ENVIRONMENTAL STUDY ON NCZ (NITROGEN … · NCZ (NITROGEN CHEMICALS OF ZAMBIA) KAFOE FACTORY . March 1987 WRITTEN BY DR. ING. L PERES ... Old Nitric Acid ; Plant 14 : ... Under the

ENVIRONMENTAL STUDY ON

NCZ (NITROGEN CHEMICALS OF ZAMBIA) KAFOE FACTORY

March 1987 WRITTEN BY DR. ING. L PERES ENICHEM 20097 S. DONATO MI. SE

ITALY

Sincere thanks to MR J MALOWA, Works Chemist of NCZ Kafue Factory and the whole Laboratory staff without whose collaboration this study would not have been carried out.

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ENVIRONMENTAL STUDY ON NCZ KAFUE FACTORY

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0.00

1 .00

2.00

3.00

EXECUTIVE SUMMARY ----------------------

INTRODUCTION --------------------------- 4

SCOPE OF THE WORK ---------------------- 6

2.01 KEY OF ABBREVIATIONS ------------ 6

SURVEY ON POLLUTION PRODUCTION FROM THE PLANTS (INTERVIEWS AND VISITS ON SITE) ---------------------------------- 7

WASTE WATER STREAMS GASEOUS STREAMS SOLID WASTES

3.01

3.02

3.03

3.04

3.05

3.06

3.07

3.08

3.09

3.10

3.11

3.12

3.13

3.14

3.15

Coal Gasification --------------- 7

Old Ammonia Plant --------------- 1 1

New Ammonia Plant --------------- 12

Methanol Plant ------------------ 14

Old Nitric Acid Plant 14

New Nitric Acid Plant 1 5

Old Ammonium Nitrate Plant------- 17

New Ammonium Nitrate Plant------- 19

Ammonium Sulphate Plant --------- 20

NPK Plant ----------------------- 21

Sulphuric Acid Plant (SAP) ------ 23

Air Separation plant ------------ 25

Water Treatment Plant ----------- 26

Boilers ------------------------- 27

Fuel Oil Storage ---------------- 27

4.00 LIQUID EFFLUENTS ----------------------- 29

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5.00 PRESENT QUAL!TY AND QUANTITY OF THE L!QUID EFFLUENTS DISCHARGED FROM THE FACTORY (OVERALL AND PLANT BY PLANT ANALYSIS) ---------------

5.01 Quality -------------------------

5.02 Quantity ------------------------

5.03 Overall pollution ---------------

5.04 Reference to local/international regulations ---------------------

6.00 GENERAL COMMENTS ON THE RESULTS OF THE ANALYTICAL CAMPAIGN --- -------------

6.01 Comparison with other Factories -------------7---------

6.02 Possible effects on the environment and health ----------

7.00 PRESENT EFFLUENT TREATMENTS ------------

7.01 Factory Effluent Treatment ------

7.02 Sulphuric Acid Plant (SAP) Effluent Treatment Facility -----

7.03 Slurry Lagoons ------------------

8.00 PRESENT SITUATION OF THE SEWERAGE SYSTEM ---------------------------------

8.01 Mixings -------------------------

8.02 Blockings and Breakings ---------

8.03 Improper convey1ngs -------------

8.04 sulphuric Acid Plant Effluents -----------------------

B.05 Latest mixing -------------------

9.00 LIQUID EFFLUENT CONTROL PLAN -----------

9.01 Sewerage system rearrangement----

9.02 Study for the completion of sewerage rearrangement ----------

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9.03 First rainy water treatment 69facility ------------------------

9.04 Storm water draining system ------ 72

9.05 Water Intake improving interventions ------------------- 72

9.06 Purchasing of mobile oil 73skimmers ------------------------

9.07 In-Plant treatment and interventions ------------ 73

9.08 Review of liquid effluent disposal system --------~--------- 77

9.09 Review of "B" effluent washwater system ----------------- 78

9.10 The problem of ammonia and nitrates: proposal of a ion exchange unit for Ammonia removal and Ammonium Nitrate recovery ------------------------- 78

9 1 1 Review of Sulphuric Acid Plant effluent treatment facilities ---- 84

9.12 Liquid effluents monitoring ------ 87

9.13 Organization and training 89needs ---------------------------

9.14 90Lay-out -------------------------

SUMMARY OF RECOMMENDATIONS WITH COST AND TIME ESTIMATES FOR THE LIQUID

92CONTROL PLAN ---------------------------

98AIR POLLUTION --------------------------

11.01 Necessity of dispersion maps ----- 98

11.02 The problem of air intake location ------------------------- 98

11.03 Possible effects on the environment and health 99

OUTLINES ON INDUSTRIAL HYGIENE 100

101SOLID WASTES ------------------

13.01 Other Solid Wastes -------- 102

IV

14.00 PRESENT QUALITY AND QU~~TITY OF THE WASTES CONVEYED TO THE LAGOONS ---------- 103

14.01 Calcine Lagoon -------------------. 103

14.02 Slurry lagoon and coal ash deposit -------------------------- 104

14.03 Possible effects on the environment ---------------------- 104

14.04 Adequacy of disposal ponds ------- 105

14.05 Leachate tests ------------------- 106

14.06 Seepages pollution risks' of the water table ------------------ 108

14.07 Possible utilization of solid wastes --------------------- 111

14.08 Solid wastes control plan -------- 111

15.00 SUMMARY OF RECOMMENDATIONS WITH COST ~~D TIME ESTIMATES FOR THE SOLID WASTES CONTROL PLAN -------------------- 113

BIBLIOGRAPHY ---------------------------- 115

0.0 EXECUTIVE SUMMARY

The execution on the field of the environmental study relevant to NCZ Kafue Factory revealed a situation really heavier than what was expected.

The most remarkable aspects, as regards the liguid effluents, are:

1 High contents of ammonium, free ammonia, nitrates and suspended solids as major pollutants in the waste waters for a total amount of about 10 tons/day ammonia in the sewers (almost 10% of the production at the time of analytical campaign) and 8 tons/day of nitrates (about 7% of ammonium nitrate production) and 56 tons/day of suspended solids (mainly coal ash and dust and calcine by-product from pyrite roasting not conveyed to the lagoon).

2 A very chaotic situation of'sewers system, with many abusive connections between industrial and storm water trenches.

3 A remarkable dispersion of the physical points of discharge practically distributing polluted streams along all the perimeter of the factory.

4 The beginning of visible pollution even in Kafue River (whose northern bank by the confluence with Kasenje River is full of coal deposits, while a chemical analysis on the coastal waters reveals high ammonia and nitrates); considerable presence of algae was noticed even in the middle of the river.

5 Operation of the two lagoons (for calcine by-product of pyrite roasting from Sulphuric Acid Plant (SAP) and for coal ash) not as closed systems of ultimate disposal for solid materials, but as open basins continuously discharging liquid overflows into the open land.

All these aspects determine a situation highly not complying with national laws (Statutory Instrument No 161/8th November 1985 of Government of Zambia as regards Trade Liquid Effluents) and with every international rules.

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To face this situation a control plan on liquid wastes has been elaborated. However the environmental control must begin with proper maintenance and operation of each single part of the plants. Sensitiveness towards the environmental problems must be awakened in all the personnel, starting from the management, by means of tailored training courses and written communications. Moreover a responsible person for environmental protection must be urgently appointed, following the model of developed countries factories, who acts as landmark both as regards the technical aspects of the desirable realization of the proposed control plan and the legal aspects relevant to the inevitable needs of dealing with public authorities about environmental matter.

The rough investment cost estimates (chapter 10.00) amount to US $3,008,000 of which only 496,000 liable to local supply (civil works, labour, electrical cable and some steel work fabrication), while the remainin'g 2,512,000 are machineries and materials to be imported.

The main objectives obtainable by means of this interventions are:

- To fully comply with the tables of standards indicated in the above mentioned Zambian law, so discharging less than 354.3mg/1 of nitrates (as N03), less than 60.7mg/l of Ammonia and Ammonium (as NH3) to the public sewer and less than 221.4mg/l of nitrates, less than 12.1mg/l of total ammonium and less than 50mg/1 of total suspended solids as regards any other effluent.

- To recover most of the above mentioned conspicuous losses of production so allowing expected savings of about 12 equivalent tons of ammonia per day for a value of US $900,000 per year (under the hypotheses of a value of 2500 Kwacha/ton NH3, an exchange rate of 10 Kwacha/US $ and 300 days of operation per year) versus an increase of operating costs only relevant to electriCity, chemicals produced in the factory (such as nitric acid) or already present (such as slaked lime), small quantities of polyelectrolite and some periodic make-up and substitution of ion exchange resins. Of courSe the proposed control plan cannot be a profitable plant, but, as it happens allover the world for

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any ecological intervention, it must be regarded as an additional cost to the business of making fertilizers (just the same as utilities, depreciation, or other associated process costs) in order to get the priceless benefit that even in Zambia is the Environment Protection.

As regards pollution caused by solid wastes, possible seepages and pollution risks of the water table have been investigated by means of some wells dug nearby the calcine lagoon site; samples from the ground water were collected at differenct depths, none of them showing contamination by the toxic metals disposed of in the lagoon. Some leachate tests (EP toxicity suggested by Environmental Protection Agency) were carried out as well on samples of the solidified materials abandoned in the lagoons: these latter indicate some reasons of worrying about the possibility of toxic substances (Selenium, Lead and Cadmium) release from these heaps. Consequently cautions on the operation of the lagoons (not to overfill above upper limit) and fencing of the whole area are suggested as recommendations.

As regards the future needs of the factory for the next fifteen years two new lagoons are required (260,OOOm2 for calcine and 215,OOOm2 for slurry and coal ash to be constructed after five years, unless a possible utilization of solid wastes is found. As to this latter point a feasibility study and marketing research are recommended to exploit the iron contents of pyrite cinders (about 50% for a total of 3MT/hr) in producing sponge iron to be sold abroad to some steel industry. As regards slurry and coal ash the heat value looks too poor to be exploited.

Moreover a fencing for the overall lagoons areas and a guard post are recommended to avoid vandalism and dangers to people who may come into contact with toxic materials due to ignorance. The amount for the new lagoons and fencing intervention is about US $250,000.

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1.00 INTRODUCTION

The present study was carried out from July 1986 to March 1987 in order to comply with EA obligations involved in the contract. Therefore the terms of reference for the study are the same as in the contract, while the inner meaning according to which it was carried out was in accordance with the guidelines of the World Bank (staff appraisal report of June 19, 1985) and following direct discussions with the World Bank specialist from 9th to 11th September 1986. For convenience sake herewith are the guidelines of the World Bank reported integrally:

1.01 ABSTRACT FROM THE WORLD BANK REPORT ~ 5658 ZA

G. Envionment and Safety Aspect.s

5.32 Presently, the NCZ FertiJ.izer complex has a severe pollution problem caused by nitrogen oxides (NOX) gaseous emissions from the NCZ I and NCZ II nitric acid plants. The current level (up to 2,200 ppm) of such emissions 1s 6-10 times the maximum levels presently permitted in most industrialized countries. Such high levels are partly due to the higher levels permitted when these plants were designed and partly due to the deterioration of the facilities. This high level of emissions affects adversely the environment and the rains generated fron NOX gases corrode the plant facilities. Under the Project, both NCZ I and NCZ II plants would be equipped with NOX abatement units to reduce contaminant in stack gases to a maximum of 500ppm, the present international standard (paras 5.18 and 5.19).

5.33 Solid waste and part of the liqUid effluents from the plant are sent to two disposal ponds. The remaining liquid effluents are neutralized in a water treatment plant before discharging into the Kafue Township sewage system. Under the Project, NCZ will rehabilitate the water treatment plant, install a closed loop system at the AN unit of NCZ II plant, and take other necessary measures to prevent pollution. After Project implementation, the liquid effluents will meet international standards. Under the environmental study to be carried out by

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OMP, by September 1986, all aspects related to solid waste and liquid effluent disposal will be reviewed in detail and recommended measures will be implemented. In addition, the proposed safety study will recommend steps to be taken to deal with any potential safety hazards at NCZ (para 5.20). Assurances will be sought at negotiations that NCZ will rehabilitate and operate its facilities under environmental and safety standards satisfactory to IDA.

2.00 SCOPE OF WORK

According to the terms of reference the scope of the study was mainly restricted to liquid effluents and solid wastes production. Air pollution and industrial hygiene probles were only outlined. However, some attention was paid to the overall ecological problem of the whole area Kafue-Lusaka, stated that the drinking water intakes for these towns are situation on the Kafue River downstream NCZ factory.

2.01 KEY OF ABBREVIATIONS

SAP = Sulphuric Acid Plant tId = MT/DAY = Metric Tons per day t/y = MT/Y = Metric TOns per Year m3 = M3 = Cubic Meter m3/hr = M3/hr = Cubic Meter per Hour M3!DAY = Cubic Metres per Day

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3.00 SURVEY ON POLLUTION PRODUCTION FROM THE PLANTS

In order to understand better the way of pollution generation from the single plants some interviews with the plant chiefs were carried out, on the basis of the questions contained in the information questionnaire, whose text is reported in Annex 1.

The contents of questionnaires are resumed in the present chapter. The plants for which the investigations were carried out are listed in Table 1.

The main purpose of this part of the study was to clarify from which apparatus or from which operations the liquid effluents, gaseous streams and solid wastes were originating from. The data were mainly drawn by the chiefs of the plants from the process books and material balance sheets.

As a general consideration it appears evident the contrast between the collected statements from the interviews and the analytical results from the proper campaign (see chapter 5.00). From the declared discharges it would result an extremely clean and dry factory, with very few systematic process streams, some leakages and almost clean waters to the sewer system. On the contrary from the analytical campaign it results a conspicuous mass of liquid discharges, moreover distributed in many points, especially of the storm water sewer, with large pollutant contents, particularly suspended solids, ammonia and nitrates (for an amount up to almost 10% ammonia production).

3.01 Coal Gasification (including coal handling and preparation)

The plant consists of 4 units (1 stand-by) of about 7000kg/h coal capacity each and produces raw gas and steam as by-product. The employed raw materials, apart from coal, are unslaked lime (supplied by Ndola Lime Company), for the purpose of reducing the melting point of the ash and oxygen from the air separation unit of the factory. The employed utilities are demineralized water as feed for the numerous waste heat boilers, cooling water, kerosene and diesel Oil, nitrogen for sealing and purging coal dust transportation. As regards chemicals, sodium phosphate and sodium sulphite are employed for the boilers. As regards pollution the following was declared during the interviews.

PRO DOC T ION

Coal Gasification

Coal Gasification Expansion

Ammonia Plant (309)

Ammonia Plant Exp (11309,

Ni tric Acid (401)

Nitric Acid Exp.

Ammonium Nitrate (501 )

Ammonium Nitrate Exp. (A501)

Ammonium Sulphate (AS03)

NPK Plant (A5041

Sulphuric Acid Plant

LIST Of'

PROCESS I

KNOW-BOW

Krupp-Koppers

Krupp-Koppers

UBE-Japan H2S removal: Stadford Process

Casale (Nil] Krupp-Koppers (CO Conversion) (Rectisol Methanol)

Montecatlni

Grande Paroisse

Sumitomo

Kestener

Kestener

Cdf Chemie

Nissan Chemicals (ShankiJapan for roasting section)

COMMISSIONING YEAR

1970

1981 ,

1970

1981

1970

1981

1970

1981

1 9 El1

1981

198]

TABLr, 1

REI!AllIL 1 TAT ION YEAR

1986

1986

1988

CD

1986

1988

1986

1988

1988

1988

PLANT_S AT PRES!,:I'l'1' UNDER

CONSTRUCTOR

Kobe Steel (Line 0) NeZ Line A

Klockner (Line B.C,

Kobe Steel

Klockner

Kobe Steel

Klockner

Kobe Steel

Klockner

Klockner

Klockner

Kobe Steel

DESIGN CAPACI'l'Y

320MT/d) of Coal)

, )

320~lT/d) ofCcal)

95MT/d

217MT/d

172MT/d

212MT/d

226M'r/d

242MT/d

151M'r/d

OPERATION

ACTUAL

CAPACITY

306

84MT/d

128MT/d

I,j nde

172MT/d

1 95MT/ d

205MT/d

242MT/d

1 51 WI'IeI

142000Mt/y 100000MT/y

60000MT/y 22000MT/y

2

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3.01.1 Waste-water streams

20M3/hr slurry from the wet scrubbers of the old coal handling plant (301) continuously flowing to an ash pit and then to storm water, containing coal dust)

Continuous leakages from pumps and pipes both to storm water sewer and to industrial water sewer) no identifiable as to quantity)

3 Washings of electrostatic precipitators at shutdowns (supposed once a year) to storm wateri

4 Effluents from wash towers for cleaning the gas, continuous 120M3/h per unit flow to 4 settling ponds A321 in which sedimentation occurs. Clear Water comes ba'ck to gasification and slurry is pumped out to dedicated lagoon (for further details of this facility see the proper chapter 7.00 on the present effluent treatment plants).

3.01.2 Gaseous streams

Raw gas flare; height from the ground about 40 mtrs, it occurs at start-ups for about 45 minutes without burning, contains raw gas.

2 Nitrogen from 301 B/C electro-static precipitators chimney (height about 45m), apart from N2 that is the gas carrier, contains C02 and coal dust;

3.01.3 Solid Wastes

1 Ash plus slag from gasifier chambers; continuous production of 0.5 MT/hr per unit is collected by trailers and moved to the lagoon (or some dumping areas around Kafue at the request of the Township Council). This contains unburnt carbon, Silica, calcium, aluminium and as ppm, copper, selenium, zinc, lead and arsenicj

When pumps break down the slurry from A321 is taken by means of crane buckets and dumped nearby; water evaporates and the area remains full of coal dust.

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3.01.4 Visit on Site

During the visit on site it was noticed that the water consumption was much more than expected (one reasons was the water leakage from the shafts of ash extractor G1206 which necessitated the use of a lot of external water, taken from firewater, as seal water of the shaft). Besides, most of the waste water which was supposed to go to settling ponds was flowing to storm water due to choking and breakdowns of the industrial sewer. Even the "e" effluent from the other plants, which was only supposed to cross the area of the plant, was diverted to storm water. Recently the original path was re-established. For this purpose see the proper chapter 8.00 on the situation of the sewerage systems.

Of course, the water flowing in all the open trenches loads coal dust and coal ash, while passing through the coal prepara.tion and coal gasification units.

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3.02 QlQ Ammonia Plant (303)

This plant produces an average of 84 t/day of Anhydrous Ammonia (versus a design capacity of 95 t/daY)1 raw materials are raw gas from gasification and nitrogen from air separation plant. Many chemicals are involved: phosphate for the boiler, potassium carbonate, MEA and caustic soda for C02 removal, antraquinone disulphonic acid, sodium carbonate and sodium vanadate for H2S removal: as utilities demineralized and cooling water, steam and diesel fuel are employed.


1 2M3/hr of demineralized water utilized for sealing of carbonate and caustic pumps continuously flow to the industrial sewer at room temperature without loss of solution;

2 Once a day for cleaning of H~S removal filter press 1m3 of water containing sulphur and other chemicals goes for one hours to the industrial sewer;

3 3M3/day of water at 45 Deg.C containing traces of K2C03 flow to the industrial sewer during the backwashing of K2C03 side stream filters which occur once per shift for 45 minutes;

4 0,2M3 of caustic tower spent liquor go to industrial sewer once a shift for 30 minutes, temperature is 40 Deg.C and composition 8 : 10% Na2C03 and 0,5% NaOH;

5 150 It/hr of raw gas compressors condensate drainings continuously to industrial sewer containing only water (because there are installed oil separators).

As a general consideration the plant has no emergency discharges into the sewers due to the presence of storage facilities to handle.

3.02.2 Gaseous Streams

1 Continuous flowing to atmosphere of H2S traces at 20 mtrs height from slurry tank V206. ;

2 8000NM3/hr from K2C03 regenerator vent containing C02;

3 The same from MEA regenerator;

4 600NM3/hr of purging gas from NH3 synthesis containing 1,5% NH3, at present recovered as burning gas in the coal fired boiler.

3.02.3 Solid waste production

1 Sulphur cake from H2S removal section sent to sulphuric acid plant;

2 Exhaust catalyst for NH3 synthesis, consisting of iron oxide once in 3 years is spread in the plant;

3 Exhaust CO conversion catalyst consisting of porous iron oxide is forwarded every three years to lagoon;

4 Old rashig rings are cracked and spread in the not paved areas of the plant or in fields for roads.

3.02.4 Visit QE site

The storage facilities are in common with new ammonia plant and located in old nitric acid area. They consist of two spheres, one 800m3 volume and the other 1715m3 (respectively SOOt and 1000t ammonia capacity). The operating refrigeration system is one for both the spheres and if one of the two compressors is out of order is not enough to maintain the low required storage temperatures, so that some NH3 is vented to atmosphere and, occasionally, even to the sewer; this amount can be up to 500 kg/hr.

3.03 New Ammonia Plant (A309)

The plant produces on average 128MT/day of anhydrous ammonia (versus a design capacity of 217MT/day: this is because of some bottlenecks and lack of apparatuses in the plant), moreover the plant produces 6MT/day of aqueous ammonia (25% concentration). The plant requires 5M3/day of demineralized water for start up and making NH3 solution, cooling water and chemicals for its conditioning, steam and sodium or potassium chromate for the start up of A303 plant (H2S, C02 removal).


1 Process condensate from CO conversion consisting in continuously about 6MT/hr at 45 Deg.C at maximum capacity (so supposed 2,5M3/hr at actual capacity) flowing to industrial "c" effluent; it presents alkaline pH (about 2500ppm total ammonia) and 250 free ammonia.

2 20M3/hr cyanide rich washwater going to wash water cooling tower and then recycled to gasification together with clear water from settling ponds;

3 Cooling water from raw gas compressors continuously flowing through 1" pressure pipe (say about 2,5M3/hr) to the industrial sewer, contains CO, C02, S, CN;

4 Seal water for raw gas holder continuously flowing through 2.5" pipe (say about 20M3/hr) to the industrial "c" effluent sewer; the type of water employed is cooling water.

5 Cleaning of condensers which occurs once in three months and contains ammonia and scalings.


1 1900 Nm3/hr H2S fraction from C1202 separator of A303 plant containing 3% of H2S and COS.

2 380Nm3/hr of flash gas from C02 wash containing 62% C02 and 37% H2, N2, co;

3 Ammonia synthesis off-gas, consisting in 2 KMOLS/hr at 37 Deg.C containing-CO, C02, H2, CH4, N2;

4 Ammonia synthesis off-gas, about 20 KMOLS/hr 70% H2 and 30% N2;

5 2770Nm3/hr of tail gas from T1201 liquid nitrogen wash (A308) containing CO, N2, H2, CH4 and other gases go to a dedicated holder; if this latter is full flow to atmosphere)

6 18400Nm3/hr C02 vent to atmosphere.

3.03.3 Solid Waste Production

1 Exhaust catalyst spread on the floor once in two years;

2 Packing materials for saturators: the same as above.

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3.03.4 Visit En site

This plant presents one of the few process effluents of the factory: the process condensate from CO conversion containing 2500ppm of ammonia (which is added for corrosion reasons) is responsible, together with the leakages from mechanical seals of refrigerating pumps, for one of the main industrial hygiene problems of the factory (NH3 concentration measured by means of Draeger pumps along the main road up to 150ppmJ. Some intervention is necessary for this point.

3.04 Methanol Plant

It produces methanol at 91% (design capacity 5 t/day) from synthesis gas. It utilizes cooling water and stearn as utilities. Practically daily production is 2,5t but only when the storage tank is not full.


Nothing (some discharges containing methanol can be found from Rectisol, which is the plant utilizing methanol, especially from the cleaning of pump filtersl.


46Nm3/hr off-gas from methanol receiver at 37 Deg.C containing H2, CO, CH4, N2, C02 (from Rectisol there is a loss of 1,2MT/day of CH30H from T1206 tower tail gases to atmosphere.


Exhaust catalyst once a year.

3.05 Old Nitric Acid Plant (Low pressure) (401)

This plant produces a maximum quantity of 172,5MT/day (as 100%) of nitric acid at 55.5% concentration starting from 48,3MT/day ammonia; it employs 945M3/hr cooling water, small quantities of sodium sulphite, sodium phosphate and caustic soda as chemicals. The waste heat boiler utilizes about 11MT/hr of boiler water feed producing about 10MT/hr steam at 14Kg/cm2.

The process utilizes about 3MT/hr of demineralized water for the absorption of nitrogen dioxide to produce nitric acid.


1 0.5M3 weak nitric acid during start ups to the industrial sewer;

2 Boiler blow-down containing sodium sulphite and phosphate and caustic soda; about O,5M3! hr;

3 Sporadic discharge into the sewer of some 5 Its of pure ammonia when the ammonia pumps from the storage spheres (which are located at Nitric acid area) lose priming;

4 Discharges from sampling lines;

5 Eventual leakages from mechanical seals of the three acid pumps or some we1dings.


1 NOX tail gas: average 500 : 950ppm, maximum 2200ppm;

2 Ammonia during each start up of unit: average twice a month, duration one hour.


Nil

3.06 New Nitric Acid Plant (medium pressure) A401

It produces 212Mt!day nitric acid as 100% (310MT!day as 55% concentration). It employs about 15MT!hr demineralized water (llMT!hr for boiler feed water and 4 for the process), 1800 M3/hr cooling water, 4 bar steam for ammonia evaporation and 14 bar steam for start up;besides the plant utilizes the usual chemicals (sodium sulphite and phosphate, caustic soda) for the feed water treatment to the waste heat boiler.


1 O,5M3 draining of weak nitric acid (40%) during start up for fifteen minutes to industrial water;

2 Leakages from some weldings, especially at elbows, of the piping;

3 Discharges from sampling lines: the above streams flow to a pit where sometimes lime is thrown for neutralization and then the effluent is pumped to industrial sewer;

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4 Continuous boiler blowdown;

5 Emptying of ammonia evaporators for two hours to industrial sewer for maintenance of major shutdowns;

6 Continuous 2Mt/hr steam condensate from evaporators and heaters to industrial sewer;

7 6MT/hr steam condensate from superheaters to storm water;

8 oil spillage from compressors oil seals, oil filters and coolers cleaning; about 440 ltrs/ month to storm water,

9 Emptying of some heat exchangers at shutdowns, containing weak acid.


1 36000Kg/hr NOX tail gas continuously flow to atmosphere, containing 95% nitrogen and 7500 average of NO + N02 (maximum 9800) at 72 Deg.C;

2 Ammonia preheater venting only during start up total 0,2 ton for 15 minutes at 92 Deg.C containing 100% NH3;

3 Leakages from burner flanges containing mainly NH3 and air.


Nil, because the catalyst is sent to UK for processing.

3.06.4 Visit on Site

The pump located in the above mentioned pit is not working even if the pit level is always the same. May be because of evaporation and seepages.

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3.07 Old Ammonium Nitrate Plant (501)

This plant produces 20SMT/day of ammonium nitrate (porous and dense explosive and dense fertilizer) employing 45MT!day NH3 and 16SMT/ day nitric acid (as 100% conc.). It utilizes 2400M3/day of cooling water for surfacecondensers of ammonium nitrate vapours, of which about Sm3/hr for pumps sealing do not recycle to the cooling tower but go to industrial effluent; moreover, it employs 216MT!day steam for concentration solution and as chemicals a coating agent called Nuflo, based on Mg, CO, and Si02.

3.07.1 waste-water streams

1 Continuous Sm3!hr cooling water for sealing pumps containing high concentration of ammonium nitrate and free ammonia to industrial sewer;

2 0,5m3 washing of blower casings for five minutes five times a day at 85 Deg.C containing ammonium nitrate dust to industrial sewer;

3 1,4m3/hr of first concentration condensate from the seal pot of the surface condenser V06 at 40 Deg.C containing 1,5 - 2% ammonium nitrate plus free ammonia to industrial sewer;

4 10m3/hr of steam condensate from various services, polluted in the case of leakages from jacketed pipes, to industrial sewer;

5 Salt section washings for cleaning the plant twice in a month containing some hundreds of ammonium nitrate kgs and Nuflo to industrial sewer;

6 Bucket elevators washings once in two weeks containing weak ammonium nitrate solution to industrial sewer;

7 Oil spillage from pumps oil seals and grease washings from various apparatus (drier, coolers, conveyors and bucket elevators); once in a month to industrial sewer;

8 Draining of NH3 evaporator a-t main shutdowns (average three in a year); about 200Kg NH3 to industrial sewer.

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1 60Kg/hr reactor off-gas continuously flowing to atmosphere containing 74% ammonium nitrate vapours at 60 Deg.C that sublime and fall down as dust;

2 13Kg/hr ammonium nitrate dust from the (porous) prilling tower at 45 Deg.C,

3 41Kg/hr of ammonium nitrate dust from the (dense) prilling tower at 75 Deg.C;

4 Continuous emission of NH3 and ammonium nitrate vapours at 76 Deg.C from top hole of the final concentrated solution tank V32 (receiving from falling film evaporator El0)


1 Ammonium nitrate scalings and depositions removed from the floors and the platforms once in a month;

2 Ammonium nitrate dust removed from the floors by washing once in a month.

3.07.4 Visit on site

The plant 'is provided with a recovery system consisting of the tank V25 where the sampling catches from the reactor and the washings from prilling towers are connected, and of the pump Pl1 for recovery to the reactor.

Even for emergency reasons all the necessary drainings are collected in the recovery tank V2S.

However, the losses of ammonium nitrate dust from the various handling apparatus and from the prilling tower look fairly remarkable (it is so fine as to permeate the concrete of pavements and roads) to account for the considerable contents of ammonia and nitrates in the sewer (both industrial and storm water),

Some sampling points (V04 ammonium nitrate 80% solution and nitric acid line to the reactor) are not connected to the recovery system and it is recommended to realize the connection.

,Q

3.08 ~ Ammonium Nitrate Plant (A501)

The plant is able to produce 242MT/day of ammonium nitrate of which 165MT/day is granulated fertilizer and 77MT/day of 95% aqueous solution supplied to NPK plant. The employed utilities are 9600m3/day of cooling water and 67MT/day of steam. As regards the chemicals Nuflo-10 1s utilized as coating agent.

3.08.1 waste-water streams

5,2m3/hr condensates from V1206 collection tank of multiple effect concentrator at 66 Deg.C containing small NH3 and A.N;

2 O,4m3/hr of weak ammonium nitrate (concentration 5%) solution with cooling water from tank V120S to industrial sewer;

3 0,lm3/hr of cooling water from V1217 seal pot.

4 2,5MT/hr of steam condensate at 76 Deg.C from jackets of pumps and other apparatus and from steam-traced lines to storm water trench;

S O,2MT/hr of steam condensate from heating coils of V1220 and V1202 to industrial sewer;

6 SMT/hr of clean cooling water from N1201 seal pot to industrial sewer;

72m3 of 99% ammonium nitrate solution to industrial sewer from V1210, V1211 in case of shutdown of the plant (average once a month);

8 Ammonia gas to atmosphere and liquid ammonia to the industrial sewer in Case of depressurising the ammonia system for maintenance jobs;

9 Washing of prllling tower (T1201) grill: 1MT/day of ammonium nitrate going to industrial sewer once a day due to lack of recovery tank.


1 K120S blower off-gas at 3S Deg.C containing ammonium nitrate dusts, consisting of continuous 9,26m3/sec (at 60 Deg.C and 445mm H20);

20

2 Exhaust gas from K1203 A/B ventilators of the prilling tower at 75 Deg.C containing ammonium nitrate dusts; consisting of continuous 16 : 21m3/sec (at 50 Oeg.C and 50 : 28mm H20);

3 K1201 off gas at 45 Oeg.C consisting of 0.5m3/hr (at 80 Deg.C and 150mm H20) containing ammonium nitrate dusts)

4 K1202 off gas at 36 Oeg.C consisting of continuous 0,5m3/hr (at 80 Oeg.C and 150mm H20) containing ammonium nitrate dusts.

3.08.3 Solid Wastes

Oversize material blocking Y1203 outlet chutes in dehydration section. It may happen once a day and consists of about lMT/day of ammonium nitrate sometimes recovered in bags and reclaimed to V25 or sent to NPK.

3.08.4 Visit ll site

The visit on site has pOinted out the absence, contrary to the old plant, of any recovery system in the plant. However, a new recovery system, based on technical department design, is at present under fabrication. The discharges that are intended to be collected in an underground tank of 47m3/AISI lined, and pumped back to the system (V1202 feed tank for the falling film evaporators) are the grill washings, spillages from dehydration section, solutions from V1210 and V1211 and V1205 weak solution.

3.09 Ammonium Sulphate Plant (A503)

The plant is able to produce a maximum quantity of 6,5MT/hr of crystalized ammonium sulphate, using 96% sulphuric acid, gaseous ammonia, which arrives in liquid form and is evaporated in the plant, small quantities of 25% ammonium hydroxide and 75% phosphoric acid solution (this latter for crystal growth). The employed utilities are: demineralized water (for initially filling up the reactor to get H2S04 concentration down to 5gr/lt and also for make ups), 200m3/hr cooling water for condensing process vapours from the reactor and 2MT/hr steam for the heaters (the condensate is recovered).

Waste-water streams

1 Process condensate overflow from the reservoir tank V1204 at 90 Deg.C for few minutes everyday, especially at start ups, containing ammonia and ammonium sUlphate pumped to industrial sewer (but flowing to storm water sewer if the pump is broken).

2 Centrifuges and floors washings for few minutes every shift by means of 3/4" hose pipe, containing ammonium sulphate at room temperature flowing to industrial sewer.

3 Sometimes acid leakages from reactor and pipes.

4 Mother liquor tank (V1202) overflow (very rare)

Gaseous streams

1 Continuous emission of reactor vapours to the a~mosphere at 94 Deg.C (containing ammonia).

Solid wastes

1 Losses from the conveyor belt to the ground are mostly collected in bags and go to NPK plant; after washing the floors these losses may go both to industrial and storm water sewer.

3.10 ~ Plant (A504)

The plant is designed to produce 142,000MT/yearof six compound fertilizers, namely A, C, V, X, D, R. At present the only fertilizers requestedby the farmers are X, D and R. Actual capacity is 100,OOOMT/year.

The employed raw materials are mainly liquid ammonium and solid ammonium sulphate; besides liquid sulphuric acid and small quantity (up to 300Kg/hr) of liquid anhydrous ammonia, which is evaporated in the plant itself by means of joulethomson effect; all these latters produced by NCZ itself. Moreover di-ammonium phosphate, triple super phosphate, potassium sulphate and potassium chloride imported from various countries.

22

As utilities about 7SMT/hr of fire water (new raw water network is under study) are employed for the scrubbers N1201 and N1202 A/B positioned down stream of the drier and granulator; moreover 2,2 MT/hr maximum of low pressure steam and 6MT/hr medium pressure, with condensates recovery in area 1. As fuels 4S0MT/hr of synthesis gas are burnt and mixed with air in order to dry the product in 01201.


1 OVerflow from V1211 (resevoir tank for venting scrubbers) when the pumps are under maintenance containing S% total solids at 30 Oeg.C going to industrial sewer.

2 Washings of floors by means of hose pipes for annual shutdown: Containing NPK salts going to the industrial sewer for three days without interruption.

3 Seal water for the pumps: distributed by means of 6" pipe and going to industrial sewer.

4 Emergency emptying and cleaning of scrubbing section: at least once a month for mechanical problems.


1 Dusts from the venturi scrubbers N1202 A/B.

2 Continuous dusts from the stack C1210 for the scrubbing N1201 and blower K1205.

3 Continuous dusts from the stack C1211 in service to screens, bucket elevators, conveyor belts and coating drum.

4 Dusts from stack C1212 for the cooler J1201 about ten times a month, if some problem arises in ammonia or gasification plant.

S From C1247 stack when the plant stops the combustible gases go to the atmosphere automatically.

6 Dusts of coating agent, conSisting of clay and ammines, from V1207 (while transferring).

23

3.10.3 Solid wastes

Materials swept everyday and for the annual shutdown are recovered in off specification hopper V1205 and recycled.

2 Spillages of raw materials from conveyor belts: are reclaimed into the bags.

3.11 Sulphuric Acid Plant (S.A.P)

The plant is designed to produce 60,000MT/year of H2S04 at 98.5% concentration, but practically the actual production is 22,000MT/year due to lack of ammonia to be used in the production of Ammonium Sulphate. The raw materials are 176MT/ day (design quantity) of pyrite mineral from Nampundwe Mine and sulphur cake from area 2 (gasification).

As regards utilities S.A.P. is provided with its own pumping station (capacity 160m3/h) of raw water from Kafue River and its own water treatment plant and cooling water tower; practically the necessary quantities are less than 100m3/hr of raw water and 20m3/hr of cooling water but in order to avoid choking of the pumps due to the growth of sea weed the pumping station is operated at maximum rate and a continuous overflow of water is flowing to new Kasenje River through the point of discharge SW3.

As chemicals for water treatment there are employed 400Kg/week of alum, 400Kg/week of caustic soda, 2Kg/week of aid coagulant and 5MT/day lime for the neutralization in the waste water treatment (100 bags per shift).

As fuels 20,000 Itrs of diesel oil are utilized every start up of roaster and converter.


Most of the discharges go to the autonomous S.A.P. waste-water treatment plant, which is briefly described below and in the proper paragraph 7.02.

Back washing of F401 A/B/C/D sand filters for cooling water: 55m3 for 3 minutes every shift at room temperature to the anti-acid painted basin V1001.

24

2 Spillages from sampling points and leakages from piping connected to pumps P201, P202, P203, and 400 section (acidic) to Vl001.

3 Washings of V201 settler, T201 cooling tower, T202 washing tower (for which design figure is 8,7m3/hr) even to Vl001.

4 Washings of the "mist cottrell" electrostatic precipitators; very small for 2 minutes each day to V1001.

5 Continuous sludge from V201; about 8m3/hr at 80 Deg.C containing diluted sulphuric acid to the basin V901 (feeding for the neutrali2ation tanks V902, V903).

6 6m3/hr of continuous spillage from packed tower T202 at 65 Deg.C containing diluted sulphuric acid conveyed to V901.

7 Continuous calcine mixer IV108) effluent. It is surely the most important effluent of the plant (and perhaps of the factory), consisting of 76 : 90m3/hr (capacity of pumps Pl03 A/B) of sludge at 40 Deg.C containing mainly iron oxide Fe203 going now to the ageing tank V904 (V907 as design) and from there pumped by means of P902 to the dedicated lagoon.

8 Overflow of pyrite heap pit in case of rain: directly to new Kasenje River, in consideration of lack of the pump Pl003 which has been moved to Vl001.

9 Overflow of raw water in case of water treatment shutdown: to storm water (point SW3).

10 Drainings from T203, T204, V201 in case of bad operations; the full contents of vessels to V1001 without pumping out.

11 Drainings from compressors, containing oil spillages, to storm water.


Continuous about 20,OOONm3/hr of SOX stack emissions at 80 Deg.C containing less than 550ppm of S02 plus S03 (1,7ppm).

25

3.11.3 Solid wastes

The calcine by-product of pyrite roasting is pumped out of the plant in liquid form but in the lagoon water is progressively evaporating and there remains solid waste perfectly able to be trampled on.

3.11.4 Visit 2n site

The areas around waste water treatment facility are full of calcine losses, so that it is hard to walk around.

Most of raw water drawn goes overflooding, due to the fact that the pumps must work always at maximum capacity, otherwise choking occurs of too much living plants in the water.

3.12 Air Separation Plant

It consists of two units; the old one employs 22,OOONm3/hr of air to produce 2,800Nm3/hr of nitrogen and 3,850Nm3/hr of oxygen (the rest being impure nitrogen), the new one utilizes 52,OOONm3/hr of air to produce 9,OOONm3/hr of nitrogen, 7,800Nm3/hr of oxygen and the remainder, most part, is impure nitrogen.

For the coolers and air scrubbing the old plant requires 1000m3/hr of cooling water while the new 3000m3/hr, all recirculated on own cooling tower.

3.12.1 Waste-water Streams

Only 30m3/day of cooling water for sealing oxygen, raw gas and impure nitrogen holders: coming from the not conditioned cooling tower located near the water treatment and flowing to storm water sewer.


Impure nitrogen vented to the atmosphere when coal handling or gasification are shutdown (air separation plant is not stopped because start up is a big problem).

3.12.3 Solid wastes

None

26

3.13 Water Treatment Plant

The water treatment plant for all the areas except SAP has a practical capacity of 400m3/hr. It consists of two precipitators 501 and A501 (the new one is called npretreatorn ) followed by the settling basin S601-1 from where water is pumped by means of 601 P03 A/B to the valveless filters. The chemicals employed in the precipitator are alum, lime and an aid coagulant called Himoloc. As demineralization plant there are an old NCZ unit consisting of one cationic and one anionic exchanger at present not working; therefore another unit, built up by Kobe Steel, consisting of cationic, degasifier and anionic sections for a capacity of 38m3/hr is running together with the newer Klockner unit, also consisting of cationic, degasifier and anionic sections for a capacity of 48m3/hr. Downstream of the treatment there are two reservoirs for demineralized water of capacity 140m3 and 210m3.


1 Sludge from precipitator: it is intermittent, consisting of about 2m3 every 8 hours for half a minute containing 2% suspended solids and flowing to the same neutralization tank of the following point.

2 Eluates from resins regeneration flow to a pit of about 100m3 volume where partly autoneutralize themselves; then the effluent (an average of Sm3/hr) is pumped to the waste-water treatment (nOn effluent pond 605 Cl0 A/B).

3 Backwashings of sand valveless filters (No 1 Kobe and No 2 built up by NCZ): overall 10m3 once per day, duration 4 minutes, containing suspended solids.


None

3.13.3 Solid Wastes

Old resins (changed about every 2-5 years).

27

3.14 Boilers

At present in the factory four boilers are working (a new boiler is under erection): one coal operated and three fuel oil operated (even if two of them, called "twins" were designed for coal but were modified by NCZ to fuel oil). The new boiler will have a capacity of 30MT/hr steam and will be coal operated.

The capacities are: 11t/hr of steam for the "carbon" boiler (which works with coal dust mixture with little fuel oil), 9t/hr for the for the "twins" and 6t/hr for the last "diesel boiler" (which is operated with light fuel oil and was degraded in the past from the initial design capacity of 10t/hr steam at 29 bar due to four explosion accidents.


Sharp blow down twice per shift for each boiler: about 5m3/each flowing to industrial sewer ("C" effluent).

2 Effluent from sedimentation basin for the ashes of coal boiler: consisting of fire water containing suspended solids going to industrial sewer ("C" effluent).


Coal fired boiler is provided with a 30 mtrs high chimney. The other boilers are provided with only 6 mtrs high chimneys. The new boiler will be provided with a 35 mtrs high chimney. Sometimes, due to difficulties of pulverisers operation, light fuel oil is being used in the coal fired boiler, resulting in a dark smoke to the atmosphere for short time. A dark smoke is also coming out from the "twins" boilers during soot blowing operation every shift and at start-ups.

3.14.3 Solid Wastes

None

3.15 Fuel Oil Storage

Fuel oil is supplied by Ndola Refinery; it travels by means of tankers on the roads.

28

Daily consumption is about 35MT/day. The storage consists of the two 70m3 tanks VOG A/B (of which one has no heater) one 100m3 tank (V06/C) for light fuel oil and of the new 300m3 tank for "diesel" fuel oil (this latter to supply gasifiers, coal handling furnaces, ammonia plants, and in emergency, the boilers)

Fuel oil is transferred to the storage tanks by means of a centrifugal pump (capacity 10m3/hr)1 if this latter is broken a mohno portable pump is employed.


1 Leakages from the coupling with the flexible pipe.

2 In order to drain about the last 100 ltrs remaining at the bottom of the tankers after pump transferring to the tanks the workers drain this oil in some drums and then pump the contents of the drum to storage. During this operation some losses of fuel oil in the surrounding areas occur, spreading mainly to the storm water sewer. Sometimes these losses are covered with lime.

3.15.2 Visit 2n site

Fuel storage is located just close to the open trench effluent from the waste water treatment plant. There are restraining walls, but an eventual leak from the tasks risk to pollute the treated water.

29

4.00 LIQUID EFFLUENTS

This aspect covers most of the efforts employed in the study. A considerable analytical campaign was carried out by the laboratory from 23/07/86 to 19/09/86 and some supplementary analyses and tests were accomplished in October and November. Checking analyses were carried out in December 1986 and February 1987 to verify eventual changes after the turnaround of the factory. For this purpose some points of sampling, practically coincident with the main points of discharge of the factory sewerage systems, were located and the analysis schedule reported in Annex 2 was drawn up. Eight points of the storm water (SW) sewer were specified and eleven of the industrial sewer (namely IW1 : IW11), moreover three points for the sulphuric acid plant were specified and some intensification of the NOX and S02 controls were required as regards air pollutiorl.

The location of these points can be found on the enclosed "map of sewers and points of sampling" (Drawing A201-0064). The data collected, together with the flow rate measurements and considerations on the actual situation of the sewerage systems of the factory were utilized to outline the necessary recommendations to be adopted for the pollution control of the factory.

The analytical data collected during the campaign are contained in the Tables of Annex 3 (pages 1 - 17). These data must be read in connection with the production situation of the plants of the factory during the time of samples collection, which is summarized in Annex 4 (pages 1 - 2).

The results of the flow measurements (carried out by means of several methods, in comparison with them when possible: propeller hydrometer, chronometer calculations of the paths of some floating materials and gauging weires) are reported in Tables 2 and 3. Some difficulties were met during the measurement, due to considerable amounts of sediments along the trenches and outward fouling in some of them.

The location of points of sampling and the summary tables of the analytical campaign are even shown on the "simplified diagram of sewers system with points of sampling and analytical results" (Drawing No A60S-0010).

30

5.00 PRESENT QUALITY AND QUANTITY OF THE LIQUID EFFLUENTS DISCHARGED FROM THE FACTORY (OVERALL AND PLANT BY~T ANALYSIS)

5.01 QUALITY (POINTS OF SAMPLING SWl :11 AND IW1:11 ON THE DRAWINGS A201-0064 AND A60S0010)

The analytical campaign was driven as much as possible into the details of the single plants effluents; however, due to objective difficulties in catching representative samples, as usual in these kinds of studies, it was not possible to investigate every small branch of sewer inside the plants, but only the main collectors from the plants.

The analytical results in the above mentioned sampling points are summarized in the following Table 2, for industrial waste water, and Table 3, for storm water, elaborated from the single analysis by means of simple statistical methods and rejecting not representative data (samples taken during days of shutdown of some plants or figures visibly out of standard.

During the execution of the analytical campaign two more points of sampling from the storm water sewer as to the previous schedule, namely SW9 and SW10, were considered worthy of investigation.

As regards the parameters investigated in the Table 2 and 3 chromium, nickel and cadmium are neglected since they were always found equal to nil in all the analyses.

As to the sulphuric acid plant investigations and A321 slurry the analytical results are shown in Table 4.

5.02 QUANTITY

The series of flow measurements were driven as much as possible into the single plants effluents; however, due to objective difficulties in introducing measurement instruments, it was not possible to investigate every small branch of sewer, but only the main collectors.

Whenever the flow was so low as not to affect the sensitivity of the employed methods, it is assumed the flow be equal to lm3!hr or less. The results are shown as "Hourly Rate" parameter in the same above mentioned Tables 2 and 3.

SUMMARY OF INDUSTRIAL SEWERS ANALYTICAL CAMPAIGN

IWI 100ES

IAMBII IW 2 IW) IW 4 IW5 lW 6 lW 7 lW8 IW9 IIW10 IIW11BAllKtE R E ,ULAliOI II[V/ LA

lANK RELEVANI lI~IIS 1110 T . O .a' 010 I A MEW AI lEW Ai A104 AIIUl A5. M P !

HFlum 10 IW 1 PUBLIC SEWE. EfflUENI EFflum [fflum UfIUE!1 ElflU~1 IfFlU!iT HfIUEHI [fFlUm EfflUENT EfflUEN]

PARAMETER EXPRISSEO UHIlREf AS

HMPERATUR c 10 MIN 115 60 11 151 HI 15 6 15 6 114 115 M 111 111I MAX 11f'~ " --- -" -"--- -------- ----

1 pH 79 MIN L L 6 ; 10 83 6 4 11 151 9 15 9 7 9 Ii L-l 1;MIX 96 _ .. 3 TOTAL NH4

""""---.--''Jr

./~-,.--7651 3791 L04 m 11000 L16 0NH~ 18L MAX l!ll 60 I 150 m III ill

------------ --- ---------- I' , 'r-'" J"" , .. _---L FREE NH) NH) " 41 MIlS! lIMES 56 III 36 I MIl II4L 11,0 13 III 115 III

CYANlOit" r'Nil """ - - ---------- " -,'

s CN - 02 MOS! liMES 05 o 005 o Ii 51 Nil "l 5 o 98 -.. ill c, .. ,-- E HIOCYANATES SCN .. o 0, HOIMIME! NIL ill 1 06 ill III . .. "

r" .. r" , 7 SUlPHATES SO = .. 361 I~:~ " 500 3LL m 191 190 II 35 15 10 130 ODD LUlO r ",LI'"'' IIIL I PHOSPHATES PO,' .. 01 Mil N~L Ill! oII o Ii 014 DO. 015 - - - ~ 2111

" IIAUi I's NITRATES NG3~ .. m MIN II JlL 160 IlL III 501 1495 Hl6 1&1 81 141 1151 Iii

MAX 1)" SUlPHlliES S= .. II MOIl ilKS 1 016 19 L1 Mil o 06 " - - -.... 1Il "' ,"""" ----- , II SHMIUM Se .. oIll! IllilY 111(

SUMMARV Ot STORM WAHR SEWERS ANAIVJI(AI. [AMPAILN

I"R'ME1Rr[ , 11 M" RAT URE 1 1 pH

,IDIAII

iH" -

f " fREl I H 1

(IAm!sf: 11HIWU.1EI 11 j'llIPHAltS r I 'HO"H'IES 'f! Ki1"HS ,10 IUIPHIDI

,11 !5IOIUM

[17 AR![ HI( WIER[Tl 11M~11; IRQ! l [An

,:: I au IOlAl

11 I ~Q II OS IUIHHOEO 101lDS['"

*''* OUR"G ORY Wf'IRIR

t\

H R,'

H" J [I

SW91SW101_

2~ ] f ~

c.,~

II

7 n 1/:-;, -I }~z/!. :J ,- -I

NIL '>~ i I .i we

lUll: n':> Iq-:~~

I :A~/j1~

I Hili i!1 ;;' 2

0.1'"

- - 1 , -;r-- /hI7/:/177>',--- ,- -- ,-

t. '"JI~ I, 7 ~.

/, :;,tj ;.,,~ "//~1 ~/;) )/l~/~; 14 ~ 2~~~~~- 7//~~=-'0 I. t,'Ill.] 1 ~ 2"'4 - ~48' 1(;"'4 s~ 1 8 o.~:tl 72 11 "<

I.J~I~ oo~~' 0 4; 0,;-'\ :;~: ~-I-Jo 006 ~'~I ... I- II t' ,~- - J /:;r,:; -/-0-"/ 7/~ 7,.)""h. 7~! 1.--:,,// ~~~----Ij",lt l ~il:. __ 0 ZJ t.;// ~e. ~ ?? ~ ~~P ~'f ~t ~.~~! 9> _"1 -Jill .. 1& liD,"') """3:y' "'''''', G.~"'~ ~?~.!!1 7"'8 I IOe. .. 4.. I' 1Z?7-.,..'/~>/ //~ ////'1 rQ/. //,.-;.. //"/ ........//;:.:t 7""'-..'lj . P-?'..... -~----I

1:j "':'I':~' f';:~:1:~ ::oi::L~:1::r~,-... ~~tf I

7(" I? 07' Ill>?>I" Zz I 0"2 I ! 0 74~4-"'M;1/,T/ I ,,,.;/'/ ~-/"r~

e.8 !>4a.;' lOt; 142"" I?:>"i ./ 'l; .7:~ - - //7/'~,"I:;" ;!. ~I ~ ""j I ':> j' 0 _I'" I a. I?

--------

- 3J TABLE 4

SAP I SAP 2 SAP 3 A 321 Vl00l V901 V 904 SLURRY EFFL. EFFL. EFFL. TO

L.I\GOON

EXPRESSEDREF. PARJlMETER UNITAS

Temperature c 33.5 30 32 31.5 2 pH 8.93 O. 12 0.57 11.9 3 Total NH4+ NH4+ ppm 26.6 4 Free NH3 NH3 " NIL

5 CyanIdes CN " 6 Tr, i ocyanates SCN- " 11.5

7 Sulphates S04 = " 270 975 4980 8 Phosphctes P04= " NIL

9 ~Iltrates N03 61

10 Sulphides S= 8.7

I I SelenIum Se " 0,045 6 2.3

12 ArsenIc As " 4 47 5

13 Co;;per Cu " 2,2 158 1539 449

14 Zinc Zn " 0,34 1,5 363 52

15 I ror, Fe " 29.3 0,047 2 12300

16 Lead Pb " 0,4 0,29 9.7 2,5

17 Oi 1 " NIL NIL NIL NIL

18 Total so 1ids " 59102

19 SusDended " 58555 1500 58000 44600so 11 ds

SULPHUR IN S 6,6SOLIDS

34

As regards point IW2 "D" effluent the flow rate is nil because at the time of the analyses the flow of this sewer was deviated into others and no effluent was flowing to the double "D" effluent pump. Where a dash is indicated instead of a figure the flow rate measurement was impossible because of too much sediment in the sewer or of the lack of the discharge pump in the pit of investigation (thus resulting in standing water in the pit and overflooding of polluted water into some storm water sewers. See the chapter 8.00 for this).

5.03 OVERALL POLLUTION

By combining average flow rates with average analysis relevant to the most meaningful parameters as regards the complying with the law (see next paragraph 5.04 for the reference to discharge regulations) it results that Kafue NCZ factory is discharging towards the surrounding environment (mainly new Kasenje River or open drainages conveying into the Kasenje River), the quantities of pollutants exceeding the limits from the final points of discharge indicated in Table 5. Of course these computations are based on the hypothesis that 24 hours a day both the hourly rate and the discharge of pollutants are constant and equal to the average.

The considerable amount of suspended solids has been directly confirmed during a boat trip taken along the Kafue River by the compiler of this study together with NCZ Works Chemist as far as the confluence of Kasenje River with Kafue River. Here the distressing and impressive sight of some hundred square meters of Kafue northern side covered with black sediment could be observed. The height of the sediment layer was so big that the sampling bottle could not be immersed in the river water, even many meters from the bank. Samples of the sediment and of the supernatant water were taken. The analytical results, shown in Annex 5 and 6 indicate that some alteration has started in the Kafue River natural geochemical concentration, at least on that portion of northern bank in proximity of the Kasenje confluence. Infact, ammonia, nitrates, salinity and solids are rather high, (see analysis of sample 2 in Annex 5) while at the center of the river ammonia and nitrates are nil. The position of sampling points on Kafue River are shown in Table 6 BIS.

SUMMARY TABLE FOR OVERALL PRESENT LIQUID POLLUTION FROM NC.Z FACTORY KAFUE

IflNAI POINIS OF DISCHARGEINTU'I.IlUC SEWER OR WAHRCOURSESI nONlY PARAMETER fiGURES ABOVE ZAMBIAN SIANOAROS ARE REPORlfO

lW 1 SW10 *I SW2 SW 3 SW 4 SW5 *1 SW6 *1 SW7 SW 8 SW9 OURlY DAILY HOURtY IlAlty mum DAILI IlliIJlLV DAILI HOURLV OAlli IIIlJ11l! DAILV ~~l~LV IlIIlY Houm D~LY 1111118Ll OAIlV IIIURIV '.VAII i RAT! AMIl1IHl RAT AHlUHl lilt AHlUIl HAlE IMOlMl tAl[ IMlIUH1+..!.!! _ AHlIIi1 RAIE AMOIllH RATE AMOOHl W "!lMOUHI

lOlA~ .f.1351",W~ 3S'%, 93.6% 9.~,. 456%; lUV9~~ 263.5~68h, a.s" ~!~'I CYANIDES 07~ 17~ O]2~ 77D/. ID5I~ 2S I!. 20 9 , ().51}.

t .. ..-. _.. ...... . ..-. . "- . ..-...- ...-. ..._. .......- ..hf.. .''''L ....'. ..d"1 ...., day /t

-------

TABL-E 6 Q,..$

SI

37

THE REPUBLIC OF ZAMBIA TA B LE'" 6

O~ 'IS '16 '11 '18 '19 "20 '21 '11

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nat ~"~_" l< ENG _ ),.,)""" (...~

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/ ,,'Us.

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,~

. . .....,:--,--- -'1~--"

'/ (

38

It is necessary to point out that the 20ppm of ammonia and the 32ppm of nitrates found in the water supernatant the above mentioned coal ash layer were relevant to a day, 14th November, during the general shutdown of the factory. The position of NCZ factory as to Kafue River is shown in the small map of Table 6.

5.04 REFERENCE TO LOCAL/INTERNATIONAL REGULATIONS

Till last year in Zambia there were in force only some old Local Government Acts regulating the discharge of "Trade Effluents". The ones which we got acquainted with (Kafue Township Council and City of Ndola) were rather lacking as regards contents and indications in the sense that many important parameters (among them the main pollutants of NCZ Kafue factory) were missing and for some of the others the concentration limits were not given.

On the contrary on 8th November 1985 the Statutory Instrument No 161 (herein enclosed as Annex 7) was issued with the aim of disciplining in all the Republic of Zambia, the discharge of trade effluents both into a public sewer and into any water courses or lakes. of course, the limit specifications valid for any water course are stricter than those valid for the discharge into a public sewer. This law appears very clear, including even a very detailed formula for calculating the charge for the disposal of trade effluents into a public sewer and the amounts of fines in case of offences to any provision of these regulations. As regards the standard figures some parameter limits appear too high in comparison with European or USA ones, but it looks quite reasonable taking into account the substantially different level of Zambia industrialization.

If someone just wants to move some critiques to some points of the Law, it appears unusual the presence of a limit for thallium, which is not taken into account by any international regulation. Moreover, the limit of 25mg/1 for zinc appears too permissible, as in all countries this compound is considered rather tOXic, on the contrary tin limit of 2mg/l looks too low, stated that this metal is generally not considered toxic. Even the limit for oil (1-2mg/l) is quite'low (for Italian Law if 5). Moreover, biological pollutants (coliforms and streptococci) are missing.

However, the Statutory Instrument No 161/1985 looks, in this context, the most reliable and complete term of reference for the aim of present Environment Stury and it will be taken into consideration as the national regulation in force which is mentioned in the contract, neglecting any not very clear reference to mysterious "International Standards",

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6.00 GENERAL COMMENTS Qli THE RESULTS OF THE ANALYTICAL CAMPAING

The previous pargaraphs with enclosed Tables 2, 3, 4 and 5 practically reply to the demand of investigating the present quality and quantity, overall and plant by plant, of the liquid effluents.

As regards the expected level of pollutants after completion of the technical rehabilitation of both the Kobe and the Klockner line it is likely not to be a large change to be expected; that is why on the one hand the capacity increase will produce higher level of pollutants, but on the other hand the ameliorations to the condition of apparatuses will involve a minor amount of leakages and losses of pollutants at present higher because of poor maintenance. Which of the two effects will be prevailing is rather hard to forecast, but we believe that to consider valid present levels of pollution even for the future will be quite conservative.

AS general comments it appears evident that the final effluent from the industrial sewer (IW1), which is discharging, together with the sanitary sewer, into the main council public sewer line is, by itself, out of the Zambian Law as regards ammonia, nitrates and slightly, sulphides.

If we consider the combined industrial/sanitary effluent from the factory, as confirmed by some analysiS, this latter remains faulty as to ammonia and nitrates. This is quite reasonable stated that, even if we do not know in detail the township sewage treatment plant project, a municipal waste water treatment plant usuallydoes not present high capacities of nitrification and denitrification, while a fertilizer factory like NCZ typically discharges mainly ammonia and nitrates.

However, the major problem for NCZ factory is the large number of storm water drainings polluted at a higher extent than the industrial sewer. The discharges through storm water drains must comply with column 3 regulation 4 of the Statutory Instrument No 161 of 1985, as they do not occur in a public sewer, so that the standards to be observed are stricter. As pointed out by the dashed lines in Table 3, at present storm water discharges not complying with the Law are the following for the mentioned parameters:

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SW10: Total ammonia, sulphates, phosphates, nitrates, sulphides, iron, oil and suspended solids.

SW2: Copper and suspended solids.

SW3: pH, sulphates, sulphides, arsenic, copper, iron, salinity and suspended solids.

SW4: pH, sulphates, selenium, arsenic, copper, iron, salinity and suspended solids.

sws: Total ammonia, cyanides, copper, iron, oil and suspended solids.

SW6: Total ammonia, cyanides, sulphides, iron, oil and suspended solids.

SW7: (Which represents the biggest effluents from the factory, even in dry weather): Total ammonia, cyanides, nitrates, sulphides, oil, salinity and suspended solids.

SW8: Total ammonia, cyanides, sulphides, oil, and suspended solids.

SW9: Nitrates, oil and suspended solids.

The overall situation is summarized on the simplified diagram (Drawing No A60S-0010).

It appears evident that the major responsibility of this heavy and so widely dispersed pollution is the chaotic situation of the sewerage system, with a big mess of mixtures between industrial and storm water trenches, breakages, blockages and, may be, even improper conveyances of polluted discharges to the wrong sewer for design or construction mistakes.

As regards the sulphuric acid plant sewer (SW2, SW3, SW4) responsible is the the heavy corrosion and abrasion of piping and pumps, which often are not working, resulting in discharging effluents directly to new Kasenje River instead of conveying them to the waste water treatment plant and then to the lagoon.

To the above mentioned pollution frame there must be added the overflow from the lagoon which, as results from the analysis enclosed in Annex 8 (pages 1 - 6), is systematically out for sulphates.

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For precision's sake Nez factory, apart from other branches of storm water sewers which are surely not dry only in rainy weather, has another discharge into the public sewer from the sanitary sewer collecting buildings located in the western area of the factory, but this latter, as it originates exclusively from hygienic facilities, surely comply with column 2 standards.

As further general comment, if we compare the quantities of ammonia and nitrates averagely lost with the polluted discharges with the production amounts in the period of the analytical campaign, we can say that almost 10% of ammonia production and 7% of ammonium nitrate production has been lost with the polluted waste water in this period (though plants were stopped many days). If this percentage persists, once rehabilitated the plants at maximum capacity, the lost amounts will be 31t/day of ammonia and 35t/day of nitric acid for the considerable value of Kwacha/year 43 million.

Of course, not the whole pollution is removable with practical and economical methods, as it,occurs invevitably in every factory of the world, but very much can be done at Kafue factory to reduce present big amounts, only by means of simple interventions, good maintenance and some precautions, as we shall strive to indicate with our recommendations.

A particular comment is worthwhile for oil parameter: The standard limit of 1-2mg/l (it is odd that for this parameter there is not indicated a clear figure "one" of "two") for "any discharge other than sub-regulation 1" looks quite low, especially in comparison with the 100mg/l for the discharge into public sewer; so that all the storm water drains appear out of law as to oil, even if this parameter can be easily assessed bringing back the discharge to the proper industrial sewer.

As regards the visible effect of iridescence that can strike the average man in the streeet it is necessary to bear in mind that it is only a matter of the presence on surface of a molecular layer of oil, but no massive amount of oil is in the bulk of the waste water, as it results from all the analyses.

Infact according to an experimental table supplied by A.P.I. (American Petroleum Institute) in its "Manual on disposal of refinery wastes" (see bibliography 1) to the appearance of visible bright bands of colour it corresponds an approximate thickness of 0,0000120 inch film and a quantity of 200 gallons of oil for film 1 square mile in area; it means that about O,73cc of oil everyone meter of iridescent open trench, since the average trenches width is about 40cms.

43

As regards the s~z~ng data for the review of effluent treatment plant for the fertilizers area We can notice that, apart from smaller streams, the major contributors are IW1 and SW7 for a total of about 700m3/hr, that is approximately the same amount drawn from the water intake for the same area.

Actually there is another water immission of water into the factory, namely the drinking water coming from the council; this latter flows through a 4" pipe and a meter (supplied by Bosco & Co. Torino which however is not working) and serves all the control rooms, toilets, the canteen and the laboratory. The used tap water is supposed to flow to the sanitary sewer system, so that, even if some losses can be found in other sewers, this contribution to the effluent treatment plant is not remarkable. It is not at all clear as to why the conspicuous figure of 700m3/hr are corning from the practical observation and flow measurement of the main factory effluents, while from the theoretical examination of the waste water streams plant by plant not more than an overall 100m3/hr are arising. The suspicion that may be the balance tank effluent was not really flowing to main council sewer, due to some breakage in the sewer system and was in communication with the storm water sewer discharging through SW7 must be dispelled due to the different elevations of the two sewers. On the contrary direct observation of the very small flow in the branch of sewer directed to main council sewer (by lifting the grating of a man hole located in front of bagging house on the other side of the railway/and the concomitant big flow at swa (usually dry) in the period of the collapse of sanitary/ industrial sewer (see point 12 of Chapter a.OO) convinced that the balance tank effluent contributes, in case, to swa, not to SW7, so that the only likely explanation for this discrepancy is that the number of abnormal operations involving emptying and flushing of apparatuses and various washings of vessels and plant areas are very much more than what even the plant chiefs can realize, due to the frequent shutdowns and leakages of parts of the plants that occur for poor maintenance, lack of spare parts or electric power failures.

Generally speaking no plant operating people interviewed on the pollution control matter were conscious of the problem, but their main interest was the production and the operation of the plants without troubles. This can explain the numerous diversions to the wrong sewer and the other anomalies that will be object of the next chapters a.oo and 9.00. Moreover this lack of sensitiveness stresses the hypothesis of urgently designating a responsible person for the environmental control of the factory as proposed in paragraph 9.14

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6.01 COMPARISON WITH OTHER FACTORIES

As rough consideration if we compare the pollution generation from NCZ Kafue Factory with know figures from similar European Factories, we can state that NCZ is polluting more than 3 - 4 times bigger factories.

This statement is indirectly confirmed by an application of American E.P.A. (Environmental Protection Agency) "Effluent Guidelines and Standards for Fertilizer Manufacturing" (see Bibliography 2), which supply some reference figures for effluent limitations as to well operated plants subdivided in the main fertilizer manufacturing categories.

The subcategories of NCZ interest are as shown on the following tables: 7, 8, 9.,

By applying the figures suggested by EPA to NCZ Plants, it results, as shown in table 10 that NCZ level of pollution is a long, way off the best practical control technology currently available, so that many improvements are still possible inside the Fertilizer Manufacturing Plants in order both to reduce pollution level and to increase valuable products recovery.

Subpart 8-Ammoni& Subc_tcgo(')' ... "':' '

~ 418,20 Applieabi1i1'f~ d"$orrtp1ion of (hI:' ammoni. U.bc.lorr;Or}.

The pro\i.slons of thIs f;ubpart ce ap.. phenol/;' to cLs:.:hal'lt~~ re!>u1tmg from the manufacture 01 alTlJnoru5 .

4 18,2'3 Emuornl Hmi...tton:. cu'drHtu::t~ '18.:22 Emurnl U0halion, "'Id"lin~~ NprnC'Jltinf I-ht' dt'1t1"H" of II:fRu(OntrrprrK"ntiDt: th.. de,Jnl' or "'fth.... nt nduction .U,IIIin.bl,t- bv thC' .ppl1~~'Muortion aU.inablt' b~ thr applln;

tion of 'he' ""t pndk.abl(' r(fn1t'o. lion of t.he b"a, ..", .. nahle u:chnolt V ~ onomieaU, .c:hh.,\'uJe.": It:

Subpart [~ltriC Acla Subcategory TAB lE" g 418.50 Appli(;.bjlil"~ d~ription of Ih~ nitric "t'id .ube.t~f:Of"'.

'nit proVi.zlons .of th.!s 6ubpart art .p.. Pueable to ducharrts r-esWU.lli Irom prDducUon o! n1t.rle acId in ooncentra liom up tl 68 perCent. D1.Sch~rge.l. from Ihlpping los5es.... re excludtd.

(b) The following I11:nttatiOn.!l es1&b.. ll!h the quanUty or quality of pollut~ liLts wh1eh maY be dlscna.rcf'd U'. process ....a.:si..e water from J:)jtrtc Acid P1'OOuc1.lon in ...b.kh .ll lohe taT mat.enaJ a.mJDon.i& 15 in tbt ablPptd liquh1 form.:

rw.ll"!t t'roE!. "\:'r iiI rtOOo"l; !nf1ul') t'llIu.11',1.!J"".1. of pr0\3IX:\\

F t:"J~,.1 A...~.w, of.c.,." d.'''.'''''H'' "u f"lUIr' flY ".,..,~, lor.

IIIr} J (1;!~ '7H~C1JW'" {hn .Ii,,- nt'l .~~-

Amti'lQnl. (.... S) II ()1 ....

"!:.n.~ 1&.1 P'I (1..11;.n,tt ("" N;".". 1Ui, ..... ,. ,."_ 0.0'.:3

(

47 TAB LE :3

SubPirt G--Mi.-d ,nd Blend rertm:er ~~rr;Jldurtio" $\,lbl;.ltebory

418.10 App)k..bilitr; d:~.CI'ipllon ot lilt' .,i:.;cd .nd bl'nd (t'nilil:t'r I'rOo ductton auhrult'for).

The provl.sioxa of this aubpart lore apJi;lJcabJt' &0 C1I.&h..re~ resuJti,lli:' from tht production of m1:ttd ftrUhzn &l'\d blend: terUllZer,

418.72 Emu~nl liMitllionuJd~fin~1 HprTU'n',ne th~ d~J'l'~ of "-fh'(,rl:l r~du

BES'T P~AC.TI c:.A L c::.ONT~oL

Ac..TUAL I -re.C.HNOLOE,';;;I c:. .. I{a.E.NTL::I Pl_ANT (OR.DeSIG"'~ ./lVAILABLE' (t::PA GUIDeLINeS)

Ptl.OPUc.T

c.. A fA

49

6.02 POSSIBLE EFFECTS ON THE ENVIRON~NT AND HEALTH

Water is considered polluted when it is altered in composition or condition so that it becomes less suitable for any or all of the functions and purposes for which it would be suitable in its natural state. This definition includes changes in the physical, chemical and biological properties of water or such discharges of liquid gaseous or solid substances into water as will or are likely to create nuisances or render such waters harmful to public health, safety or welfare, or to domestic, commercial, industrial, agricultural, recreational or other legitimate uses of water, or to livestock, wild animals, fish or other aquatic life. It also includes changes in temperature due to the discharge of hot water (Thermal Pollution). From these principles inspiration was drawn by all the legislation of the world, not excluding the statutory instrument No 161 of Zambia.

Human Health may be affected by ingesting water directly or in food, by using it in personal hygiene or for agriculture, industry or recreation, and by living near it.

Herein we shall briefly deal with possible hazards from some chemical pollutants, which are present in the discharges of NCZ Factory Wastes, since the hazards from biological agents (Pathogenic Bacteria, Viruses, Parasites and Nuisance Organisms) should be faced and covered by the Kafue Township Council Effluent treatment.

If present above a certain level, some chemicals pollutants (eg Nitrates, Arsenic and Lead) may constitute a direct toxic hazard when ingested in water. Other water constituents, such as Fluorides, are benefiCial, and may be essential to health, if present in small concentrations, though toxic if taken in large amounts. Certain other substances or chemical characteristics may affect the acceptability of water for drinking purposes.

Ingestion is, however, only one possible pathway to exposure. Man can be exposed to water pollutants through other types 0: direct contact, eg in recreation or the use of water for personal hygiene. The possible health implications of these non-drinking uses of water (including agricultural and industrial uses) are

50

less well understood and no international criteria or guidelines exist for the control of such exposure. In addition to the possible effects of ingestion and other direct water contacts, chemical water pollutants may influence man's health indirectly by disturbing the aquatic ecosystems or by accumulating in aquatic organisms used in human food: for some pollutants these effects may be the most important public health aspects of water pollution.

6.02.1 NITRATES

The concentration of Nitrate in surface waters is usually below 5mg/l. Much higher concentration are sometimes found in ground water. The consumption of water (or baby food preparations) with a Nitrate concentration higher than 45mg/1 may result in infant methaemoglobinaemia. Another hazard is the formation of Nitrosammines due to the reaction of Nitrites (coming from Nitrates reduction by means of intestinal bacteria) with secondary and tertiary Ammines present in food. Because of its carcinogenic power, Nitrosammines constitute a risk to man's health. The presence of high nitrate concentrations in the watercourses gives rise to the so-called phenomenon of "Eutrophication", that is the abnormal and excessive growth of Algae.

6.02.2 ARSENIC

Concentrations of Arsenic in surface water bodies are usually low. Rather high concentrations (0.2 - 0.9mg/l) have been reported in some drinking water supplies and are associated with endemic Arsenic poisoning and the so-called "Blackfoot" disease. Arsenic is also known to accumulate in some marine organisms, such as clams and shrimps. Certain epidemiological studies assign arsenic even a carcinogenic power.

6.02.3 SELENIUM

Selenium seems to couteract Arsenic toxicity; however the specific protective action of Selenium seems well established against the toxic effects of cadmium and mercury. Selenium levels in water appear to be subject to natural control by absorption by sediments and precipitation. In trace amounts Selenium is a

51

micronutrient; at higher levels (over 2mg/l) it may have adverse effects on mammals. Some studies have indicated that Selenium increased the susceptibility to dental caries in early life.

6.02.4 TURBIDITY (SUSPENDED SOLIDS)

The presence of Turbidity in a water body is mostly noxious for the interception of sun radiations, thus disturbing the regular chlorophyll photosynthesis. In many cases suspended solids may directly damage fishes by means of abrasion or choking action or, indirectly, preventing them from a good sight of the prey, thus interfering with food assumption.

6.02.5 These have toxic effect on human health if present in drinking water above 0.05mg/1 concentration.

6.02.6 METALS

Copper concentration above 0.05mg/1 provides the water with astringent flavour, colour and corrosive properties. Lead content (even due to the use of lead pipes or of plastic pipes stabilized with lead compounds) may accumulate in shell-fish. Zinc gives the water an astringent flavour and opalescence. Iron causes unpleasant taste, colour, turbidity and ironbacterial proliferation. Cadmium and Nickel, fortunately not present in NCZ discharges, are very toxic even in small concentrations.

6.02.7 SULPHATES

In presence of Magnesium or Sodium, Sulphates, if ingested cause gastro-intestinal irritation.

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7.00 PRESENT EFFLUENT TREATMENTS

At present NCZ Kafue factory is provided with two effluent treatment facilities, one dedicated to Sulphuric Acid Plant and the other for the remaining areas; within this latter the settling pond and cooling tower system for hot slurries from coal gasification is inserted, at present operated in autonomous way, but before interconnected with the main system. A separate talk must be dedicated to the lagoons system.

7.01 FACTORY EFFLUENT SYSTEM (Refer to the part of the Drawing 605-0049 enclosed by dotted lines and entitled "Existing Neutralization Plant")

The effluents treated in the Plant are the following;

- The so-called "S"-Effluent (point of sampling IW4) corning from Coal Gasification (the "A"Effluent which was coming from the Carbon Dioxide removal at present does not exist any more due to the change of the removal process).

- The "c" Effluent (point of sampling IW2) from Ammonia, Nitric Acid, Ammonium Nitrate, Ammonium Sulphate and NPK Plants.

- "0" Effluent (point of sampling IW3) from Compressor House, Air Separation and Water Treatment (Precipitator and Demineralisation Unit) Plants.

"B" Effluent orignates mainly from the T1201 Cooling Washer for cleaning the gas corning from Gasifiers; the resulting Hot slurry (about 40Deg.C) is conveyed by a gravity canal to the Four settling ponds A321 in which separation of coal dust from clear water 1s supposed to occur. After sedimentation the clear water recycles to T1201 Wash Water Cooling Tower; the average flowrate with three running Gasifiers is 360m3/hr. If too high water losses occur due to evaporation, windage or other a make-up water from A601-E01 is provided. Two slurry pumps (1211 A/B: 80m3/hr 13.89 Bar) are sending the slurry collected at the bottom of the settling ponds to the dedicated lagoon outside the factory fence, from where overflow water is supposed to corne back to the ponds.

53

The condition of the whole system is poor. The settling ponds are equipped with moving scrapers not working since years and the original slurry pumps, which were not good have been substituted by a submersible pump which is alternately moved from a pond to another by means of a crane. The practical result is to often get an off-specification raw synthesis gas with some problems at Ammonia Plant. Moreover the pumping station for the clarified water from the lagoon is not working since it was stolen years ago, resulting in waste of water for the Factory and awkward overflow out of the lagoon. Sound interventions are required for this section in order to establish an efficiency situation as regards solids separation and clear water recycle from the lagoon, as to the recommendations contained in the chapter 9.00 "Liquid Effluents Control Plant")

However the present way of operating this section of the Effluent Treatment Plant as an autonomous service to the Gasification Units remains an idea to share.

The so-called "c" Effluent, most of the time basic, is conveyed by gravity to the proper 605 C09 "c" Effluent Pond of about 160m3 volume ; the contents of the pond is maintained in agitation by means of air flowing through slotted pipes positioned on the bottom. The air is coming from the service network of the factory, while in the past was furnished by proper blowers. The pond material is concrete lined with acid proof asphalt. By means of the

"Ctt605 POS AlB pumps Effluent is then pumped to 60S Cll neutralizing tank together with "0" Effluent. Here neutralization begins with the help, if necessary, of lime milk or sulphuric acid addition: this tank is provided with a vertical mixer (Impeller Diameter 500mrn of S.SKw power) and is built up in concrete coated with epoxy paint.

DM Unit Effluent, together with sludge intermittently spilt from Precipitator, is collected into a transfer basin of about 100m3 volume located at the site of Water Treatment Plant, from which is pumped through an aerial pipe to the "0" Effluent double pond 605 C10 A/B. No more effluents are going at present by gravity to this pond, due to blocks and improper deviations of the sewerage system.

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However the forecast figures for effluent flowrates are low in comparison with "c" effluent, so that it looks singular to provide storage volume of 2 x 160m3 for the minor one. The material of construction of "D" effluent double pond is concrete lined with acid-proof mortar.

The 605 neutralizing tank has a volume of about 22m3, such as to assure the contact time of five minutes sufficient for a "flash mixer" service. A pH indicator-controller regulates the neutralization. The neutralized effluents flow by gravity to the so-called "Balance Tank" 605 C08 (vo

Documents

ENVIRONMENTAL STUDY ON NCZ (NITROGEN … · NCZ (NITROGEN CHEMICALS OF ZAMBIA) KAFOE FACTORY . March 1987 WRITTEN BY DR. ING. L PERES ... Old Nitric Acid ; Plant 14 : ... Under the