33

3. CHARACTERISTICS OF TANNERY EFFLUENTS

IN TIRUCHIRAPPALLI DISTRICT

3.1 INTRODUCTION

The conventional leather tanning technology is highly polluting as it

produces large amounts of organic and chemical pollutants. In general, waste

materials of tanning industries are categorized into solid waste and liquid

effluent; the solid wastes include salts, unhairing wastes, lime wastes, flesh,

‘myrob’ dust, buffing dust and trimmed waste. Some portions of these solid

wastes are sold to outside agency for further beneficiary uses. The remaining

solid waste is stored in heaps within the tannery premises. The generated liquid

waste is let out to surrounding land without proper treatment. These effluents

cause severe damage to the flora and fauna (Mariappan et al., 1997).

This industry in developing countries is mostly run as a cottage /small-

scale industry with a very few medium sized units. The lack of awareness in the

modern industrial practice has resulted in the discharge of effluent which exhibit

very high amounts of protein, chlorides, trivalent chromium, nitrogen, Sulphate,

COD, BOD, and suspended solids (Kadam, 1990).

The tannery operations consist of transforming the raw hides, a highly

putrescible material, into leather, a stable product which can be conserved

indefinitely and has a significant value (Suresh et al., 2001). These operations

follow a sequence of chemical reactions and mechanical processes using

specialized machinery. Among these, tanning is the fundamental stage which

confers to leather its stability and essential characteristics. Only chromium (III)

34

sulphate possesses tanning proprieties with respect to skin collagen. To obtain

good quality leather, it is necessary to use a quantity of chromium salts

representing 2 to 2.5% (calculated as Cr2O3) pf the mass of skins to be tanned

(Rao et al., 2002).

These pollutants, which are mostly contained in the effluent discharged

by tanneries, are a serious threat to the environment. The tannery effluent, if not

treated properly, can cause serious damage to soil and water bodies. The high

amount of salt contained in the effluent, for example, can increase soil salinity,

reduce fertility and damage farming in large areas. Tanneries also produce

harmful gases, dust and a large amount of solid waste.

The groundwaters in the vicinity of tanneries of Pallavaram, Chrompet,

Ambur, Ranipet, Pernampet, Vaniyambadi, Dindugal and Tiruchirappalli have

been found to be deteriorated in quality. At Ambur well water has TDS ranging

from 1200 mg/1 to 6000 mg/L. Subsurface water of Palar at Vaniyambadi has

TDS and chlorides of about 2000 mg/1 and 800 mg/1 respectively (Sastry,

1984).

When tannery effluent-gains access to cultivable lands or when the lands

are irrigated with effluent, the fertility of the soil is affected, it changes the

characteristics of soil and interferes with intake of water by plants. Presence of

chromium influences the metabolic processes of plants (Devarajan et al., 1993).

Appa Rao et al. (1991) studied the extent of pollution of ground water sources in

and around the tannery units located in Dindigul town and reported that the

35

parameters like total solids, hardness and chlorides in the ground water sources

are higher than the admissible limit for drinking water.

In Tiruchirappalli tanneries are clustered at Sempattu area and their waste

water had been discharged without proper treatment upto 1995. The supreme

court of India by its order dated 01.05.1995 and 08.09.1995 issued direction for

the closure of tanneries which had not installed Effluent Treatment Plant (ETP)

individually or collectively. Thereafter all the tanneries established their own

ETP or common Effluent Treatment plant (CETP) for the tannery waste water

treatment. Main objective of the present study was to characterize the tannery

effluents of Tiruchirappalli district, with particular attention to their physico-

chemical and biological properties.

Ground water quality was also checked in and around the cluster of

tanning industries situated around sempattu, Tiruchirappalli to confirm the

pollution by tannery waste water.

3.2. MATERIAL AND METHODS

3.2.1 Study Area

The clusters of tanning industries are situated in the Sempattu area, south

of Tiruchirappalli Railway Junction. These tanneries produce semi-finished

vegetable tanned leathers. The ground water is the main source for various

leather processing operations. About 350 M3/day waste water is generated from

different processing units of the industry. In the present study the ground water

quality was also checked in and around the cluster of tanning industries at

Sempattu. There are 11 tanneries functioning in Sempattu. The ground water

36

sampling area of the village Sempattu for the present study was located at a

distance of 1.5 km from the tanning industries. This village has 2 hand pumps, 6

open wells and 4 bore wells.

3.2.2. Collection of Effluent Samples

For the present study, effluent was collected from a tannery at Sempattu,

Tiruchirappalli District, Tamilnadu, India. The effluent samples were collected

raw from the composite stream. The effluent was collected in polythene

containers [2 litre capacity], and were brought to the laboratory with due care.

The samples were collected for a period of 12 months from January 2008 to

December 2008.

3.2.3. Physico - Chemical Characteristics of Tannery Effluent

The physico-chemical parameters such as colour, odour, temperature pH,

Electrical Conductivity (EC), Total Suspended Solids (TSS), Total Dissolved

Solids (TDS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand

(COD), Total Hardness, Magnesium Hardness, Calcium Hardness, Sodium,

Sulphate, Chloride and Total Chromium were determined as per the methods

mentioned in the Table 3.1

Sampling of ground water from Sempattu was carried out during 2008.

Water samples were collected in polythene containers from hand pumps and

bore wells after running them for 15 minutes. All samples were refrigerated in

laboratory at 4°C. Background information regarding the location of hand

pumps, open wells and bore wells were recorded. The physico-chemical

parameters such as pH, total alkalinity, total hardness, chlorides, total dissolved

37

solids, turbidity, dissolved oxygen, chemical oxygen demand and biochemical

oxygen demand were analysed. The pH of the water was measured using a

digital pH meter (Elicomodel No. LI120).

The dissolved oxygen was estimated at the site of collection following

Winkler’s method (APHA, 1989). Turbidity was estimated using Nephelo

turbidity meter (Systronics Model No. 131) and the results were expressed in

Nephelo Turbidity Units (NTU). Estimation of remaining parameters was made

following the methods described by Trivedi & Goel (1984).The methods of

analysis for various parameters are listed in Table 3.1.

3.3 RESULTS

3.3.1 Physico-Chemical Characteristics of Tannery Effluent

Analysis of physico-chemical characteristics of the tannery effluent for

a period of 12 months (from January 2008 to December 2008) has been

studied and their results are given below.

3.3.1.1 Colour and Odour

The colour of the tannery effluent was grey when observed visually and

the odour ,disagreeable (Table 3.2).

3.3.1.2. pH

The pH of the tannery effluent during the period of study is shown in

table 3.2 and it ranged between 5.8 and 6.6. The lowest pH 5.8 was observed

during the month of April 2008, where as the highest pH, value was 6.6 during

November 2008, indicating thus the acidic nature of the tannery effluent.

38

3.3.1.3. Electrical Conductivity (pmhos / cm)

The values of EC were found to be between 11960 and 12859 pmhos/cm.

(Table 3.2).

3.3.1.4. Total Suspended Solids

TSS level of the tannery effluent during January 2008 and December

2008 are depicted in table 1. In this study the TSS level ranged between a

minimum of 1650 mg/L to a maximum of 1785 mg/L.

3.3.1.5. Total Dissolved Solids

The TDS level ranged between a minimum of 2100 mg/L to a maximum

of 3190 mg/L which is beyond the permissible limit (Table 3.2).

3.3.1.6. Biochemical Oxygen Demand

BOD level of the tannery effluent during the period of study is given in

table 3.2. In this study, BOD ranged between a minimum of 830 mg/L to a

maximum of 940 mg/L.

3.3.1.7. Chemical Oxygen Demand

COD of tannery effluent January 2008 and December 2008 are depicted

in table 3.2. The COD level ranged between a minimum of 2380 mg/L to a

maximum of 2500 mg/L.

39

3.3.1.8. Total Hardness

Total hardness of tannery effluent during the period of January 2008 and

December 2008 is shown in table 3.2. Total hardness ranged between a

minimum of 1400 mg/L to a maximum of 1700mg/L.

3.3.1.9. Calcium Hardness

Levels of calcium in the tannery effluent during the period of January

2008 and December 2008 are depicted in table 3.2 and calcium level ranged

between a minimum of 420 mg/L to a maximum of 520 mg/L.

3.3.1.10. Magnesium Hardness

Levels of magnesium hardness in the tannery effluent during the period of

January 2008 and December 2008 are depicted in table 3.2. In this study, the

magnesium level ranged between a minimum of 251 mg/L to a maximum of

289 mg/L.

3.3.1.11. Sodium

Sodium levels in tannery effluent estimated between January 2008 and

December 2008 are depicted in table 3.2. The sodium level ranged between a

minimum of 1260 ppm to a maximum of 1400 ppm.

3.3.1.12. Chloride

Levels of chloride in the tannery effluent collected during the period of

January 2008 and December 2008 are depicted in table 3.2 and the chloride

levels ranged between a minimum of 1620 mg/L to a maximum of 1760 mg/L.

40

3.3.1.13. Sulphate

Sulphate in tannery effluent during the period of January 2008 and

December 2008 is shown in table 3.2. Sulphate ranged between a minimum of

1390 mg/L to a maximum of 1460 mg/L.

3.3.2. Biological Characteristics

Among the biological characteristics, total heterotrophic bacterial

population (THB) was monitored during the course of study from January 2008

to December 2008

Total Heterotrophic Bacteria (THB)

THB population did not show any significant variation in the tannery

effluents during the one year of study and almost similar levels of THB were

recorded . THB varied from a minimum of 34.10 x 107 / 100 ml in the month of

April 2008 and a maximum of 39.50 x 107 / 100 ml in November 2008.

3.3.3. Heavy Metals

Heavy metals present in the tannery effluent during the period of January

2008 and December 2008 is shown in table 3.2. Zinc level ranged between a

minimum of 1.16 mg/L to a maximum of 1.36mg/L. Levels of copper in the

tannery effluent ranged between a minimum of 1.24 mg/ml to a maximum of

1.39mg/ml. Iron level ranged between 4.47 mg/ml and 4.62 mg/ml. Manganese

ranged between a minimum of 2.40 mg/ml and a maximum of 2.50 mg/ml.

Chromium level was between 0.51mg/ml and 0.58 mg/ml.

41

3.3.4. Ground Water Quality

To study the impact of tanning industry on the ground water quality,

water samples were collected from different ground water sources from

Sempattu. Details of the sampling of ground water in and around tanning

industries of Tiruchirappalli are given in Table 3.4. Details of ground water

sampling stations of Sempattu village are presented in Table 3.5. Water quality

parameters of ground water samples for Sempattu village was analysed and the

results are presented in Table 3.3.

Table 3.4 shows the details of sampling of ground water in and around the

cluster of tanning industries. The total number of tanneries in the study area is 7.

Total number-of sampling points including hand pumps, open wells and

borewells at Sempattu is 12.

Table 3.5 provides information of ground water sampling stations in

Sempattu and their distances from Tanning industries. The samples were

collected from the ground water source such as hand pumps that were located

about 50m from the tanning industries. The open wells (6) sampled from the

present study were located at variable distances from the tanning industries (200

m to 500 m) and the bore wells (4) ( 300 m to 500 m).

Table 3.3 provides data on the water quality parameters such as pH, Total

Alkalinity (TA), Total Hardness (TH), Chlorides (Cl), Total Dissolved Solids

(TDS), Turbidity (NTU), Dissolved Oxygen (DO), Chemical Oxygen Demand

(COD) and Biochemical Oxygen Demand (BOD) of the water samples collected

from the hand pumps, open wells and borewells of the Sempattu village. Various

42

water quality parameters measured in the water samples collected from the hand

pumps, open wells and borewells of Sempattu did not show any remarkable

variation with respect to the type of water source (HP, OW & BW). The pH

ranged from 6.49 to 6.75, TA 420 to 446.5 mg/L, TH 450 to 480 mg/L, Cl 4430

to 480 mg/L, TDS 810 to 830 mg/L, Turbidity 21.9 to 2.13 NTU, DO 2.4 to 2.7

mg/L, COD 12.2 to 13.8 mg/L and BOD 5.1 to 5.6 mg/L.

3.4 DISCUSSION

Leather industry has today attained well-merited recognition in the

international market, besides occupying a place of pride among the top exporters

of the country. This industry provides direct and indirect employment to around

2.5 million persons and is one of the major foreign exchange earners for the

country (exports of US $ 1576.12 million) thereby contributing significantly to

the Indian economy (16th Indian International Leather Fair 2001, CLRI) and

generates effluent which is estimated to be about 75,000 m9day (Sahasranaman

and Buljan, 2000), while Jawahar et al., (1998) estimates that the wastewater

discharged from these tanneries range from 80,000 to 1,00,000 m3/day. Tannery

effluent is highly polluted with high concentration of protein, chlorides, trivalent

chromium, sulphate, COD, BOD, TSS, TDS etc (More et al., 2001). Processing

of skins and hides require large amount of water and generate huge quantities of

tannery effluent which is discharged indiscriminately into nearby fields either

treated or untreated. Water and land pollution problems related to tannery

effluent have been reported as a serious problem in many countries

(Sahasranaman and Buljan, 2000). There are reports of chromium recovery but

the major issue like TDS, TSS, BOD and COD are still an unsolved misery to

the tanneries.

43

The present study on the tannery effluent from Tiruchirappalli district was

aimed at analyzing the characteristics of tannery effluent and to study the nature

of pollutants present in the tannery effluent. In the present investigation, the

physico-chemical characteristics of the untreated tannery effluent has revealed

that it is acidic, with high BOD, COD, organic particulate matter, unpleasant

odour and colour. The raw effluent was dark ash coloured, and the colour may

be derived from tanning sub-process such as bating, pickling, neutralisation,

dyeing and fat liquoring. According to Clayton and Clayton (1981), dyeing is

one of the major causes for development of colour in the effluent. Unpleasant

odour may be due to microbial growth or may be due to decomposition

(Panneerselvam, 1998). Microbial load of the effluents was heavy and well

above seven log number irrespective of the months of analysis. Moreover a large

number of pollutants can impart colour, taste and odour to the receiving waters,

thereby making them unaesthetic and unfit for any use (Goel, 2000). The pH of

the tannery effluent was highly acidic (5.8 to 6.6) and did not meet the general

standards recommended by CPCB (1995) for the discharge of effluents into

inland surface water or for irrigation purposes.

Discharge of untreated effluents with such a low pH into ponds, rivers or

on lands for any purpose may be detrimental to soil fauna and aquatic biota such

as zooplankton and fishes, since low pH level may affect the physiology of

fishes (From, 1980, Geetha et al., 1996). Further the toxicity of certain

substances present in water may be enhanced due to their interaction with the

low level of pH prevailing, which may further be detrimental to the aquatic

organisms (McCaull and Crossland, 1974).

44

Electrical conductivity is a numerical expression of the ability of water

sample to carry an electric current. The number depends on the total

concentrations of the ionised substances dissolved in water and to the

temperature at which the measurement is made. The conductivity of tannery

effluent in the present study was very high during most of the months, but it was

highest, during April, July and November 2008. High level of conductivity may

be due to the presence of inorganic substances and salts which show good

conductivity (Robinson and Stokes, 1959). It may be pointed out that, amount of

salts added while processing the hides and skins differs from tannery to tannery

and also on the type of processing.

The reason for the highest electrical conductivity during April, July and

November 2008 may be due to quantity of skins and hides processed and the

amount of salts used. According to Kataria et al., (1995) high electrical

conductivity level may be due to higher concentration of acid-base and salt in

water.

High level of total suspended solids (Table 3.3) present in the tannery

effluent could be attributed to their accumulation during the processing of

finished leather. Moreover, presence of total suspended solids leads to turbidity

resulting in poor penetration of light in the aquatic system, thereby curtailing the

light for photosynthetic activity (Goel, 2000). Further the settling of suspended

particles on soil and soil fauna, might lead to various damages like change in soil

porosity, soil texture, water holding capacity on one hand (Narasimha et al.,

1999) and clogging of gills and respiratory surfaces of fishes on the other hand

45

(Alabaster and Lloyd, 1980). TSS in effluents may affect fisheries -directly,

thereby destroying bottom fauna necessary for fish as food or reduce the

spawning ground of fisheries.

The composition of solids present in tannery effluent mainly depends

upon the nature and quality of hides and skins processed in the tannery. High

level of total dissolved solids may be due to high salt content. The total

dissolved solids level was found to exceed the permissible limit of 2100 mg/I

prescribed by the CPCB (1995). According to Goel (2000), high level of TDS in

the effluent renders it unsuitable for irrigation. According to Manivasakam

(1984a), high amount of total dissolved solids-recorded in the tannery effluent

could be attributed to processes like soaking, liming, dehairing, defleshing and

deliming.

Biochemical. Oxygen Demand is one of the important parameters used in

water pollution studies to evaluate the impact of wastewaters on receiving waters

(Subbarao and Gadgil, 1996). The present study has revealed that the high levels

of biological oxygen demand in the tannery effluents (830 - 940 mg/1) indicating

high organic load. Present investigation is in agreement with the studies on

tannery effluent (Gokulakrishnan, 2003), sugar mill effluent (Bhatnagar et al.,

1986), sago effluent (Panneerselvam, 1998) and distillery effluent (Prabakar,

1999).

According to Poole et al. (1978), increase in BOD is a reflection of

microbial oxygen demand, which leads to depletion of dissolved oxygen which

may cause hypoxic conditions with consequent adverse effects on aquatic biota.

46

Under such a condition no aquatic life can survive, except anaerobic micro-

organisms. Further the presence of organic matter will promote anaerobic action

leading to the accumulation of toxic compounds in the water bodies (Goel,

2000).

Chemical Oxygen Demand is the best method of organic matter

estimation and is a rapid test for the determination of total oxygen demand by

organic material present in the effluent. In the present investigation, high level of

COD was recorded (2380 - 2500 mg/L) and these values did not meet the

standard prescribed by CPCB (1995) for effluent discharge into inland surface

water (permissible COD level 250 mg/1). This indicates that the effluent is

unsuitable for the existence of the aquatic organisms, due to the reduction in the

dissolved oxygen content. Raj et al. (1996) recorded higher values of COD for

the treated tannery effluent of Chrompet (Chennai - India), and concluded that

high COD might be due to vegetable tannins and non-tannin which would

increases the COD. Further high COD may be due to high amount of inorganic

compounds which were not affected by the bacterial decomposition (Nagarajan

and Ramachandramoorthy, 2002)

Ions especially calcium, sulphate, magnesium and sodium impart

hardness to water. The values obtained for the tannery effluent reveal that the

concentrations of ions were more than the prescribed limit by CPCB

(1000 mg/L). The hardness of water and high concentration of salts may produce

scaling in boilers, corrosion of machinery and result in degraded quality of the

product (Goel, 2000). Moreover high salt content will deposit salts, resulting in

scaling of the equipment thus resulting in higher energy cost to the industry.

47

According to Lehr et al. (1980), the water is very hard if the value is beyond 180

mg/L. In the present study the value ranges between 2400 - 3500 mg/L which

indicated that the water hardness was very high. According to Goel (2000), high

concentration of salts (3000 mg/L) produces distress in cattle and livestock,

hence the tannery effluent should not be released into inland or surface land,

without adequate treatment.

High levels of chlorides in the tannery effluent could be attributed to the

soaking process involved (Athappan et al., 1992). More over high content of

calcium, magnesium, sodium, chlorides, sulphates, hardness present in the

tannery effluent might be due to mixing of tannery effluents with the aqueous

system from the different sources of processing within the tannery.

Acidic pH, excessive hardness, high TSS, TDS, BOD, COD of the

tannery effluent revealed that, the tannery effluent was highly polluted and it

has to be treated, but reports indicate that even the treated effluent do not satisfy

the prescribed limits of the CPCB (1995). Hence it is imperative to adopt

technologies that could reduce or degrade the tannery effluent effectively.

According to McEldowney et al. (1993), the most appropriate method for

pollution control depends on various factors linked to the nature and type of

pollution with environmental statutes, cost benefit analysis and commodity

acceptance, Since no single technology can satisfy all these requirements,

combined treatment strategies could be a wise and prudent option.

Chromium is a heavy metal which is widely used leather tanning

industries. Trivalent and hexavalent chromium compounds are predominant,

48

having various industrial applications (Dugan, 1972). There are many ways

by which chromium is released into the environment. It is one of the

constituents in effluents from a large number of industries, particularly the

tanning industries and this creates a potential threat to aquatic organisms. The

chrome tanning method is most widely used process in the tannery industries

located in Ambur, Vaniyambadi, Pernambut and Ranipet zones of the Vellore

district. However, the vegetable tanning method is practiced in the tanneries

located at Tiruchirappalli district. All the heavy metals reported in the effluent

are at very low concentrations and satisfy the prescribed limits of the CPCB

(1995).

Leather industries use about seventeen different kinds of tanning

substances but chromium is the most commonly used tanning agent (Venier

et al., 1985). Nearly 90% of all leather produced is tanned using chromium. In

chrome tanning process chromium actually cross links the collagen fibres and

thus decreases the porosity of the leather (Kathrine and Schwedt, 1994).

The ground water quality has been studied in Sempattu area of

Tiruchirappalli. Tiruchirappalli is the one of the active centres of Tanning

Industries and it occupies fifth rank among Tanning Industry of the state, next

only to Ambur, Vaniambadi, Erode and Dindigul. Of the 13 tanning industries in

Tiruchirappalli 7 tanneries are located in and around Sempattu as a small cluster.

They fall under the category of small scale tanneries. The tanning capacity of

each industry is about 2 tonnes of skins and hides. They produce semi finished

skins and hides by following the method of East-Indian Tanning or vegetable

tanning. The tanning processes release huge volumes of effluent which has a

49

high oxygen demanding wastes and dissolved solids. After Supreme Court

Judgement (May, 1995), all the tanneries established their own individual

Effluent Treatment plant or CETP to treat waste water arising from tannery.

However the impact of untreated tannery effluent released prior to the

establishment of ETPs on the ground water sources has not been studied so far.

Hence the present study is undertaken with the primary objective of assessing

the impact of tanning industry on the quality of ground water. 78 sampling

points at different sources like hand pumps (HP1-HP13), Open wells (OW1 -

OW34) and Bore wells (BW1-BW31) were selected around the cluster of

tanning industries. Their sampling points are located in 6 villages situated at

varying distance from the sources of pollution 0. 5km - 3.5 km.

The physico-chemical parameters, such as pH, Total alkalinity, Total

hardness, chlorides, Total dissolved solids, turbidity, dissolved oxygen, chemical

oxygen demand and biochemical oxygen demand were analysed and the mean

values for all the 12 sampling points are given in Table. Water quality

parameters of the different sources of the same village did not show any

significant variation. The pH value in the sampling source of hand pumps, open

wells and bore wells in all the sampling points were in the range of 6.4 to 6.75.

Total alkalinity in the sampling source of hand pumps, open wells and bore wells

of chosen villages around the cluster of tanneries varied from 297 to 445.5 mg/L,

TH 307 to 483 mg/L, Cl 262 to 460 mg/L, TDS 491 to 817 mg/L, NTU 1.1 to

2.1 mg/L, DO 2.3 to 4.66 mg/L, COD 3.3 to 13.6 mg/L and BOD 1.2 to 5.5

mg/L. The variation of water quality parameters like TA, TH, Cl and TDS in

hand pumps, open wells and borewells of surrounding villages of tanning

industries in Tiruchirappalli are given in Fig.

50

In Sempattu area possibly water flows faster from the sources eastwards

and percolates into the ground and hence elevates the levels of various water

quality parameters. The gradient in the pollutional status of sempattu village may

be attributed to distance between sources of pollution and village. However,

ground water quality of Sempattu had been severely affected. Among the

parameters tested the levels of TA, TH, Cl and TDS were highly varying.

The variation with respect to the parameters like pH, NTU, DO, COD and

BOD were insignificant. By comparing the range of these values with Indian

Bureau of standard (1991) for desirable drinking water quality parameters, pH

and NTU were well within the standard and other parameters exceeded the

desirable levels. The quality of ground water in the study area was not suitable

for drinking purpose. From the generated data, it could be concluded that

Sempattu village was more affected because most of waste water were generated

there itself. The ground water pollution in Sempattu may be attributed due to two

factors. One is the closeness to pollution source and another is geological

gradient towards east. It is quite natural that water will always flow east in this

region and hence Sempattu recorded a steep decline in ground water quality as

compared to other villages.

It could be concluded that the ground water of Sempattu was not safe to

drink. The impact of tanning industries has declined the ground water quality

only in this village Sempattu. This observation advocates the need for a thorough

evaluation of the effluent treatment efficiency as existing at present and for an

effective remediatory option.

Table 3.1. Components of the experimental programme and analytical

techniques

S.No Parameters Analytical Method Reference

1 pH pH Meter APHA, 1989

2 Electrical conductivity Conductivity bridge(0.920) APHA, 1989

3 Oil & Grease Gravimetric APHA, 1989

4 TSS mg/L Gravimetric APHA, 1989

5 TDS mg/L Gravimetric APHA, 1989

6 BOD BOD chamber (20) APHA, 1989

7 COD COD mantle APHA, 1989

8 Total Hardness Titrimetric APHA, 1989

9 Dissolved oxygen Titrimetric APHA, 1989

10 Total Alkalinity Titrimetric APHA, 1989

11 Calcium Flame photometer APHA, 1989

12 Magnesium Flame photometer APHA, 1989

13 Sodium Flame photometer APHA, 1989

14 Chloride Titrimetric APHA, 1989

15 Sulphate Spectrophotometric APHA, 1989

16 Heavy metal AAS (Varian Techtron) APHA, 1989

17 Total Heterotrophic Bacterial population (THBP)

Pour Plate Technique (CFU)

Table 3.2. Physico-chemical analysis of tannery effluent from January 2008 to

December 2008

Characteristics Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec

Colour GREY COLOUR

Odour DISAGREEABLE SMELL

pH 6.2 6.4 6.3 5.8 6.5 6.2 5.9 6.1 6.4 6.5 6.6 6.5

Ec pmhos/cm 12770 12700 12600 11960 12560 12180 12650 12750 12859 12380 12500 12820

TSS mg/L 1720 1690 1650 1650 1730 1755 1736 1695 1700 1785 1740 1770

TDS mg/L 3100 2990 2910 2900 3160 3170 3140 3190 2100 2995 3150 3110

BOD mg/L 880 830 940 910 886 840 870 910 890 900 882 870

COD mg/L 2439 2380 2400 2420 2470 2450 2480 2400 2500 2480 2460 2450

Total Hardness mg/L

1500 1400 1600 1550 1650 1600 1620 1680 1700 1650 1610 1630

Calcium mg/L 430 460 520 490 460 440 470 490 510 480 420 430

Magnesium mg/L

289 264 272 275 283 261 248 252 267 251 265 260

Sodium mg/L 1260 1300 1320 1310 1350 1380 1330 1370 1400 1375 1360 1380

Chloride mg/L 1660 1620 1670 1720 1760 1710 1690 1680 1700 1620 1640 1650

Sulphate mg/L 1430 1410 1390 1395 1400 1430 1420 1440 1460 1410 1390 1410

Total Heterotrophic Bacterial population (THBP)

(x107/100ml)

38.65 36.27 35.54 34.10 36.65 37.90 35.61 38.25 38.45 35.12 39.50 37.85

Heavy Metals

Zinc (mg/L) 1.26 1.27 1.36 1.17 1.16 1.26 1.25 1.21 1.24 1.19 1.21 1.26

Copper (mg/L) 1.39 1.26 1.32 1.30 1.35 1.36 1.30 1.27 1.24 1.32 1.28 1.30

Iron (mg/L) 4.59 4.62 4.60 4.61 4.55 4.48 4.47 4.56 4.55 4.60 4.58 4.60

Manganese (mg/L) 2.48 2.42 2.46 2.40 2.42 2.45 2.47 2.48 2.49 2.44 2.45 2.50

Chromium (mg/L) 0.57 0.56 0.55 0.51 0.53 0.59 0.57 0.58 0.53 0.59 0.52 0.57

Table 3.3. Water Quality Parameters of Ground Water Samples Collected from Sempattu

Sources of

Ground Water

Sampling Station

pH Total

Alkalinity Total

Hardness Chloride TDS

Turbidity NTU

DO COD BOD

Hand Pump

HP1 6.5 430 480 445 830 2.1 2.7 13.8 5.3

HP2 6.7 440 475 455 820 1.9 2.5 13.6 5.1

Mean ± SD

6.5-6.7 (Range)

435±7.07 478±3.53 450±7.07 825±7.07 2±0.14 2.6±0.14 13.7±0.14 5.2±0.41

Open well

Ow1 6.67 445 460 480 825 2.1 2.6 12.2 5.6

OW2 6.72 430 480 460 800 2.3 2.5 12.8 5.3

OW3 6.55 420 475 470 810 2.1 2.6 13.2 5.4

OW4 6.49 435 465 450 820 2.3 2.4 12.9 5.3

OW5 6.53 440 450 460 830 2.1 2.5 13.1 5.5

OW6 6.56 420 460 480 815 2.2 2.6 12.8 5.3

Mean ± SD

6.49-6.72 (Range)

431.7±10.33 465±10.95 466±12.1 816.7±10.80 2.18±0.09 2.53±0.08 12.83±0.35 5.4±0.13

Borewell

Bw1 6.83 457 465 440 820 2.3 2.6 12.6 5.1

Bw2 6.75 440 450 430 810 2.1 2.4 12.5 5.3

Bw3 6.68 445 455 440 820 2.0 2.5 12.2 5.5

Bw4 6.70 444 460 450 810 2.1 2.4 12.4 5.2

Mean ± SD

6.68-6.75 (Range)

446.5±7.32 457.5±6.45 440±8.16 815±5.77 2.12±0.12 2.47±0.09 12.42±0.17 5.27±0.17

Table 3.4. Details of Sampling of ground water in and around Tanning

Industries of Tiruchirappalli

Sampling Area Tannery

(No.)

Hand Pump (No.)

Open well (No.)

Borewell (No)

Total sampling

points (No.)

Sempattu 7 2 6 4 12

Table 3.5. Details of ground water sampling stations in Sempattu

Sampling Area Groundwater

Source Sampling

Station Distance from Tanning

Industry (m)

Sempattu

Hand Pump HP1 50

HP2 75

Open Well

OW1 200

OW2 250

OW3 300

OW4 350

OW5 400

OW6 500

Bore well

BW1 450

BW2 400

BW3 350

BW4 500