USE OF WASTEWATER FOR IRRIGATION IN VEGETABLE GROWING IN THE KAFUE LAGOON AREAS AND ALONG               NGWERERE RIVER    ...
DISCLAIMERThe views expressed in this report are those of the researchers and not the Zambia SocialInvestment Fund (Zamsif...
TABLE OF CONTENTSAcknowledgement                                                                                          ...
4.1              Secondary Data collection ..................................................................................
ACKNOWLEDGEMENTWe would like to thank the Zambia Investment Social Fund (Zamsif) for financial support toundertake the stu...
LIST OF TABLESTable                                                                                                       ...
Table 5.22: Analyzed Shikoswe stream and Lee Yeast sediments from the Kafue            Lagoon area compared to Dutch Sedim...
LIST OF PLATESPlate                                                                                                      P...
LIST OF APPENDICESAppendix            .......................................................................................
Abbreviations and AcronymsBOD     Biochemical Oxygen DemandCd      CadmiumCOD     Chemical oxygen DemandCu      CopperDFID...
Executive SummaryIntroductionIn urban and peri-urban zones in developing countries, poor farmers commonly use nutrient-enr...
In Zambia stabilization ponds are used for treating wastewater. These consist of the anaerobic,facultative and maturation ...
Irrigation with wastewater could be an attractive way of disposing wastewater from anenvironmental point of view. The comb...
Policy aspectsThe Zambian National Water Policy of 1994 specifies that water for irrigation should be fit forhuman consump...
A total of eight (8) sampling campaigns at each site in Ngwerere and four (4) at each site inKafue were carried out betwee...
Ngwerere River AreaIn Ngwerere River Area the education levels of the respondents were such that 14% had noformal educatio...
Public health issuesIt was found that the prevalent diseases in the study Area were malaria, bilharzias anddiarrhoea. For ...
feasible in both situations because the contaminated water was also the water used forirrigation by the peasant farmers in...
in the Ngwerere River was only fit for restricted irrigation whereby the crops that could be safelygrown were cereal crops...
The first two sites (N1, Garden/Olympia area and N2, Ngwerere Estate Weir) on the NgwerereRiver had a higher concentration...
2. The Ministry of Health (MoH) and NGOs (e.g., Water and Sanitation Association of Zambia,   CARE International and Lifeg...
CHAPTER 1: INTRODUCTION1.1     BackgroundIn urban and peri-urban zones in developing countries, poor farmers commonly use ...
Similarly the Ngwerere River has its share of urban and peri-urban agricultural activities despitethe river being chemical...
associated with wastewater use are groundwater contamination through high concentrations ofnitrates, salts and micro-organ...
CHAPTER 2: LITERATURE REVIEW2.1       GeneralDomestic human waste is defined as human excreta, urine, and the associated s...
•   Water based fish-aquaculture transforms the nutrients that are present in wastewater        into proteins. The fish fe...
design capacity was exceeded. These figures were obtained from Lusaka Water and SewerageCompany. Average effluent discharg...
most authors cite the table of phytotoxic threshold prepared by the National Academy ofScience and National Academy of Eng...
2.6     Agronomic AspectsWastewater has phosphates and nitrates, which are channeled into land as fertilizers(Karpagma, 19...
2.7     Environmental Evaluation of WastewaterGenerally speaking, environmental valuation is used to determine the willing...
Unrestricted irrigation refers to all crops grown for direct human consumption and eaten raw(e.g., lettuce, salads, cucumb...
Wastewater reuse zamsif report_12122004_updated
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  1. 1. USE OF WASTEWATER FOR IRRIGATION IN VEGETABLE GROWING IN THE KAFUE LAGOON AREAS AND ALONG NGWERERE RIVER Report PMA 24 (Final Report) By Charles Bwalya Chisanga, Water and Sanitation Association of Zambia Oscar Musweu Silembo, Department of Water Affairs, Ministry of Energy and Water DevelopmentFinanced by the Zambia Social investment Fund of the Ministry of Finance and National Planning November 2004 i
  2. 2. DISCLAIMERThe views expressed in this report are those of the researchers and not the Zambia SocialInvestment Fund (Zamsif) as a funding agency. Any errors or omissions are the responsibilitiesof the researchers. ii
  3. 3. TABLE OF CONTENTSAcknowledgement ivList of Tables vList of Figures viiList of Plates viiiAbbreviations and Acronyms xExecutive Summary x CHAPTER 1 INTRODUCTION ....................................................................................................1 1.1 Background................................................................................................................1 1.2 Objectives ..................................................................................................................2 1.3 Justification ................................................................................................................2 1.4 Significance of the Parameters.................................................................................3 CHAPTER 2: LITERATURE REVIEW ........................................................................................4 2.1 General ......................................................................................................................4 2.7 Treatment of Wastewater..........................................................................................4 2.3 Quantity of Wastewater Produced ............................................................................6 2.4 Toxicological Aspects of Wastewater.......................................................................6 2.5 Costs and benefits of Using Wastewater .................................................................7 2.6 Agronomic Aspects....................................................................................................8 2.7 Environmental Evaluation of Wastewater.................................................................9 2.8 Public Health Aspects ...............................................................................................9 2.9 Environmental Aspects............................................................................................11 2.10 Sociocultural Aspects ..............................................................................................11 2.11 Irrigation Methods....................................................................................................13 2.12 Policy Aspects..........................................................................................................13 CHAPTER 3: DESCRIPTION OF THE STUDY AREAS..........................................................14 3.1 Kafue Lagoon...........................................................................................................14 3.1.1 Site 1 (Shikoswe Stream) ...................................................................................15 3.1.2 Site 2 (Near Lee Yeast, LY)................................................................................15 3.1.3 Site 3 (Nitrogen Chemicals of Zambia, NCZ) ....................................................15 3.2 Ngwerere River Area...............................................................................................17 3.2.1 Site 1 (Near Garden Site 3 ponds, N1) ..............................................................18 3.2.2 Site 2 (At Ngwerere Estate Weir, N2) ................................................................18 3.2.3 Site 3 (Below Kasisi Dam, N3) ...........................................................................18 CHAPTER 4: METHODOLOGY ................................................................................................20 iii
  4. 4. 4.1 Secondary Data collection ......................................................................................204.2 Primary Data Collection...........................................................................................204.2.1 Field Interviews ...................................................................................................204.2.2 Computation of the Quantity of Wastewater......................................................214.2.3 Plant sampling.....................................................................................................214.3.4 Sampling of Water, Sediments and Plants ........................................................214.4 Measurements of the Parameters ..........................................................................234.4.1 Laboratory Analysis ............................................................................................234.4 Data Analysis ...........................................................................................................234.5 Limitation of the study .............................................................................................24CHAPTER 5: RESULTS AND DISCUSSION ...........................................................................265.0 Field interviews ........................................................................................................265.1.1 Demographic information on households using the wastewater ......................265.1.2 Kafue Lagoon Area .............................................................................................265.1.3 Ngwerere River Area ..........................................................................................265.1.4 Agricultural Practice ............................................................................................275.1.5 Crop choice .........................................................................................................275.1.6 Water Management and Sources ......................................................................295.1.7 Conveyance of water and field application ........................................................305.1.8 Crop yields and earnings from their sells...........................................................315.1.9 Crop marketing by farmers in the Ngwerere and Kafue Lagoon areas............315.1.10 Crop marketing by the farmers in the Ngwerere Area.......................................315.1.11 Crop marketing by farmers in the Kafue Lagoon area ......................................325.1.12 Earnings from sales of crops in Kafue Lagoon Areas......................................335.1.13 Earnings from sales of crops in Ngwerere River Area ......................................345.1.14 Public health issues ............................................................................................345.1.15 Constraints faced by farmers in Kafue Lagoon and the Ngwerere areas ........365.2 Quantity of wastewater in the Ngwerere river .......................................................365.3 Plant sample analysis..............................................................................................395.4 Water quality analysis .............................................................................................405.4.1 Physico-chemical results ....................................................................................405.4.2 Microbiological Results .......................................................................................505.5 Sediment analysis from the Ngwerere river and Kafue lagoon Area ....................52CHAPTER 6: CONCLUSION AND RECOMMENDATIONS.....................................................546.1 Introduction ..............................................................................................................546.2 Achievement of specific objectives of the study.....................................................576.3 Conclusions .............................................................................................................546.2 Recommendations ...................................................................................57REFERENCES............................................................................................................................58APPENDICES.............................................................................................................................63 iv
  5. 5. ACKNOWLEDGEMENTWe would like to thank the Zambia Investment Social Fund (Zamsif) for financial support toundertake the study under the Poverty Monitoring and Analysis (PMA). We also thank theEnvironmental Engineering Laboratory of the School of Engineering and the Food ScienceLaboratory in the School of Agricultural Sciences of the University of Zambia for carrying outthe water quality testing and the quality testing of crops for heavy metals, respectively. Theirlarge contribution to the study is gratefully acknowledged.We would also like to extend our thanks to the research assistants Cosmas Chalo and SiwaleChisanga (all employees of Department of Water Affairs), Mainess K. Manninga (member ofWater and Sanitation Association of Zambia), and Constancy Zulu (student of University ofZambia in the School of Natural Sciences) who assisted in administering the questionnaires,data entry and data analysis. We also appreciate the service rendered by the Water andSanitation association of Zambia (WASAZA) for assisting in making use of the printer. v
  6. 6. LIST OF TABLESTable PageTable 2.1: WHO and EU Drinking Water Quality Guidelines for Heavy Metals and Threshold Values Leading to Crop Damage (mg/l)………………..……………7Table 2.2: Recommended Revised Microbiological Quality Guidelines for Wastewater Use in Agriculture ...........................................................................12Table 4.1: Parameters sampled and methods used for analysis .......................................23Table 5.1: Gender and age of respondent regarding use of wastewater for irrigation......26Table 5.2: General agricultural practices in the study areas ..............................................27Table 5.3: General crop selection by farmers in the two study areas ................................29Table 5.4: Comparative methods of marketing crops practiced in Ngwerere and Kafue Lagoon area……….. ................................................................................31Table 5.5: General crop growing season, acreage, yield, unit and unit price in the Kafue Lagoon area.. ...........................................................................................33Table 5.6: Farmers’ total income in Kafue Lagoon and Ngwerere River Areas ................33Table 5.7: General crop growing season, acreage, yield, unit and unit price in the Ngwerere area……………….. ............................................................................34Table 5.8: Clinical data from Kasisi Rural Health Centre showing prevalent diseases in Ngwerere area.................................................................................35Tables 5.9: Constraints faced by farmers in growing their crops/vegetables ......................36Table 5.10: Exploratory Analysis of Heavy Metals in Crops at Ngwerere River and Kafue Lagoon Areas ...........................................................................................39Table 5.11: Physical and chemical parameter of water sample analysis from Ngwerere River three sampling sites ..................................................................................41Table 5.12: Physical and chemical parameter of water sample analysis from Ngwerere River three sampling sites and their standard deviations .................................42Table 5.16: Physical and chemical parameter of water sample analysis from Lee Yeast compared with ECZ effluent and wastewater standards...................................48Table 5.17: Sodium Adsorption Ratio for Ngwerere River....................................................50Table 5.18: Bacteriological analysis in the Ngwerere at three sampling sites showing organisms per 100ml ..........................................................................................50Table 5.19: Bacteriological analysis in the Kafue Lagoon area at three sampling sites showing organisms per 100ml............................................................................51Table 5.20: Ranges of Contamination and Recommendations (after Westcot, 1997)........51Table 5.21: Analyzed sediment quality from Ngwerere three sampling sites compared to Dutch Sediment Quality Guidelines ...............................................................53 vi
  7. 7. Table 5.22: Analyzed Shikoswe stream and Lee Yeast sediments from the Kafue Lagoon area compared to Dutch Sediment Quality Guidelines..................53 LIST OF FIGURESFigure PageFigure 5.1: Water sources used for irrigating crops in Kafue Lagoon.....................................30Figure 5.2: Conveyance of water for irrigation in Kafue Lagoon Area ....................................30Figure 5.3: Conveyance of water for irrigation in Ngwerere River ..........................................31Figure 5.4: Market channels for crops grown in the Ngwerere River Area.............................32Figure 5.5: Mechanism in Marketing of Produce by Farmers in Kafue Lagoon……………...32Figure 5.6: Ngwerere River mean monthly flows .....................................................................37Figure 5.7: Flow Duration Curve for Ngwerere River...............................................................38Figure 5.8: Total, Base-flow and Surface Runoff .....................................................................38Figure 5.9: Total hydrograph and Base-flow from October 2002 to August 2003 ..................39Figure 5.10: Logarithmic plot of microorganisms at 3 sites along Ngwerere River ................52Figure 5.11: Logarithmic plot of number of microorganisms at 2 sites at Kafue Lagoon..….52 vii
  8. 8. LIST OF PLATESPlate Page Plate 5.1: A plot of Rape in Ngwerere River Area near Ngwerere Estate Weir................28 Plate 5.2: Plots of Rape in Chamba Valley near the Ngwerere River...............................28 Plate 5.3: Below Spill way at Kasisi Dam (third sampling point) .......................................45 Plate 5.4: Crop in Kafue Lagoon Area near effluent channel from Lee Yeast..................49 Plate 5.5: NCZ effluent channel near the footbridge on the Left side of the picture (Sampling point)………………............................................................................49 Plate 5.6: Shikoswe stream carrying sewerage effluent near NCZ going into the Lagoon (NCZ right side of the picture)…………………………..……………….49 viii
  9. 9. LIST OF APPENDICESAppendix ........................................................................................................................PageAppendix I: Questionnaires for the project on the use of nutrient enriched water for growing food crops in the Ngwerere river catchment and at the Kafue Lagoon Areas......................................................................................................63Appendix II: Table A.1: Wastewater treatment and quality criteria for irrigation (State of California 1978)...................................................................................................69Appendix III: Irrigation Water Quality Guidelines ....................................................................70Appendix IV: Table 2B: Recommended Maximum Concentrations of Trace Elements in Irrigation Water....................................................................................................71Appendix V: Table C. 3: Constituents of concern in wastewater treatment and irrigation using reclaimed municipal wastewater ..............................................................72Appendix VI: Questionnaire results ..........................................................................................73Appendix VII: Analyzed water quality data from Ngwerere River sampling points .................81Appendix VIII: Analyzed water quality data from Kafue Lagoon Area ....................................83Appendix IX: Analyzed sediments from Ngwerere area from Ngwerere sampling points......84Appendix X: Analyzed sediments from Kafue Lagoon Area....................................................85Appendix IX: Base flow index calculation for Ngwerere Estate Weir ......................................86Appendix XII: Current national water quality standards in use in Zambia ..............................87Appendix XIII: Results of effluents from Nitrogen Chemicals of Zambia (NCZ) .....................88Appendix XIV: Chemical analysis of effluents from Lee Yeast Factory ..................................89Appendix XV: Rapporteur’s Report...........................................................................................97 ix
  10. 10. Abbreviations and AcronymsBOD Biochemical Oxygen DemandCd CadmiumCOD Chemical oxygen DemandCu CopperDFID Department for International DevelopmentDO Dissolved OxygenDWA Department of Water AffairsECZ Environmental Council of ZambiaEU European UnionFDC Flow Duration CurveHg MercuryLCC Lusaka City CouncilMFNP Ministry of Finance and National PlanningNCZ Nitrogen Chemicals of ZambiaNSR National Scientific ResearchPb LeadPMA Poverty monitoring AnalysisPRSP Poverty Reduction Strategy PaperWHO World Health OrganizationWSP Waste Stabilization PondsZESCO Zambia Electricity Supply CorporationZn ZincZNS Zambia National Service x
  11. 11. Executive SummaryIntroductionIn urban and peri-urban zones in developing countries, poor farmers commonly use nutrient-enriched sewage and wastewater to irrigate high-value crops. In many places, this untreatedwastewater is their only source of irrigation water-so their livelihoods depend on it. On the otherhand, the unregulated use of wastewater also poses risks to human health and theenvironment. Wastewater irrigation can also significantly contribute to urban food security andnutrition. Recent studies in several Asian and African cities have revealed that wastewateragriculture has accounted for over 50% of urban vegetable supply. it is estimated that one tenthor more of the world’s population currently eats food produced on wastewater (but not alwaysin a safe way).In Zambia despite the health hazards associated with crops grown in the Kafue Lagoon usingwastewater from Nitrogen Chemicals of Zambia (NCZ), Shikoswe stream and Lee Yeast, trucksloaded with a variety of vegetables and sugar cane came from Kafue about 50 kilometressouth-west of Lusaka to Kamwala and Soweto markets to sell these products. Most of thismerchandise bought in bulk by marketers was sold to unsuspecting consumers. But manyKafue residents earned their living by growing and selling these crops in the lagoon usingeffluents from canals carrying industrial and domestic wastewater.Similarly the Ngwerere River has its share of urban and peri-urban agricultural activities despitethe river being biologically polluted. it was demonstrated that the river exhibited significant self-purification capacity along its stretch from Garden Compound to the confluence with theChongwe River. The current study incorporated BOD, COD, and total nitrogen and flowmeasurements as recommended in previous studies. The current study also linked wateranalysis to the users of water, a link that was left out in previous studies.Main objectiveThe main objective of the study was to assess the effects of using wastewater on vegetablegrowing and the associated socio-economic impacts on farmers in the Kafue Lagoon Areasand along Ngwerere River.Literature reviewIntroductionDomestic human waste is defined as human excreta, urine, and the associated sludgecollectively known as black-water, as well as, kitchen wastewater and wastewater generallythrough bathing (collectively known as grey-water). Wastewater defined as waste matterentering water and its disposal involves the collection, treatment, and sanitary disposal. Thesources of wastewater are domestic, industrial, storm water and by groundwater seepageentering municipal sewage network. Wastewater is composed of organic matter, nutrients,inorganic matter, toxic chemicals and pathogens. Reclaiming municipal wastewater foragricultural reuse is increasingly recognized as an essential management strategy in areas ofthe world where water was in short supply. Wastewater reuse in agriculture requiredconsideration of the health impact, agricultural productivity, economic feasibility andsociocultural aspects.Treatment of wastewater xi
  12. 12. In Zambia stabilization ponds are used for treating wastewater. These consist of the anaerobic,facultative and maturation ponds. Anaerobic ponds receive effluents of high organic loadingand have retention time of one to five days and depth of 2-4 meters. Facultative ponds areused to treat the wastewater and generally have a depth of 1-1.5 meters. The retention time forthe wastewater is 5 to 30 days. Maturation ponds on the other hand, remove faecal bacteriaand the retention period of the effluent is 5-10 days and their depth is 1-1.5 meters. In principle,a natural pond could be aerobic, facultative, or anaerobic.Quantity of wastewaterDomestic sewage resulting from people’s day-to-day activities, such as bathing, bodyelimination, food preparation, and recreation, averages about 227 litres (about 60 gal) perperson daily. Raw sewage included waterborne waste from toilets, sinks and industrialprocesses. The average monthly water consumption for an average household size of 7.5inhabitants living in high/medium cost areas and 6.0 inhabitants living in low cost Area (asfound valid in various urban centres in Zambia) were 50, 690 cubic meters per month and 43,446 cubic meters per month respectively. 17 percent of the households in Zambia used flushtoilets. The quantity of industrial wastewater varies depending on the industry and managementof its water usage, and the degree of treatment before it is discharged. Domestic wastewaterconsists of about 99.9 percent water and 0.1 percent solids.At the time of the study, Manchichi Sewage Treatment Plant was discharging effluents to theNgwerere River. Prior to discharging, the wastewater was treated using biological filters andthen pumped to the maturation pond in Garden Compound. In April, May, June and July 2004the average discharges from Manchinchi were 72, 545 m3/day, 58,805 m3/day, 39, 357 m3/dayand 32, 803 m3/day, respectively. The design capacity of the treatment plant was 36, 000m3/day. Therefore for April, May and June 2004 the design capacity was exceeded. Thesefigures were obtained from Lusaka Water and Sewerage Company. As a result of overloadingthe treatment plant, the final effluent lost its quality to 59 % removal efficiency in terms of BOD,23 % in terms of COD and 52 % in terms of TSS due to untreated raw sewage from the Plantby-pass line.Toxicology aspects of wastewaterIt is widely accepted that levels of trace elements and heavy metals in irrigation water werelikely to be toxic to plants at concentration below that which they pose a significant risk tohuman health. Heavy metals in wastewater posed a health risk if they were ingested insufficient concentrations, and could be dangerous. In principle, uptake of heavy metals bycrops and the risk posed to consumers may not be an issue as plants could not resist highconcentrations of these pollutants and die off before they become a threat to humans. Thisprovides a degree of natural protection of irrigators and consumers as plants fail to thrive andfarmers abandon the source well before levels present a risk to human health. There arecurrently no guidelines for permissible levels of trace elements and heavy metals in wastewaterused for irrigation, which relate to the potential risk to human health as a consequence of cropuptake and bio-accumulation.Apart from heavy metals and trace elements, wastewater also contains high concentrations ofdissolved salts. Salinity-related impacts of wastewater irrigation on soil resources could beexpressed in economic terms such as (1) potential yield and income loss; (2) loss of soilproductivity; (3) depreciation in market value of land; and (4) cost of soil reclamation measures.Cost benefit of using wastewater xii
  13. 13. Irrigation with wastewater could be an attractive way of disposing wastewater from anenvironmental point of view. The combined benefits of reduced treatment and disposal costand increased agricultural production may justify investment in an irrigation system.Wastewater has phosphates and nitrates, which can be channelled onto land as fertilizers.Other important uses of wastewater include recharge of groundwater, as cooling water inindustry, recreational water, construction and dust control, wildlife habitat improvement,aquaculture and municipal non-portable uses such as landscape and golf course irrigation.Reuse of (pre) treated wastewater, especially in agriculture, can considerably contribute towater resources conservation, recycling of nutrients and prevention of surface water pollution.Agronomic and public health aspectsWhile wastewater is a resource for productive uses, it can be dangerous if used in an untreatedform. The dangerous practice of direct and indirect use of untreated wastewater was commonin regions like Lima, Mexico City, and Santiago. This is a serious concern with respect to publichealth. The use of untreated wastewater for irrigation poses a high risk to human health in allage groups. Untreated wastewater irrigation led to relatively higher prevalence of hookwormand Ascariasis infections among children. The DFID-sponsored research in North-east Brazilshowed that bacterial pathogens such as Vibrio cholerii, Salmonella species andCampylobacter species were present in wastewater.Irrigation methodsSome crops can be irrigated using unrestricted guideline of the WHO. Unrestricted irrigationrefers to all crops grown for direct human consumption and eaten raw (e.g., lettuce, salads,cucumber) and also the irrigation of sports fields, public parks, hotel lawns, and tourist areas.Restricted irrigation refers to the irrigation of crops not intended for direct human consumptionand there should be no more than one viable human intestinal nematode egg per litre, implyinga greater than 99% treatment level. This guideline was introduced to protect the health of fieldworkers and to indirectly protect consumers and grazing cattle. Restricted irrigation can beapplied to industrial crops (e.g., cotton, sisal, and sunflower, wheat, barley, oats); and fruittrees, fodder crops and pastures.Sociocultural aspectsPeri-urban and urban agriculture are understood to be the agricultural activities undertakenwithin the area immediately surrounding the city, where the presence of the city had an impacton land use, property rights and where proximity to the urban market and urban demand drovechange in agricultural production. Furthermore, urban agriculture is one of the severalstrategies used by the urban and peri-urban dwellers to cope with poverty.A physical, natural resources-oriented survey complemented by a socio-economic study of thecommunity affected by the reuse project would reveal the need for reuse. The acceptance ofwastewater reuse and the adoption of practices for its safe implementation will be influenced bythe sociocultural makeup of the people involved (that is the values, beliefs, and customs thatare concerned with water supply, sanitation, hygiene and other activities related to water use).There were few reconnaissance-type studies that describe sociocultural aspects of reuse.The social concerns about the potential risk of wastewater irrigation originated from concernsregarding impacts on environmental quality, public health and safety. These concerns may beaddressed with appropriate educational and public awareness programs. The cost of publiceducation, awareness and demonstration programmes could be used as a choice for thevaluation of social impacts of wastewater irrigation programmes, using awareness andsensitization educational models. xiii
  14. 14. Policy aspectsThe Zambian National Water Policy of 1994 specifies that water for irrigation should be fit forhuman consumption and not cause soil degradation but enhance high crop yield. Within thebroad objective for agriculture, the Poverty Reduction Strategy Paper (PRSP) indicated thatsince the poor often relied on the environment for their livelihood, attacking poverty in ruralareas was necessarily improving people’s ability to derive livelihood from natural resources. Onthe other hand, the Zambian Health Policy fosters that in order to have a well-nourished andhealthy population that could contribute to the national economic development there was needto achieve sustainable food and nutrition security.Study areasKafue Lagoon AreaThe study focused on two study areas. The Kafue Lagoon area and along the Ngwerere river.The Kafue lagoon Area is located about 45km south of the City of Lusaka. The Area spans atotal of over 50 hectares of land under mostly sugar cane cultivation. Sampling was done atthree locations; Shikoswe Stream, Lee Yeast effluent stream and effluent canal from NitrogenChemicals of Zambia (NCZ). Questionnaire administration was not restricted to the watersampling locations.Ngwererer River AreaThe Ngwerere is a small river whose origin is in the city of Lusaka and it stretches over adistance of approximately 30 kilometers. The catchment size is 662 km2. The sampling andquestionnaire administration took place at three locations along the river, namely Near GardenSite 3 pond in Garden compound (N1), at Ngwerere Estate Weir (N2) in Chamba Valley areaand at Kasisi Mission Dam diversion (N3).MethodologyThe methods used during the study were both qualitative and quantitative in the generation ofinformation as well as documenting the findings. Various documents were reviewed on thework done on utilization of wastewater or nutrient enriched water in Zambia and other parts ofthe world. Various legislative articles from institutions such as the Environmental Council ofZambia, Department of Water Affairs and Ministry of Health were also reviewed. Otherdocuments such as the WHO guidelines and ECZ wastewater standards on the safe use ofwater for irrigation were also reviewed.Information was gathered by using a combination of observations, field surveys and structuredinterviews with selected growers. Surveys were carried out to ascertain the types of cropsgrown within the Ngwerere catchment and at Kafue Lagoon area. Questionnaires wereadministered in the field to gather information on how the communities or peasant farmers’value enriched wastewater in irrigation. The sample size used was 30 respondents from KafueLagoon and 42 respondents from the Ngwerere Area.The sampling technique used before administering the questionnaires was sampling by a GridSystem technique. The Grid System method involved putting a screen with squares on a studymap and the areas falling within selected squares were selected samples.The quantity of wastewater in the Ngwerere stream was computed by analysing thehydrological data from the Ngwerere Hydrological Station of the Department of Water Affairs(or N2 sampling station). Hydata and Arida software were used to compute the total surfacerun-off and then separating the base-flow from the total surface runoff in cubic meters. xiv
  15. 15. A total of eight (8) sampling campaigns at each site in Ngwerere and four (4) at each site inKafue were carried out between 6th July 2004 and 20thAugust 2004. In total two (2) campaignsin Ngwerere involved one (1) duplicate sample for each site and in Kafue two (2) campaignsincluded one (1) duplicate sample at three (3) sites.The full stretch of the Ngwerere River was surveyed to select three points for sampling (water,sediment, plants) and testing over a period of 2 months. Being a narrow channelled stream, theNgwerere was assumed to be completely mixed over its depth and width. A grab sample in themiddle of the stream was considered representative enough. The water sample was obtainedby immersing a sample bottle about 5cm below the water surface and collecting the water. Forchemical analysis a polythene bottle (1000ml) was used while for heavy metals a 500ml bottlewith 2ml nitric acid inside was used. Sterilized glass bottles were used for microbiologicalsampling. The bottles were then kept in a cool box packed with ice blocks. Another 1000ml-polythene bottle was used to store bottom sediment, which was scooped from the riverbedwhere it had accumulated. This was stored separate from the water samples.In-situ water quality tests of water temperature, pH, conductivity and salinity were carried outusing the Horiba Water Checker U-10 model. Crop samples were collected in Chamba Valleynear Ngwerere Estate Weir (N2). Only the leaves of rape were collected and taken to FoodScience Laboratory at the University of Zambia in the School of Agriculture.Three points for sampling were selected to cover the effluent canals, which were used forirrigation by farmers in the lagoon area. The effluent canals were the Shikoswe stream, Leeyeast effluent canal and Nitrogen Chemicals of Zambia. Water, plant and sediment sampleswere collected at these points. The collection of samples was similar to NgwerereThe samples were analysed at the Environmental Engineering laboratory of the School ofEngineering at the University of Zambia. The samples were transported to the laboratory within7 hours of sampling. The methods of analysis of parameters included gravimetric, titrimetric,photometric and electrometric determinations for physicochemical parameters, atomicabsorption spectrometry for heavy metals and membrane filtration method for microbiologicalparameters. For quality control/assurance, duplicate samples were obtained during selectedsampling campaigns and some samples taken to an independent laboratory for crosschecking.Data was analyzed using excel spreadsheet, Arid Region Drought Analysis (ARIDA) andHydrological Data Analysis (Hydata) software, graphs and tables.Results and discussionField interviewsKafue Lagoon AreaIt was found that 60% of the farmers producing irrigated crops in Kafue Lagoon Area werewomen and only 40% were men. On the other hand, Ngwerere Area presented the oppositescenario with 81% of the farmers being men and only 19% women.In Kafue Lagoon Area the educational levels of the respondents varied; 26% didn’t have anyformal education and 74% had (17% had secondary level education and 57% had gone up toprimary level). The main occupation of respondents in the Lagoon was gardening whilst thesecond occupation included various activities such as selling of charcoal, piecework andkeeping of livestock.The main source of income for the peasant farmers in Kafue Lagoon Areaswas from sale of vegetables, sugar canes and gardening. xv
  16. 16. Ngwerere River AreaIn Ngwerere River Area the education levels of the respondents were such that 14% had noformal education and 86% had formal education (31% - secondary level education, 53% - up toprimary level and 2% - up to tertiary level). The main occupation of the respondents in theNgwerere River Area was producing and selling of vegetables and maize. The main sources ofincome for the peasant farmers in Ngwerere River Area were selling of vegetables andgardening. The alternative sources of income were retirement package (pension money), rentalfrom houses, business and piece of work, selling of pesticides.Land tenureLand tenure was leasehold, farmer’s own land, Zambia National Services land or communalland in the Ngwerere Area and main crops grown were vegetables and maize. In the KafueLagoon Area land tenure was freehold. The cropping pattern was composed of vegetables,maize and sugar cane.Water management and sourcesIn the Kafue Lagoon, 32% of the respondents relied on shallow dug out wells while 68% usedcanals. The canal water mostly used came from the Nitrogen Chemicals of Zambia (NCZ)canal. The water was conveyed onto the fields by watering cans or buckets and furrows. Themajor water source for irrigation was the Ngwerere River and the most common method ofapplying water was to collect from the stream or river, and to apply it to the crops using watercans or buckets (10 to 20 litre containers). This was a laborious task.Marketing of cropsThe single commonest means of marketing the produce in Ngwerere was for growers to selltheir produce at markets: Soweto, Town Centre, Kabanana, Chipata Compound, Ng’ombe,Katambalala, Chaisa, Garden, and Kaunda Square markets, which was at 69%. Five (5)% ofthe farmers sold their produce to Fresh Mark in Lusaka town. It was also found that 83% of thefarmers marketed their crops individually, 12% as a formal group, 3% as traders whopurchased the produce from the farmers. In Kafue all the respondents sold theircrops/vegetables individually in different parts of Kafue (Kalukungu, Kafue Estates, ZambiaCompound and Solloboni markets), Chilanga and Lusaka (urban and rural) including Chirunduin Siavonga.The yield of vegetables varied from one respondent to the other and the figures were based onthe data obtained from the farmers through interviews. A further analysis of income andexpenditure pattern at household level could be a subject of another research.Earnings from crop salesThe income realized from the sale of different crops varied depending on the type of crop,number of customers and season (with respect to price). In the Kafue Lagoon Area, thefarmers’ income ranged from K800, 000 to K1, 000,000 per year while in Ngwerere River Areait ranged from K400, 000 to K2, 500,000 per year. The Ngwerere farmers had wider marketcoverage and relatively shorter distances to bigger markets and had higher demand for thecrops.Constraints faced by farmersThe major constraints faced by farmers in growing their crops/vegetables were inadequatetechnical support, conveyance of water onto field, crop storage, and transport expenses (tomarkets), lack of credit for capital investment and price variation xvi
  17. 17. Public health issuesIt was found that the prevalent diseases in the study Area were malaria, bilharzias anddiarrhoea. For the Ngwerere Area, secondary data obtained at Kasisi Rural Health Centreconfirmed the findings. Malaria topped the list as the most prevalent, followed by diarrhoea,bilharzias and lastly dysentery. Other parts of the river catchment near stabilization ponds ingarden Compound and near overgrown parts of the river were likely to be affected by thesediseases. Fifty four percent (54%) of the respondents in Ngwerere catchment said the riverwater was not fit for drinking but was good for irrigation. However, fifty percent (50%) of themsaid none of the members of their household had suffered from any disease associated withthe river water in the past one year. The case at Kafue Lagoon was quite similar to theNgwerere situation. Fifty three percent (53%) of the respondents said the water used forirrigation posed a threat to human health while fifty percent (50%) said none of the members oftheir household had suffered any illness as a result of the water they used for irrigation.Quantity of wastewater in the Ngwerere River AreaThe total surface runoff and base-flow was computed by using the Hydata, spreadsheet andARIDA software at the Department of Water Affairs Water Resources Unit were used. Thesurface runoff was estimated by using Flow Duration Curves (FDC). The groundwater storagein the Ngwerere catchment contributed significantly (as base-flow) to the total surface runoff,enough to keep the stream flowing during the study period.Plant sample analysisMercury and copper were not detected in all the plant samples. This could mean that it was notpresent as a waste product. Given the high pH values copper could have precipitated out ofsolution into the sediments and so not much of it was available for the plant uptake afterirrigation. A previous study by Sinkala et al in 1996 reported less than 0.02 mg/l (detection limit)of Cu in the wastewater from NCZ and less than 0.011 and 0.018 mg/l (detection limits) of Cuin Lee Yeast effluents.Documents indicated that cadmium could be present in the water column at very lowconcentrations and yet build up in the plant tissue to levels that were harmful to human health.For Cd the recommended maximum concentration was 0.01 mg/l in water. Others like Pb it was5.0 mg/l, Zn 2.0 mg/l and Cu 0.20 mg/l. In the absence of local guideline values for heavymetals in plants against which comparisons could have been made, guideline values from astudy (personal communication) were used: 50 mg/kg as maximum concentration of Cu andZn, and 5mg/kg of Pb in plant tissues. Apart from Cd (0.028 to 0.049 mg/l), all the other heavymetals analysed were below the recommended maximum concentrations in plants. Cd mightbe a threat to human health in both study areas but further investigations would be required toquantify and mitigate the threat.Water quality analysisWestcot argued that the WHO or Engelberg standards for faecal coliform were designguidelines and suggested that in the absence of better information, it was “prudent” to use themas the quality standard to aim for in waters that were known to currently fall short of that quality.Therefore, in the current study, the water quality was interpreted with respect to the WHOguidelines and recommendations by Westcot considering the fact that adequateepidemiological and water quality information was not available at the time of the study.The water at both Ngwerere and Kafue Lagoon Area was potentially safe for irrigation as longas the pollution sources were eliminated. But elimination of the sources of pollution was not xvii
  18. 18. feasible in both situations because the contaminated water was also the water used forirrigation by the peasant farmers in these areas and was their main source of income and food.Other options such as improving the efficiency of wastewater treatment plants (especiallydesludging) upstream or expanding the treatment plants could be considered. There werelarge variations in the faecal coliform numbers at each point on the Ngwerere River over thestudy period, hence high standard deviations. This was probably due to variation in wastewaterdischarges and composition, flow pattern of the river and its tributaries and abstraction forirrigation. Such variations in coliform counts were also reported in a study in Ghana carried outby Cornish.In terms of the spatial distribution of the more microorganisms on the Ngwerere River werefound upstream in the urban/peri-urban area of Lusaka City (N1 and N2) than downstream inthe rural area.Effluents from Lee Yeast and Shikoswe were also heavily contaminated with respect to faecalcoliform. The water was not safe for use without treatment.Most of the parameters including conductivity, salinity, calcium, sulphate, total nitrogen, totalphosphate, BOD, total suspended solids and iron tended to reduce in concentration from theupstream reaches in the urban area to the downstream reaches in the rural area of the rivercatchment. This indicated that the pollution was heavier in the former than in the latterstretches of the river. There were no heavy metals detected in the water samples. Metals likeCu and Pb easily precipitated out of solution at high pH values (8-10) as found in the river.Generally the physicochemical parameters for Ngwerere River were within the limits of theECZ, WHO, DWA and EU guidelines for water quality. However, the pH was higher than therecommended upper limit of 9 in a few cases especially at Kasisi Mission. Ammonia levels atN1 and N2 (that was urban and peri-urban areas) were higher than the WHO drinking waterguideline value of 0.5mg/l. On average sodium was higher than the guideline value of 200mg/l,which could lead to the problem of specific ion toxicity. TSS at N1 and N3 were also higherthan the ECZ guideline value of 100mg/l.Though most of the physical and chemical parameters were within the recommended limits forirrigation and other water uses, microbiological parameters showed that the river was heavilypolluted. Throughout the river stretch, the water was not suitable for drinking and at somepoints even for irrigation according to WHO and FAO guidelines.All the other parameters measured were lower than the recommended maximum concentrationin irrigation water, according to Pescod. The concentration of heavy metals and boron in thewater at all the sampling points were below the detection limit of the method of analysis whichwas also far below the recommended maximum concentrations.From the results it was clear that the main problem with respect to the risk to human health wasthe pollution by microorganisms in the watercourses where the farmers drew water for irrigatingtheir crops. This was common in both study areas –Ngwerere River and Kafue Lagoon.For Ngwerere River only the last point (N3, Kasisi Mission, about 23 km from source) qualifiedfor unrestricted irrigation according to the WHO guideline value of ≤1000 faecal coliform/100ml,if only the mean value for July 2004 was considered (900 faecal coliform/100ml). Underunrestricted irrigation vegetables and salad crops could be grown using water with ≤1000faecal coliform/100ml. Therefore, the growing of vegetables at the other sites (N1 and N2)posed a health risk to workers (or producers) and the consumers. On the other hand the water xviii
  19. 19. in the Ngwerere River was only fit for restricted irrigation whereby the crops that could be safelygrown were cereal crops, industrial and folder crops, and pasture and trees (fruit trees).The reduction in pathogens at the lower reaches of the river (Kasisi Mission) was evidenced bythe reducing counts of E.coli and Faecal streptococci. At all the stations on the river the waterwas not suitable for drinking. Previous studies also demonstrated a similar pattern andmoreover some of the sampling points used in this study were also used in the past studies.In Kafue Lagoon Areas, the Shikoswe and Lee Yeast effluent streams also had their meanvalues above the WHO guideline of <1000 faecal coliforms/100ml.For NCZ, the parameters measured were within the ECZ recommended limits. This was verydifferent from the situation in 1996 under the study of Sinkala et al, which reported higher levelsof magnesium, calcium, total suspended solids and total dissolved solids. The difference maybe attributed to slowed or no production at NCZ at the time of the present study. In fact thewater in the effluent canal was visibly clear. At the time of sampling it was found that thefarmers were mixing this water with that from Lee Yeast factory and Shikoswe stream throughdiversion canals.For Lee Yeast the conductivity was higher than the recommended standard of 4300uS/cm(ECZ). The phosphate and calcium levels were abnormally higher that the recommended limitsby ECZ although this was just for one sample. High calcium and conductivity (as TDS) levelswere also reported by Sinkala et al (1996). The source of the calcium was mainly the geologyof the area. The high conductivity corresponded to high sodium content of the effluent.The parameters measured at NCZ, were within the ECZ recommended limits. This was verydifferent from the situation in 1996 in the study of Sinkala et al, which reported higher levels ofmagnesium, calcium, total suspended solids and total dissolved solids. The difference may beattributed to slowed or no production at NCZ at the time of the present study. In fact the waterin the effluent canal was visibly clear. At the time of sampling the farmers were mixing thiswater with that from Lee Yeast factory and Shikoswe stream through diversion canals.As in Ngwerere the concentration of heavy metals and boron in the water at all the samplingpoints were below the detection limit of the method of analysis which was also far below therecommended maximum concentrations.The Shikoswe effluent had relatively high levels of ammonia and phosphate, the reason beingthat it carried mainly sewage effluents. As in Lee Yeast effluents, Shikoswe also had highlevels of iron. However, iron posed no known threat to human health.The high salt content (as conductivity) of the irrigation water used at both study sites,threatened the well being of the soil in the fields under irrigation. The sodium adsorption ratio(SAR) at N1, N2 and N3 and at Kafue Lagoon Areas (NCZ) were 31, 28, 32 and 22,respectively. The values were higher than the Ayers and Westcot (1985) guideline value of 9(beyond which the fields under irrigation would experience severe specific ion toxicity affectingsensitive crops and also increasing soil salinity problems. High salinity led to reduced uptake ofwater and nutrients by plants.The sediment samples were analysed at both sites for exploratory purposes. Detailedinvestigations should be carried out in future. The spot samples analyzed would help to explainor confirm variations in the other sample types in limited mass balance terms. xix
  20. 20. The first two sites (N1, Garden/Olympia area and N2, Ngwerere Estate Weir) on the NgwerereRiver had a higher concentration of Zn, Fe, Pb and Cu in sediment than at the last site (N3,Kasisi Mission. At Kafue lagoon and Ngwerere the highest concentration of iron was 1503 and1596 mg/kg iron, respectively. Cd (<0.002) and Hg (0.0002) concentrations were below thedetection limit of the method of analysis at all the sampling points in the two study sites,suggesting that very little quantities of the two metals were introduced in the watercourses.Since there were no local guidelines for heavy metals in sediments, the results in this studywere compared with the standards for polluted sediments in the Netherlands. although thiscountry was more industrialized than Zambia. From the comparison with Class I (best class)out of four classes, all the samples were way below the maximum heavy metal classconcentrations except for Cu (58 mg/kg) at Shikoswe stream, which was very high. But thiswas a one off value, which would require further verification.ConclusionBased on the findings from the study, the following were the conclusions: The growing and selling of crops in both study areas was the main source of cash income and food for most of the peasant farmers The average income earned from sale of crops ranged from K800, 000 to K1, 000, 000 in Kafue Lagoon and K400, 000 to K2, 500, 000 in the Ngwerere River Area. Using ECZ, WHO, EU, DWA, ZABS and other guidelines the suitability of the water for various uses especially irrigation was determined. It was found that the water in the Ngwerere River and Kafue Lagoon Area was suitable for restricted irrigation of folder crops, and fruit trees and but not for salad crops and vegetables except at Kasisi Mission (Ngwerere). The water at all sampling points was not suitable for drinking. Heavy metals in the water at all the sampling points were below the detection limit. The heavy metals in plant tissue and to some extent in the sediments were below the maximum recommended limits although bioaccumulation capacities of cadmium and lead need to be further investigated. There was no evidence of pollution by heavy metals that may pose a threat to the irrigated crop consumers during the study period. Health risks associated with the use of water in the Ngwerere and Kafue Lagoon Area could be reduced if the contaminants (especially pathogens) were reduced or eliminated at the source through improved treatment of wastewater The main irrigation method practiced during the study was the use of containers that accentuated the risk of contamination of the plants and farmers In both study areas the users considered the wastewater to be economically valuable for irrigating crops in spite of risks associated with using such water. Measurement of impacts of using the wastewater on crop yield would require a longer study period (not less than one year) than that allowed for the present study, and the same applies to seasonal variations in the quality and quantity of water used for irrigation. For instance the impact of high sodium adsorption ratio (SAR), averaged 30 for Ngwerere River water, could be understood better after collecting more data throughout the year.RecommendationsFrom the study the following were the recommendations:1. The Ministry of Agriculture and Cooperatives (MACO) should incorporate reuse of wastewater or nutrient enriched water in the irrigation strategy which aims at improving food security and poverty alleviation in the country xx
  21. 21. 2. The Ministry of Health (MoH) and NGOs (e.g., Water and Sanitation Association of Zambia, CARE International and Lifegate Foundation) should sensitize and raise public awareness on health risks associated with using and handling of untreated or pre-treated wastewater3. The MoH, NGOs and other interested public and private institutions should support and fund surveys and research on reuse of wastewater and how waterborne diseases and helminth infestation could be prevented4. The government (e.g., through MACO and water user associations) should promote urban and peri-urban agriculture so that there is continued supply of food to the households5. The government should consider policy changes (especially Irrigation Policy, National Water Policy and National Environment Policy) with a view to incorporate urban and peri- urban agriculture as a legitimate urban land use6. The Ministry of Local Government and Housing (MLGH) should support the rehabilitation of the various sewerage treatment facilities7. The government should assist peasant farmers in forming urban farmers associations or co-operatives8. The government (through e.g., University of Zambia, National Institute for Scientific and Industrial research, National Science and Technology Council and MLGH) should focus on how the water quality could be improved through pre-treating wastewater prior to use, perhaps with small-scale wetland systems or shallow wells or other appropriate technology9. The government should support another study which to check the seasonal variation of the parameters and prevention of helminthes among irrigators and consumers from both study areas xxi
  22. 22. CHAPTER 1: INTRODUCTION1.1 BackgroundIn urban and peri-urban zones in developing countries, poor farmers commonly use nutrient-enriched sewage and wastewater to irrigate high-value crops. In many places, this untreatedwastewater is their only source of irrigation water—so their livelihoods depend on it. On theother hand, the unregulated use of wastewater also poses risks to human health and theenvironment. Wastewater irrigation can also significantly contribute to urban food security andnutrition. Recent studies in several Asian and African cities have revealed that wastewateragriculture has accounted for over 50% of urban vegetable supply (IWMI, 2003). Wastewater isused as a source of irrigation water as well as a source of plant nutrients (such as nitrogen,phosphorus and potassium) and trace elements (K, Na, etc) allowing farmers to reduce or eveneliminate the purchase of chemical fertilizer and organic matter that serves as a soil conditionerand humus replenisher (IWMI-RUAF, 2002). The report by IWMI-RUAF (2002) as reported byLunven (1992) estimated that one tenth or more of the world’s population currently eats foodproduced on wastewater (but not always in a safe way).Wastewater reuse in agriculture is the economically feasible, environmentally sound use ofmunicipal wastewater for irrigation and aquaculture. Reclaiming municipal wastewater foragricultural reuse is becoming increasingly recognized as an essential management strategy inareas of the world where water is in short supply (Khouri et al., 1994). Wastewater reuse hastwo main objectives, that of improving the environment in that it reduces the amount of waste(treated or untreated) discharge into watercourses, and it conserves water resources bylowering the demand for freshwater abstraction. In the process, reuse has the potential toreduce the cost of both wastewater disposal and the provision of irrigation water, mainly bypracticing urban and peri-urban agriculture. Wastewater is defined as waste matter enteringwater (Huang, 1994). The sources of wastewater as indicated by Hussain et al., (2002) aremade up of domestic wastewater, industrial wastewater, storm-water and groundwaterseepage entering municipal sewage network. Domestic wastewater is made up of effluentdischarge from household, institutions, and commercial buildings. Industrial wastewater is theeffluent discharged by manufacturing plants. Wastewater is composed of organic matter,nutrients, inorganic matter, toxic chemicals and pathogens. The final composition of rawwastewater depends on the sources and its characteristics. Its disposal involves the collection,treatment, and sanitary disposal.Wastewater is used widely in both the industrialized and developing countries (Idelovitch andRingskog, 1997) and is increasingly seen as a resource, and it is often reused legally andclandestinely (Hussain et al., 2002; Idelovitch and Ringskog, 1997). Wastewater as a resourcecan be applied to productive uses since it contains nutrients that have the potential for use inagriculture, aquaculture, and other activities (Hussain et al., 2002). However, the same raw orpre-treated wastewater could pose health hazard to handlers and consumers of the cropsgrown using it (Westcot, 1997).Despite the health hazards associated with crops grown in the Kafue Lagoon due to the use ofNCZ wastewater for irrigation, findings by Enviro-line (1998) revealed that trucks loaded with avariety of vegetables and sugar cane came from Kafue about 50 kilometer south-west ofLusaka to Kamwala and Soweto markets to sell these products. Most of this merchandisebought in bulk by marketers is sold to unsuspecting Lusaka consumers. Many Kafue residentsearn their living by selling these crops grown in the lagoon using effluents from punctured pipesand from canals carrying industrial and domestic wastewater, to water their crops. 1
  23. 23. Similarly the Ngwerere River has its share of urban and peri-urban agricultural activities despitethe river being chemically and biologically polluted (NSR, 1983). Later studies also proved thatNgwerere River was polluted (Tembo et al., 1997; Silembo, 1998). The report by Tembo et al(1997) and Silembo (1998) revealed, through laboratory investigation, that the water inNgwerere River was not suitable for drinking and but could be used for irrigation and fishingpurposes. The water would pose a health risk to the water users and consumers of crops. Itwas further demonstrated that the river exhibits significant self-purification capacity along itsstretch from Garden Compound to the confluence with the Chongwe River. For instance in1996, faecal coliform spatially reduced from 18, 000, 000 colonies per 100 ml in the upperreaches to less than 1000 colonies per 100 ml in the lower reaches near the Chongwe-Ngwerere confluence. In the lower reach water could also be safely used for fishing andwashing. At such low levels of coliform (1000/100 ml) and other parameters being acceptable,the water could be used for irrigation according to the WHO guidelines value of≤ 1000 per 100 ml for unrestricted irrigation and ≤ 100, 000 per 100 ml for restricted irrigation.Tembo et al (1997) recommended that future research on the river should incorporate totalnitrogen, biological oxygen demand and chemical oxygen demand tests in order to understandthe pollution of the river in greater detail.The current study incorporated BOD, COD, total nitrogen and flow measurements asrecommended by the previous studies. The research also linked water analysis to the users ofwater, a link that was left out in previous studies. Therefore socio-economic factors wereconsidered in the study.1.2 ObjectivesThe main objectives of the study was to assess the effects of using wastewater on vegetablegrowing and the associated socio-economic impacts on farmers in the Kafue Lagoon Areasand along Ngwerere River.Specific objectives1.2.1 To measure the impacts of using wastewater on crops/vegetables yield in the Kafue Lagoon and Ngwerere River areas, and how this is associated with the socio-economic status of farmers in these areas1.2.2 To analyze the wastewater for the relevant physico-chemical and biological parameters n order to determine the possible health hazards that may be associated with the use of such water1.2.3 To suggest measures of reducing health hazards associated with the use of wastewater in vegetables growing1.2.4 To determine environmental valuation of wastewater by the community and its contribution to poverty reduction.1.3 JustificationWastewater as a resource can be put to productive use. It can also be dangerous if used in anuntreated form, which poses high risks to human health. The dangerous practice of direct andindirect use of untreated wastewater is common practice in regions such as Lima, Mexico City.Reusing untreated wastewater in irrigation can lead to high prevalence of hookworms andAscariasis infections among all age groups. It may also contain bacteria pathogens such asVibro cholera, Salmonella and Campylobacter species. The negative environmental impacts 2
  24. 24. associated with wastewater use are groundwater contamination through high concentrations ofnitrates, salts and micro-organisms.Though sewage wastewater is thought to be a health hazard, it is possible to make it good forseveral beneficial uses. Wastewater from the municipalities can be reclaimed for agriculturalreuse, which is increasingly recognized as an essential management strategy in areas of theworld where water is in short supply. Wastewater reuse in agriculture requires consideration ofthe health impact, agricultural productivity, economic feasibility and sociocultural aspects. Thewastewater used in developed countries is treated prior to its use in irrigation andenvironmental standards are applied. The wastewater is used to irrigate fodder, fiber and otherseed crops and, to a limited extent for the irrigating of orchards, vineyards, and other crops.The water and nutrient content found in wastewater is useful for agricultural purposes. Thenutrients and trace elements such as phosphorous, nitrogen and potassium are necessary forplant growth.Studies have indicated that urban agriculture (UA) is practiced inside (intra urban) or on theoutskirts (peri-urban) of a town or a city. This focuses on growing crops and raising animals. Italso includes recycling household waste and wastewater for agricultural purposes, theprocessing and distribution of different food and non-food products using human and materialresources, products and services that are found in the surrounding areas. An increasingnumber of local and national governments in countries such as Pakistani, Mexico and Moroccoare promoting UA in response to serious problems of poverty, food insecurity, andenvironmental degradation.Bearing in mind the hazards and benefits associated with wastewater reuse, there was needtherefore, to undertake this study and gain more insight into the situations at Ngwerere Riverand Kafue Lagoon areas where wastewater was increasingly used for irrigating crops andvegetables, which were mainly sold in Kafue town and Lusaka City. Since a lot of people inZambia spent time to grow crops as a means of earning a living in peri-urban and urbanagriculture, this would contribute a lot to poverty alleviation in the study areas. The study wouldenable the analysis of the costs and benefits of using such water for agriculture. Scientific datawas thus required to establish the relationship between the quality of water and crop yield.Greater yields would indicate that there is more income for peasant farmers and this couldhave a direct relation with poverty alleviation.1.4 Significance of the ParametersThe choice of parameters to be tested was based on the type of pollution expected from thedomestic and industrial wastewater since a considerable portion of the stream’s inflow is fromthese two sectors. The parameters tested were pH, temperature, conductivity, total suspendedsolids, BOD, COD, nitrates, ammonia, total phosphates, total nitrogen and E. coli, faecalstreptococci, faecal coliform, magnesium, calcium, boron, sodium, iron, lead, copper, cadmiumand mercury. The parameters, with an indication of their relevance, are listed in annex 15. 3
  25. 25. CHAPTER 2: LITERATURE REVIEW2.1 GeneralDomestic human waste is defined as human excreta, urine, and the associated sludgecollectively known as black-water, as well as, kitchen wastewater and wastewater generallythrough bathing (collectively known as grey-water) (Rose, 1999). Wastewater as alreadydefined, is waste matter entering water and its disposal involves the collection, treatment, andsanitary disposal (Huang, 1994). According to Huang (1994) the issue of sewage disposalassumed increasing importance in the early 1970s. Hussain et al. (2002) noted that sources ofwastewater are domestic wastewater, industrial wastewater, storm water and by groundwaterseepage entering municipal sewage network. Domestic wastewater is made up of effluentdischarge from households, institutions and commercial buildings. Industrial wastewater is theeffluent discharged by industries. Wastewater is composed of organic matter, nutrients,inorganic matter, toxic chemicals and pathogens. The final composition of raw wastewaterdepends on the sources and its characteristics.According to Nicholas ODwyer and Partners Consulting Engineers, (1978) and WWI (1989) themost common analysis of wastewater includes the measurements of solids, biochemicaloxygen demand (BOD), total coliform, chemical oxygen demand (COD), chloride, sodium,phosphate, total nitrogen, calcium, temperature and pH. The solids include both the dissolvedand suspended solids. Sewage treatment proceeds in three stages in some countries –primary, secondary and tertiary stages. In the primary treatment stage, solid wastes areremoved through mechanical process and organic matter is removed by biological process inthe secondary treatment stage. The third stage is the tertiary treatment stage, which is thepolishing stage. Normally, it involves the removal of phosphorus and nitrogen.2.7 Treatment of WastewaterAccording to Proprasset et al (2000) any type of wastewater treatment system is based onnatural processes, be it chemical, physical or biological, and its design is aimed at creating theoptimum conditions for enhancement of the rate of these natural processes. Natural systemsfor wastewater management include a host of treatment techniques apart from the use ofstabilization ponds, which is common in Zambia. • Anaerobic treatment of wastewater is carried out in low-rate systems (septic tank or lined pit) or in high-rate systems (anaerobic filter, upflow anaerobic sludge blanket reactor, anaerobic contact process). All anaerobic systems are based on the degradation of organic material by a consortium of anaerobic bacteria. The process results in the production of biogas, which contains up to 80% of methane that can be re-used for electricity generation • Wetlands are plots of land where the water is at (or above) the ground surface long enough each year to maintain saturated soil conditions and the growth of related vegetation. Constructed wetlands are plots of land specifically designed to act as wetlands for purification of wastewater. The two types of constructed wetlands are free water surface and subsurface flow constructed wetlands • Macrophyte ponds are modified waste stabilization ponds. A cover of floating plants floats on the water surface. Plants such as water hyacinth (Eichhornia crassipes) and duckweed (Lemnacaea) are used to take up nutrients from the wastewater and to provide a pond environment that is not disturbed by wind action so that sedimentation is optimal 4
  26. 26. • Water based fish-aquaculture transforms the nutrients that are present in wastewater into proteins. The fish feed on algae or macrophytes that grow using the nutrients • Terrestrial methods can be divided into slow rate (or irrigation) processes (SR), rapid infiltration processes (RI) and overland flow (OF) processesIn Zambia stabilization ponds are used for treating wastewater. These are comprised of theanaerobic, facultative and maturation ponds. Anaerobic ponds receive effluents of high organicloading and have retention time of one to five days and depth of 2-4 meters. Facultative pondsare used to treat the wastewater and have generally a depth of 1-1.5 meters. The retentiontime for the wastewater is five to thirty days. Maturation ponds on the other hand, removefaecal bacteria and the retention period of the effluent is 5-10 days and their depth is 1-1.5meters (GKW Consult, 2001). In principle, natural pond can be aerobic, facultative, oranaerobic. Aerated ponds are a manmade development and these reduce the amount of landrequired by adding artificial aeration.Stabilization or oxidation ponds are used extensively in developing countries. A relatively newsystem of natural stabilization ponds used extensively in Israel, and also in Spain, California,and Santiago, Chile, is the deep reservoir treatment, which consists of deep stabilization ponds(8-12 meters deep) (Idelovitch and Ringskog, 1997). Mara (1997) as cited by DFID indicatedthat these are used for both seasonal storage and effluent purification. The system can reducebacteria level in the effluent by as much as 99.999 percent depending on retention time (Mara,2000). In Northeast Brazil Waste Stabilization Ponds (WSP) comprise one or more series ofanaerobic, facultative and maturation ponds (Mara, 1997). The anaerobic ponds receive a highorganic loading that they are devoid of oxygen and BOD removals are very high over 70percent with retention time of only one day at 25oC.Facultative ponds (biological treatment) with a retention time of only 3-5 days at 25oC canreduce filtered BOD to well below the 25 mg/l EU requirement for WSP effluents and theoxygen needed by the heterotrophic bacteria are supplied through photosynthesis of the pondalgae (Mara, 1997). The wastewater treated in this way can be used for restricted irrigation.Aerobic bacteria convert the organic matter to stable forms such as carbon dioxide, water,nitrates, and phosphates as well as other organic materials (Huang, 1994). Nicholas ODwyerand Partners Consulting Engineers (1978) indicated that present treatment has very littleeffects on reducing the BOD of raw sewage, solid content, chlorides, sulfate, ammonia, andorganic nitrogen and trace metals.Maturation ponds are primarily used to ensure the removal of faecal bacteria and viruses tosafe levels so that the effluents can be used without risk to public health for crop irrigationand/or fish culture (Mara, 1997). Price (2003) indicated that the treatment and use ofwastewater is both a challenge and an opportunity for municipalities. It is a challenge becausethe use of non-treated wastewater is often the only option available for peri-urban farmers. Thisposes potential serious health problems of the presence of bacteria, viruses and parasites. It isan opportunity because wastewater is a valuable resource, not only from an economicviewpoint but also from an environment perspective (conservation of water resources, nutrientrecycling etc).At the time of the study, Manchinchi Sewage Treatment Plant was discharging effluents to theNgwerere River. Prior to discharging, the wastewater was treated using biological filters andthen pumped to the maturation pond (commonly called Garden Ponds). In June and July 2004the actual discharge from Manchinchi were 39, 357 m3/day and 32, 803 m3/day, respectively.The design capacity of the treatment plant was 36, 000 m3/day. Therefore for June 2004 the 5
  27. 27. design capacity was exceeded. These figures were obtained from Lusaka Water and SewerageCompany. Average effluent discharge went up to 60, 000 m3/day. As a result of overloading thetreatment plant the final effluent lost its quality to 59 % in terms of BOD, 23 % in terms of CODand 52 % in terms of TSS due to untreated raw sewage from the Plant by-pass line. The riverdischarge at Garden/Olympia site (N1) which is downstream of Manchinchi WastewaterTreatment Plant discharge point on the Ngwerere River in August 2004 was 52,445 m3/day.Two other sources contributed water to the Ngwerere River at this point but clearly the largestsingle contribution (over 60%) came from the Manchinchi Wastewater Treatment Plant.2.3 Quantity of Wastewater ProducedAccording to Huang (1994) domestic sewage results from people’s day-to-day activities, suchas bathing, body elimination, food preparation, and recreation, averages about 227 litres (about60 gal) per person daily. Raw sewage includes waterborne waste from toilets, sinks andindustrial processes. The average monthly water consumption for an average household sizeof 7.5 inhabitants living in high/medium cost areas and 6.0 inhabitants living in low cost area(as found valid in various urban centers in Zambia) are 50, 690 cubic meters per month and 43,446 cubic meters per month respectively (GKW Consult, 2001). 17 percent of the householdsin Zambia use flush toilets. The quantity of industrial wastewater varies depending on theindustry and management of its water usage, and the degree of treatment before it isdischarge. Domestic wastewater consists of about 99.9 percent water and 0.1 percent solids.With increasing global population, the gap between the supply and demand for water iswidening and is reaching such alarming levels that in some parts of the world it is posing athreat to human existence (Hussain et al., 2002). Society on the other hand, is subjected tocontinuous expansion with increased food requirements and food insecurity.Lusaka Water and Sewerage Company is responsible for management of sewerage andsludge in Lusaka (ECZ and LCC, 1997). According to ECZ and LCC (1997) there are basicallyfour plants in Lusaka that handle the sewerage sludge produced in Lusaka; the Chelston andKaunda Square maturation ponds and the Chunga and Manchinchi conventional plants.Lusaka Province has 21 percent of households with flush toilets and 3 percent(communal/shared flush toilets), 35 percent (own pit latrine), 37 percent (communal/shared pitlatrine), 1 percent (other toilet facilities) and 3 per cent have no toilet facilities (CSO, 1998).Literature from CSO (2000 census) revealed that the total number of households in Lusaka is275, 000.2.4 Toxicological Aspects of WastewaterHide et al (2001) reported that it is widely accepted that levels of trace elements and heavymetals in irrigation water are likely to be toxic to plants at concentration below that which theypose a significant risk to human health (see Annex III). According to Hussain et al (2002) heavymetals in wastewater pose a health risk if they are ingested in sufficient concentrations, andcan be dangerous. In principle, uptake of heavy metals by crops and the risk posed toconsumers may not be an issue as plants cannot resist high concentrations of these pollutantsand die off before they become a threat to humans (see Table 2.1 and Annex III and IV). Thisprovides a degree of natural protection of irrigators and consumers as plants fail to thrive andfarmers abandon the source well before levels present a risk to human health. Hide et al (2001)indicated that there are currently no guidelines for permissible levels of trace elements andheavy metals in wastewater used for irrigation, which relate to the potential risk to humanhealth as a consequence of crop uptake and bio-accumulation. According to Hide et al (2001) 6
  28. 28. most authors cite the table of phytotoxic threshold prepared by the National Academy ofScience and National Academy of Engineering (1972) and Pratt (1972), or refer to the WHOdrinking water guidelines (WHO, 1993). The data is indicated in Table 2.1.Table 2.1: WHO and EU Drinking Water Quality Guidelines for Heavy Metals and ThresholdValues Leading to Crop Damage (mg/l)Element WHO drinking water EU drinking water Recommended maximum guidelinesa guidelinesb concentration for cropcArsenic 0.01 0.05 0.1Cadmium 0.003 0.005 0.01Chromium 0.05 0.05 0.1Copper 2 0.2Iron 0.3 0.1-3.0 5.0Mercury 0.001 0.2 -Manganese 0.5 0.001 0.2Nickel 0.02 0.05 0.2Lead 0.01 0.05 5.0Zinc 3 0.1-5.0 2.0Sources:a WHO (1993)b Cited by Chapman (1996)c Cited by Pescod (1992)Scott et al (2000) noted that environmental accumulation of heavy metals resulting fromwastewater irrigation and sludge is a contentious issue. Khouri et al (1994) indicated thatcadmium (Cd), for example could be present in municipal wastewater at levels that are nottoxic to plants but could build up inside the plant tissue to levels harmful to humans or animals.Similar build up can occur in animals such that heavy metals contained in forage have beenshown to accumulate in cow’s milk, which could lead to hazardous build up in the consumer’sbody. Ensink et al (2002) indicated in a study undertaken in Pakistan that accumulation ofheavy metals proved to be almost negligible, with only increased levels of lead, copper andmanganese, even in the fields that had received wastewater for over 30 years.Apart from containing heavy metals and trace elements, wastewater also contains highconcentrations of dissolved salts (Hussain et al., 2002). Salinity-related impacts of wastewaterirrigation on soil resources can be expressed in economic terms such as (1) potential yield andincome loss; (2) loss of soil productivity; (3) depreciation in market value of land; and (4) cost ofsoil reclamation measures.2.5 Costs and benefits of Using WastewaterIrrigation with wastewater could be an attractive way of disposing wastewater from anenvironmental point of view (Khouri et al., 1994). The combined benefits of reduced treatmentand disposal cost and increased agricultural production may justify investment in an irrigationsystem. Before one can endorse wastewater irrigation as a means of increasing water supplyfor agriculture (Hussain et al., 2002), a thorough analysis must be undertaken from aneconomic perspective as well. The economic effects of wastewater irrigation need to beevaluated not only from the social, economic, and ecological standpoint, but also from thesustainable development perspective. 7
  29. 29. 2.6 Agronomic AspectsWastewater has phosphates and nitrates, which are channeled into land as fertilizers(Karpagma, 1999). Mara (1998) discovered that Community based approaches (in LatinAmerica in particular) separate ‘grey’ wastewater (non-faecally contaminated wastewater) from‘black’ wastewater (that is faecally contaminated) so that they can be reused as irrigation waterand fertilizers respectively. The wastewater can be used for unrestricted irrigation of crops suchas lettuce, salads and cucumbers grown for direct human consumption and eaten raw and forrestricted irrigation of crops not intended for direct human consumption such as cotton, sisal,wheat and sunflower (WHO, 1989). Idelovitch and Ringskog (1997) observed that the mostattractive and widespread reuse of effluents is to irrigate agricultural crops, pasture, or naturalvegetation. Other important uses of wastewater include recharge of groundwater, as coolingwater, recreational water, industry construction and dust control, wildlife habitat improvement,aquaculture and municipal non-portable uses such as landscape and golf course irrigation(Hussain et al., 2002; Idelovitch and Ringskog 1997). Reuse of (pre) treated wastewater,especially in agriculture, could considerably contribute to water resources conservation,recycling of nutrients and prevention of surface water pollution. Water quality guidelines arenecessary for wastewater irrigation, but they are rather strict and developing countries cannotafford the expensive treatment (Steenvoorden et al., 2004).Wastewater is used widely in many parts of the world, both in industrialized and developingcountries (Idelovitch and Ringskog, 1997). Increasing sewage or wastewater is seen as aresource, and it is often reused legally and clandestinely (Hussain et al., 2002; Idelovitch andRingskog, 1997). Hussain et al., (2002) observed that wastewater in developed countries istreated prior to its use in irrigation and environmental standards are applied. The wastewater isused for irrigation of fodder, fiber and other seed crops and, to a limited extent for the irrigationof orchards, vineyards, and other crops. Mara (1998) revealed that the water and nutrientcontent in particular can be very useful for agriculture purposes - for example through irrigation.Khouri et al (1994) indicated that wastewater contains nutrients and trace elements necessaryfor plant growth. Five million cubic meters (Mm3) of wastewater contain about 250, 000kg ofphosphorous, and 150, 000kg of potassium. Whether additional fertilizer is required dependson the crop being irrigated. Soil deficiency can be corrected by the trace elements inwastewater and clearly speaking the nutrients in wastewater are beneficial.While wastewater is a resource for productive uses, it can be dangerous to use in an untreatedform. The dangerous practice of direct and indirect use of untreated wastewater is commonpractice in regions like Lima, Mexico City, and Santiago (Mara, 1998; Idelovitch and Ringskog,1997). The practice can be made safe by treating the waste, restricting its use to only onindustrial or fodder crops or applying the waste in specific ways or at certain times (Mara,1998).Moreover, the report by Hussain et al. (2002) revealed that in developing countries, thoughstandards are set, these are not strictly adhered to and wastewater, in its untreated form, iswidely used for agriculture and aquaculture. Idelovitch and Ringskog (1997) have observed intheir report that the most attractive and widespread reuse of effluents is to irrigate agriculturalcrops, pasture, or natural vegetation. Other important uses of wastewater include, recharge ofgroundwater, industry construction and dust control and wildlife habitat improvement (Hussainet al., 2002; Idelovitch and Ringskog, 1997). 8
  30. 30. 2.7 Environmental Evaluation of WastewaterGenerally speaking, environmental valuation is used to determine the willingness of people toattach a value of an environmental good such as use of nutrient enriched water in agriculture.There are two types of techniques used in environmental valuation: those relying on revealedpreferences or what humans actually do in the markets; and those relying on statedpreferences or what humans say they would do in a hypothetical market context. Thus both ofthese approaches attempt to evaluate human behavior in economic terms but they differ in thesense that the former is based on actual or observed behavior while the latter is based onpotential or likely behavior (Hussain et al., 2002).2.8 Public Health AspectsThe use of untreated wastewater for irrigation poses a high risk to human health in all agegroups. However, the degree of risk may vary among the various age groups. Untreatedwastewater irrigation leads to relatively higher prevalence of hookworm (Feenstra et al., 2000),and Ascariasis infections among children (Cifuentes et al., 2000; and Habbari et al., 2000). TheDFID-sponsored research in North-east Brazil has shown that bacterial pathogens such asVibrio cholera, Salmonella species and Campylobacter species are present in wastewater(Mara, 1998).With many guidelines dealing with water quality for irrigation purposes, the microbiologicalaspects have always predominated perhaps, because of their immediate human healthconsequences. Chang et al (1996), notes that, few of the irrigation water quality criteria weredeveloped specifically for wastewater irrigation. The public health risks associated withwastewater reuse include increased exposure to infectious diseases, trace organic compounds(Cooper, 1991), and heavy metals. Wastewater contains the full spectrum of enteric pathogensendemic within a community (Scott et al., 2000). Many of these can survive for weeks whendischarged on the land, notwithstanding the presence of infective organisms, however,epidemiological studies have shown that the mere presence of pathogen does not necessarilyincrease human diseases. Of particular interest from a public health perspective are thehelminthes (Ascaris and Trichuris), which have both a relatively long persistence and a smallinfective dose. The risks of intestinal nematodes in untreated wastewater are recognized asimportant, both for consumers and irrigators (Shuval, 1991).According to Rose (1999), the most recent guidelines directing the reuse of wastewater to alevel considered safe to protect human health are those outlined in the Engelberg Standards,later adopted as the WHO of 1989 ‘‘Health Guidelines for the Use of Wastewater in Agricultureand Aquaculture’’. According to Mara and Cairncross (1989) the WHO guidelines outlineacceptable microbial pathogen levels for treated wastewater for reuse in unrestricted andrestricted irrigation. In practice, most developing countries use untreated wastewater foragriculture for a variety of reasons. These include the cost of treatment and the loss of preciousnutrients. However, treatment of wastewater prior to agricultural use is believed to be essential:first from the public health protection point of view and to respect local social and religiousbeliefs (Mara, 2000). According to Hussain et al (2002) in view of these requirements, waterscarcity, dry land farming, hot climatic conditions and the high economic value of fresh waterresources, a great deal of research and development effort has been undertaken particularly inIsrael, for the reuse of wastewater. Furthermore, in the absence of too high a concentration ofwaste from industrial sources, an efficient treatment option for conventional wastewatertreatment is to use primary sedimentation followed by secondary biological treatment usinghigh-rate biological processes. 9
  31. 31. Unrestricted irrigation refers to all crops grown for direct human consumption and eaten raw(e.g., lettuce, salads, cucumber) and also the irrigation of sports fields, public parks, hotellawns, and tourist areas. The criteria for unrestricted irrigation, contain the same helminthescriteria for restricted irrigation, in addition to a restriction of no more than a geometric meanconcentration of less than or equal to 1000 faecal coliforms per 100ml treated effluents. Theseguidelines as noted by Mara and Cairncross (1989) have been introduced to protect the healthof consumers who may eat uncooked crops such as vegetables and salads (Table 2.2). Inorder to achieve the microbiological quality, a series of stabilization ponds need to be designed(WHO, 1989). These are a series of ponds, which are used in treating the wastewater before itis discharged into the environment.Restricted irrigation refers to the irrigation of crops not intended for direct human consumptionand there should be no more than one viable human intestinal nematode egg per liter implyinga greater than 99% treatment level (Table 2.2). This guideline has been introduced to protectthe health of field workers and to indirectly protect consumers and grazing cattle (Hussain etal., 2002). Restricted irrigation can be applied to industrial crops (e.g., cotton, sisal, andsunflower, wheat, barley, oats); and fruit trees, fodder crops and pastures (WHO, 1989). Thewastewater retention in stabilization ponds should be 8-10 days or equivalent helminthes andfaecal coliform removal (Hussain et al., 2002). The human intestinal nematodes include,roundworm (Ascaris lumbricoides); hookworm (Ancylostoma duodenale and Necatoramericanus); and whipworm (Trichuris trichiura) Mara (2000).Apart from the biological considerations, nitrates and trace organic chemicals leaching to thegroundwater are considered to pose a potential health risk. However, there is very limiteddocumented evidence that these chemicals have been the cause of human disease (Cooper1991). The leaching of salts, nitrates and microorganisms would be of little concern anyway inareas where groundwater cannot be utilized because of high fluoride, iron, arsenic or saltlevels. In these cases the groundwater has no valuable use attached to it (Hussain et al. 2002).According to Sinkala et al (1996), the storm water collected in storm water drains and joins theShikoswe stream which passes through the Nitrogen Chemicals of Zambia (NCZ) plant andfinally into the Kafue river. The washing from the ammonium plant contain ammonia andnitrates. These are not allowed to go in the storm water drains but go to the balance tank wherethe effluent is neutralized by addition of lime before pumping to the ponds located 2 kilometersout the plant. Some of the results from the study which was conducted in 1996 to 1997 bySinkala et al noted that the concentration of nitrates from NCZ were higher than the ECZ limitof nitrate levels found in the effluents (Appendix XIII).The effluent from Lee Yeast is used by the community between the factory and the KafueRiver, for vegetable growing. The effluent is known to contain low nutrient level except for highChemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). Sinkala et al (1996)indicated that the effluents from Lee Yeast contain very high total coliforms count per 100mlcompared to ECZ limit. The Total Dissolved Solids (TDS) and Total Solids (TS) were alsohigher than the ECZ limit for effluents and wastewater (Appendix XIV). 10

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