{mg/fJ .··.••

• Analoglcally tó the calculation ofBOD-kiad and concen• tration, thë estJmated .foad and C()l7c;entratlon · of Sus­pended Solids (SS) ca11 be found. Relative ~load is 138 gfkg raw hidtfls. Production was 6000 kgjday. .· • .· • .· · · ...... . .. < ... . .. . SS·Io8.d = 6000 {kgjday) * 138 * 10~Jkg SS/kg hkies] = 82B{kg SSjday] · · · · · · · · ·

:· .. :.·.:::_:.:::·:::::·: .· .·· ::::::::· .·. ·>:.::.::>>·<<:::.:.··::.:. :.·::· -:_:::::: ·. ····.····The $Sëo11cë11tratiÓn I$< 1~ * lf2B(jkgjday) ./ 312 .····

l~fday} = 2700{1J1f1/ll . . ···.·· .. · .. . ··.·.· .. ·. .. . ·.·.·.··.·· .. · .

.............. ... . . · .. ·.·.· .. · .. · .. ·.· ...... ·.·.· ..

• On• Jn/)abftänt equiya/ent piDdudes a BOD of 54[g BoDfcläy). WitflJhe BO~töad lcrio\vnin {gjday]. t1re

· ·. number Of inhabitänt e(luivalenis. e(liJals 534,000 1 54 • .. 9900.

55

4.3.2. RESUL TS

The textile lndustry

In the visited factorles averagely 61% eetton fibre, 27% polyester fibre and 12% other synthetic fiberes are processed. Cotton processing causes a higher BOD than synthetic fibre processing, but Is less toxic.

The daily wastewater volumes of the textile factorles are In all cases except one significantly higher than the volumes whlch were given to me In the interviews. These ditterences might find their crigin in:

• Lack of knowledge of the Interviawed persen. He might have used wrong units or conversion factors.

• Inadequate maasurement of the wastewater flowrate. Batch discharges were perhaps nottaken lnto account.

• Inadequate estirnations. The method might be inapplicable to the Sri Jankan textile lndustry. This Is however not plausible, since the method is designed and propagated especially for developing nations. [Economopoulos, 1981)

• Underestirnation of negative wastewater characteristics by purpose, in order to avoid negative publicity for the company.

• Not rightly chosen assumption about the weight of one meter textile (0.22 kg/meter)

The estimated wastewater production ranges trom 200 to 4000 cubic meters per day.

The total BOD-Ioad produced by the 8 factorles Is equivalent to the sewage of a popuiatien of 133,000 inhabltants. The largast contributors are Baksons, MKC and Pugoda, together accounting for 79% of the total BOD load. When the 171argest polJuters within the textile lndustry [CEA, 1989] are taken together, their wastewater can be compared to the sewage of a Western Europaan town of 235,000 lnhabitants. 43% of this hypothetical sewage Is produced by the three government owned companies. Remark: privatisation of the textile industry is envlsaged on the short term.

BOD concentrations of the wastewaters trom the 8 factorles are all 10 to 114 times higher than the toleranee llmits. They are ranging trom 500 to 7000 mgjl. The estlmated BOD concentratlons do not conform to the samples taken by locallaboratories. According to these samples the concentrations are 2 to 25 times higher than allowed. These ditterences mlght be the result of the issues mentioned above (p.46), but they can also be caused by inadequate monitoring. The BOD should be maasured every hour during one full week in order to take into account the batchwise discharge of the wastewater and obtain a reliable picture. This type of monitoring is rarely carried out in Sri Lanka. Sampling Is rather done at random.

Suspendeel Solids concentratlons are ranging from 400 to 3200 mgjl, which is 8 to 64 times the maximum allowed concentration.

Leather lndustry

Two tanneries, Tan Lanka and CLPC, account for 50% of the total chrome tanned laather production In Sri Lanka (as registered by CEA). Four of the vislted tanneries produce for more than 96% chrome laather. One tannery, Anthony, Is a 100% bark tanner.

The wastewaters trom chrome laather tanneries vary trom 100 to 500 cublc meters per day. Anthony has a lower wastewater volume, because of lts low productlon. The estlmatlons were raasonably accurate when compared to the figures on wastewater volume obtained by Interview.

The five tannerles produce together a polJution load which is equivalent to the sewage of a town with

56

34,500 inhabitants. When theeleven largest polluters are taken together (CEA, 1989), then the pollution load is equivalent to a town of 50,500 people. When the future tannery also starts produclng the planned amount of leather and the other tanneries will continue tanning, then more than 80,000 people are living in "Leather city".

The chrome tanners discharge wastewater with high BOD concentrations, ranging from 2000 to 3500 mgjl. This Is 30 to 60 times higher than the allowed toleranee limits in Sri L.anka. The vegetabla or bark tanner produces an wastewater with a BOD concentratien of around 600 mgjl.

The total amount of chromium discharged into the environment by the eleven largest polluters is estimated to be 86 kgjday. tn the wastewater treatment plant of Tan L.anka 21 kg chromium is expected to be removed daily. The chromium concentratien in the wastewater of chrome tanners is estimated to be between 76 and 130 mg/1, while the toleranee limits do not anow concentrations of more than 2.0 mgjl. Suspended soliels concentrations are ranging from 1200 to 5000 mgjl, which is 12 to 50 times the toleranee limits.

Rubber industry

The total rubber production of Sri L.anka Is about 410,000 kgjday (RRI, 1990). The majority is produced by small holders and medium scale units. Ceyrnac alone accounts for 11% of the total Sri L.ankan rubber production. In the six factorles visited by me, a total amount of 59,000 kg rubber is produced per day. The estimated wastewaster flows correspond very well to the wastewater flows obtained by interview,

· with one exception: Ceyrnac. The factory wastewaters are ranging from 35 to 72 cubic meters per day, except the wastewater from Ceyrnac. ' This company is an exception, because the lt owns two medium/large scale factories; One factory is the largast manufacturer of crepe rubbef" and the other is the only significant producer of TSR-rubber. For the production of the latter rubber type excessive amounts of water are used. The collectiva wastewater volume is 3500 cublc meters per day (interview), which Is more than twice the estimated value. lt is controversial, that the factory manager finds lts wastewater enough diluted to be a hazard to the environment.

The 6 factorles produce a collectiva BOD-Ioad which is camparabie to the sewage of 58,000 inhabltant equivalents. Ceyrnac is responsible tor 84% of this load The entire rubber industry of Sri L.anka produces an organic pollution load equivalenttoa city of 410,000 (Dutch) people. Of course the environmental impact is difficult to estimate, since the rubber industry is scattered over the island rnainly in rural areas. Only the pollution by biodegradable compounds are considered. The total pollution of the rubber industry is higher because also inorganic substances, acids etc are discharged. The BOD concentrations are all very high ranging from 1000 to 5000 mg/1. The concentrations of Ceymac wastewater is the lowest, because the waste is very much ddiluted by a high wastewater volume. However the BOD Is still15 times too high. In the worst case - Dippad products - the BOD concentratien is 1 oo times higher than the toleranee limits. Fortunately a successfull treatment plant has been installed he re.

The concentrations of Total Solids are ranging from 900 to 5000 for producers of natural rubber, which is maximally 5 times the toleranee llmits which are set at 1000 mgjl. The lowest concentration, 900 mgjl, is estimated at Ceymac, where the wastewater is very much diluted. The load of waste solids in the wastewater from this factory is 3000 kgjday. The wastewater of Dippad products as a latex centrifugator contains a very high amount of total solids. (18,000 mg/1) .

57

General Remarlcs to 4.3.2.

The total wastewater In the textile, leather and rubber industry is shown In table 4.1. The volumes repre­sent the significant polJuters In Sri Lanka (CEA,1989). The textile and rubber sectors produce roughly ten times more polluted wastewater than the leather lndustry.

lndustrial sector daily wastewater pro-duetion

Textile 20 miJlion liters per day Leather 1.6 miJlion liters per day Rubber 14 miJlion liters per day

Table 4. 1 - amount of wastewater produced per sector

Most of the vislted factorles In the three sectors are being monitored by one of the Sri Lankan labora­tories. Sampling of the wastewaters of the vlsited factorles Is done by several agencies. From most factory wastewaters samples have been taken once. Some factorles are not monltored at all. Others very lrregularly (see table 4.2). Most data from the sample analyses carried out by the various laboratorles are not very reliable because they are outdated and because they reprasent the wastewater characteris­tics of one partlcular moment.

Name of the Sampling monitoring frequency factory yesjno Iaberatory of sampling

Textile industry Swastik no - -Kundanmal yes CEA only once Velona no - -Pugoda yes NBRO 6 months MKC yes CIS IR 6 weeks Duro yes CIS IR 6 months Bakson yes CEA only once Fairtine yes CEA only once

Leather lndustry SA Perera no - -Tan Lanka yes NARA 2 weeks Anthony no - -CLPC yes CEA only once Mubarak yes CIS IR 1 week

Rubber lndustry Ceymac yes RRI 3 months Matugama no - -Dartonfield yes RRI 1 day Glenross yes CEA only once Dipped Products yes own lab 1 week Ellakanda yes RRI unknown

Table 4.2 - monitoring of the wastewater of the visited factorles

58

Summary of 4.3.2.

When the wastewater flowrates are considereef, it is ditticuit to take conclusions. The water consumption given by the CEA, the wastewater volumes obtaineef through interviews and the calculateef expecteef wastewater flowrates are dittering significantly, see table below /appendix.

From the rough estimates In this chapter one can conlude, that in all vlsiteef factones wastewaters are produceef with hlghly pollutlng characteristics. All concentratlons of BOD, Suspendeef solids and Total solids are at least 10 and In a few cases over 100 times exceeding the toleranee limits. Insome cases-like the case of Ceymac Rubber - the concentrations are not very high because the wastewater Is very

much diluteef. However, because the waste load remains the same, the danger to the environment still exists. lt is ditticuit to take direct conclusions from the wastewater characteristics, because the estimation method is very rough and therefore not enough reliable. Furthermore, other sourees of information (interviews and CEA) arealso not always reliable for the reasons menticneef above. The flgures only can serve as an lllustration and a proof that the textile, leather and rubber industry in Sri Lanka cause sifgnificant pollution, for which measures have to be taken. So it is obvious, that all factorles In the three sectors with 3 exceptions (Tan Lanka, Pugoda and Dipped Products) neeef to reefuce the polJution load intheir wastewater significantly. This polJution reefuction can be obtaineef by low waste technology andjor by wastewater treatment.

Concludingly in the three sectors, which I have analyseef, the total wastewater is equal to the sewage from a city of 695,000 inhabitants. Thls comparison is only regarding the biodegradable part of the wastewater. Other wastewater characterlstics are not consldereef in the comparlson. Thus the total pollution of organlc matter from the textile, rubber and leather sector can be compareef to the wastewater dischargeef by a city of almost 700,000 Europaan lnhabitants (a city like Amsterdam).

These results are presenteef in table 4.3. The textlle and rubber sector are causlng the highest amount of organic pollutlon. In the textile industry thls Is because of the high concentrateef wastes in the wastewaters of a few factories. In the robber lndustry because of the large amount of industries. When the populatlon equivalent to the discharge by the visiteef factorles Is compareef to the countries total (columns 0 and B respectively), one can see, that the factorles visiteef In the textile and teather sectors are producing more than half of total organic waste produceef by the sector as a whole. In the rubber sector I visiteef only a small fraction of the total amount.

The state of the art in Sri Lanka with respect to polJution reefucing methods is outlineef In the following chapter, 4.4.

Sector Estimated number Equivalent popula- Number of Equivalent population of significantly tion based on the factorles based on the total blode-polluting factorles total biodegradable vislted gradable waste load, [CEA, 1989] waste load (Visiled factorles on/y)

A B c D

textile 17 235,000 8 133,000

leather 11 50,500 5 35,000

rubber 234 410,000 6 57,000

Table 4.3- equivalent popu/at/ons basedon organic waste loads.

59

4.4. PRESENT STATUS OF WASTE REDUCING TECHNOLOGIES BEING APPLIED IN THE VISITED FACTORlES

In this chapter the actual efforts are dlscussed which are taken to abate industrlal water pollutlon. The results are based on observation during the factory vislts and interviews with environmental experts Oocal as wellas foreign experts). The type of pollution abating efforts can be threefold: • Research and development by industrialists or by specially assigned institutes • The appllcation of waste reducing technologies withln the industrlal production processas (shortly called

•1ow waste technology-). • Final wastewater treatment.

4.4.1. RESEARCH AND DEVELOPMENT

Environmental research Is done in the laboratorles of several institutes (CEA, NARA, GCEC, Cl SIR, RRI, NBRO, Environmental Laboratorles Ltd, see chapter 2). The development of wastewater treatment technologieshowever only takes place In the environmental sectien of the Cl SIR. Practical results of this research are hardly vlsible. The development of in-plant low waste technology is done by a few lndustrial­ists whowant to increase their profits by minimizing the use of chemicals. Only mediumjlarge scale industries with large amounts of capital are able to finance this. In the rubber industry the Rubber Research lnstitute (RRI) is doing research in this field. Recycling of water Is hardly applied, because lts abundant availability. Recycling of chemieals Is in an experimental phase insome high capitallndustries (Tan Lanka, S.A. Perera). Summarizing, the research and development of low waste technology and wastewatertreatment methods is still In a very premature stage. Foreign assistance is used for the design of speeltic treatment plants. The final reports however are not used and imlementation does not take place. -.

4.4.2. PRESENT STATUS OF LOW WASTE TECHNOLOGY

In the case of low waste technology only the visited factorles are discussed, because no ether information Is available. In most factorles the machinery is outdated, dating trom the sixtles, and consequently not optimal in chemica! use. These machines are also lmproperly maintained. The water use is often unnecessarily high due to leaking machines. This results in splashes on the workfloor.

At the chemica! mixing department, I often observed very Inadequate measuring instruments and bad housekeeping methods. Insome cases the administration of chemica! use was inadequate. Chemieals are stored without labels In a small corner near the drain. No recycling of chemieals nor reuse of waste and by-products have been observed. Recycling of process water is not practised because no real water scarcity exists and because water is free of charge. Many factorles have their own tube wells. lf the willingness to recycle is present, then there is the problem of lacking expertise and the lack of a suitable recycling infrastructure (large process changes are necessary).

General constraints for the introduetion of low waste technology are: • lack of flnance • no effectlve incentives from government • incentives In the form of profit maximisation are only marginally seen • no expertise

60

The textile industry

In the textile industry, some factorles have - rasponding to the market demand - recently installed high tech machlnery (Duro, Pugoda, Velona). Thls Is generally the cleanest part of the factory, while In the dirty corners the old machines are still In operation. Of course only the companies with high capital can afford such machlnery. The introduetion of low waste technology Is still in an experlmental phase in a few (2 out of 8) factories. Where recycling Is applied, only boiler-water is recirculated. In most factorles no in-plant pollution reduction is undertaken at all. The following reasons were given:

- lack of funds, financlal problems - there is no water shortage, so why reduce the water consumption? - suitable infrastructure for recycling is lacking.

In Sri Lanka the textile industry uses the processas described In the Appendix 111. A brief summary of the processas Is also given In paragraph 3.1. The production procedure is divided In a dry section and a wet sectlon. The main souree of water polJution Is obviously the wet section, especially the subprocessas deslzing, scourlng, bleaching, dyelng and printing. An investigation of textile Industries by Cl SIR [Mathes, 1989] concludes that all technology substitutions made to mlnimlze waste have been effective, albeit only in medium scala Industries. large scale industries have some constraints in introduclng low-waste technology. Most waste reducing measures have been employed to reduce costs while produclng the same amount of textile and to increase proflts.

Further souree reductlon and reasonable traat­ment is practicabie if more incentives are given to respond to existing envlronmental regulations. Of the waste reducing measures as mentioned in chapter 3.1, no applications have been seen in the visited factories.

Examples of inplant waste redûction in the textiie fndustry: i< > . ·..•. . . > ···•··· } .· ·.

Caustlc SOda has bei/'1 riKJUêedJrt the sco.uring process: Hypochloride in the bleaching process has been be reduced. Dechlorinatrionhas been elimlnated by upgrad­ing the scouring and bleachfng i.Jnlt operations. Dyeing with jiggers generafes less Wastewater than dyeing

I through beafTI and wffiCh ~rät/on. Some general remarks: 1· .. ·

* Housekeeping is unsatisfactory In most of the ·. · ·· .. ·· textile factorles

* No applications of segregation of waste streams has been observed. * Equipment is generally badly malntained.

.···

* The administration of used chemieals is Insome cases unsatisfactory, which hindersexact and minimal chemica! dosing.

* ear props against noise polfution are not used, noteven in the weaving section. * No process water is recycled.

The lesther industry

In the leather industry, two factorles are taking efforts to maximize the chromium absorption of the hldes In order to minimize the chemica! use and to reduce the chromium concentratien In the wastewater. (S.A. Perera, Tan lanka, the former owns 52% of the latter) Hence there is some research on recycling: experiments with water recycling are taken (Tan lanka). Agaln at Tan lanka a foreign donor organisation proposed a system for the recycling of chromium. However, no measures have been taken because funds are lacklng. In noother visited factorles any visible in-plant waste minimization is practiced. There are no efforts to reduce the water use in tanneries, because water Is not scarce in Sri Lanka. In one tannery research Is being done to increase the chromium uptake by using other process chemicals. Tan lanka is the only tannery with a succestul treatment plant. Further actlvities in the field of waste minimization can not be observed.

61

The rubber industry

In the rubber industry no special polJution reducing measures are taken within the production process. lf any recycling is taking place, it's only for coollng water of the mills, which is the least polluting waste stream. At Dipped Products Ltd experlments are taken to recycle washing effluent (reduclng the wastewater with 25%). Because generally the year water is not scarce in the South-West of Sri L.anka, there is no interest in reducing the water consumption. Even though the production of some factorles is limited by water scarcity in the dry season!

With respect to clean technology, still many improvements can be accomplished. A clean workfloor is a first step. The water used for milling should be separated from the serum water. Chemieals should be dosed in exact amounts.

4.4.3. PRESENT STATUS OF WASTEWATER TREATMENT

General

The factorles which have been visited are not givlng a representative overview of the Sri L.ankan textile, leather and rubber industry. After discussJon wlth CEA-experts, it became logical to vlsit all factorles wlthln the sector with access to an wastewater treatment system. In addition those factorles have been visited, which are characterised by an extremely high water pollution. Therefore the lnformatlon presented in thi!!l paragraph gives a complete overview of the available applications of wastewater treatment as applied in the three industial sectors.

In Sri L.anka not one sewage treatmenf system was in eperation during the research period. There are no drain systems where industrial wastewaters can be divicled from dornestic sewage. All wastewater is directly flowing through the same drains into nearby streams, rivers or low lying land. There were two plants for the purification of sewage from the city of Colombo, but they closed down because their capscity became too small. Since no money was available for increase of the treatment capacity, the easiest salution was preferred: close down and discharge dlrectly and untreated into the Keiani Alver.

In the following paragraphs the state of the art is described of the wastewater treatment applied in the visited factories. Subsequently the situation is described regarding wastewater treatment within the Export Processing Zones. In the last paragraph the factors which influence the selection of an appropriate trestment system (see paragraph 3.2.5) are discussed with respect to the actual situation.

The textile industry

In this sector, one treatment plant is functioning reasonably all right (at Pugoda), despita the tact that the plant is not removing the color caused by excess dyes. The major waste content of the wastewater is blodegraded aerobically. Only the system is so expensively overdeslgned, that it will not serve as an example for other industrialists to treat their wastewater In this way. The treatment system consistsof a neutralisatlon tank, aeration tanks, a clarification tank, three stabilization ponds and sludge drying beds. The total area of the Jnstallation, including the ponds, is about one third of the factory premises.

Two companies, Duro and MKC, have taken attempts to treat their wastewater. Duro is treating only half of lts wastewater (from dying, nottrom printing). The system, belng equalisatlon and aeration foliowed by sludge drying beds, is still in an experimental stage. The results are hopeful,

62

but how can lmprovements be made if there's no process control? CISIR Is taklng samples of the wastewater only once In 6 months!

MKC is tess successtut In treating lts wastewater. In the compacted area of 600 m2 some sedlmentatlon pits, an aeration tank, a flocculatlon tank, sand filters and flnal settling tanks are connected to each other. The system doesn't work at all. The aerator Is out of order, the sand filter is clogging up, etc. The final wastewater is still colored. The company Is awaltlng advlee trom the CEA, has to respond to GCEC-Iaw and the samples are taken by CISIR and has to respond to GCEC-Iaw. This is very confusing!

Swastlk has also planned a complex system, but is awaltlng CEA advlce. The system includes a grit trap, colteetion tank, focculation tank, clarifier, holding tank and sludge drylng beds. The system is a cernpro­mise to the high costs and space requirement of biological treatment. In other words, a biologica! treatment system Is recommended, but due to Jack of space and Jack of funds, a flocculation system is designed. Costs 1 miltion Rs.

Finally Ceylon synthetics has planned an anaerobic system. The equipment is already available, but the funds are lacking for lnstallation.

The reasens why the remaining cernpanles are not treating their wastewater are in most cases financlal problems. In some cases lack of space is the cruelal factor. However, the factorles in the Ratmalana­Moratuwa area are very posltive towards a central treatment plant for the entire textile industry in that area, even if the plant is partly at thelr expense. Suggestion to the government is to provide low interest loans for this purpose. However wlth the high concentratien of dylng plants some form of special treatment for theis wastewater should be provided befere lt enters a biologica! treatment plant, otherwise the biomass wilt not work properly. In-plant treatment depends on the types of dyes being used and the types of fibres being dyed. lt Is also advlsable to separate waste streams in the same plant to give optimal treatment wlth possible recycle. In any case a thorough study of the type of toxic chemieals in the textile wastewater should beundertaken befere deslgning a pretraatment plant. (Oxley, 1990) Most industrialists leave the inltiative to the government (CEA)

Summarizlng: Samples are often not taken regularly. Once In slx months as at Pugoda and Duro Is certainly not suftielent for a proper operatien of any treatment system. Hence sampling is done by different laboratorles. Somatimes several environmental organlsatlons are involved In the poltution abatement of one factory. Communication problems can be a logical consequence. Sampling Is done by CEA, NBRO, CISIR, NARA and occasionally by laboratorles owned by the company ltself.

The industrialists show willingness in constructing a treatment plant, but in the first place don't have any expertise in this field. The factorles wlth treatment often have no special chemist for maintenance (example: Pugoda). Secondlyfinancial problems form an obstacle. Thirdly Insome cases the construction of a treatment plant is impossible because there is simply no space left for lt. Due to these obstacles, the industrialists leave all initiatives to the CEA.

The teather industry

In the teather sector, only Tan Lanka is treatlng lts wastewater successfully, but wlth some questlon marks. The system is physicaljchemical and includes screening, aeration + equalisation, flocculation, clarification and sludge drying. (see photographs 4.6 and 4.7). Daily maintenance is required. Samples are taken twice a month. However, the results of these samples indlcate a BOD which is still too high. Furthermore there are some question marks about the sludge. The composition is unknown and 1t Is dumped into abandoned paddy fJelds. Have the environmental consequences been investigated? How is the conversion of toxlc chromium (VI) into less toxic chromium (111)? For what period are the paddy fields abandoned?

There are three factorles which claim to have a wastewater treatment system: S.A. Perera, Mubarak (see photo 4.8) and the ceylon Leather Products Corporation.

63

However, in all cases these systems consist of ene or more seetimentation pits, to which certain chemieals are addeet and from where the sludge is removeet periodically. No stirring is done. The sludge of unknown composition is useet as a fertilizer!

Mubarak intends to construct a treatment plant, castingabout 1 million Rupees, and is assisteet by foreign expertise. The Ceylon Leather Products Corporatien (CLPC) plans to instaU an additional equalization tank. No expertise on the treatment of tanning wastewater Is present here. For S.A. Perera a treatment plant on its own premises is the worst alternative. Subcontracting the production of tanneet hides ("wet blue") to another tannery is more realistic.

The smallest and paorest tannery in Sri Lanka (Anthony) also intends to build a treatment system tor the same price as Mubarak's (ene million rupees). lt will be built at the new location of the tannery, which has to cease tanning at lts actual location tor environmental reasons. The factory is expecteet to be allocateet in Ja-Eia, 20 km north of colombo.

In the near future plans have been made tor a central tannery, where only chrome tanning takes place. Finishing of the tanneet hides will be done in the existing tanneries. Eleven tanneries will become shareholder in the new tannery and receive their share in the production. The location is nat definite yet, but rumours point In the direction of Chilaw. Except a brand new tannery also a wastewater treatment plant wUI be constructeet there. Because of these rigarous plans, most tanneries Qike Mubarak, S.A. Perera, Anthony) are waiting with the instanation of any pollution reetuclng measures. Lack of funds might be an extra reason.

In the leather lndustry the wastewater sampling Is done by saveral organisations: NARA (doing Tan Lanka), CEA (doing CLPC) and CISIR (doing Mubarak).

The rubber industry

In the natural rubber manufacturing industry, only ene company - Dippeel Products Ltd.- manages to operatea treatment system with success. In ene ether factory- Dartonfield-serieus experiments are taken by the Rubber Research lnstitute (RRI) for the treatment of rubber wastewater. At Glenross a non­serieus experiment is carrieet out under the name "land-application of rubber wastewater".

Dippeel Products Ltd. is a hightech -thus high capital-lndustry manufacturing rubber gloves. lts treatment system consistsof a fat trap, an oxidation ditch, a seetimentation tank and sludge drying beets. Washing wastewater is filtereet in sand filters. The whole system is successful in reetucing the BOD and rubber contents; only sandfiltration causes some problems (clogging). The factory has its own Iabaratory where wastewater samples are analyseet weekly. Unfortunately this treatment system Is toa expensive to serve as a pilot plant for ether rubber factories, which are small scale and lew capital.

At Dartonfield seclimentation tanks, an aeration basln and sand filters have been installeet. This construc­tion happeneet uncarefully slnce ene wall of the seclimentation tank collapseet. Additionally the sand filter is clogging up due to high soliels In the aerateet effluent. RRI is taking experiments and analyslng samples in the local lab to imprave the treatment performance.

Glenross' land application is goed In lntention, but nat functioning because the land Is to steep, causing corrosion. One can observe, that all vegetation Is dylng off due to certain chemlcals.

Other factorles are also aware that they have to treat their wastewater in the near futura, but are waiting tor advlee trom the RRI. This RRI is consequently overlaadeet with requests and has some expertise, but lacks persenneland equipment (like vehicles totransport the experts trom ene factory to another). Lack of finance and lack of initiative are the main reasans for delay in the installation of a treatment system in this sector.

64

In one factory the unaware­ness of the pollution causeel by rubber wastewater surpris­eel me. At Ceyrnac the man­ager finds wastewater traat­ment unnecessary, because the wastewater Is enough diluteel.

The Rubber Research lnstl­tute publisheel a report (author: Yapa, 1984) in which is indicateel the rubber fac­torles which need a wastewater treatment system for their wastewater. Two categories have been made:

.. ·.·.·.·.· . .·

·An e~ample of bad manageiTtenäs the feasibillty report frofT) BKH (foreign ~ssist- .. > ance, tfie.Netherlands).ln thls report from 19881w0 concrete p(OpoSals for effluent •. · .. / · treatrflentpla,nts were provldfi<J for 1w0 robberpiodueers of natura/ rubber(a RBC

••••••· fJ)(JM 9xic!ation ditr;h for the Ellaka!Jt:Ja and Fpteesterfactor/e~ respeëtîvely) .. ~ < êapftal and construction casts (~. 7 miJlJOn each) could be PJUd from a long terin > :toat)) o/dr!Jtfth6 Ne~rlands àJSo prövided fl8e technica/ ~~~tane(l.. .. ·. · · · · · ·.· .·.

~f~ ~~misslon oftiJis ,.;tf ftJ the CEA, rw ~/1f)e, ~s ha~ been taken,·• · • ·• ·. J?Qt ät thè C!A, fiOt at the RRJ, n(>t at the lndivldual facto~s. Re~SOtJ$ oehirid thi~ .· fi#sÇQ Y;sie!~k#./iiltiäf/Ve frOtt! fo/1 ski8 ofÇEA 8ndJorRRf. Th6 RRt(r" tf1e fitst t!m. ®~/tled ~ copy Ot Ïhe repört through tiJ! unc/erslgrie<j/n 1990. ......... . .

.... i.•~··~uisl·~·.~rJi·~·ftll••t~~stl)t•~})lantllfion•IQr~rova',••illt·~n·•hc,·an~r•·• • } ~.l!Q .~re ~tJ()fl ~s ~r@c~Î/.1"ftis minis6y cin be 1:>/amed laëk Of.

iespanse. PEA IJS \WjH IJS RRl, bt$. Uilf:let d~J'ent miniSfritJs, t/kl notmanage fO .. >p~f1Nf1~s torthe~.·········. · · · ... · · .· .. ··· ···· ·· ·.·.· ... ·.· .·· ·· ·.· ... ·.··.·.· .. ·.·

first and second priority. With foreign assistsnee (trom BKH) a feasibility study has been carrieel out in 1988 on the selection and construction of two treatment plants for two different factorles (see cadre above).

Wastewater trestment In the Export Processing Zones Katunayake and Biyagama

In each Export Processing Zone, Biyagama and Katunayake, a central treatment plant Is In operatien for the purlficatlon of wastewater colleeteel from the factorles inside the zone. Biologica! treatment 1 Is carrieel out with satlsfactory results. Strict toleranee llmits for the influent of the system are useel. Consequently the Industries have to purlfy thelr wastewater themselves before it Is dischargeel lnto the central treatment system, lf their wastewater does not conform to the limits. The companies all bear the in-house treatment costs themselves.

40 textile factorles are in operatien of which 8 have their own in house treatment facilities. 9 factorles are producing leather products. No in-plant treatment is performeel here. 6 factorles produce rubber products like gloves. Of these industries, 2 have in-house wastewater treatment (see table 4.4, below). Mostly the inhouse treatment conslsts of chemica! precipitation or adsorption on activateel carbon. I can not determine whether these industries are significant polluters, because I was not admitteel to the factorles in the Export Processing Zones. However it Is suspeeteel that most of the textile factorles carry out wet fibre processing. For the wastewaters of these processas biologica! treatment alone will not be suftleient (see 3.1.). The factorles making dippeel rubber products are thought to centrlfugate the latex themselves.

Without havlng vlsiteel the factorles In the two zones I can not take further conluslons. Generally however I have the Imprassion that the control of water pollution Is very adequately organiseel. The final effluent of the common treatment plant conforms to the Sri lankan standards, accordlng to samples taken by the National Aquatic Resources Agency (NARA)

1 The system consists of a screen and grit chamber, aerated lagoons, a settling tank, sludge drying beds and stabilization ponds.

65

Factors which have been influencing the selection of the actually applied trestment method.

When the treatment systems applieet in Sri lanka are considereet critically with respect to the factors, which play a role in the selection of an appropriate treatment system (see paragraph 3.2.5.), the following can be said:

• Generally the treatment method selecteet Is capable of handling the type of wastewater tor which it is applieet. In the course of this research it is not possible to judge whether the treatment capacitles of the observeet systems are sufficient.

• Space avallability is a limitlng factor for the selection of the appropriate wastewater system.

• Generally the systems are constructeet with the simplest means: as cheap as posslble. The capital costs are also an Important limiting factor in Sri lanka.

• Maintenance eausas problems when a high level of expertise Is requireet. Generally the cernpanles don't have any persennel which is adequately traineet to operate a treatment plant. For this reasen complex treatment technology will not be understood and thus lmproperly rnaintaineet. Either training courses or the Introduetion of simple technology can solve this problem.

• In Sri lanka to my opinion not enough attention Is given to the sludge problem. Since sludge Is dumpeet uncontrolleet, thóse treatment systems should have priority, which produce low sludge volumes.

• The social effects of wastewater treatment such as nuisance to the neighbouring residents are not always taken into account.

• Somatimes complex treatment systems are lnstaneet, consisting of saveral unit operations, while there is no proper understanding of the pollutlonal character of the processas and of the treatment mechan­isms. Instanation has often taken plaéè with assistance trom an environmental lnstitutlon (foreign or local). However after the instanation the assistanceis stopped, rasuiting in eperation problems.

So concludingly, saveral factors are hardly or not taken into consideration for the selection of an appropriate treatment plant. These factors are: level of maintenance (skilleetjunskilleet), the sludge problem, social effects, environmental awareness. Other factors have been taken lnto account, being limiting factors for the selection of an adequate wastewater treatment system. These limiting factors are: space availability and capital costs.

66

lndustrial sector number of industries number of industries In the two EPZ's having in-house

treatment

Textile products 40 8

Leather products 9 0

Rubber products 6 2

Other sectors 91 n.a.

TOT AL 146 n.a.

Table 4.4 - industries in the export processing zones

-.. : .. ·~·

Photo 4.6 - The coagulation - precipitation system of Tan Lanka

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Photo 4. 7 - The sludge drying beds of Tan Lanka, where sludge is put in bags

5

CONCLUSIONS AND RECOMMENDATIONS

5

CONCLUSIONS AND RECOMMENDATIONS

5.1. CONCLUSIONS

The conclusions are divided into two parts, corresponding to the research objectives. In the first part the present status of the environmental pollution in Sri Lanka is discussed, with emphasis on industrial water pollution. The water pollution caused by leather, rubber and textile industries is discussed in particular. In the second part the present status of the waste reducing technologles is discussed. An overview is given of the end-of-pipe trestment systems and in-plant waste reducing measures which are presently applied in Sri Lanka in the three sectors (leather, rubber and textile).

PART ONE • ENVIRONMENTAL PROBLEMS

General environmental problems

Environmental pollution in Srl Lanka is considered to have increasing impacts. The main problems on the national level are deforestation, soil and beach erosion, siltation of soli due to excessive irrigation and soil damages caused by the use of fertilizer and pestieldes in agriculture. Air pollution, uncontrolled sewage disposal and solid waste disposal are causing hazards to public health in urban areas. These waste problems are aggravated by the population density.

In addition industries are polluting waterbodles in and near urban areas. These waterbodles are used for purposes as drinking water supply, washing and bathing. Since the number of industries is still overseeable, the industrial pollution seems manageable. However rapid industrialisation will seriously aggravate environmental problems in the near futura, since more and more private industries are being established and the existing industries are expanding their capacities.

In the field of solid waste disposal the problem exists that there are no official dumpsites. Paddy fields or abandoned land is used for the dumping of industrial wastas and sludges. Dornestic waste is often burned in the open air.

Environmental organisation and legislation

Environmental legislation is in most respects sufficient. Strict toleranee limits have been set and the required powers and legislative instruments have been provided for an effective pollution abatement. Among these instruments the environmental licensing system for all industries is considered as an important step.

Although the required legislative powers are available and the number of governmental institutions involved in the abstement and monitoring of environmental pollution is considerable, still no concrete results can beseen of pollution reduction as a consequence of governmental action.

69

The environmental institutions or departments of the Sri L.ankan government are rnainly kept alive by a few initiatlve-taking professionals. But achieving actual results can not only depend on a few people. The awareness that pollution control should necessarily accompany industrial development, must penetrate into the various ministries which are responsible for the allocation of budgets. The intiative takers must be capable of being an lntermediate between the cumbrous and buroeratic governmental body and the executlve engineers.

Saveral constraints are preventing the organisations from achlaving an effectlve abatement of the environmentaJ ~lution, which is in fact the reason of the existence of these organisations. In general the environmental organisations are confronted with the following constraints:

• Organisations spend too much of their time and manpower on buroeratic actlvities, such as administration and the production of various reports.

• The actlvities of the organisations are often limited because the financlal support from the ministries is inadequate.

• Most environmental organisations are understaffed. Especially qualified personnel is ditticuit to recruit, for two reasons: low salaries and scarcity of trained personnel.

• LaboratOlies are lacking the required capacity for adequate monitoring of the numerous polluting industries. The consequence is irregular and at random sampling of polluted wastewater. Therefore the data from the wastewater analyses are often not rellable.

• Different institutions are somatimes overtapping in their actlvities and responsibilities

• Transport is an underestimated problem. The lack of vehicles is a major eenstraint for frequent inspeetion of factorles and monitoring of their wastewater.

The Central Environmental Authority (CEA) Is the coordinating agency on environmental issues and Is the overall responsible institution. Besides the constraints mentioned above, the organisation is confronted with the lack of a coherent philosophy. In addition there is no permanent leadership: for various raasons chairmen are not remaining in their positions for long. As a result of extenslve foreign assistance the prospects became more hopeful, but most constraints still have not been solved.

At the moment the Greater Colombo Economie Commission (GCEC) is having the highest expertise in the field of pollution controf and in its export processing zones an extended infrastructure for wastewater treatment can serve as example for the rest of the country. lt is even so, that people of CEA are trained at the environmental dlvision of the GCEC. A reason tor success in these zones is the tact that the construction of the infrastructure of drains and purification plants took place before industrial development started. Behind the iron curtains of these zones, the factorles seem to be effectlve in the abatement of their water pollution. This could however not be checked, because admittance to the factorles was refused.

Water pollution caused by textile, lesther and rubber factorles

In Sri L.anka industries mostly are concentraled in approved lndustrial zones. These areas were once the outskirtsof towns but due to rapid urbanisatlon resldents started to build their houses lnslde the zones. CEA is imposing strict regulations to the waste producing industries in the form of environmental licences. Some lndustrialists react very realistic: "OK, we are willing to purify our wastewater but you (the CEA) have to teil us how this should be done and who is going to finance it."

70

The awareness of the pollutional consequences of the processas is not satisfactory. Same industrialists simply don't understand that their wastewater might be a danger for the environment.

In the following paragraphs the water pollution caused by the three industrial sectors is described. The findings are based on detailed lnformatlon about 19 factories, which have been visited durlng the research period (8 textile, 5 leather and 6 rubber factories). The flndlngs within each sector are not representative for the sector as a whole, because predominantly the highest polluting campanles were selected.

Textile industry Most textile factorles are concentrated In a few mixed urban/industrial areas. The private campanles are mostly medium scale with 100 to 1000 werkers, while the state campanles are large scale with over 2000 labourers. Generally the factorles are discharging thelr wastewater untreated through drains into nearby streams or lakes. These waterbodles are often used for bathing, washing or the supply of drinking water. The wastewaters contain highly concentraled waste rnaterials. This waste is characterised by a high biodegradable waste laad and varylng colours trom excess dyes which are not biodegradable. lnorganic chemieals such as salts cause high solids concentrations .

Processas take place on old machinery, mostly dating from the sixties. Housekeeping Is insufficient. Labour conditions are not optlmal because the labourers have regular physical cantacts with chemicals. Noise pollution Is causing problems in the weavlng section. Often there is no knowledge on the pollutlonal character of the chemieals used. Most chemieals -especially dyes- are only known under their trade name.

Leather industry

.... :... . :·· . ··... :·:.:·<:.:. .:·:. .··::::-: .....

· rfr. Çlhighest pol/utilfg -* ~ ~ flitimateèf tö. produce an OÎT/anic waste lóad equivälellt fo • the se~age of a popu/ation of 235,()00 people (With

· Westem ~uropean· staiJdards)~ ThiiJ means that fot the . biologlcaJ batment of the . totäf ië.idite wasiëwater a

plant ~apacltf is tequired eqûaJ to a sewage f78atrnent plant (N 235.000 /)4)0~. Thls Is· a city like Efndhovën (NL)/ . . ...

........ ·.·.· .. ·. ... . .. . ..... · .·· .· .. ····

Orgäillc waSte dJndelliiatiOns Öf taCtories visited are exCfiiding t11e toferanee JimitS iNitJi a faCtor 10 :to ·100. The ·Volumes of~ 11ff/uents á~ high ••

Most lesther tanneries started with vegetable tanning several decades ago, but started with the more polluting chrome tanning in recent years. The chrome tanneries are all smali/medium scale with 50 to 1 00 labourers. They are often located in approved lndustrial zones, which are also partly resident lal. Mostly the leather tanning process takes place with minimal technology, while the final finishing is done with more advsneed equipment.

Especially the wastewater trom chrome tanneries causes environmental hazards because it contains a high biodegradable waste laad and toxic, non-biodegradable chromium salts. This wastewater is generally discharged untreated into marshes or lnto the Keiani river.

Labour conditions are not satisfactory, because of improper housekeeping. People are worklng almost naked in the saaking pits, where the

The otqanic waste load of the •elevsri larpest ~1/ute~ in the Jeallw ~Is equNaJefitto a the se~ Öf a

. · towrtÖf 50;000 people. Or: for b/Oioflicältreatinef)t of •· the tiJtä(Wa&teWater from the taiJTierHis a cBI'acity Is. ..

nHded whfch is equaJ to á seW8ge treatrnent plant for ••.•. $0,000 peopte,·a smalt rown.

fhèi èJèW*n ia,ge~ ~ftanne~s ~r~~~· .. ··· .·. 1(}() kg chromium daily. The chrórh/lit'TI coneentraf/ons

.· are aixiut so times the 81/oV'Ied arnollnt.

••••••••11Je••concJnbä#ons•••t1he··o~an~···~··liJats~··~··t~te·•··· · \Vasf8W8fttr of the visifed factorles are 30 to. 60 times •··••• hififier t/lan the tolefanÇe lirnits. < . ·.·. .·.· · · · ·. ·

hides are saaked in a bath of chemicals. Sores and infections are vislble as a result of the frequent physical contact to the process chemicals. Raw hides are causlng unpleasant smells. The process liquids including the chemieals are flowing over the factory floor.

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Rubber industry The rubber industry is dispersed over the southwestern part of the country. Most rubber processing units have a smali/medium scale character. In most cases a factory employs about 50 workers. Pollution is caused malnly In rural areas by wastewater contalnlng rubber particles and organic and lnorganlc process chemlcals. Poor knowledge exists about the envlronmental hazards caused by using these chemicals. The wastewater volumes are relatlvely small but the number of factorles is high in the rubber sector. In most cases the wastewater is discharged into nearby streams or paddy fields. SmeU, toxic chemieals and acidity of the rubber wastewaters are causing complaints from neighbouring residents. Crops of coconut and paddy (rice) are damaged in some cases.

·The ennre lUbber..., in Srl 1-ankals est/rnated to ·. ptr:Jduce ll Ofl1anlç waste k>1UJ equhlale(lt to the

.·. $eWagé of IJ jiopulatiön of410,000,.ir(Ot!Jer Words, the••· · capaclty W ~ bk>fi>(}icat trflaimellf $ystem ·.. .· b' · ·

·• .. · purificatiofl ()( this tc>ta1 waslewster is eqiJar to a .· ·•· ·.·. ~ge treatment plant· of a lárge · town · w1th · 41Ö,OOO · . >.inhäbttantS? > . . . . . ·. . . . .. · ... · ·.· ... · ·.. . . . . . ·. . . . . . · .. ·.

············~···~aiJY··~~···Q/··~watlt, .• clf •• ~ ••• ~, •••• ~,··········· ptT:)ëesslng IJnft is at)c)Ut so cubiC ~~ J)ttt däi; ()11e (àc:f[)!Y,. ~ •. di1J(;hafl16$ ~~ t:ufj1c Wléte~. pe' > .

<< däy and fiflds lts .t/lüent enoUgh dllüfêc!~ Thls ~'r afone diS6hatges · .•• .w ... · Ofl1anlc /()ad Wflich ·····~·••i•bc!l· ..... . co;npareci .. ~. t11e sewage of a ~ o/ ~ll'X?~ 5();()()().

• .. /people.

doncentra~s of ~lflanlc wasfit ~ 1$ to 100 ~mes ······· hlQher than the toleranee limttS~ · .· .· ·.·.· · · ·.· · .· · .·.· · · .. ·.·.·.· · · .· ·. · · .· ·

Overall conclusion on water polfution in the three sectors The results which are presenteel in the cadres glve an indication of the extent of the water polJution caused by the three sectors textile, leather and rubber. In general it can be said, that all factorles visited r-----~------------, are producing wastewaters with waste concen­trations of organic waste as well as suspended solids or total solids which are exe8eding the toleranee limits with at least a factor 1 0 and in some cases with a factor 100.

Water pollution from textile, teather and rubber

. ·. The. estimated tota/ waste Joad óf .the TalpeSt pol/uters Withln. thê tht8e sectors is equivälent to a the organlc

· waste of a popu/ation of too,ooo people, or a city llke Amsfltrdam (NL). · · · ·

factorles is very often causing hazards to the neighbouring residents, because the factory wastewater is significantly polluted and because the residents are living too close to the factory. Polluted waterbodles in urban as well as in rural areas are still used for drinking water, washing and bathing. There are no effective incentives which force the industrialists to purify the wastewater themselves.

When the estimated daily wastewater volumes of the visited factorles are compared to locally measured volumes, one can conlude that significant differences exist between these values. In most cases the estimated values were higher.

Concludingly, all factorles which were vislted produce wastewaters whlch urgently need purification in combination wlth in-plant waste reducing measures. Exception are formed by the three factorles with are oparating a wastewater treatment plant wlth success. These matters are discussed in part two of the conclusions.

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PART 1WO - WASTE REDUCING TECHNOLOGY IN TEXTILE, LEATHER AND RUBBER FACTORJES

Waste reducing technology can be divided into two types: Wastewater trestment systems on the one hand are purifying the wastewater at the end of the pipe, while in-plant pollution control or low waste technology on the other hand are measures to recluce the production of waste wlthin the process. Both types of waste reduction have been investigated tor the textile, lesther and rubber Industries In Sri lanka.

Wastewater trestment

Wastewater trestment in Sri Lanka Is rather an exception than commonly practised. The two dornestic sewage trestment systems tor the city of Colombo, the only two in the country, have ceased oparation because their capaclty was too low.

Most of the significant polluters of the three industrial sectors are not having any trestment facilities at all. Within the three sectors all factorles which were said to be oparating a wastewater trestment plant have been vlslted. Totally nine attempts have been observed of wastewater treatment. Only three of these nine plants can be called reasonably effective in reducing pollutlon. Two of the three are pilot plants (leather: Tan Lanka

The follow1ngtypet1 of tiNtment ~llls ~ .Pk1fe(t fl1 the three sectors (tel(tilë, ieather and rubber): < · · ·

~ sedimentátiontanksft1Jbe sëttling• • aellfledlagoons · · · · · · ·

. .-. stabmzatiOn pC)nds .... . .. chëmical p,ectpitatfon .

'" Oxidation ditch. . ~ OV.rland.flow. •.

and textile: Pugoda) which have been deslgned wlth foreign assistance. The thlrd successful wastewater trestment system is designed wlth lnhouse expertise by a large scale rubber processing company (Dipped Products). The Pugoda trestment plant is unnecessarily expensive and only removing the biodegradable part of the pollution. Being a pilot plant lt is certainly not serving as an incentive for other companles to construct this type of treatment.

There are no trestment systems in oparation without any operational problems or without doubts about their functioning. The six improperly functloning plants are very poor and cheap copies of existing trestment methods. This, in combination with bad design and inaccurate operation, resulted inthefact that no significant wastewater purification has been achieved.

Monitoring of the wastewaters is not done frequently enough in some cases. This makes the adequate oparation of a trestment plant - if present - very difficult. The choice of the factorles being monitored is not logical: from some factory wastewaters samples are taken very frequent (weekly or monthly), while other factorles with a substantlally higher pollution are monitored less than twlce a year. Only a tew lndustrialists are aware of the fact that they are pollutlng the environment. They show willingness in constructing a trestment plant. However, lack of expertise, lack of finsnee and lack of space are given as reasons for delay In lnstallatlon. The consequence Is that almost all lndustriallsts leave the initatives to the CEA. Projects planned tor the instanation of wastewater trestment plants usually terminated after the designing stage.

In the textile industry studies are carrled out tor the construction of a central trestment plant In the Ratmalana area. In the lesther industry, a central tannery Is planned wlth a central trestment plant. Research on trestment of industrial wastewaters is carried out at two institutlons: the Ceylon lnstitute of Scientific and lndustrial research (CISIR) and the Rubber Research lnstitute (RRI). This research is done with a very limited staff.

73

Most factorles inside the Export Processing Zones of the Grester Colombo Economie Commission have no inplant wastewater trestment The destlnatlon of thelr wastewaters might be elther a nearby stream or the common biologlcal trestment plant. Some factorles do have In house trestment (mostly chemlcal precipitation and adsorption of actlvated carbon). The common trestment plant seems properly designed; the final effluent conforms to the Sri lankan standerds. Because access to the foreign owned factorles wlthln the zones was not provided, the performance of these companies regarding pollution abstement could not be checked.

In general, saveral factors have hardly or not been taken lnto consideratlon before a trestment system was selected.These factors are: • the level of rnaintensnee (required skilied operators are not always available), • the sludge problem which accompanles almost every wastewater trestment system, • social effects like odour nuisance, • lack of environmental awareness wlthin the factorles (especially the management team).

Other factors have been taken into account, being limlting factors for the selection of an adequate wastewater trestment system. These limiting factors are: • lacking space availability. Even in rural areas factorles were seen which did not have space

for a simple ponding system. • high capital costs. Due to these factors only small size and low capltal systems are in most cases sultabla to the Sri Lankan situation.

In-plant pollution control

In-plant waste reducing measures are not practiced wlth a few exceptions. In a few cases lt Is done for profit maximisation or resources minimisation. Most factorles are uslng old technology from the sixties and seventies. Advsneed technology is an exception. The housekeeping Is in most cases unsatisfactory, often to such an extent, that the health of the workers is endangered. The awareness of the polluting character of the used chemieals is also unsatisfactory.

Recycling of water or by-products is hardly practiced, because no need is feit for recycling. (For instanee water is not scarce, so why recycling?) The industrialists seem not to understand that the wastewater production can be reduced wlth recycling of process water. lf they do understand, they are not aware of the environmental consequences.

lt is expected on basis of observation and interview, that the cleanest factorles are generally newer, medium scale companies wlth high capital lnvestment. Further scientific research Is needed to check this statement. In this respect lt also appeared, that the old large scale Industries whlch are (or were) government-owned, are limited In the appllcatlon of waste minlmlzatlon technlques for the processas for two reasons: firstly because of the exlstlng old machinery ancl secondly because of their buroeratic organisation which does not allow quick changes. In their case, only end-of-pipe trestment can solve environmental problems. Also the processas can be improved by better chemical dosing. Process water is not recycled, in

most cases because water is not scarce enough. Most campanles have their own tube wells. Recycling or reuse of valuable chemieals has not been observed anywhere.

74

5.2. RECOMMENDATIONS

• Organisations

When environmental organisations alm to abate polJution effectively, then in the first place they should be more action-oriented instead of legislation-oriented. For this purpose it will be necessary to build a strong professional cadre of environmental experts. These experts should have practical knowledge In the field of wastewater treatment. At the same time the capscity of monitoring industrial wastewaters should be increased. The access to the available lnformation wlthln an organisatlon llke the Central Environmental Authorlty can easily be improved by creating a proper data retrieval system for the llbrary.

The interrelated responsibilities and actlvities of the various envlronmental lnstitutlons should be made clear, not only to the institutions, but also to the lndustrialists. A coherent philosophy should be developed in the field of polJution abatement by the organlsatlons involved. Effective assistsnee by foreign donor organisations is only feasible if this condition is fulfilled.

Peripheral units are needed to conduct sampling of wastewater in remote aereas effectively. Therefore the existing District Environmental Agencies should be strengthened with additional powers: more manpower and Iabaratory equipment.

• lndustrial water pollution.

lndustrial water polJution can better be controlled and monitored when special industrial zones are allocated, where no residentlal dwellings are allowed. The allocation should be preceded by an Environmentslimpact Assessment.

lndustrialists like factory managers should be lnvolved in the polJution abatement, for instanee in the form of seminars or training courses, in order to increase thelr awareness about the environmental consequences of their industrial activities.

• wastewater trestment

The wastewater characteristics of all the factorles which were analysed In the course of this research are exceeding the Sri Lankan toleranee llmits largely, with at least a factor ten. The rivers, lakes and small streams are recelvlng excessive amounts of wastes trom these Industries. Therefore it should have first priorlty to reduce the sum of these waste leads slgnificantly, say for 70%, rather than trying to purify only one factory wastewater for the full 100%. The development of common wastewater trestment plants for groups of industries is already a positive slgn.

lnstalling a common trestment plant finsneed by a group of lndustrialists is more economical than one trestment system tor each factory. lnhouse pretraatment wlll then be necessary. In this respect some campanles in the Export Processing Zones may serve as an example tor in house treatment. The wastewater trestment lnfrastructure in the two Zones, includlng the common trestment plants, may serve as an example of effective polJution abatement for the rest of the country.

75

Apart from the lack of expertise and the lack of space, the lack of financlal resources is given as a reason for delay in the instanation of trestment systems. When the lndustrialists change their attitude and decrease the sales price of the products thls problem can be solved. Possibly the government can provide low interest loans for the capltal expendltures for the trestment plant.

Organlsations like the Greater Colombo Economie Commlssion, the Central Environmental Authorlty or the Ceylon lnstltute of Scientific and lndustrial Research should provide training courses In order to build up the required expertise for adequate operatien of a wastewater trestment system.

The research capscity which is actuaJiy used for the development of sultable wastewater trestment systems should be incresased. Technology can be sultable, when a number of conditlans are met. Some of these condltions are:

- Trestment technology should be comparatively low in capital costs, - the operatien costs should be low. - Wastewater trestment systems which produce low amounts of sludge are preferred. - The level of rnaintensnee or eperating skilis should be low.

• In plant polJution control

In the first place housekeeping and Iabour clrcumstances wlthin the factorles should be improved. When in a company opportunities exist, recycling of process water and recycling of toxic chemieals (like dyes in the textile industry and chromium in the leather industry) should be practised lf the opportunities do not exist -which is usual- then effectlve Incentives should be introduced by the authorities. lt should be made clear to the factory owners, that recycling of process water and chemieals reduce the adverse impact of the wastewater to the environment.

• Suggestions for further research

The following issues can be interesting for further research: * The wastewater produced by electroplating Is very toxic, because 1t contains heavy metals.

*

*

*

The extent of the pollution from the electroplating industry in Sri Lanka should be investigated as well as lts environmental consequences.

Does a relation exist between the level of rnaintensnee and the age of machines in a production process on the one hand and the wastewater volume which Is produced in that process on the other hand?

The transfer of modern technologles for the trestment of lndustrial wastewater can be recommended, but various condltions have to be met. For Instanee a professional cadre of experts has to be built first. The governmental lnstltutlons which are providing the funds for pollution abstement should first be convineed that these technologles are needed. Further research is needed in order to select sultable modern technologles to be transferred to the Sri Lankan situation.

Further research can indicate if a tax rebate system on water polJution is a better Incentive for companies to treat their wastewater than lmposing financlal penaltles on polluters.

76

APPENDIX I

LOW WASTE TECHNOLOGY FOR THE TEXTILE AND LEATHER INDUSTRY (ad 3.1.)

APPENDIX I • RECOMMENDED LOW WASTE TECHNOLOGY FOR THE TEXTILE AND LEATHER INDUSTRY (AD 3.1.)

A. Textile industry

Low waste technology or in-plant waste reducing measures ean be divided into six eategories, mentioned below. Of each eategory some examples will be given.

1 improved process control 2 process modlfication/ chemieal substitution (cleaner technology) 3 recovery of chemieals 4 water conservation by process modlfieation and reuse 5 clean housekeeping practices 6 segregation of waste streams.

Ad 1 improved process control applieation of correct quantity of sizing agent reeluctien of kerosine use in preparing dye paste by understanding of the process

Ad 2 process modification conversion of winch dyers into jiggers with lower liquor ratio combined processing with appropriate chemieals (desizing + mercerizing; desizing + scouring + bleaching) Heat transfer printing method requires smaller quantities of dye and water Use of pre-hydrolysed low viscosity starch in sizing results in a better penetratien and thus reduces the requirement of size mix. Carboxy-Methyi-Cellullose (CMC) reduces the pollution load with 50% A CMC-starch-mixture ean also be used. Soap ean be substitued by detergents with a low COD /BOD (35% reeluctien of the BOD) Leveling, emulslfying and dispersing agents with a low BOD ean be used (5-15% reeluctien of BOD) Replacement of acetic acid with inorganic salts such as ammonium sulphates and chloridesin the dyeing operatien (100% reeluctien of BOD).

Ad 3 recovery of chemieals 60% of the eaustic soda from merearlzing ean be reecvered (squeezing-soaking-squee-zing • principle). CMC in sizing is precipitated as metallic salts and foliowed by conversion to sodium derivatives 30-35% of VAT dyes is amenable to recovery and reuse. Basic, azo and reactive dyes can be precipitated as metallic salts.

Ad 4 water saving techniques ("water conservation by process modification") Machanical movement of cloth with countercurrent washing systems High intensity soaking - squeezing - soaklng washing cycles Heat exchangers instead of direct steam heating Reuse of clean water from flnal effluents from washing for operations that do not require a high water quality. Reuse of dye baths

Ad 5 clean housekeeping practices The wastage of chemieals ean be preventeel through close control of operations and clean housekeeping practices.

I · 1

Ad 6 Segregation of waste streams

Process Organlc lnorganlc mixed less polluted

wastewater wastewater wastewater wastewater

Sizing x Desizing x Scouring x Rinslng x

Bleaching x Rinsing x

Merearlzing x Rinsing x

Dyeing x Prlnting x Finishing x

B. Leather tanneries

lmprovements of the leather-tanning process can be divlded into three categorles:

• Good housekeeping and water conservation a) goed housekeeping b) alteratien of processes and the adeption of lew float systems to use less water. Example: batch washing insteadof continuous washing (drums use less water than paddles). c) segregation of less-pollut,jd wastewater fractions for direct reuse without treatment. Example:washwater from secend soaking can be used for preparing the sulphide lime liquor. d) recycling after complete or partlal trestment

• Recovery and use of by-products a) reuse of hairs, fleshings, trimmings, splits, llme sludge, tan-liquor sludge, tan bark, laather trimmlngs and shavings.

• process changes for reducing pol/ution load a) Largest contributor to pollution: unhairing. Less pollutlng techniques using sulphide-free biodegradable materials. b) Water saving techniques, such as recycling In liming, bating, deliming, plckling, chrome tanning. Better techniques can reduce the water consumption in vegetabla tanning (drum), fat-liquoring & dyeing. c) lmproved chrome tanning methods enable higher levels of chromium fixatien in leather leaving much less chromium in the effluent.

[NBRO, 1989]

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APPENDIX 11

ADVANTAGES AND DISADVANTAGES OF THE DISCUSSED TREATMENT METHOOS (ad 3.2.)

APPENDIX 11 - ADVANTAGES AND DISADVANTAGES OF THE DESCRIBED WASTEWATER TREATMENT METHOOS (AD 3.2.)

Inthls appendix addltionallnformatlon is given to the overview provided In chapter 3.2. for the interestad reader. For each system dlscussed prevlously, a brief summary, the advantages and dlsadvantages will be given. The followlng systems are discussed here:

Physical trestment Screening Equalization Grit and sand removal Oil and grease removal Gravlty settling Dissolved air flotation

Chemica! trestment Neutralization Coagulation-precipltation

Biologica! trestment Conventienat activated sludge Aerated lagcon

• Screening

Oxidation dltch Low rate trickling filter High rate trickling filter Rotating blo-disc Aerobic lagcon Facultative lagcon Anaerobic lagcon Anaerobic digestion Uplflow Anaerobic Sludge Blanket Anaerobic filter Overland flow

Sludge trestment Aerobic sludge digestion Sludge drying beds

Sereens are necessary if subsequent trestment Is planned, In order to prevent damages to the system. Instanation costs are very low and, if proper1y designed, also the operatien costs can be negligible (especially in cheap Iabour countries).

Advantages: 1. removal of large undesirable pieces from a waste stream is centralized at a single location and the need for at-source control or prevention can be minlmized. 2. recovery and recycling of captured materials may be advantageous from an economie standpoint 3. downstraam trestment equipment is protected and the performance of the overall trestment system generally improves.

Disadvantages: 1. eperation and rnaintensnee required, 2. improper1y handling of waste may cause odor and nuisance problems.

• Equslization (flow snd load balsncing 1 homogenisation)

A balancing tank is especially required for small industries wlth highly polluting batch discharges (tanneries, cocon ut oll, electroplating). The instanation of a balancing tank reduces the operatien costs of a subsequent biologica! trestment system as well as the risk of damages due to shock loads. However, because of the relatively high costs, the small scale trestment plants may be unable to afford a completely equipped equalization tank. In that case cernpromises have to be taken, like using the force of gravlty instead of pumps.

11 - 1

Advantages: 1. minimization of downstraam trestment casts. For systems employing biologica! treatment, equalization can proteet biologica! processas trom failure due to shock loads. lt can also minimize the slze of biologica! reactors and aeratlon equipment requlrements. 2. minimization of downstraam eperating problems; 3. reduces the COC 1 BOD load and the peak overflow rates, rasuiting In lmproved effluent quality; 4. reduces pH range In biologica! units.

Disadvantages: 1. high construction, operatien and rnaintensnee casts 2. associated equlpment (pumps, mixers) are required 3. lmproper1y monitored equafi2ation basins can become septic, causing odor problems and impacting downstraam trestment processes.

Operating problems: 1. Scum formation 2. sedimentation 3. anaerobic conditlans (low pH, odour, additional aeration) 4. nutriant stripping (addition of nutriant required downstraam biologica! reactor)

• Grit and sand removal

Gravel, sand and other large particles are removed to avoid deposits In channels and pipes, to proteet pumps and to avoid overloading. Applied to speeltic production processes, mainly in the food lndustry.

• Oil and grease removal 1 fat traps

Oil and grease remaval is widely used in the food industry (slaughterhouses, meatcanning, oil mills) for remaval of fats and oil prior to discharge into sewer or biologica! treatment. Recovery of valuable oils is possible. Sedimentation and flotation are two common methods to remave small particles from the wastewater. Sedimentation is aften used after biologica! trestment to remave the sludge. Flotation can be used for trestment of low strength wastewater.

• Gravity settling (clarification 1 sedimentation)

Through clarification, suspended solids are removed trom the effluent to reduce BOD and to prevent clogging. A settling tank is generally a necessary part of a blologlcal trestment system or a coagulatlon -precipitation system. The clarificatlon process Is cheap and slmple In operatlon, but the construction

casts are high.

Advantages 1. effective in removing a substantial portion of suspended solids and BOD from an industrial wastewater. 2. Clarification aids in the performance of downstraam trestment systems and also protacts them from negative effects such as clogging. 3. technology is receptive to modifications (such as chemica! addition which allows for alterations to compensate changes in the wastewater characteristics) 4. relatively simple operation, requiring nelther sophisticated equipment nor highly skilied operators.

11-2

Disadvantages: 1. high construction casts 2. difficulties to accommodate large varlatlans or increases in wastewater flow or pollutant loadings, beeause design and operatien are based on specific flows or loadings.

• Dissolveel air flotation

Dissoved air flotation is only a sultabla option for Industries with access to expensive and complex technology and highly skilied personnel. With thls method particles with a low specific gravity such as flnely divlded suspended sollds, oils and greases ean effectively be removed from the waste stream. The applieation Is very specific. The eapital casts are lower than a fat trap, however oparation casts are higher.

Advantages: 1. oil and grease, finely divided suspended solids, grit etc are effectively removed in one unit; 2. the resulting float may be usabie as an auxiliary fuel source; 3. more efficient than simpte flotation 4. lower eapital cost than for instanee fat trap (higher overflow rates and shorter datention times mean that smaller tanks are required) 5. lower ratention time 6. higher sludge solids concentratien 7. not adversely affected by thermal changes 8. reduction in odour problem, beeause of shorter datention times and presence of dissolved oxygen. 9. higher quantity fat reeavered than fat trap.

Disadvantages: 1. higher oparating and maintenace casts than for other solids remaval processes; 2. extra power and chemieals are usually needed; 3. heavier suspended solids are not effectively treated (compared to sedimentation); 4. highly skilied personnet required

• Neutralisation

lf the effluent is strongly basic or acidic, neutralisatlon Is recommended in order to prevent eerrosion of the pipes and the subsequent treatment units. However, the use of chemieals for this purpose should be reduced as much as possible for lnstance:

a) by treating only the most acidie/basic portion of the effluent, b) by exact dosing and c) by equalisation.

Advantages: 1. eliminatien of adverse impacts on the water quality, 2. proteetion of subsequent treatment units and plpes against corrosion.

Disadvantage: 1. Chemieals used in the treatment process are corrosive themselves and ean be dangerous. The plant personnet and the surrounding operations should be properly protected. 2. The processis costly

11 - 3

• Coagulation - preclpitatlon

Wlth relatively simple trestment technology and the addltion of coagulating chemieals eertsin pollutants ean be removed (metal ions, ultrafine colloldal particles). This is a low cost trestment method, but lt is not eapable of solving the waste problem adequately, beeause a water pollution problem is replaced by a solld waste problem (sludge).

Advantages: 1. existing trestment technology ean be utilized (clarifieatlon units), providing better pollutant removals.

Thus trestment is maximized while costs are minimized. 2. automatic control possible 3. changes ean be handled through adjustments in the addltion of coagulating chemieals 4. ean operate at ambient temperatures.

Disadvantages: 1. chemieal Interterences may adversely affect the process's performance. 2. substantial quantlties of excess sludge are generated, leading to increased sludge disposal problems.

• Conventional activaled sludge

The activated sludge system is a technologleally complex and expensive system, which is characterized by a high dagree of treatment. This trestment method ean be an interesting alternative, but has some constraints:

• Skilied Iabour is required for proper maintenance; • high technology means that difficulties may alse In obtaining spares. • The construction and oparation costs are relatively high. • A reliable power soure has to be available.

Advantages of smal/ instal/ation with extended aeration: 1. wide range of industrial wastewaters are treatable; 2. procurement, handling and storage of chemieals Is small or non-existant; 3. the trestment ean easily be expanded to accommodate increased flows. 4. Lower sensitivity to shock loads due to large basin volume; 5. stabilized excess sludge.

Disadvantages 1. long ratention time (2-3 days for 1 OOOmgjl BOD5)

2. sludge odor 3. Problems may arise In:

- flow messurement of sludge - waste-sludge pumping - solids settleabillty - sludge handling - foam

4. best performance under uniform hydraulic and pollutant loadings; 5. operational skilis and controls required relatively high; 6. energy costs In mixing and aeratlon lncrease rapldly.

11-4

• Aerated lagcon

The aerated lagcon is a suitable treatment system for streng industrial wastes (high BOD, no taxie substances). The operatien Is simple, no skilied persennel needed. The eapital casts are low and the reliability is high. However there are some constraints: a large land area is needed for this type of treatment and electrlc power has to be supplied to the aerators. The effluent is not entirely clean. lt still contains some suspended solids and algae. Generally the effluent has to be foliowed by a settling unit (clarlfieation tank).

Compared to ponds, the aerated lagcon Is uslng less land area and dalivers a superior effluent agalnst a llttle higher eperation casts. Compared to the activated sludge system, the surface area of an aerated lagoen is larger, but the eapital casts are lower.

Advantages 1. easy to take in jout of service. 2. wide range of industrial wastewaters are treatable; 3. procurement, handllng and starage of chemieals is small or non-existant; 4. the treatment ean easily be expanded to accommodate lncreased flows.

Disadvantages: 1. best performance under uniform hydraulic and pollutant loadings; 2. operational skilis and controts required relatively high; 3. energy casts in mixing and aeration lncrease rapldly.

• Oxidetien dHch

The oxidation ditch functions as an activated sludge system with extended aeration and interminent operatlon. The oxidation ditch is useful for small plants with malnly biodegradable or organic wastas (like rubber effluent). lt requires a large area, but less space than ponding systems. The eapital and construction casts are high. Processcontrolof the ditch Is less difficult than control and eperation of a conventional activated sludge system. The required operational skilis are consequently lower.

Advantages: 1. Large volume and high concentratien of active sludge enables the system to cape with fluctuations in flow and laad. 2. The lncrease in sludge volume ean be small during extended aeration. 3. wide range of industrial wastewaters are treatable; 4. procurement, handling and starage of chemieals is srnall or non-existant; 5. the treatment ean easily be expanded to accommodate increased flows.

Disadvantages: 1. best performance under uniform hydraullc and pollutant loadings; 2. operational skilis and cantreis required relatively high; 3. energy casts in mixing and aeratlon increase rapidly. 4. high eapital casts. 5. large land area requlred. 6. when aeration is stoppad (intermittent operation), anaerobic conditlans may arise in warm climates.

11-5

• Low rate trickling filter

advantages: 1. simple and highly reliable treatment facility 2. easy reinstitution of micro-organism growth after accldental kill; 3. Oxygen Is supplied naturally, no need for aeration equlpment; 4. because of the simple operatien and the absence of aeration equipment, no highly skilied persennel is required; 5. substantial cost and energy savings.

disadvantages: 1. modification in treatment process limited; 2. Because of the low leading rate, problems will arise with industrial waste. In that case a large land area Is required 3. Intest by files and pests; odeur problems. 4. excessive growth of microorganisms and algae at the surface prevents the flow of liquid.

• High rate trickling filters

High rate filters use plastic media and are widely used tor treatment of industrial wastewaters (food & beverages, distillery, brewery, dairy). These filters are often used as partlal treatment at very high leading rates (very high pollution leads per m3 filter). They are expensive in capital cost, construction costand operation.

Advantages 1. Requlred land area is relatively small, because the filters can be built in tewers (appr. 6 mtrs). 2. High leading rates. The system,; capable of handling high pollution leads per cubic meter filter.

Disadvantages 1. In comparison to rock media, plastic is an expensive medium. 2. Effluent recycling is necessary to dilute streng wastes (maintain wetting rate). 3. The capital and construction costs are high; 4. Advsneed technology involves requirement of a skilied operator. 5. intest by flies and pests; odeur problems. 6. excessive growth of microorganisms and algae at the surface prevents the flow of liquid.

• Rotating biologica! contactor

The Rotating Bio-Contactor flnds its application In small communlties with low strength wastewater (like hotels). The system requires very little space and energy. The eperation costs are low, but the capita! costs are high. The effluent has to be settled in a sedimentation tank. The ABC can be recommended tor upgrading an existing treatment facility, because it's easy to install. The system is capable to treat lndustrial wastewater trom small units.

advantages 1. easy to instaU for upgrading an existing treatment facility, 2. better chance of withstandlng shock or toxic leads. 3. easy reinstltution of micro-organism growth after accidental klll; 4. Oxygen is supplied naturally, no need for aeration equipment; 5. because of the simpte operatien and the absence of aeration equipment, no highly skilied persennel is required; 6. substantial cost and energy savings.

11-6

disadvantages 1. modification in treatment process limited, 2. lower dagree of treatment than suspended growth systems, 3. high organic losding may cause problems like septicity, 4. clogging.

• Aerobic lagoon (or stabllization pond)

Aerobic lagoons are capable of treating weak lndustrial wastewater with negligible amounts of toxic components. The costs of this treatment system are minimaL The technology is very simple and the reliability is high. However a large land area is needed. lnhabitants surrounding the lagoon may have complaints about odour (bad smeU). Furthermore wastewater can seep into the groundwater. The effluent still contains suspended solids and algae.

advantages: 1. low capital cost; 2. simpilcity of oparation (little oparation expertise required); 3. low oparation and maintenance costs 4. high reliability.

disadvantages: 1. high land requirements; 2. noxious vegetative growths; 3. odour emission; 4. seepage of wastewater into groundwater; 5. seasonal changes; 6. effluents normally have suspended solids of 100-300 mg/1

• FacuHative lagoon (stabllizatlon pond)

The facultative lagoon has same properties as an aerobic lagoon (large land uyse, low costs, etc.). However, due to thermal stratification of the pond can become anoxic. Wind can solve this problem. Facultative lagoons can treat weak industrial wastewaters which have been screeneet or clarified.

advantages: 1. low capital cost; 2. simpilcity of oparation (little oparation expertise required); 3. low oparation and rnaintensnee costs 4. high reliability.

disadvantages: 1. high land requirements; 2. noxlous vegetative growths; 3. odor emission; 4. seepage of wastewater into groundwater; 5. seasonal changes; 6. effluents normally have suspended solids of 100-300 mg/1

11-7

• Anaerobic lagoon (stablllzation pond)

Thls type of lagoon has a smaller surface area and a higher depth than the aerobic ponds. The The detentlon time Is relatlvely long. Biologlcal degradable matter can be treated trom industrial effluents. The strength (BOD) of the effluent delermines the size of the pond. An anaeroblc treatment system should not be built wlthin 500m of dwellings because of the smell. Anaerobic lagoons are effective as roughlng units prior to aerobic treatment of high strength organic wastewater.

advantages: 1. low capltal cost; 2. simpilcity of oparation (little eperation expertise required); 3. low operatien and maîntenance costs 4. high reliabillty.

disadvantages: 1. high land requirements; 2. noxious vegetative growths; 3. these ponds should not be in eperation within 500 meters distance of dwellings because of odor emission and files nuisance; 4. seepage of wastewater into groundwater; 5. seasonal changes; 6. effluents normally have high concentrations of suspended solids and algae.

• Anaerobic digestion

Anaerobic digestion can be an interesting alternative if skilied Iabour is available and spares can be obtained without difficulties. A reliable power souree must also be available. The system is technologically complex and thus expensive. Posttreatment of the effluent is necessary. Anaerobic digestion is mainly used for low or medium strength wastewaters (BOD concentrations 800-4000 mgjl) discharged by food processing, breweries and sugar factorles, for example. Digestion is often used for waste sludges.

Advantages: 1. low production of biologica! solids, less excess sludge than aerobic processes; 2. usabie by-product: Methane formation -> energy use for reactor heating, factory gas, conversion to electric power. 3. use of aeration equipment not required, which means energy and cost savings; 4. less land utilization than aerobic processes; 5. lower operatien costs than aerobic processes. 6. higher degree of waste stabilization than aerobic processes; 7. lower nutrient requirement than tor aerobic processes; 8. covered reactor, reduces odor and transmission of airborne bacterie 9. eperation and control similar to technologies which exlst in industries which use the following processes: fermentation, destillation. (pharmaceutical) 10. measurable end product which can be used tor very simplefeed back control system.

Disadvantages: 1. long solids residence times, minimum 15 to 20 days, which means a large reactor is required.; 2. sensitive to eperating conditions (sensibillty of methanogens to shock loadings and pH variations); 3. possible odor generation. 4. temperature 30-3"flC 5. slow growth rate of methanogenic bacterie 6. high level of operator required.

11-8

• Upflow Anaerobic Sludge Blanket (UASB)

advantages 1. the system produces low amounts of sludge 2. the eperation costs are low 3. the capita! costs can be compared to the costs of a simpte aerated lagoon, thus not extremely high. 4. The system can be successtut In treating lndustrial wastes with high conversion of organic material. 5. the system is applicable In tropical countries because the costs are reduced with lncreasing tempersture of the wastewater. The reactor volume of the UASB (especially in troplcal countries) is signiflcantly smaller than the aerated lagoon system, which means that a smaller land area is needed for UASB.

disadvantages 1. Skilied personnet is required for proper oparation of the trestment system

• Anaerobic fiHer

The most common anaerobic attached growth process is the anaerobic filter process used for the trestment of both dornestic and industrial wastes. The filter is a column fitled with media used for the trestment of organic matter in the wastewater. The waste flows upward through the column contacting the medium on which anaerobic bacteria grow and are retained . The anaerobic filter can be used for the trestment of low-strength wastes at ambient temperature. The system is high in capita! costs and low in operatien costs. The useful by-product methane is formed during the process of biodegradation.

Advantages: 1. low production of biologica! solids, less excess sludge than aerobic processes; 2. usabie by-product: Methane formatlon. Methane can serve as energy for reactor heating, factory gas or the conversion to electric power. 3. use of aeration equipment not required, which means energy and cost savings; 4. less land utilization than aerobic processes; 5. lower operatien costs than aerobic processes. 6. higher degree of waste stabilization than aerobic processes; 7. lower nutriant requirement than for aerobic processes; 8. covered reactor, reduces odour and transmission of airborne bacteria 9. oparation and control similar to technologies which exist in industries which use fermentation and destillation. (pharmaceutical industry) 10. resistant to input variations;

Disadvantages: 1. only for low solids and low organic wastes, to prevent clogging up. 2. high construction costs

• Overland flow

Overland flow has two functions: wastewater trestment and, to a minor extent, erop production. The trestment methad can be considered applicable if research has shown, that toxic components do not adversely affect the vegetatlon, the soli and groundwater. Also large land area should be available. However, this land should not be too steep, because of the danger of corrosion, deforestation etc. Knowledge of wastewater characteristics, trestment mechanisms, vegetalion and conditlans of the soil as well as pubtic health requirements (bacteriological contamination, transmission of dlseases, toxic chemicals, danger to erop quality) is very important for a successtut application of land treatment. Screening and grit & grease removal are required to prevent clogging. Lagoon pre-traatment can be recommended. Also pre-disinfection may be advantageous.

11-9

advantages: 1. cast effectlve; 2. energy conserving; 3. social, econonomical and environmental benefits through:

- agriculture, - creation of green beits, - preservetion of open space, - energy savings, - conservatlon of potable water resources, - groundwater recharge, - profits from sales and crops. [Yapa, 1984]

4. no addition of chemieals required. 5. no sludge production 6. low oparation and maintenance casts.

disadvantages: 1. large land area required: 10 to 45 ha for effluent volume of 158 m

3/hr;

2. taxie constituents may adversely affect the soil and groundwater. 3. when the effluent contains high suspended solids, the soil can clog up and consequently die. 4. danger to public health (bacteriological contamination, transmission of diseases, taxie chemicals, danger toerop quality).

• Aerobic sludge digestion

Aerobic digestion is a sludge stabiltzing technique, to reduce pathogens, odour nuisance and putrefaction. lt is easier in oparation than anaerobic digestion, but more expenslve. However, capita! casts are lower. Bath treatment systems are relatively expenslve and complex in technology. Aerobic digestion glves better results, but no methane as by-product. lt can be used to treat sludges from actlvated sludge treatment and trickling filtration.

advantages over anaerobic digestion: 1. lower BOD concentrations in final effluent, 2. odorless biologically stabie end-product, 3. higher fertilizer value, 4. better dewatering characteristics, 5. easier in operation, 6. lower capita! casts.

disadvantages 1. higher power cast requlred for the supply of oxygen. 2. no useful methane as by-product.

• Sludge drying beds

Drying beds are used to dewater the sludge, which can consequently be used for land fill, as fertilizer or be incinerated. Drying beds, especially in hot cllmates, cast al most nothing because they are utillzing solar heat. Only the land use is very high.

Advantages: 1. low construction, oparation and maintenance casts

Disadvantages: 1. occasional odours 2. high land use

11 - 10

BIBLIOGRAPHV TO APPENDIX 11

For more detailed information and for technica! details the reader is referred to the following literature:

1. Handbock of lndustrial Residues, Jon C. Dyer, 1986 2. Water and Wastewater Treatment, Edward Schroeder, 1977 3. lndustrial Wastewater Management, Sven Erik Jc~>rgensen, 1978 4. Management of lndustrial wastewater inDeveloping Nations, David Stuckey and Ahmed Hamza, 1981 5. Treatment and Disposal of lndustrial wastewaters inDeveloping Countries, Dr G.K. Anderson, 1989 6. Metcalf & Eddy, 1979, Wastewater engineering: treatmentjdisposalfreuse; McGraw Hili series 11. 7. Lettinga, 1978, Feasibility of anaerobic digestion for the purification of industrial wastewater, Munich.

11 - 11

APPENDIX 111

PRODUCTION PROCESSES IN TEXTILE, LEATHER & RUBBER INDUSTRY {ad 4.2.)

APPENDIX 111- DETAILED DESCRIPTION OF PRODUCTION PROCESSES (AD 4.2.)

In this appendix the processas which are applied in the textlle lndustry, the laather industry and the rubber lndustry are described in more detail.

A. THE TEXTILE INDUSTRY

In the dry processas no significant wastewater Is produced, but for a proper understandlng these processas will be explained briefly. The wet processas are the major causa of water pollutlon. The dry and wet processas are described for cotton fibre processing. Synthetic fibre processing Is essentially the same, except the fact that different chemieals are used.

Dry processes:

1. Blowing

2. CBrding

3. Combing

4. Drawing

5. Roving

6. Spinning

7. Winding

8. Warping

9. Wefting

10. Sizing

11. Weeving

12. Singeing

Cotton In bales comes to the blow room, where the fibres are loosened and excess dust Is removed and the cotton Is wound in rolls known as Iaps.

The raw cotton fibres are further cleened and aligned parallel into a web, which Is gathered together to form a sliver. Short fibres and dust are eliminated.

Optional process for high quality yarn. Slivers are combed to eliminste short fibres upto 1 14 Inches.

Saveral slivers are combined to form a single sliver to lmprove strength and uniformity of yarn. Blending of different flbres takes place at thls stage.

The draw yarn Is doubled and given a twist rasuiting In a single thread.

The yarn Is further drawn and twisted and spun lnto bobbings.

The thread is then wound onto cardboeert vones. Oefacts In the thread are controlled and eliminated.

Stretching of fibres mechanlcally and setting mechanically onto beams in the pattarn required for weaving.

The act of inserting the cross threeds in the weeving process. The weft is wound previously onto pirns.

The warp threed Is treated with sizing agents such as starch in order to Impart strength and stiffness which are necesssary tor the subsequent weeving operatlon. Antiseptlcs, penetrants, softeners and other additives may also be added.

Yarn is woven lnto the gray cloth.

When a better quality smooth cloth Is desired, the protruding fibres on the surface of the cloth are singed by flame treatment.

111 - 1

Wet processes:

13. Desizing The slze addeel In the weaving process (1 to 11) Is removeel to prepare the cloth for dyeing and further processing, by hydrolyzing the starch to glucose with acid (sulphurlc acid) or enzymic treatment in the presence of penetrants (salt) for a pertod of 3 to 12 hours. The spent reagents, hydrolyzeel products and penetrants are removeel by means of a water rinse.

14. Scouring 1 Kier boiling

15. Bleaching

16. Mercerizing

17. Dyeing

Treatment with eaustin soda and sodlum earbonate at 1 00°C for a few hours removes natural and acquireel lmpurlties such as natural waxes, pectins, grease, oil, dirt etc. Penetrants may also be addeel to aid in scouring operatlons. Resulting effluent after treatment Is pale brown In colour. The cloth is washeel and rinseel until no brown colour is retaineel in the rinse water. Continuous scour method wlth steam drying is more commonly useel.

Coloureel lmpuritles natural or acquireel are removeel in bleaching, which is achieveel by treatment with Sodlum or Calcium Hypochlorite of hydrogen peroxide at 100°C for 30 minutes. Hydrogen peroxide is addeel when white cloth or yarn Is desireel. Penetrants are addeel to impart better contact. Subsequent rinsing removes all the waste.

CJoth to be dyeel Is treateel with cold 1 0-30% eaustic soda solution for a few minutes while cloth is kept under tension. Mercerizlng swells the fibres and Imparts fabric luster and dye affinity to cloth or yarn. eaustic soda is neutrailzeel with acid and washeel away with water.

Thls process ean be performeel in various ways, depending on the type of dye useel and the method of applieation.

a. Vat Dyeing - Dye is applieel in the reeluceel state and oxidizeel. Useel for cotton and polyviscose blends. Not useel very commonly in Sri Lanka.

b. Sulfur Dyeing - Dye Is applieel in the reeluceel state and oxidizeel to develop the color.

c. Aniline Dyeing - Aniline applieel on cloth is oxidizeel by air of steam to develop the color.

d. Direct Dyeing - Coloreel dye Is applieel dlrectly on the cloth. These dyes are water soluble and mostly useel for conons and polyviscose blends.

e. Naphtol Dyeing - The dye Is sybtheslzeel on the fibre. The napthol is applieel to the fabric and passeel through a developer.

f. Disperse Dyeing - This method is useel for nylon and polyester fibres.

g. Reactive Dyeing - This is a newer development in the field of dyeing. The color results through chemleal reaction with the fabric. Useel mostly for cotton.

111-2

18. Printing

19. Final finishlng:

The methods in use are roller printing, screen printing (manual methad is also in use) and the modern rotary scereen printing which imparts a better quality print to the fabric. The dye is applied in the form of a paste. Printing paste may contain dye, thickeners, hydroscopic substances, penetrants, binders, catalysts, warter and ether chemicals. Some of the chemieals used art starch, gums, synthetic resins, urea, emulsifying oils (kerosine oil), diammonium phosphate etc.

19.1 Ageing or curing The dye or printed cotton is aged in order to fix the dye by steam treatment of by other means.

19.2 Washing Excess dye, penetrants and binder on cloth are removed by washing with detergents and soap. This increases the color fastness in the fabric.

19.3 Stentering Tension is applied to cloth by stretching to give dimensional stability to the cloth.

19.4 Finishing Depending on the finish required (crease, soft, water repellent, etc.) various agents are added. Slzing with stacrch, polyvlnyl acetate, addition of sortenres, fungicides etc are done at this stage.

19.5 Calendering This is done when required, to impart a shiny satin finish to the cloth.

B. THE LEATHER TANNING INDUSTRY

The following processas are applied in the leather tanning industry.

1. Salting

2. Liming

3. Fleshing

Tanneries receive raw hides of salted from the slaughterhouse. Fresh hides are trimmed of tails, flesh and larger hair particles and salted wen for storage.

(Soaking which may be carried out in pit, paddie or drum Is to rehydrate the skin and rafverse the cure process. Duration up to 48 hours, dependent on degree and type of cure and ambient temperature. Dirt, blood and dung may also be removed.)

Hides are allowed to remain in the lime baths for a perioei of about seven days. In the more sophisticated tannerles, paddies are In use. The liming process causes the hides to swell, thus enabling the flesh and dermallayers of the hides to be removed with ease. Liming also destroys bacteria and other microorganisms surviving on the hides. In vegetabla tanning, sodium sulphide (Na2S) is seldom used in the liming process. However, in chrome tanning, sodium sulphide Is always added to the lime baths.

The layers of flesh tissue and derlms are removes = d leaving the inner corium from which the leather is made. This is done in a fleshing machine or in some cases, manually.

111-3

4. Deliming

5. Unhairing

6 Pickling

7. Tanning

Ammonium sulphate is used as the deliming agent. This removes most ot the lime absortdeel during the llmiing process. Ammonium sulphate also loosens hair follicles so that most of the hair bacomes detached at this stage. lt further reduces the foul odour of hides by removing protein degradation products.

Finer hair particles not already detached during deliming are serapad off using a "roller type" knife.

(Bating - An enzymatle process which has pronounced effect on the grain of the hide or skin and general run and stretch of subnsequyent leathers. Possibly accomplished by acting on the elastin network of the grain, the degraded protein (which has partially been attacked during liming) and the erector pili muscle. The current enzymatle aqueous trestment employing 0.5% bating material, of 1/2 to 12 hours duration in drum or paddie reptaces the age-old processing which entailed trestment with dogdungor pigeon droppings.)

A brine and acid solution (H2S04) is used tobring hides to an acid condition before tanning. Pickling is mostly done in chrome tanning but is somatimes as a preservative step in vegetabla tanning.

7.1 Vegetabla tanning

7.2 Chrome tanning

8. Splitting

Tannin used in most cases is wattie bark resin extracted in water to obtain the tanning liquor. Some tanneries use tannigan or mimosa extract. The oparation involves soaking the hides in tan liquor tor twenty days. Usually there are twenty baths. Hides are transferred daily trom one bath to another bath together with the original tan liquor in the first batch. Thus the concentratien of the tan liquir gets reduced progressively at each batch. The final bath liquor is discarded after tlkenty days. The last four baths contain a layer of crushed gall nut (aralu). Gall nut helps the hides to absorb an even coating of tan.

In the chrome tanning drum the hides undergo multiple stages of processing namely, deliming (4), pickling (6) and tanning. Common salt is added before pickling. Washing is done after deliming. Salty and acid trestment conditions the hides for tanning and also prevents chromium salt precipitation during the process. The chromium souree used in Sri L.ankan tanneries is basic chrome sulphate salt, which contains 27-30% chromium. Fungicide is added after chrome tanning to prevent fungal growth on the hides.

Splitting is done mechanically to obtain various thicknesses tor different laather products.

Other post-tanning operations are: Sammying, Shaving, Neutralizing, Dying, Retanning, Fat liquor

9. Drying & Finishing Tanned laather is finally treated with a mixture of coconut oil and tallow, to replace the natural oils lost during the tanning process. lt is then dried and spray painted with the desired colours.

111 - 4

C. THE NATURAL RUBBER PRODUCING INDUSTRY

1) Processing of latex into Ribbed Smoked Sheet

Field latex Is tapped from the rubber trees lnto barrels. Anticoagulants, sodium sulphate or ammonia, are added to the latex to prevent premature rubberformation ( = coagulation). The content of the barrels is bulked In the factory In large baslns, where sodium bisulphite and oxallc acid are added to the latex for conservation. As a result from washing,, a milky liquid (wastewater A) emerges here. Formlc acid is added for coagulation In the coagulating basins. The rubber polymeres are formed now. The acidlc serum, (I.e. the excess water + chemieals after coagulation) plus the washing water result In wastewater B. After coagulatlon, milling takes place several times to "stretch the molecules" or to get a tight crystallic molecule structure which gives rubber its properties. Each milling operatien is foliowed by washing. The washingfmilling water is discharged as wastewater C. Subsequently the rubber is drained, smoked and packed.

2) Processing of latex and field coagula lnto crepe rubber

Tapped field latex with anticoagulants (sodiumsulphite or ammonia) Is transported to the bulking baslns, where sodiumbisuphite, formic acid and mercaptans are added. lntermediate washing leads to the milky wastewater A. Coagulation takes place In the coagulating tanks, causing a acidic serum water, wastewater B. The rubber Is formed now and can be milled into thin white laces to "stretch the molecules". After washing (wastewater C) these laces are drled and packed as sole crepe or pale crepe (depends on purpose and desired qualities). The so-called scrap crepe, being the field coagula from cuplumps and tree laces, starts with being milled and washed (wastewater C). The milled brown laces are subsequently dried and packed.

3) The processing of latex into Technicafly Specified Rubber ( = block rubber)

Field latex is collected and preservated with ammoniafboric acid. After reception lnto the bulk tank sodium sulphite Is added and washing takes place (wastewater A). The bulk coagulates with formic acid lnto rubber (wastewater B from acidic serum) which Is consequently analysed in a Iabaratory (sampled) for its properties. The coagulation of rubber does not necessarily take place in the TSR factory. TSR is often produced (in Sri Lanka) from a mixture of ribbed smoked sheets, scrap crepe, skim rubber and other "waste" rubber. This mixture of rubber raw materials, from which the quality is known, is fed to rubber breakers or shredders where the rubber is broken lnto smaller pieces and washed several times (wastewater C). These are dried in an oven, welghed and pressed into bales of a standardised weight (e.g. in Sri Lanka often 33.3 kg). The bales are wrapped and palletised.

4) The processing of latex into (centrifuged) latex concentrare

Ammonia Is added to field latex to prevent premature rubber formation. The latex is transported to the factory where it is centrifuged. The intended product is concentrated latex, which can be used to produce "dipped products" like gloves, balloons, condoms. Washings from bowls, the floor etc. result in wastewater A. By-product is skim latex, the liquid remaining after the centrifugation, having a very low rubber concentration. Th is skim latex can be coagulated into skim rubber with concentrated sulphuric acid. The liquid part in the coagulation tank, after coagulation, is called the skim serum and is discharged as wastewater B. Washing water and water from milling of skim rubber are discharged as wastewater C

Explanation Wastewater A: Washing wastewater Wastewater B: Serum or coagulation wastewater Wastewater C: Milling wastewater

111- 5

APPENDIX IV

CALCULATION OF THE ESTIMATED WASTEWATER CHARACTERISTICS (ad 4.3)

APPENDIX IV- CALCULATION OF ESTIMATED WASTEWATER CHARACTERISTICS (AD 4.3)

In this appendix first the theory Is explalned which was used for the calculation of the estimated wastewater characteristics. Subsequently the results of these calculations are presented and discussed. Discussion and interpretation of the calculations Is given first, foliowed by the presentstion of the results In the form of the tables IV-1, IV-2, IV-3 and IV-4. These tables can be found at the end of this appendix.

A. THEORY:

The calculation of the expected flow of the wastewater Is as fellows: When the production-level of productsis known in [kgfday), then this production is multiplied by the relativa effluent flow in order to obtain the expected effluent flow in (m3 fday]; see (1). This expected effluent flow is the estimated value of the wastewater discharged daily by the partJeular factory. In formula:

Estimated effluent flowrata = Relativa effluent flow * Production level (1)

{m3 effluent/kg product] {kg productjday]

The next step is to calculate the expected BOD-Ioad. This is done by multiplying the relativa BOD­Ioad (in kg BOD/metric ton product) with the production level (kg/day); see (2). The Expected BOD­Lead is a messure for the daily produced biodegradable waste material (kgfday) in the effluent, discharged by the partJeular factory. Dividing this BOD-Ioad by the Real Wastewater Flow results in the Expected BOD-Concentratien in (mgfl); see (3). In formula:

Estimated BOD load = Relativa BOD-Ioad * Production level (2)

{kg BODjday} [kg BOD/kg product] {kg productjday]

Estimated BOD concentration = Estimated BOD load * 103 I Estimated effluent flowrata (3)

[mgjl] {kg BODjday}

I made these calculations for the factorles which I have visited. The calculations of the estimated BOD-Ioad and the estimated wastewater flow are presented in the tables 1, 2 and 3 for the textile industry, the laather industry and the rubber lndustry respectively. For the laather industry also the estimated chromium production is calculated in analogically. The loads and concentrations of Suspended Solids are calculated in an analogical way. The results of these calculations are presented in table 4. The calculated BOD and Solicls-concentrations will be compared to the toleranee limits which are vlid for the three sectors in Sri Lanka (see table 5)

The relativa effluent flowrates and the relativa BOD-Ioads being used in the calculations, have been provided by Economopoulos (1981), WHO (1982) and RRI (interview, 1990). These factors are presented in the three cadres below.

In the textile industry four categorles can be distinguished according to the type of fibre processed:

IV- 1

Cotton, Polyester, Nylon and Rayon. For each category different waste factors are specified. Most textile mills In Srl Lanka use a mixture of these fibres for raw materiaL Of course other types exist, but thelr share in production in Srl Lanka is negligible.

In the Laather industry two types of laather tannlng are performed: chrome tannlng and vegetabla (or bark) tanning. For bath categorles the waste factors are specified. Four of the vislted factorles are chrome tanners for more than 96% of thelr production (in welght). They can be consldered as full chrome tanners. One tannery, Anthony, Is a 100% vegetabla tanner.

The types of rubber produced in Srl Lanka can be dlvided lnto four categories; Ribbed Smoked Sheet, Technically Speelfled Rubber, Crepe Rubber and Concentraled Latex. Hereby is assumed that crepe and RSS rubber manufacturing produce the same amount of BOD and Total Solicis in their wastewater. (thls assumption was necessary because the relatlve BOD-laad of RSS was lacklng In the data).

The waste factors, being the relatlve BOD-Iaads and the relatlve effluent flowrates tor each category, are presented in the cadres below.

Textile Some remarks on the textile waste factors High BOD and high effluent volumes are caused by polyester and catton manufacturing. With the manufacturing of synthetlc fibres however, taxie non-biodegradable waste is discharged, which Is nat lncluded in the BOD­laad. Therefore the low BOD-Iaads of Rayon and Nylon do nat mean, that the production of these fibres is causing less pollution. On the contrary, dyes for synthetic fibres are generally more taxie or pathogenie than dyes for catton fibres. Processing of polyester fibre causes the highest solids In the wastewater: 9.5% of the welght of the raw materiaL

Leather Some ramarks on the laather waste factors

Collon: SOD-Ioad [g/kg texti/e] effluent flowrate [I/kg textile] suspënded so/ids {gjkg textile]

Po/yesiBr. BOD-Ioad [gjkg textile] effluent flow [ljkg textile] suspeneled solids {gjkg textile]

Ra)ioo:

.... facbts (Economopoulos. '111)

155(150: WHO, 1982) 317 {381:WHO, 1982) 70

185 100 (120: Nemw, 78) 95

BOD-Ioad [g/kg textile] 30 effluent flow [I/kg textile] 42 suspeneled solids {g/kg textile] 55

Nylon: BOD-/oad {gjkg textile] 45 effluent flow {I/kg textile] 125 suspendeel solids {gjkg textile} 30

When BOD, COD and suspended soliels are considered, there is no significant difference between the pollution of vegetabla (or bark) tannlng and chrome tanning. Also the effluent volumes per kg laather are approximately identicaL When Suspended solids are consldered, thelr welght amounts almast 14% of the welght of raw hides.

The only significant difference is the discharge of taxie chromium in chrome tanning. The amount of chromium discharged by a vegetabla tannery can be neglected. Hence the tannery wastewater contains considerable amounts of all, (bark tanning effluent more than chrome tannlng effluent). For further calculations only the BOD-laad, the Effluent flowrate, the Suspended Solids and the Chromium content will be considered.

IV- 2

wast&facbs (Economopoulos, '81)

Panlmslsts waselacbs [LDhanl, 7hanh, 1978; RR/, 1990]

Ribbed Smoled Sheet Rubber Relative BOD-Ioad [g BOD/kg dry rubber] 48.8

89 . . Rel. effluent flowrate [//kg dry rubber] 30.0 Cbtome tannery BOD [gjkg hidesj COD [gjkg hldes] Effluent Fowrate {I/kg hides} Ofl[gjkg hides)

175 (~: WHO, •1982) 52 (52: ESCAP, 1982)

Total Solids 94.6

20 . Cnlpe Rubber Chromium [gjkg hides] Suspendeel so/lds

3.5 ~: ESCAP, 1982) 138

Relative BOD-laad [g BOD/kg dry rubber] 48.8 Rel. effluent flowrate [ljkg dry rubber] 40.0

·~ tannery (Wf«>, 1982) 800 [g/Jcg hides] 67 COD [gjkg hides] 250 Effluent Flowrate [I/kg hides] 50 oil (g/Jcg hides] · 33 chromium [gjkg hldes] 0.2 Suspended Sotids 135

Rubber Some remarks on the rubber waste factors: The pH is low for all rubber types, which means acidic. The concen­trated latex effluent is very acidlc (pH 3.5); the nitrogen content is high (8.4 kgfton DRC or al most 1% of the weight of produced rubber). For most rubber types a bout 10% of the raw material (weight of dry rubber content) ends up in the drain, measured as Total Solids. (exception Is TSR: 5%) Note: lt is assumed, that the Total Solids and BOD for RSS and crepe rubber are the same, slnce the process is basically the same.

Example An example of the calculations for the estimatlon of BOD-Ioad and effluent volume can be found in the cadre on the rlght.-+

Total Soliels 94.6 .. . ..

·· ·. • Technlcally Speellied Rubber . . Relative BOD-laad [g BOD/kg dry rubber] 58.3 Ref. effluent flowrate [ljkg dry rubber] 30.0 Total Solidt · 55.8

Concenfraled ·~.s~ex Relative BOD-Ioad [g BOD/kg dry rubber] 40.0 Rel. effluent flowrate [ljkg dry rubber] 10.0 Total Solids 109.0

Exampfe: Tan Lanka. Jeather tannery Production of Tan Lanka: 6000 kg teather jday. The expected flow of the wastewater is 52 1/Jcg * 6000 kgjday = 312,000 ljday = 312 m3jday.

This amount can be compared to the measured value or the vatue obtained by interview. The CEA measured 275 m3jday.

Re/ative ·BOD load for chrome teather manufacturing: 89 . kg BOD/ton Jeather; the production was 6000 kgjday. The Expected BOD-Load is consequently: 89 * 10-3 * 6000 = 534 kg BODjday.

Tfle Expected BOD-concentration is: 534 [kg BODjday] J 275 [m3jday] = 1.942 {kgjm3] = 1900 {mg/1]

Analogically to the calcu/ation of BOD-Ioad and concentration, · the estimated load and concentration of Suspendeel Solids (SS) can b6 found. Relative SS-Ioad is 138 gjkg raw hides. Production was 6000 kgjday. SS-laad = .6000 [kgjday} • 138 * 10-3 [kg SS/kg hidesj. = 828

· [kg SS/day]

The SS concentrat/on ·is ·10S * 828/kg/dayj j312[m3jday] = 2700 {mg/1] . .

IV- 3

8. INTERPRETATION OF THE CALCULATIONS

In the following text I will discuss the results of the estimations of the pollution. The calculations of the estlmated wastewater characteristics are presented in the ferm of tables. These tables 1,2,3 and 4 can be found at the end of this appendix, pages IV-7 to IV-10. The interpretation of the results Is dlscussed below. The findings wlll also be compared to the maximum allowed concentrations of the pollution parameters. These toleranee limlts are set for the effluents of the Sri Lankan textile, laather and rubber lndustry lndividually. An overview of these toleranee limlts is presented In table 5, page IV-11.

Discussion of Table 1: textile lndustry

Ad column B1

Ad column B2

Ad column A & C

Ad column D

First I have calcu1ated the production of cloth In kgjday from the production In mjday, wlth the assumption, that the average weight of produced textile is 0.22 kgjm. Thls assumption is based on three data: for three factorles the textile-weight per meter is known: - Duro: 0.17 kgfm textile - MKC: 0.29 kgjm textile - Pugoda: 0.21 kgjm textile (Mathes, 1989)

General remark: the production from the visited factorles together consists for 61% of eonen, 27% polyester and 12% ether synthetic fibres.

The estimated daily effluent volume is in all cases except Kundanmal slgnificantly higher than the volume which was given to me via interviews. These differences might find their crigin in: - Lack of knowledge of the interviawed persen. He might have used wrong units or conversipn factors. - Inadequate maasurement of the effluent flowrate. Batch discharges were perhaps net taken into account. - Inadequate estimations. The methad might be inapplicable to the Sri lankan textile lndustry. This is however net plausible, since the methad Is designed and propagated especially for developlng nations. [Economopoulos, 1981] - Underestimation of negative wastewater characterlstics by purpose, in order to avoid negative publicity for the company. - Net right\y chosen assumption about the weight of ene meter textile (0.22 kg/meter)

The total BOD-lead produced by the 8 factorles together amounts 7200 kgjday. When a Europaan citizen produces an equivalent BOD lead of 54 gjday, then the 8 factorles are producing a waste lead which is cernparabie to the sewage of 7,200,000/54= 133,000 inhabitants. The toxic compounds, such as pathogenie dyestuffs and inorganic wastes, have net been taken into consideration.

Analogically the total pollution lead (BOD only) from the 17 significant polluting textile cernpanles in Sri Lanka (CEA, 1989) can be compared to the sewage of a Europaan city wlth 235,000 inhabitants. (see calculation below) The state sector or 3 factorles account for 43% of this city effluent or 101,000 inhabitants. Remark: slnce in Sri Lanka privatisation Is envisaged on the short term, the government is dlsposing of the textlle sector.

IV- 4

Ad column E

Ad column E & F

Calculation: Average BOD-Ioad per kg textile = 61% * 155 (cotton) + 27% * 185 (polyester) + 12% * 38 (other) = 149.2 [g BOD/kg textile]

Total textile production by 17 factories: 85,000 kgjday, of which 43% in the state sector (3 factor/es) and 57% in the private sector (14 factories) (CEA, 1989)

The total BOD load is 85,000 * 149.2 = 12,700,000 g BODjday. 12,700,000 [g BOD/day] / 54 [g BODjday.lnhabitant] = 235,000 inhabitants

The BOD concentrations based on effluent volumes trom the interviews are all very high, ranging trom 10 to 114 times the toleranee limits for textile effluent in Sri lanka. When these BOD concentrations are calculated on basis of the estimated effluent volume, then they are only 10 to 15 times higher than the toleranee limits.

The estimated BOD concentrations do not conform to the samples of the effluent taken be local laboratories. This is no surprise since in the textile industry is often worked with batch discharges, causlng varying concentrations. The BOD should be maasured every hour for at least one week in order to give a raai Imprassion of the average BOD concentration. I doubt if this has been done. Monitoring of textile effluent is done very irregularly and almost at random. Of course also the estimation method is very inadequate. lt gives only a rough estimate of the range or order of the pollution.

Discussion of Table 2: the leather industry

Assumptions:

Ad column A & C

Ad column B

Ad column D

* 1 wet hide = 1.5 M2

* 1 wet hide = 10 KG -+ 1 KG HIDE = 0.15 M2

* 1 cow hide = 10 kg; 1 buffalo hide = 18 kg; 1 goat skin = 2 kg

In the case of the five laather tanneries the estimations of the wastewater flows are reasonably accurate (highest davlation about 50%). The amounts of wastewater range trom 36 to 481 m3 per day.

Two tanneries (T an Lanka and CLPC) account for a bout 50% of the total production of the laather industry in Sri lanka- as registered by CEA.

Tagether these five tanneries produce 1.86 million g BODjday. One Dutch inhabitant (equivalent) produces 54 g BODfday. So the collectiva pollution load can be compared to the sewage of a town of compared to a town of 1.86 million/54 = 34,500 inhabitants.

When the aleven significant polluting tanneries (CEA, 1989) are taken together, their production is over 30,000 kg hides per day. Their effluent is equivalent to the sewage of a town of 50,500 people (Dutch lifestyle).

When the future central tannery has started and the other tanneries continue tanning, the total production will lncraase to 50,000 kg hldes per day. The town will have 83,500 lnhabitants. (see calculations)

IV- 5

Ad column E

Ad column F

Calculation: Daily 30,625 kg hides are processed in the eleven tanneries. This corresponds toa pol/ution load of 2.73 mil/ion g BODjday. 2.73 mil/ion 1 54 = 50,500 inhabitants. When the future tannery is included in the calculations, the total production willlncrease with an additional 20,000 kg hides, or 1.78 mil/ion grams BOD. When the other tanneries continue tanning, the total BOD load wil/ be 4.5 mil/ion gram BODjday. This is equivalent ot 4.5 mi//ion/54 = 83,500 inhabitants.

The chrome tanners discharge wastewater with high BOD concentrations, ranglng trom 2000 to 3500 mgjl. Thls Is 30 to 60 times higher than the toleranee limits tor tannery effluents In Sri Lanka.

Analogically to the BOD leads and the BOD concentrations the Chromium leads and concentratieins can be calculated. The total amount of chromium(lll) which Is actually discharged lnto the environment by the eleven largast tanneries is estlmated to beover 100 kgjday.

(Calculation: Total Production = 30.6 metric ton hidesjday; Relative Chromium Load = 3.5 kg Crjton hides. 30.6 * 3.5 = 107 kg Crjday)

The chromium concentratien in the effluent of the chrome tanners is estimated to be between 76 and 130 mgjl, while the toleranee limits do not allow a concentratien of more than 0.5 mg/1.

Discussion of Table 3: the rubber manufacturlng lndustry

Ad column A & C

Ad column B

Ad column D

The estimated effluent flows correspond very well to the effluent flows obtalned by interview, except Ceymac. The effluents trom all vlsited factorles except Ceymac are within a range of 35 to 72 m3 jday (averagely 50 m3 jday).

Ceymac is an exception, because it is the largast crepe manufacturer and the largest (and only significant) TSR manufacturer in Sri Lanka. Especially tor TSR manufacturing excesslve amounts of water are used. The real effluent amounts 3530 m3 jday, which is more than twice the estimated value. Obviously the water use can be and has to be reduced slgnificantly. lt is contraversial that the factory managers finds hls effluent enough diluted to be a hazard to the environment!

In the six factorles visited, a total amount of 59,000 kg natura! rubber is produced per day. The entire rubber industry produces 410,000 kg rubber per day [RRI, 1990). The majority of the rubber production Is done by smallholders (44%) and in smali/medium scale units, producing about 1000 kg rubber per day. Of the latter units, 25% is private and 31% is government­owned. Ceymac alone accounts tor 11% of the total rubber production.

The 6 factorles account tor 3135 kg BOD/day, equal to 3135 * 103/54 = the sewage of 58,000 Europeans. Ceymac alone accounts tor 84 % of the wastewater of this little town.

lt is ditticuit to estimate the total environmental impact of the Sri Lankan

IV- 6

Ad column E

Rubber industry, because many small scale factorles are scattered over the island, mainly in rural areas. But when the Sri Lankan rubber production is 410,000 kgfday (Yapa, 1989), then roughly 54 * 410,000/54 = 410,000 lnhabitants are living in "Rubber City''.

I only estimated the extent of the pollution as measured by organic biodegradable compounds (BOD). lnorganic substances, acids etc are not taken into consideration.

The BOD concentrations are all very high, ranging from 1000 to 5000 mg/1. The concentratien for Ceymac is the lowest, because the waste is very much diluted by the high amount of wastewater. However the BOD is still 15 times too high. In the worst case - Dipped products - the BOD concentratien is 100 times too high when compared to the toleranee limits for rubber effluent. Fortunately a successfull treatment plant has been installed here.

Note: the company Ceymac owns two factories. The results in the table are in all cases the sum of both factories, although in reality the effluent is not combined.

Discussion of Table 4 - Loads and Concentratlons of SuspendedjTotal Solids of all factory effluents

Ad column D & E For the textile and laather lndustry I have calculated the concentrations of Suspended Solids in the wastewater. For the rubber industry I calculated the Total Solids, because no data were available on suspended solids production by this type of industry.

Textile The estimated Suspended Solids-concentrations range from 400 to 3200 mgjl. The maximum concentratien allowed for discharge into iniand surface waters amounts 50 mg/1. The textile factorles produce roughly between 1 00 and 1500 kg suspended solids per day.

Leather The estimated Suspended Solids-concentrations range from 1200 to more than 5000 mg/1, while the toleranee llmits for the laather industry are set at 100 mg/1 for inland surface waters. In tanneries between 100 and 2400 kg susp. solids are produced daily.

Rubber Normally the Sri Lankan standards allow 1000 mg/1 Total Solids in the effluent of rubber factories. An exception is formed by the production of centrifugated latex: maximum concentratien is 1500 mg/1. The results of the calculations show, that all factorles are exceeding these limits except Ceymac. The concentrations range from 900 to 5000 for producers of rubber. Ceymac produces a wastewater with 900 mgfl suspended solids and is conforming to the standards (This is rnainly caused by the large effluent volume from the TSR production which is dlluting all other wastes). When the loads of susp. solids (column D) are considered, Ceymac produces about 10 times the amount of solids when compared to other rubber factorles (3000 kgfday and 100-600 kgfday respectively). The latex centrifuger Dipped Products Ltd. has very high solids in its effluent: 18000 mg/1 (fortunately effluent treatment is performed here)

IV- 7

Textlle Actual or real em. Production Production level in Expected emuent flow Expected BOD-Ioad Expected BOD Actual BOD-lndustry volume level in mfday kgjday in m3 jday in kgfday concentratlon in mgfl concentratlon in

Qnterview) (EFRel in I/kg) (BODRet in gjkg) mgfl in m3 jday E=103*D/A (samples)

A B1 B2 =A*0.22 C = B * 317 * 10"3 D = B * 0.15 F

Cotton 8712 8712 * 0.317 = 2760 8712 * 0.155 = 1350 Polyester 968 968 * 0.10 = 97 968 * 0.185 = 179 real effluent: 6796

Baksons 225 44,000 total 9,680 total 2860 total 1529 103*1529/2860=535 95

Cotton 400 400 * 0.317 = 127 400 * 0.155 = 62 Polyester 651 651 *0.100 = 65 651 *0.185 = 120 Nylon 618 618 * 0.125 = n 618 * 0.045 = 28 real effluent: 5250

Duro 40 10,000 total ·1,670 269 210 103*210/269=781 383

Cotton (ass) 1320 1320 * 0.317 = 418 1320 * 0.155 = 205 Polyester(ass) 1320 1320 * 0.100 = 132 1320 * 0.185 = 244 real effluent: 3454

Fairline 130 12,000 total 2,640 550 449 103*449/550=816 1500

Cotton 190 190 * 0.317 = 60 190 * 0.155 = 29 Polyester 390 390 * 0.100 = 39 390 * 0.185 = 72 Rayon 317 317 * 0.042 = 13 317 * 0.030 = 10 Nylon 158 158 * 0.125 = 20 158 * 0.045 = 7 real effluent: 576

Kundanmal 205 4,800 total 1,056 132 118 1ol*118/132=894 780

Cotton 6n6 6n6 *0.317 = 2150 6n6 * 0.155 = 1050 Polyester 2024 2024 * 0.100 = 202 2024 * 0.185 = 374 real effluent: 6846

MKC 208 30,800 total ··a,soo 2350 1424 1ol*1424/2350=606 n.a.

Cotton 10150 10150 * 0.317 = 3220 10150 * 0.155 = 1573 Polyester 5937 5937 * 0.100 = 594 5937 * 0.185 = 1098 Rayon 3064 3064 * 0.042 = 129 3064 * 0.030 = 92 real effluent: 1215

Pugoda 2275 90,000 total ••• 19,150 3940 2763 1ol*2763/3940=701 300

Cotton (ass) 1320 1320 * 0.317 = 418 1320 * 0.155 = 205 Polyester(ass) 1320 1320 * 0.100 = 132 1320 * 0.185 = 244 Rayon (ass) 1320 1320 * 0.042 = 55 1320 * 0.030 = 40 real effluent: 3075

Swastik 159 18,000 total 3,960 605 489 103*489/605=808 n.a.

Cotton (ass) 572 572 * 0.317 = 181 572 *0.155 = 89 Polyester(ass) 572 572 * 0.100 = 57 572 * 0.185 = 106 real effluent: 1383

Velona 141 5,200 total 1,144 238 195 103*195/238=819 n.a.

TABLE 1 • ESTIMATED WASTEWATER CHARACTERISTICS OF THE VISITED FACTORlES IN THE TEXTILE INDUSTRY.

IV- 8

Leather lndustry Actual or real Production level: Expected flow in m3 jday Expected BOD-Ioad Expected BOD- Expected chromium discharge effluent flow wet hides processed (Cr: 52 lfkg wet hides) in kg BODjday concentratlon (relative load = 3.5 kg Cr jton hides) Qnterview) in kg/day (Veg: 50 I/kg wet hides) (Cr: 89 gfkg hides) in mgfl in m3/day (Veg: 67 gjkg hides)

F1 = Cr-load F 2 = Cr-concen-! in (kg Cr fday) tratlon in [mgfl)

I CLPC

A B C = B * 52*10"3 D = B * 89*10"3 E = D*1ol/ A F1= 3.5*10"3 * B F2= F1 * 103 1 A

400 9250 481 823 103*823/400= 2060 32.4 81 (97% Cr)

Tan Lanka 275 6000 312 534 1ol*534/275= 1942 21.0 76 {100% Cr)

S.A.Perera 52 2000 104 178 103*178/52= 3423 7.0 130 (96% Cr)

Mubarak 112.5 3160 164 281 103*281/113= 2500 11.1 100 (97% Cr)

Anthony 80 712 36 48 103*48/80= 596 0 0 {100% veg) (no chrome

tanning) Central tannery n.a. 15,0Cl0-20,000 780-1,040 1 ,335-1 '780 1ol*1335/1040= 1284 (future; 100% Cr) (min) 52.5-70 67

103*1780/780= 2282 (max)

TABLE 2- ESTIMATED WASTEWATER CHARACTERISTICS OF THE VISITED LEATHER TANNERIES

IV- 9

Natura! rubber Effluent flow Production level Qnterview) Expected effluent flow Expected BOD-Ioad Expected BOD-c:oncentratlon manufacturlng [m3 jday), In kgjday in m3jday in [mgjl)

(interview) in kgfday

A B C = B* 10-3 * EFIW D = B * 10-3 * BODRel E = 103

• DI A

Ceymac 3530 TSR: 40,000 40 * 30 I/kg = 1,200 40 * 58.3 kg/t = 2332 625*1o3 /3530= 744 Crepe/RSS: 6,000 6 * 40 I/kg= 240 6 * 48.8 kgjt .. 293

Total: 1,440 Total: 2625

Dartonfield 48 Crepe: 1,200 1.2 * 40 I/kg= 48 1.2 * 48.8 kgjt = 58.6 58.6*103 /48= 1221

Dipped pr. 35 Gloves: 5,800 Latex processing only: 4.4 * 40 kgjt = 176 176*1 o3 /35 = 5030 (from 4400 kg DRC conc. 4.4 * 10 I/kg = 44 latex)

Ellakanda 54 Crepe: 1,800 1.8 * 40 I/kg = 72 1.8 * 48.8 kgjt ::: 87.8 87.8*103/54= 1626 (of which 10% scrap)

Glenross 58.2 Centr. latex: 2.000 2.0 * 10 ljkg = 20 2.0 * 40.0 kgjt = 80.0 129*1o3 /58.2= 2216 Skim rubber: 300 0.3 * 30 I/kg = 9 Crepe: 700 0.7 * 40 ljkg = 28 1.0 * 48.8 kgjt = 48.8

Total: 57 Total: 129

Matugama 54.6 Crepe/RSS: 1,200 1.2 * 40 I/kg = 48 1.2 * 48.8 kgjt = 58.6 58.6*1o3 /54.6= 1073

TABLE 3 - ESTIMATED WASTEWATER CHARACTERISTICS OF VISITED FACTORJES PRODUCING NATURAL RUBBER

IV- 10

The visited factorles Prodortion Relative load or Estimated load or Estimated Solids level Suspended Solids (SS) Suspended Solids concentration

(average per factory) in (kg SS/day] in [mg/1] in [kg/day] in (g SS/kg product]

A B C =A • B • 10"3 D =tol~ I WF (I'S = Total solids for (fotal solids for (WF = wastewater flowrate, rubber effluents) rubber effluents) see column A in tables 1,2,3)

TextUe: Baksons 9,680 72.5 702 3120 ss

Duro 1,670 64.6 108 2700 ss

Fairline 2,640 82.5 218 1677 ss

Kundanmal 1,056 72.7 77 376 ss

MKC 8,800 75.5 664 3192 ss

Pugoda 19,150 75.5 1446 636 ss

Swastik 3,960 73.3 290 1823 ss

Velona 1,140 82.5 94 667 ss

Leather: CLPC 9,250 138 1277 3193 ss

Tan Lanka 6,000 138 828 3010 ss

SA.Perera 2,000 138 276 5308 ss

Mubarak 3,160 138 436 3858 ss

Anthony 712 135 96 1200 ss

Central tannery 15,000-20,000 138 2415 2415 ss (future)

Rubber: Ceymac 46,000 70.8 3256 922 TS

Dartonfield 1,200 94.6 113 2354 TS

Dipped pr. 5,800 109 632 18000 TS

Ellakanda 1,800 94.6 170 3148 TS

Glenross 3,000 103 309 5328 TS

Matugama 1,200 94.6 113 2070 TS

TABLE 4 • ESTIMATED VALUES OF SUSPENDEO SOUDS or TOTAL SOUDS IN THE WASTEWATER OF THE VISITED FACTORlES

Industrial sector Suspended solids Total Solids Biologica! Oxygen Total Chromium in [mg/1] in (mg/1] Demand (5 days, in [mg/1)

20°C) in [mg/1]

TextUe industry 50 n.a. 60 2.0

Leather industry: • into in1and surface waters 100 n.a. 60 2.0 • into marine coastal areas 150 n.a. 100 2.0

Rubber industry: • RSS, Crepe, TSR 100 1000 50 n.a. • Concentraled Latex 100 1500 60 n.a.

TABLE 5 • TOLERANCE UMITS FOR EFFLUENTS FROM THE TEXTILE, LEATHER AND RUBBER INDUSI'RY IN SRI I.ANKA (CEA, 1989)

IV· 11

APPENDIX V

INFORMATION QUESTIONNAIRE, USED FOR FACTORY VISlTS

APPENDIX V- INFORMATION QUESTIONNAIRE USED FOR VISITING FACTORlES

general

1 Name 2 postal address 3 telephone 4a person interviawed b his official position

5 plant-manager 6 plant-owner(s) 7 date of cernmencement of operation: 19 ... 8 location of industry (address+maps)

production characteristics

9a type of industry (manufacturing of) b Actual production (nr of products) c Optimal production capscity (nr of products) d Product descriptions: (fill in table)

Products

By-products

lntermediate products

Specificatiens

1 oa number of shifts per day b number of workers per shift c total work force

Process details

11 subprocessas 1 sequence of operations: 1. 2. 3. 4. 5.

Production level

(if available a process flow chart should be provided)

V- 1

Unit

12. Process inputs: (fill in table)

Process actlvities 1 2 3 4 5 totai Unit

equipment

chemieals used kgfday

energy requirements kWh

quantity raw perday matenals used

waterused waterlor rrttday processing

cooling water

washing water

domest ie water

13a Is electric current available? b lf yes, what is the energy use? c Where does the power come J,tom?

14 Which ether energy sourees are used?

15 What is the souree of water supply? (public supply I groundwater (tube well) I surface water)

wastewater discharge

16 total daily wastewater discharge in [m3lday]

17 method of discharge (open channel I pipeline I covered drains I ether)

18 flnal point of wastewater discharge: (agricultural land I marshy land I sewer I lake I river I ela I estuary I sea I other)

19 possible points of wastewater discharge: (agricultural land I marshy land I sewer I lake I river 1 ela I estuary I sea 1 ether)

20a Is the water body belng used as a souree of drinking water? b Is it used for washing or bathing purposes?

21 What is the distance of discharge from the industrial plant?

22a Does the local authority receive industrial wastes? b lf yes, which toleranee limits and regulations?

V-2

23 Is there a deadline tor the company tor cessation of pollution?

24a Is the elient the only industry within the local authority? b lf no, name the exlsting industries within a 2 km radius:

wastewater characteristics

25a pH b batch periodlcity c suspended solids (mg/1) d total solids (mg/1) e 8005

20 (mg/1) f colour g taxie components h CCD [mg/1)

26a Which methods are adopted for recording characteristics of wastewater? b How aften are samples taken of the effluent? c By whom are these samples taken?

27a Which are the main pollution sources? b Is one of the processes easily identifyable as belng a major pollution cause?

28 Whlch other types of wastes are being disposed, except wastewater (atmospheric emissions,

solid wastes, noise pollution)?

wastewater trestment 1 pollution reduction

29a Is any ground area, suftleient for a waste treatment plant, available in or close to the plant

property? b lf yes, are there any obstructions against the purpose?

30 What area is available inside the industrial plant? lf no, then what Is the proximity of the area for treatment facilities?

31a Has the company access to waste treatment facilities now? b lf yes, full details c are the facilities in operation? d Is the company owning these treatment facilities?

32a Has the elient accomplishad inplant pollution raduclng measures? b lf yes, which? (recycling of water, recycling of other waste

materlal, reuse, process control, safe starage facilities, etc)

Attitude of the company

33 Is the company interestad in raducing water volume by recirculation or reuse?

34 Is the company amenable to suggestlons for changes in productive processes toraduce the volume and concentratien of wastes to raduce treatment casts?

35 Is the elient willlng to construct wastewater treatment works?

36 Is the company Interestad In other waste raducing measures?

37 Are there any plans for expansion in the near future? lf yes, give details

V-3

APPENDIX VI

CHEMICALS USED IN THE VISITED FACTORlES

APPENDIX VI - CHEMICALS USED IN THE VISITED FACTORlES

A. Chemieals used In the textlle lndustry

Hydrogen peroxide for bleaching Sodium silicate for stabilizing Sodium hydroxide (caustic soda) for scouring Sodium chloride (salt) for dyeing Acetic acid for dyeing "binder" for printing paste Urea (idem) Di ammonium phosphate (idem) "fixer" Qdem) antifoamer Qdem) Acracon B (idem)

Hydrogen peroxide (H20 2)

Sodium hydroxide (NaOH) Soda ash (N~C03) Non-ionic detergent Sulphuric acid (H2S04)

Bleaching powder Sodium sulphite (NaHS03)

"Softener" Dyes Sodium silicate (NaSi03)

Sodium sulphide (Na2S) Sodium sulphate (N~S04) Acetic acid Organic stabilizers Dispersing agent Levelling agent Urea

Baksons

Acetic acid acetone acracorn B acrafix M albegal ffd aleaprint PTF bactosol htn bleaching powder catalyst eaustic soda ceranine colour chem binder DM4 soluation ernafix tk eriopon ethyl acetate hatathrem k hydrogen peroxide imerol xn invalon htb irgalon sst irgasol co

VI- 1

quantity (kgjday)

15 7 6 50 2 60 10 10 20 2

quantity (kgjday)

53 29 42 8 1 2 2 6 1 9 4 2 1 2 1 1 8

quantity (kgjday)

28 0.4 2.4 2.6 2.4 2.4 56 8 4 740 36 67 1.0 2.0 3.5 0.2 1.0 240 4.0 2.2 3.0 2.4

leonil gae perrustol eek rumofill paa aalt sandopan sandozin aodaash sodlum blsulphlte aodlum hydro sulphlte aodlum slllcate tinofix eco extra univadine urea uvitex cid uvitex ebf

~ cibacron black, biue, red, yeliow colour chem biack, bordeaux, orange, red, violet, etc drimarene red, white, blue etc. haycolour levafix yeliow miketon black, navy blue remazoi biack, orange, red sulphoie biack terasil black, biue, yeliow, red, etc.

Kundanmal

sizing agent dye desizing agent levelling eaustic soda carriers soda ash reducing agent acetic acid finishing agent wetting agent resin fininishing agent detergents common salt bleaching agent ammonium sulphate optical brighteners

~ ·acid • disperse - reactive optica! brighteners eaustic soda hydrogen peroxide soda ash softeners levelling agent dispesing agent carriers salt detergents

VI- 2

4.8 95 12 120 8.0 16 1200 8.0 6.0 282 1.2 30 26 13.2 4.0

23.1 21.4 6.4 2.0 0.7 1.8 2.5 38 4.0

quantity (kgfday)

45 14 3 3 40 3 16 7 3 25 3 4 3 40 35 4 3

quantity (kgfday)

1.2 2.0 0.8 10 8.0 12 12 6.0 3.0 3.0 2.4 20 10

salt sulphuric acid soda ash silvafix hontex lamitex nexofix (bleach) urea eaustic soda finish polyfon softner silkasoft sunfix tri sodium phosphate tinofix uear

org. complexing agent for bleaching (securon) synergie blend & surfactant (cottoclarin) Olmethyl dihydroxy ethylene urea (stabitex) etherfieated melamine pre condensate (stabitex) fatty acid derivative (belsoft) bacterial alpha anilaze alkyl aryl polyglycol ether grease solvent polyhydroxy alkylene glycol ether solable florescent dispersing agent triazinyl fluorescent whitening fatty aced (sapamine) Chloro fluoro tryacine past compound azoics (terasil) azoics (enyonyl) eaustic soda soda ash acitic acid hydragen peroxide 50% sodium silicate flambers salt

Swastik I Nagindas

Acetic acid potassioum permanganate oxalic acid bleaching powder fabric softener detergent eaustic soda soda ash salt hydragen peroxide

Vl-3

quantity (kgfday)

165 40 110 80 65 30 20 155 750 160 40 35 35 65 20 55 125

quantity (kgfday)

10 10 5 5 20 5 5 5 5 15 10 20 25 5 5 30 20 25 25 10 50

quantity (kgfday)

2 3 15 10 30 2 20 15 25 10

B. Chemieals used In the teather lndustry

Mubarak

wetting agent (soaking) sodium sulphite (liming) lime powder Oiming) plokling salt (tanning) sulphuric acid (tanning) tormie acid (tanning) chromium salt (MS) (tanning) syntans (retanning) mimosa powder (retanning) sulphonated fish oil (fat liquoring) powder dyes (dyeing) busan 30L (soaking, tanning) prevan tal WK (soaking, tanning) antimold AA (soaking, tanning)

Anthony

lime Oiming) salt (salting) ammonium sulphate sulphuric acid (pickling) salt (pickling) wattie bark extract (S.A.)

SA Perera

lime sodium sulphite ammonium sulphate Formicacid basic chromium salt sodium tormate fat liquor vegetable tan (for retanning purpose) pigments

Ceylon Leather Products Corporatlon

Sodium sulphite (NS:~S, liming) Calcium hydroxyde (Ca(OH)2, liming) Sodium hydragen sulphide (NaHS, liming) Ammonium sulphate ((NH4)2S04, deliming) Sulphuric acid (H2S04, pickling) Salt (NaCI, pickling) enzyms pancreol (bating) Cr2(S04b (chrome tanning) vegetable tan: ME-wattle (veg. tanning)

Tan Lanka Qn the worst case)

Formicacid Oxalic acid Sodium tormate Sodium bicarbonate Syntan (condensated product of formaldehyde and phenol) Leder olinor DL (synthetic oils) cjb white (Titanium oxide) chrome leather fast black (diazenium salt for dyeing) Bay chrome = Cr2(0H)2(S04)2

VI -4

quantity (kgjday)

9.5 79 142 158 32 15.8 190 47.4 94.8 142 12 3.2 9.5 3.2

quantity (kgjday)

80 22 14 6.4 64 160

quantity (kgjday)

100 30 40 20 150 10 50 10 5

quantity (kgjday)

108 504 45 100 50 200 12 300 300

Quantity (kgjday)

60 30 90 30 180 360 30 90 180

C. Chemieals uaed In the rubber lnduatry

Dippeel products

Sulphur Titanium dioxide Zinc mercapto benzo thiazole zinc oxide tetramethyl thirium disulphide ammonia liquld ammonia calcium carbonate potaasslum hydroxide sodium poly acrylate calcium nitrate organic pigments styrenated phenol lauric acid phosphoric acid chlorine gas calcium hypochicrite hydrochloric acid sodium carbonate potasslum dichromate sulphuric acid

Glenross

centrifuging ammonia TMTD (tri methyl ... ) zinc oxide dispersal LR phosphoric acid lauric acid sulphuric acid production of sole crepe tormie acid sodium bisulphate rupepa with emulsitier oxalic acid

Dartonfield

N~S03 NaHS04 BA -Nexo bieach I Rupepa Formicacid

Ellakanda

tormie acid nexo bieach I Rupepa sodium bisulphite sodium sulphite (anti coagulum)

Ceymac Formicacid sodium bisulphite oxalic acid tolyl mercaptan

Matugama Formicacid Nexobleach sodium bisulphite

VI- 5

quantity (kglday)

64 90 38 18 4 49 67 360 24 53 60 6 16 9.6 13 25 17 60 75 7 180

quantity (kglday)

138 4 4 0.2 10 1.3 80

10 3.5 0.7 5

quantity (kglday)

3.0 6.0 2.0 5.8

quantity (kglday)

8.1 2.7 10.8 8.1

quantity (kglday) 20 10 7 3.5

quantity (kglday) 6 1.5 3.5

APPENDIX VIl

REFERENCES

APPENDIX VIl - REFERENCES

LITERATURE CONSULTED

Amitha, 1988 Analyses of Samples taken of the Wastewater trom two Leather Tanneries: Tan Lanka and the Ceylon Leather Products Corporation; Chemistry dept, University of Kelaniya.

BKH, 1988 Feasibility Report on Wastewater Treatment tor the Rubber plantation lndustry of Sri Lanka (BKH is a consultancy agency trom the Netherlands).

Callely, Forster & Stafford, 1977 Treatment of lndustrial Effluents, p 229-244

Central Environmental Authority, Colombo, 1989 Leather Tanning Industries, PolJution Control Guideline Series, nr 13

ESCAP, 1982 Tanning lndustry: lndustrial Pollution Guidelines, series no 7, {also referred to in CEA and NBRO publications}

Jq>rgensen, S. E, 1979 lndustrial Wastewater Management, p. 293-304

Lettinga, 1978, Feasibility of anaerobic digestion tor the purHication of industrtial wastewater, in hte 4th European sewage and Refuse Sypmposium, EAS, Munich.

Lohani, Thanh, 1978 Water polJution Control in Developing Countries, vol 2, p 229: "Effluents trom natural rubber processing factorles and their abatement in Malaysia."

Mathes, J.A.P, 1989 Low Waste Technology Applications in Textile lndustry in Sri Lanka.

Metcalf & Eddy inc, Tchobanoglous, G, 1979 Wastewater Engineering: Treatment, Disposal, Reuse, McGraw-Hill book company.

Ministry of Finance and Planning of Sri Lanka, National Planning Division, 1983 Sri Lanka lndustrial Statistles (in co-operation with UNDP).

National Building Resources Organisation, Colombo, 1987 Environmental Aspectsof the Tanning lndustry in Sri Lanka. Referring to [ESCAP, 1982].

National Building Resources Organisation, Colombo, 1989 Environmental Aspectsof the Textile lndustry in Sri Lanka, referring to: -H.A. Schlesinger, E. Dul, T. Fridy; Pollution Control in Textile MUis -WHO, 1982; Rapid assessment of sourees of air, water and land pollution, offset pubHeation no. 62, Geneva - 1980; Gulde for Treatment and Disposal of Effluentsof Cotton and Synthetic Textile lndustry, · lndian standards, 9508

Nemerow, N.L. 1978 lndustrial Water Pollution: origln, characteristics and treatment.

NORAD, 1989 Envlronmental Study of Sri lanka, NORAD (Norvegian Aid), Colombo

Oxley, J.H, 1990 Report on the Mission to lnvestigate Ways of Assisting the Government of Sri Lanka in controlllng and Reducing lndustrial Pollution, UNIDO, Vienna (no forma! editing)

Schoor!, Wiggers, 1988 Report on Dutch mission on Development Cooperation between Sri Lanka and the Netherlands on the Sector Environment.

Stuckey and Hamza, 1981 Management of Jndustrial Wastewater in Developing Natlons. -Page 25: A.P. Economopoulos- Rapld Wastewater lnventories for developing nations. - Page 201: D.C.Stuckey; Anaerobic trestment of industrial wastewater In developing

nations; SINTEF, Norway.

UNIDO, 1986 lndustrial Development Series Review on Sri Lanka.

WHO, 1982 Rapid assessment of sourees of air, water and land pollution, offset publication no. 62, Geneva

Yapa, P.A.J, 1984 report on the Study of factory wastewaters in Rubber Plantations in Sri Lanka; Rubber Research lnstitute.

UTERATURE RECOMMENDED FOR FURTHER READING

Atkins, M.A, Lowe J, 1979 Case studies in Pollution Control Measures in the Textile dyeing & Finishing Industries, Pergamon press.

Conway, R, Ross, R, 1981 Handbook of lndustrial Waste Disposal, Van Nostrand Relnhold.

Edde H, 1984 Environmental Control for Pulpand Paper Mills, PolJution Technology Review nr.108, Noyes publications.

Franson, M.A.H, 1981 Standard Methods for the Examinatien of Water and Wastewater; American Public Health Association, Water Pollution Control Faderation and American Water Works Association.

Mendis, D.L.O, 1975 Planning the lndustrial Revolution In Sri Lanka, OECD Development Centra, Paris, France.

Nugawela, P, 1978 International Sub-contracting and FreeTrade Zones, OECD Development Centre, Paris, France.

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Lunet, H, 1971 lndustrial Poltution Control Handboek, McGraw Hili.

Ouano, E.A.R, Lohani, B.N, Thanh, N.C, 1978 Water Poltution Control in Developing Countries, volume I, International Conference, Bangkok, Thailand.

Ouano, E.A.R, Lohani, B.N, Thanh, N.C, 1978 Water Poltution Control in Developing Countries, volume 11, International Conference, Bangkok, Thailand.

Overcash, M.R. 1987 Techniques tor lndustrial Poltution Prevention; Lewis Publishers INC.

Rich, L.G, 1980 Low-maintenance, Mechanlcally Simpte Wastewater Treatment Systems, McGraw-Hill book company.

Winters, 0, 1984 Techno-economie Study on the Measures to Mitigate the Environmentallmpact of the Leather lndustry, particularly developing nations, UNIDO, Austria.

INTERVIEWS WITH LOCAL ENVIRONMENTAL EXPERTS

Dr S.P. Amarakone, november 1990 Senior Manager Environment, Greater Colombo Economie Commission.

Prof K.O. Arudpragasam, november 1990 Chairman, Central Environmental Authority.

Mr P. lllangovan, july & october 1990 Senlor Environmental Scientist, National Building Resources lnstitute.

Dr J.A.P. Mathes, june & october 1990 Head Environmental Section, Ceylon lnstitute tor Scientific and lndustrial Research.

Dr E.D.I.H. Perera, september-october 1990 Rubber Chemist, Rubber Research lnstitute.

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