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 Development
Financed by the Zambia Social investment Fund of the Ministry of Finance
and National Planning
November 2004
i

2. DISCLAIMER
The views expressed in this report are those of the researchers and not the Zambia Social
Investment Fund (Zamsif) as a funding agency. Any errors or omissions are the responsibilities
of the researchers.
ii

3. TABLE OF CONTENTS
Acknowledgement iv
List of Tables v
List of Figures vii
List of Plates viii
Abbreviations and Acronyms x
Executive 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
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4. 4.1 Secondary Data collection ......................................................................................20
4.2 Primary Data Collection...........................................................................................20
4.2.1 Field Interviews ...................................................................................................20
4.2.2 Computation of the Quantity of Wastewater......................................................21
4.2.3 Plant sampling.....................................................................................................21
4.3.4 Sampling of Water, Sediments and Plants ........................................................21
4.4 Measurements of the Parameters ..........................................................................23
4.4.1 Laboratory Analysis ............................................................................................23
4.4 Data Analysis ...........................................................................................................23
4.5 Limitation of the study .............................................................................................24
CHAPTER 5: RESULTS AND DISCUSSION ...........................................................................26
5.0 Field interviews ........................................................................................................26
5.1.1 Demographic information on households using the wastewater ......................26
5.1.2 Kafue Lagoon Area .............................................................................................26
5.1.3 Ngwerere River Area ..........................................................................................26
5.1.4 Agricultural Practice ............................................................................................27
5.1.5 Crop choice .........................................................................................................27
5.1.6 Water Management and Sources ......................................................................29
5.1.7 Conveyance of water and field application ........................................................30
5.1.8 Crop yields and earnings from their sells...........................................................31
5.1.9 Crop marketing by farmers in the Ngwerere and Kafue Lagoon areas............31
5.1.10 Crop marketing by the farmers in the Ngwerere Area.......................................31
5.1.11 Crop marketing by farmers in the Kafue Lagoon area ......................................32
5.1.12 Earnings from sales of crops in Kafue Lagoon Areas......................................33
5.1.13 Earnings from sales of crops in Ngwerere River Area ......................................34
5.1.14 Public health issues ............................................................................................34
5.1.15 Constraints faced by farmers in Kafue Lagoon and the Ngwerere areas ........36
5.2 Quantity of wastewater in the Ngwerere river .......................................................36
5.3 Plant sample analysis..............................................................................................39
5.4 Water quality analysis .............................................................................................40
5.4.1 Physico-chemical results ....................................................................................40
5.4.2 Microbiological Results .......................................................................................50
5.5 Sediment analysis from the Ngwerere river and Kafue lagoon Area ....................52
CHAPTER 6: CONCLUSION AND RECOMMENDATIONS.....................................................54
6.1 Introduction ..............................................................................................................54
6.2 Achievement of specific objectives of the study.....................................................57
6.3 Conclusions .............................................................................................................54
6.2 Recommendations ...................................................................................57
REFERENCES............................................................................................................................58
APPENDICES.............................................................................................................................63
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5. ACKNOWLEDGEMENT
We would like to thank the Zambia Investment Social Fund (Zamsif) for financial support to
undertake the study under the Poverty Monitoring and Analysis (PMA). We also thank the
Environmental Engineering Laboratory of the School of Engineering and the Food Science
Laboratory in the School of Agricultural Sciences of the University of Zambia for carrying out
the water quality testing and the quality testing of crops for heavy metals, respectively. Their
large contribution to the study is gratefully acknowledged.
We would also like to extend our thanks to the research assistants Cosmas Chalo and Siwale
Chisanga (all employees of Department of Water Affairs), Mainess K. Manninga (member of
Water and Sanitation Association of Zambia), and Constancy Zulu (student of University of
Zambia 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 and
Sanitation association of Zambia (WASAZA) for assisting in making use of the printer.
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6. LIST OF TABLES
Table Page
Table 2.1: WHO and EU Drinking Water Quality Guidelines for Heavy Metals and
Threshold Values Leading to Crop Damage (mg/l)………………..……………7
Table 2.2: Recommended Revised Microbiological Quality Guidelines for
Wastewater Use in Agriculture ...........................................................................12
Table 4.1: Parameters sampled and methods used for analysis .......................................23
Table 5.1: Gender and age of respondent regarding use of wastewater for irrigation......26
Table 5.2: General agricultural practices in the study areas ..............................................27
Table 5.3: General crop selection by farmers in the two study areas ................................29
Table 5.4: Comparative methods of marketing crops practiced in Ngwerere and
Kafue Lagoon area……….. ................................................................................31
Table 5.5: General crop growing season, acreage, yield, unit and unit price in the
Kafue Lagoon area.. ...........................................................................................33
Table 5.6: Farmers’ total income in Kafue Lagoon and Ngwerere River Areas ................33
Table 5.7: General crop growing season, acreage, yield, unit and unit price in the
Ngwerere area……………….. ............................................................................34
Table 5.8: Clinical data from Kasisi Rural Health Centre showing prevalent
diseases in Ngwerere area.................................................................................35
Tables 5.9: Constraints faced by farmers in growing their crops/vegetables ......................36
Table 5.10: Exploratory Analysis of Heavy Metals in Crops at Ngwerere River and
Kafue Lagoon Areas ...........................................................................................39
Table 5.11: Physical and chemical parameter of water sample analysis from Ngwerere
River three sampling sites ..................................................................................41
Table 5.12: Physical and chemical parameter of water sample analysis from Ngwerere
River three sampling sites and their standard deviations .................................42
Table 5.16: Physical and chemical parameter of water sample analysis from Lee Yeast
compared with ECZ effluent and wastewater standards...................................48
Table 5.17: Sodium Adsorption Ratio for Ngwerere River....................................................50
Table 5.18: Bacteriological analysis in the Ngwerere at three sampling sites showing
organisms per 100ml ..........................................................................................50
Table 5.19: Bacteriological analysis in the Kafue Lagoon area at three sampling sites
showing organisms per 100ml............................................................................51
Table 5.20: Ranges of Contamination and Recommendations (after Westcot, 1997)........51
Table 5.21: Analyzed sediment quality from Ngwerere three sampling sites compared
to Dutch Sediment Quality Guidelines ...............................................................53
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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 FIGURES
Figure Page
Figure 5.1: Water sources used for irrigating crops in Kafue Lagoon.....................................30
Figure 5.2: Conveyance of water for irrigation in Kafue Lagoon Area ....................................30
Figure 5.3: Conveyance of water for irrigation in Ngwerere River ..........................................31
Figure 5.4: Market channels for crops grown in the Ngwerere River Area.............................32
Figure 5.5: Mechanism in Marketing of Produce by Farmers in Kafue Lagoon……………...32
Figure 5.6: Ngwerere River mean monthly flows .....................................................................37
Figure 5.7: Flow Duration Curve for Ngwerere River...............................................................38
Figure 5.8: Total, Base-flow and Surface Runoff .....................................................................38
Figure 5.9: Total hydrograph and Base-flow from October 2002 to August 2003 ..................39
Figure 5.10: Logarithmic plot of microorganisms at 3 sites along Ngwerere River ................52
Figure 5.11: Logarithmic plot of number of microorganisms at 2 sites at Kafue Lagoon..….52
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8. LIST OF PLATES
Plate 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
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9. LIST OF APPENDICES
Appendix ........................................................................................................................Page
Appendix 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......................................................................................................63
Appendix II: Table A.1: Wastewater treatment and quality criteria for irrigation (State of
California 1978)...................................................................................................69
Appendix III: Irrigation Water Quality Guidelines ....................................................................70
Appendix IV: Table 2B: Recommended Maximum Concentrations of Trace Elements in
Irrigation Water....................................................................................................71
Appendix V: Table C. 3: Constituents of concern in wastewater treatment and irrigation
using reclaimed municipal wastewater ..............................................................72
Appendix VI: Questionnaire results ..........................................................................................73
Appendix VII: Analyzed water quality data from Ngwerere River sampling points .................81
Appendix VIII: Analyzed water quality data from Kafue Lagoon Area ....................................83
Appendix IX: Analyzed sediments from Ngwerere area from Ngwerere sampling points......84
Appendix X: Analyzed sediments from Kafue Lagoon Area....................................................85
Appendix IX: Base flow index calculation for Ngwerere Estate Weir ......................................86
Appendix XII: Current national water quality standards in use in Zambia ..............................87
Appendix XIII: Results of effluents from Nitrogen Chemicals of Zambia (NCZ) .....................88
Appendix XIV: Chemical analysis of effluents from Lee Yeast Factory ..................................89
Appendix XV: Rapporteur’s Report...........................................................................................97
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10. Abbreviations and Acronyms
BOD Biochemical Oxygen Demand
Cd Cadmium
COD Chemical oxygen Demand
Cu Copper
DFID Department for International Development
DO Dissolved Oxygen
DWA Department of Water Affairs
ECZ Environmental Council of Zambia
EU European Union
FDC Flow Duration Curve
Hg Mercury
LCC Lusaka City Council
MFNP Ministry of Finance and National Planning
NCZ Nitrogen Chemicals of Zambia
NSR National Scientific Research
Pb Lead
PMA Poverty monitoring Analysis
PRSP Poverty Reduction Strategy Paper
WHO World Health Organization
WSP Waste Stabilization Ponds
ZESCO Zambia Electricity Supply Corporation
Zn Zinc
ZNS Zambia National Service
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11. Executive Summary
Introduction
In 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 untreated
wastewater is their only source of irrigation water-so their livelihoods depend on it. On the other
hand, the unregulated use of wastewater also poses risks to human health and the
environment. Wastewater irrigation can also significantly contribute to urban food security and
nutrition. Recent studies in several Asian and African cities have revealed that wastewater
agriculture has accounted for over 50% of urban vegetable supply. it is estimated that one tenth
or more of the world’s population currently eats food produced on wastewater (but not always
in a safe way).
In Zambia despite the health hazards associated with crops grown in the Kafue Lagoon using
wastewater from Nitrogen Chemicals of Zambia (NCZ), Shikoswe stream and Lee Yeast, trucks
loaded with a variety of vegetables and sugar cane came from Kafue about 50 kilometres
south-west of Lusaka to Kamwala and Soweto markets to sell these products. Most of this
merchandise bought in bulk by marketers was sold to unsuspecting consumers. But many
Kafue residents earned their living by growing and selling these crops in the lagoon using
effluents from canals carrying industrial and domestic wastewater.
Similarly the Ngwerere River has its share of urban and peri-urban agricultural activities despite
the 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 the
Chongwe River. The current study incorporated BOD, COD, and total nitrogen and flow
measurements as recommended in previous studies. The current study also linked water
analysis to the users of water, a link that was left out in previous studies.
Main objective
The main objective of the study was to assess the effects of using wastewater on vegetable
growing and the associated socio-economic impacts on farmers in the Kafue Lagoon Areas
and along Ngwerere River.
Literature review
Introduction
Domestic human waste is defined as human excreta, urine, and the associated sludge
collectively known as black-water, as well as, kitchen wastewater and wastewater generally
through bathing (collectively known as grey-water). Wastewater defined as waste matter
entering water and its disposal involves the collection, treatment, and sanitary disposal. The
sources of wastewater are domestic, industrial, storm water and by groundwater seepage
entering municipal sewage network. Wastewater is composed of organic matter, nutrients,
inorganic matter, toxic chemicals and pathogens. Reclaiming municipal wastewater for
agricultural reuse is increasingly recognized as an essential management strategy in areas of
the world where water was in short supply. Wastewater reuse in agriculture required
consideration of the health impact, agricultural productivity, economic feasibility and
sociocultural aspects.
Treatment of wastewater
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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 loading
and have retention time of one to five days and depth of 2-4 meters. Facultative ponds are
used to treat the wastewater and generally have a depth of 1-1.5 meters. The retention time for
the wastewater is 5 to 30 days. Maturation ponds on the other hand, remove faecal bacteria
and 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 wastewater
Domestic sewage resulting from people’s day-to-day activities, such as bathing, body
elimination, food preparation, and recreation, averages about 227 litres (about 60 gal) per
person daily. Raw sewage included waterborne waste from toilets, sinks and industrial
processes. The average monthly water consumption for an average household size of 7.5
inhabitants living in high/medium cost areas and 6.0 inhabitants living in low cost Area (as
found 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 flush
toilets. The quantity of industrial wastewater varies depending on the industry and management
of its water usage, and the degree of treatment before it is discharged. Domestic wastewater
consists 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 the
Ngwerere River. Prior to discharging, the wastewater was treated using biological filters and
then pumped to the maturation pond in Garden Compound. In April, May, June and July 2004
the average discharges from Manchinchi were 72, 545 m3/day, 58,805 m3/day, 39, 357 m3/day
and 32, 803 m3/day, respectively. The design capacity of the treatment plant was 36, 000
m3/day. Therefore for April, May and June 2004 the design capacity was exceeded. These
figures were obtained from Lusaka Water and Sewerage Company. As a result of overloading
the 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 Plant
by-pass line.
Toxicology aspects of wastewater
It is widely accepted that levels of trace elements and heavy metals in irrigation water were
likely to be toxic to plants at concentration below that which they pose a significant risk to
human health. Heavy metals in wastewater posed a health risk if they were ingested in
sufficient concentrations, and could be dangerous. In principle, uptake of heavy metals by
crops and the risk posed to consumers may not be an issue as plants could not resist high
concentrations of these pollutants and die off before they become a threat to humans. This
provides a degree of natural protection of irrigators and consumers as plants fail to thrive and
farmers abandon the source well before levels present a risk to human health. There are
currently no guidelines for permissible levels of trace elements and heavy metals in wastewater
used for irrigation, which relate to the potential risk to human health as a consequence of crop
uptake and bio-accumulation.
Apart from heavy metals and trace elements, wastewater also contains high concentrations of
dissolved salts. Salinity-related impacts of wastewater irrigation on soil resources could be
expressed in economic terms such as (1) potential yield and income loss; (2) loss of soil
productivity; (3) depreciation in market value of land; and (4) cost of soil reclamation measures.
Cost benefit of using wastewater
xii

13. Irrigation with wastewater could be an attractive way of disposing wastewater from an
environmental point of view. The combined benefits of reduced treatment and disposal cost
and 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 in
industry, 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 to
water resources conservation, recycling of nutrients and prevention of surface water pollution.
Agronomic and public health aspects
While wastewater is a resource for productive uses, it can be dangerous if used in an untreated
form. The dangerous practice of direct and indirect use of untreated wastewater was common
in regions like Lima, Mexico City, and Santiago. This is a serious concern with respect to public
health. The use of untreated wastewater for irrigation poses a high risk to human health in all
age groups. Untreated wastewater irrigation led to relatively higher prevalence of hookworm
and Ascariasis infections among children. The DFID-sponsored research in North-east Brazil
showed that bacterial pathogens such as Vibrio cholerii, Salmonella species and
Campylobacter species were present in wastewater.
Irrigation methods
Some crops can be irrigated using unrestricted guideline of the WHO. 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, hotel lawns, and tourist areas.
Restricted irrigation refers to the irrigation of crops not intended for direct human consumption
and there should be no more than one viable human intestinal nematode egg per litre, implying
a greater than 99% treatment level. This guideline was introduced to protect the health of field
workers and to indirectly protect consumers and grazing cattle. Restricted irrigation can be
applied to industrial crops (e.g., cotton, sisal, and sunflower, wheat, barley, oats); and fruit
trees, fodder crops and pastures.
Sociocultural aspects
Peri-urban and urban agriculture are understood to be the agricultural activities undertaken
within the area immediately surrounding the city, where the presence of the city had an impact
on land use, property rights and where proximity to the urban market and urban demand drove
change in agricultural production. Furthermore, urban agriculture is one of the several
strategies 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 the
community affected by the reuse project would reveal the need for reuse. The acceptance of
wastewater reuse and the adoption of practices for its safe implementation will be influenced by
the sociocultural makeup of the people involved (that is the values, beliefs, and customs that
are 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 concerns
regarding impacts on environmental quality, public health and safety. These concerns may be
addressed with appropriate educational and public awareness programs. The cost of public
education, awareness and demonstration programmes could be used as a choice for the
valuation of social impacts of wastewater irrigation programmes, using awareness and
sensitization educational models.
xiii

14. Policy aspects
The Zambian National Water Policy of 1994 specifies that water for irrigation should be fit for
human consumption and not cause soil degradation but enhance high crop yield. Within the
broad objective for agriculture, the Poverty Reduction Strategy Paper (PRSP) indicated that
since the poor often relied on the environment for their livelihood, attacking poverty in rural
areas was necessarily improving people’s ability to derive livelihood from natural resources. On
the other hand, the Zambian Health Policy fosters that in order to have a well-nourished and
healthy population that could contribute to the national economic development there was need
to achieve sustainable food and nutrition security.
Study areas
Kafue Lagoon Area
The 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 a
total of over 50 hectares of land under mostly sugar cane cultivation. Sampling was done at
three locations; Shikoswe Stream, Lee Yeast effluent stream and effluent canal from Nitrogen
Chemicals of Zambia (NCZ). Questionnaire administration was not restricted to the water
sampling locations.
Ngwererer River Area
The Ngwerere is a small river whose origin is in the city of Lusaka and it stretches over a
distance of approximately 30 kilometers. The catchment size is 662 km2. The sampling and
questionnaire administration took place at three locations along the river, namely Near Garden
Site 3 pond in Garden compound (N1), at Ngwerere Estate Weir (N2) in Chamba Valley area
and at Kasisi Mission Dam diversion (N3).
Methodology
The methods used during the study were both qualitative and quantitative in the generation of
information as well as documenting the findings. Various documents were reviewed on the
work done on utilization of wastewater or nutrient enriched water in Zambia and other parts of
the world. Various legislative articles from institutions such as the Environmental Council of
Zambia, Department of Water Affairs and Ministry of Health were also reviewed. Other
documents such as the WHO guidelines and ECZ wastewater standards on the safe use of
water for irrigation were also reviewed.
Information was gathered by using a combination of observations, field surveys and structured
interviews with selected growers. Surveys were carried out to ascertain the types of crops
grown within the Ngwerere catchment and at Kafue Lagoon area. Questionnaires were
administered 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 Kafue
Lagoon and 42 respondents from the Ngwerere Area.
The sampling technique used before administering the questionnaires was sampling by a Grid
System technique. The Grid System method involved putting a screen with squares on a study
map and the areas falling within selected squares were selected samples.
The quantity of wastewater in the Ngwerere stream was computed by analysing the
hydrological 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 surface
run-off and then separating the base-flow from the total surface runoff in cubic meters.
xiv

15. A total of eight (8) sampling campaigns at each site in Ngwerere and four (4) at each site in
Kafue were carried out between 6th July 2004 and 20thAugust 2004. In total two (2) campaigns
in Ngwerere involved one (1) duplicate sample for each site and in Kafue two (2) campaigns
included 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, the
Ngwerere was assumed to be completely mixed over its depth and width. A grab sample in the
middle of the stream was considered representative enough. The water sample was obtained
by immersing a sample bottle about 5cm below the water surface and collecting the water. For
chemical analysis a polythene bottle (1000ml) was used while for heavy metals a 500ml bottle
with 2ml nitric acid inside was used. Sterilized glass bottles were used for microbiological
sampling. 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 riverbed
where 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 out
using the Horiba Water Checker U-10 model. Crop samples were collected in Chamba Valley
near Ngwerere Estate Weir (N2). Only the leaves of rape were collected and taken to Food
Science 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 for
irrigation by farmers in the lagoon area. The effluent canals were the Shikoswe stream, Lee
yeast effluent canal and Nitrogen Chemicals of Zambia. Water, plant and sediment samples
were collected at these points. The collection of samples was similar to Ngwerere
The samples were analysed at the Environmental Engineering laboratory of the School of
Engineering at the University of Zambia. The samples were transported to the laboratory within
7 hours of sampling. The methods of analysis of parameters included gravimetric, titrimetric,
photometric and electrometric determinations for physicochemical parameters, atomic
absorption spectrometry for heavy metals and membrane filtration method for microbiological
parameters. For quality control/assurance, duplicate samples were obtained during selected
sampling campaigns and some samples taken to an independent laboratory for crosschecking.
Data was analyzed using excel spreadsheet, Arid Region Drought Analysis (ARIDA) and
Hydrological Data Analysis (Hydata) software, graphs and tables.
Results and discussion
Field interviews
Kafue Lagoon Area
It was found that 60% of the farmers producing irrigated crops in Kafue Lagoon Area were
women and only 40% were men. On the other hand, Ngwerere Area presented the opposite
scenario 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 any
formal education and 74% had (17% had secondary level education and 57% had gone up to
primary level). The main occupation of respondents in the Lagoon was gardening whilst the
second occupation included various activities such as selling of charcoal, piecework and
keeping of livestock.The main source of income for the peasant farmers in Kafue Lagoon Areas
was from sale of vegetables, sugar canes and gardening.
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16. Ngwerere River Area
In Ngwerere River Area the education levels of the respondents were such that 14% had no
formal education and 86% had formal education (31% - secondary level education, 53% - up to
primary level and 2% - up to tertiary level). The main occupation of the respondents in the
Ngwerere River Area was producing and selling of vegetables and maize. The main sources of
income for the peasant farmers in Ngwerere River Area were selling of vegetables and
gardening. The alternative sources of income were retirement package (pension money), rental
from houses, business and piece of work, selling of pesticides.
Land tenure
Land tenure was leasehold, farmer’s own land, Zambia National Services land or communal
land in the Ngwerere Area and main crops grown were vegetables and maize. In the Kafue
Lagoon Area land tenure was freehold. The cropping pattern was composed of vegetables,
maize and sugar cane.
Water management and sources
In the Kafue Lagoon, 32% of the respondents relied on shallow dug out wells while 68% used
canals. 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. The
major water source for irrigation was the Ngwerere River and the most common method of
applying water was to collect from the stream or river, and to apply it to the crops using water
cans or buckets (10 to 20 litre containers). This was a laborious task.
Marketing of crops
The single commonest means of marketing the produce in Ngwerere was for growers to sell
their produce at markets: Soweto, Town Centre, Kabanana, Chipata Compound, Ng’ombe,
Katambalala, Chaisa, Garden, and Kaunda Square markets, which was at 69%. Five (5)% of
the farmers sold their produce to Fresh Mark in Lusaka town. It was also found that 83% of the
farmers marketed their crops individually, 12% as a formal group, 3% as traders who
purchased the produce from the farmers. In Kafue all the respondents sold their
crops/vegetables individually in different parts of Kafue (Kalukungu, Kafue Estates, Zambia
Compound and Solloboni markets), Chilanga and Lusaka (urban and rural) including Chirundu
in Siavonga.
The yield of vegetables varied from one respondent to the other and the figures were based on
the data obtained from the farmers through interviews. A further analysis of income and
expenditure pattern at household level could be a subject of another research.
Earnings from crop sales
The 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, the
farmers’ income ranged from K800, 000 to K1, 000,000 per year while in Ngwerere River Area
it ranged from K400, 000 to K2, 500,000 per year. The Ngwerere farmers had wider market
coverage and relatively shorter distances to bigger markets and had higher demand for the
crops.
Constraints faced by farmers
The major constraints faced by farmers in growing their crops/vegetables were inadequate
technical support, conveyance of water onto field, crop storage, and transport expenses (to
markets), lack of credit for capital investment and price variation
xvi

17. Public health issues
It was found that the prevalent diseases in the study Area were malaria, bilharzias and
diarrhoea. For the Ngwerere Area, secondary data obtained at Kasisi Rural Health Centre
confirmed 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 in
garden Compound and near overgrown parts of the river were likely to be affected by these
diseases. Fifty four percent (54%) of the respondents in Ngwerere catchment said the river
water was not fit for drinking but was good for irrigation. However, fifty percent (50%) of them
said none of the members of their household had suffered from any disease associated with
the river water in the past one year. The case at Kafue Lagoon was quite similar to the
Ngwerere situation. Fifty three percent (53%) of the respondents said the water used for
irrigation posed a threat to human health while fifty percent (50%) said none of the members of
their household had suffered any illness as a result of the water they used for irrigation.
Quantity of wastewater in the Ngwerere River Area
The total surface runoff and base-flow was computed by using the Hydata, spreadsheet and
ARIDA software at the Department of Water Affairs Water Resources Unit were used. The
surface runoff was estimated by using Flow Duration Curves (FDC). The groundwater storage
in 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 analysis
Mercury and copper were not detected in all the plant samples. This could mean that it was not
present as a waste product. Given the high pH values copper could have precipitated out of
solution into the sediments and so not much of it was available for the plant uptake after
irrigation. 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 Cu
in Lee Yeast effluents.
Documents indicated that cadmium could be present in the water column at very low
concentrations 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 was
5.0 mg/l, Zn 2.0 mg/l and Cu 0.20 mg/l. In the absence of local guideline values for heavy
metals in plants against which comparisons could have been made, guideline values from a
study (personal communication) were used: 50 mg/kg as maximum concentration of Cu and
Zn, and 5mg/kg of Pb in plant tissues. Apart from Cd (0.028 to 0.049 mg/l), all the other heavy
metals analysed were below the recommended maximum concentrations in plants. Cd might
be a threat to human health in both study areas but further investigations would be required to
quantify and mitigate the threat.
Water quality analysis
Westcot argued that the WHO or Engelberg standards for faecal coliform were design
guidelines and suggested that in the absence of better information, it was “prudent” to use them
as 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 WHO
guidelines and recommendations by Westcot considering the fact that adequate
epidemiological 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 long
as the pollution sources were eliminated. But elimination of the sources of pollution was not
xvii

18. feasible in both situations because the contaminated water was also the water used for
irrigation 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 (especially
desludging) upstream or expanding the treatment plants could be considered. There were
large variations in the faecal coliform numbers at each point on the Ngwerere River over the
study period, hence high standard deviations. This was probably due to variation in wastewater
discharges and composition, flow pattern of the river and its tributaries and abstraction for
irrigation. Such variations in coliform counts were also reported in a study in Ghana carried out
by Cornish.
In terms of the spatial distribution of the more microorganisms on the Ngwerere River were
found upstream in the urban/peri-urban area of Lusaka City (N1 and N2) than downstream in
the rural area.
Effluents from Lee Yeast and Shikoswe were also heavily contaminated with respect to faecal
coliform. The water was not safe for use without treatment.
Most of the parameters including conductivity, salinity, calcium, sulphate, total nitrogen, total
phosphate, BOD, total suspended solids and iron tended to reduce in concentration from the
upstream reaches in the urban area to the downstream reaches in the rural area of the river
catchment. This indicated that the pollution was heavier in the former than in the latter
stretches of the river. There were no heavy metals detected in the water samples. Metals like
Cu 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 the
ECZ, WHO, DWA and EU guidelines for water quality. However, the pH was higher than the
recommended upper limit of 9 in a few cases especially at Kasisi Mission. Ammonia levels at
N1 and N2 (that was urban and peri-urban areas) were higher than the WHO drinking water
guideline 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 higher
than the ECZ guideline value of 100mg/l.
Though most of the physical and chemical parameters were within the recommended limits for
irrigation and other water uses, microbiological parameters showed that the river was heavily
polluted. Throughout the river stretch, the water was not suitable for drinking and at some
points even for irrigation according to WHO and FAO guidelines.
All the other parameters measured were lower than the recommended maximum concentration
in irrigation water, according to Pescod. The concentration of heavy metals and boron in the
water at all the sampling points were below the detection limit of the method of analysis which
was 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 was
the pollution by microorganisms in the watercourses where the farmers drew water for irrigating
their 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) qualified
for 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). Under
unrestricted irrigation vegetables and salad crops could be grown using water with ≤1000
faecal 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. in the Ngwerere River was only fit for restricted irrigation whereby the crops that could be safely
grown 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 by
the reducing counts of E.coli and Faecal streptococci. At all the stations on the river the water
was not suitable for drinking. Previous studies also demonstrated a similar pattern and
moreover 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 mean
values above the WHO guideline of <1000 faecal coliforms/100ml.
For NCZ, the parameters measured were within the ECZ recommended limits. This was very
different from the situation in 1996 under the study of Sinkala et al, which reported higher levels
of magnesium, calcium, total suspended solids and total dissolved solids. The difference may
be attributed to slowed or no production at NCZ at the time of the present study. In fact the
water in the effluent canal was visibly clear. At the time of sampling it was found that the
farmers were mixing this water with that from Lee Yeast factory and Shikoswe stream through
diversion 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 limits
by ECZ although this was just for one sample. High calcium and conductivity (as TDS) levels
were also reported by Sinkala et al (1996). The source of the calcium was mainly the geology
of 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 very
different from the situation in 1996 in the study of Sinkala et al, which reported higher levels of
magnesium, calcium, total suspended solids and total dissolved solids. The difference may be
attributed to slowed or no production at NCZ at the time of the present study. In fact the water
in the effluent canal was visibly clear. At the time of sampling the farmers were mixing this
water 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 sampling
points were below the detection limit of the method of analysis which was also far below the
recommended maximum concentrations.
The Shikoswe effluent had relatively high levels of ammonia and phosphate, the reason being
that it carried mainly sewage effluents. As in Lee Yeast effluents, Shikoswe also had high
levels 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 affecting
sensitive crops and also increasing soil salinity problems. High salinity led to reduced uptake of
water and nutrients by plants.
The sediment samples were analysed at both sites for exploratory purposes. Detailed
investigations should be carried out in future. The spot samples analyzed would help to explain
or confirm variations in the other sample types in limited mass balance terms.
xix

20. The first two sites (N1, Garden/Olympia area and N2, Ngwerere Estate Weir) on the Ngwerere
River 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 and
1596 mg/kg iron, respectively. Cd (<0.002) and Hg (0.0002) concentrations were below the
detection 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 study
were compared with the standards for polluted sediments in the Netherlands. although this
country 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 class
concentrations except for Cu (58 mg/kg) at Shikoswe stream, which was very high. But this
was a one off value, which would require further verification.
Conclusion
Based 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.
Recommendations
From 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. 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 wastewater
3. 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 prevented
4. 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 households
5. 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 use
6. The Ministry of Local Government and Housing (MLGH) should support the rehabilitation of
the various sewerage treatment facilities
7. The government should assist peasant farmers in forming urban farmers associations or
co-operatives
8. 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 technology
9. 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. CHAPTER 1: INTRODUCTION
1.1 Background
In 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 untreated
wastewater is their only source of irrigation water—so their livelihoods depend on it. On the
other hand, the unregulated use of wastewater also poses risks to human health and the
environment. Wastewater irrigation can also significantly contribute to urban food security and
nutrition. Recent studies in several Asian and African cities have revealed that wastewater
agriculture has accounted for over 50% of urban vegetable supply (IWMI, 2003). Wastewater is
used 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 even
eliminate the purchase of chemical fertilizer and organic matter that serves as a soil conditioner
and humus replenisher (IWMI-RUAF, 2002). The report by IWMI-RUAF (2002) as reported by
Lunven (1992) estimated that one tenth or more of the world’s population currently eats food
produced on wastewater (but not always in a safe way).
Wastewater reuse in agriculture is the economically feasible, environmentally sound use of
municipal wastewater for irrigation and aquaculture. Reclaiming municipal wastewater for
agricultural reuse is becoming increasingly recognized as an essential management strategy in
areas of the world where water is in short supply (Khouri et al., 1994). Wastewater reuse has
two 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 by
lowering the demand for freshwater abstraction. In the process, reuse has the potential to
reduce the cost of both wastewater disposal and the provision of irrigation water, mainly by
practicing urban and peri-urban agriculture. Wastewater is defined as waste matter entering
water (Huang, 1994). The sources of wastewater as indicated by Hussain et al., (2002) are
made up of domestic wastewater, industrial wastewater, storm-water and groundwater
seepage entering municipal sewage network. Domestic wastewater is made up of effluent
discharge from household, institutions, and commercial buildings. Industrial wastewater is the
effluent discharged by manufacturing plants. Wastewater is composed of organic matter,
nutrients, inorganic matter, toxic chemicals and pathogens. The final composition of raw
wastewater 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 and
Ringskog, 1997) and is increasingly seen as a resource, and it is often reused legally and
clandestinely (Hussain et al., 2002; Idelovitch and Ringskog, 1997). Wastewater as a resource
can be applied to productive uses since it contains nutrients that have the potential for use in
agriculture, aquaculture, and other activities (Hussain et al., 2002). However, the same raw or
pre-treated wastewater could pose health hazard to handlers and consumers of the crops
grown using it (Westcot, 1997).
Despite the health hazards associated with crops grown in the Kafue Lagoon due to the use of
NCZ wastewater for irrigation, findings by Enviro-line (1998) revealed that trucks loaded with a
variety of vegetables and sugar cane came from Kafue about 50 kilometer south-west of
Lusaka to Kamwala and Soweto markets to sell these products. Most of this merchandise
bought in bulk by marketers is sold to unsuspecting Lusaka consumers. Many Kafue residents
earn their living by selling these crops grown in the lagoon using effluents from punctured pipes
and from canals carrying industrial and domestic wastewater, to water their crops.
1

23. Similarly the Ngwerere River has its share of urban and peri-urban agricultural activities despite
the river being chemically and biologically polluted (NSR, 1983). Later studies also proved that
Ngwerere 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 in
Ngwerere River was not suitable for drinking and but could be used for irrigation and fishing
purposes. The water would pose a health risk to the water users and consumers of crops. It
was further demonstrated that the river exhibits significant self-purification capacity along its
stretch from Garden Compound to the confluence with the Chongwe River. For instance in
1996, faecal coliform spatially reduced from 18, 000, 000 colonies per 100 ml in the upper
reaches 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 and
washing. 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 total
nitrogen, biological oxygen demand and chemical oxygen demand tests in order to understand
the pollution of the river in greater detail.
The current study incorporated BOD, COD, total nitrogen and flow measurements as
recommended by the previous studies. The research also linked water analysis to the users of
water, a link that was left out in previous studies. Therefore socio-economic factors were
considered in the study.
1.2 Objectives
The main objectives of the study was to assess the effects of using wastewater on vegetable
growing and the associated socio-economic impacts on farmers in the Kafue Lagoon Areas
and along Ngwerere River.
Specific objectives
1.2.1 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 areas
1.2.2 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 water
1.2.3 To suggest measures of reducing health hazards associated with the use of
wastewater in vegetables growing
1.2.4 To determine environmental valuation of wastewater by the community and its
contribution to poverty reduction.
1.3 Justification
Wastewater as a resource can be put to productive use. It can also be dangerous if used in an
untreated form, which poses high risks to human health. The dangerous practice of direct and
indirect 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 and
Ascariasis infections among all age groups. It may also contain bacteria pathogens such as
Vibro cholera, Salmonella and Campylobacter species. The negative environmental impacts
2

24. associated with wastewater use are groundwater contamination through high concentrations of
nitrates, salts and micro-organisms.
Though sewage wastewater is thought to be a health hazard, it is possible to make it good for
several beneficial uses. Wastewater from the municipalities can be reclaimed for agricultural
reuse, which is increasingly recognized as an essential management strategy in areas of the
world where water is in short supply. Wastewater reuse in agriculture requires consideration of
the health impact, agricultural productivity, economic feasibility and sociocultural aspects. The
wastewater used in developed countries is treated prior to its use in irrigation and
environmental standards are applied. The wastewater is used to irrigate fodder, fiber and other
seed 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. The
nutrients and trace elements such as phosphorous, nitrogen and potassium are necessary for
plant growth.
Studies have indicated that urban agriculture (UA) is practiced inside (intra urban) or on the
outskirts (peri-urban) of a town or a city. This focuses on growing crops and raising animals. It
also includes recycling household waste and wastewater for agricultural purposes, the
processing and distribution of different food and non-food products using human and material
resources, products and services that are found in the surrounding areas. An increasing
number of local and national governments in countries such as Pakistani, Mexico and Morocco
are promoting UA in response to serious problems of poverty, food insecurity, and
environmental degradation.
Bearing in mind the hazards and benefits associated with wastewater reuse, there was need
therefore, to undertake this study and gain more insight into the situations at Ngwerere River
and Kafue Lagoon areas where wastewater was increasingly used for irrigating crops and
vegetables, which were mainly sold in Kafue town and Lusaka City. Since a lot of people in
Zambia spent time to grow crops as a means of earning a living in peri-urban and urban
agriculture, this would contribute a lot to poverty alleviation in the study areas. The study would
enable the analysis of the costs and benefits of using such water for agriculture. Scientific data
was 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 could
have a direct relation with poverty alleviation.
1.4 Significance of the Parameters
The choice of parameters to be tested was based on the type of pollution expected from the
domestic and industrial wastewater since a considerable portion of the stream’s inflow is from
these two sectors. The parameters tested were pH, temperature, conductivity, total suspended
solids, BOD, COD, nitrates, ammonia, total phosphates, total nitrogen and E. coli, faecal
streptococci, faecal coliform, magnesium, calcium, boron, sodium, iron, lead, copper, cadmium
and mercury. The parameters, with an indication of their relevance, are listed in annex 15.
3

25. CHAPTER 2: LITERATURE REVIEW
2.1 General
Domestic human waste is defined as human excreta, urine, and the associated sludge
collectively known as black-water, as well as, kitchen wastewater and wastewater generally
through bathing (collectively known as grey-water) (Rose, 1999). Wastewater as already
defined, is waste matter entering water and its disposal involves the collection, treatment, and
sanitary disposal (Huang, 1994). According to Huang (1994) the issue of sewage disposal
assumed increasing importance in the early 1970s. Hussain et al. (2002) noted that sources of
wastewater are domestic wastewater, industrial wastewater, storm water and by groundwater
seepage entering municipal sewage network. Domestic wastewater is made up of effluent
discharge from households, institutions and commercial buildings. Industrial wastewater is the
effluent discharged by industries. Wastewater is composed of organic matter, nutrients,
inorganic matter, toxic chemicals and pathogens. The final composition of raw wastewater
depends on the sources and its characteristics.
According to Nicholas O'Dwyer and Partners Consulting Engineers, (1978) and WWI (1989) the
most common analysis of wastewater includes the measurements of solids, biochemical
oxygen demand (BOD), total coliform, chemical oxygen demand (COD), chloride, sodium,
phosphate, total nitrogen, calcium, temperature and pH. The solids include both the dissolved
and suspended solids. Sewage treatment proceeds in three stages in some countries –
primary, secondary and tertiary stages. In the primary treatment stage, solid wastes are
removed through mechanical process and organic matter is removed by biological process in
the secondary treatment stage. The third stage is the tertiary treatment stage, which is the
polishing stage. Normally, it involves the removal of phosphorus and nitrogen.
2.7 Treatment of Wastewater
According to Proprasset et al (2000) any type of wastewater treatment system is based on
natural processes, be it chemical, physical or biological, and its design is aimed at creating the
optimum conditions for enhancement of the rate of these natural processes. Natural systems
for wastewater management include a host of treatment techniques apart from the use of
stabilization 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. • 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) processes
In Zambia stabilization ponds are used for treating wastewater. These are comprised of the
anaerobic, facultative and maturation ponds. Anaerobic ponds receive effluents of high organic
loading and have retention time of one to five days and depth of 2-4 meters. Facultative ponds
are used to treat the wastewater and have generally a depth of 1-1.5 meters. The retention
time for the wastewater is five to thirty days. Maturation ponds on the other hand, remove
faecal bacteria and the retention period of the effluent is 5-10 days and their depth is 1-1.5
meters (GKW Consult, 2001). In principle, natural pond can be aerobic, facultative, or
anaerobic. Aerated ponds are a manmade development and these reduce the amount of land
required by adding artificial aeration.
Stabilization or oxidation ponds are used extensively in developing countries. A relatively new
system 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 indicated
that these are used for both seasonal storage and effluent purification. The system can reduce
bacteria 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 of
anaerobic, facultative and maturation ponds (Mara, 1997). The anaerobic ponds receive a high
organic loading that they are devoid of oxygen and BOD removals are very high over 70
percent with retention time of only one day at 25oC.
Facultative ponds (biological treatment) with a retention time of only 3-5 days at 25oC can
reduce filtered BOD to well below the 25 mg/l EU requirement for WSP effluents and the
oxygen needed by the heterotrophic bacteria are supplied through photosynthesis of the pond
algae (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 O'Dwyer
and Partners Consulting Engineers (1978) indicated that present treatment has very little
effects on reducing the BOD of raw sewage, solid content, chlorides, sulfate, ammonia, and
organic nitrogen and trace metals.
Maturation ponds are primarily used to ensure the removal of faecal bacteria and viruses to
safe levels so that the effluents can be used without risk to public health for crop irrigation
and/or fish culture (Mara, 1997). Price (2003) indicated that the treatment and use of
wastewater is both a challenge and an opportunity for municipalities. It is a challenge because
the use of non-treated wastewater is often the only option available for peri-urban farmers. This
poses potential serious health problems of the presence of bacteria, viruses and parasites. It is
an opportunity because wastewater is a valuable resource, not only from an economic
viewpoint but also from an environment perspective (conservation of water resources, nutrient
recycling etc).
At the time of the study, Manchinchi Sewage Treatment Plant was discharging effluents to the
Ngwerere River. Prior to discharging, the wastewater was treated using biological filters and
then pumped to the maturation pond (commonly called Garden Ponds). In June and July 2004
the 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. design capacity was exceeded. These figures were obtained from Lusaka Water and Sewerage
Company. Average effluent discharge went up to 60, 000 m3/day. As a result of overloading the
treatment plant the final effluent lost its quality to 59 % in terms of BOD, 23 % in terms of COD
and 52 % in terms of TSS due to untreated raw sewage from the Plant by-pass line. The river
discharge at Garden/Olympia site (N1) which is downstream of Manchinchi Wastewater
Treatment 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 largest
single contribution (over 60%) came from the Manchinchi Wastewater Treatment Plant.
2.3 Quantity of Wastewater Produced
According to Huang (1994) domestic sewage results from people’s day-to-day activities, such
as bathing, body elimination, food preparation, and recreation, averages about 227 litres (about
60 gal) per person daily. Raw sewage includes waterborne waste from toilets, sinks and
industrial processes. The average monthly water consumption for an average household size
of 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 households
in Zambia use flush toilets. The quantity of industrial wastewater varies depending on the
industry and management of its water usage, and the degree of treatment before it is
discharge. 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 is
widening and is reaching such alarming levels that in some parts of the world it is posing a
threat to human existence (Hussain et al., 2002). Society on the other hand, is subjected to
continuous expansion with increased food requirements and food insecurity.
Lusaka Water and Sewerage Company is responsible for management of sewerage and
sludge in Lusaka (ECZ and LCC, 1997). According to ECZ and LCC (1997) there are basically
four plants in Lusaka that handle the sewerage sludge produced in Lusaka; the Chelston and
Kaunda 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 pit
latrine), 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 is
275, 000.
2.4 Toxicological Aspects of Wastewater
Hide et al (2001) reported that it is widely accepted that levels of trace elements and heavy
metals in irrigation water are likely to be toxic to plants at concentration below that which they
pose a significant risk to human health (see Annex III). According to Hussain et al (2002) heavy
metals in wastewater pose a health risk if they are ingested in sufficient concentrations, and
can be dangerous. In principle, uptake of heavy metals by crops and the risk posed to
consumers may not be an issue as plants cannot resist high concentrations of these pollutants
and die off before they become a threat to humans (see Table 2.1 and Annex III and IV). This
provides a degree of natural protection of irrigators and consumers as plants fail to thrive and
farmers 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 and
heavy metals in wastewater used for irrigation, which relate to the potential risk to human
health as a consequence of crop uptake and bio-accumulation. According to Hide et al (2001)
6

28. most authors cite the table of phytotoxic threshold prepared by the National Academy of
Science and National Academy of Engineering (1972) and Pratt (1972), or refer to the WHO
drinking 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 Threshold
Values Leading to Crop Damage (mg/l)
Element WHO drinking water EU drinking water Recommended maximum
guidelinesa guidelinesb concentration for cropc
Arsenic 0.01 0.05 0.1
Cadmium 0.003 0.005 0.01
Chromium 0.05 0.05 0.1
Copper 2 0.2
Iron 0.3 0.1-3.0 5.0
Mercury 0.001 0.2 -
Manganese 0.5 0.001 0.2
Nickel 0.02 0.05 0.2
Lead 0.01 0.05 5.0
Zinc 3 0.1-5.0 2.0
Sources:
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 from
wastewater irrigation and sludge is a contentious issue. Khouri et al (1994) indicated that
cadmium (Cd), for example could be present in municipal wastewater at levels that are not
toxic 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 been
shown to accumulate in cow’s milk, which could lead to hazardous build up in the consumer’s
body. Ensink et al (2002) indicated in a study undertaken in Pakistan that accumulation of
heavy metals proved to be almost negligible, with only increased levels of lead, copper and
manganese, even in the fields that had received wastewater for over 30 years.
Apart from containing heavy metals and trace elements, wastewater also contains high
concentrations of dissolved salts (Hussain et al., 2002). Salinity-related impacts of wastewater
irrigation on soil resources can be expressed in economic terms such as (1) potential yield and
income loss; (2) loss of soil productivity; (3) depreciation in market value of land; and (4) cost of
soil reclamation measures.
2.5 Costs and benefits of Using Wastewater
Irrigation with wastewater could be an attractive way of disposing wastewater from an
environmental point of view (Khouri et al., 1994). The combined benefits of reduced treatment
and disposal cost and increased agricultural production may justify investment in an irrigation
system. Before one can endorse wastewater irrigation as a means of increasing water supply
for agriculture (Hussain et al., 2002), a thorough analysis must be undertaken from an
economic perspective as well. The economic effects of wastewater irrigation need to be
evaluated not only from the social, economic, and ecological standpoint, but also from the
sustainable development perspective.
7

29. 2.6 Agronomic Aspects
Wastewater has phosphates and nitrates, which are channeled into land as fertilizers
(Karpagma, 1999). Mara (1998) discovered that Community based approaches (in Latin
America in particular) separate ‘grey’ wastewater (non-faecally contaminated wastewater) from
‘black’ wastewater (that is faecally contaminated) so that they can be reused as irrigation water
and fertilizers respectively. The wastewater can be used for unrestricted irrigation of crops such
as lettuce, salads and cucumbers grown for direct human consumption and eaten raw and for
restricted 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 most
attractive and widespread reuse of effluents is to irrigate agricultural crops, pasture, or natural
vegetation. Other important uses of wastewater include recharge of groundwater, as cooling
water, 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 are
necessary for wastewater irrigation, but they are rather strict and developing countries cannot
afford the expensive treatment (Steenvoorden et al., 2004).
Wastewater is used widely in many parts of the world, both in industrialized and developing
countries (Idelovitch and Ringskog, 1997). Increasing sewage or wastewater is seen as a
resource, and it is often reused legally and clandestinely (Hussain et al., 2002; Idelovitch and
Ringskog, 1997). Hussain et al., (2002) observed that wastewater in developed countries is
treated prior to its use in irrigation and environmental standards are applied. The wastewater is
used for irrigation of fodder, fiber and other seed crops and, to a limited extent for the irrigation
of orchards, vineyards, and other crops. Mara (1998) revealed that the water and nutrient
content 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 necessary
for plant growth. Five million cubic meters (Mm3) of wastewater contain about 250, 000kg of
phosphorous, and 150, 000kg of potassium. Whether additional fertilizer is required depends
on the crop being irrigated. Soil deficiency can be corrected by the trace elements in
wastewater 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 untreated
form. The dangerous practice of direct and indirect use of untreated wastewater is common
practice 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 on
industrial 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, though
standards are set, these are not strictly adhered to and wastewater, in its untreated form, is
widely used for agriculture and aquaculture. Idelovitch and Ringskog (1997) have observed in
their report that the most attractive and widespread reuse of effluents is to irrigate agricultural
crops, pasture, or natural vegetation. Other important uses of wastewater include, recharge of
groundwater, industry construction and dust control and wildlife habitat improvement (Hussain
et al., 2002; Idelovitch and Ringskog, 1997).
8

30. 2.7 Environmental Evaluation of Wastewater
Generally speaking, environmental valuation is used to determine the willingness of people to
attach 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 revealed
preferences or what humans actually do in the markets; and those relying on stated
preferences or what humans say they would do in a hypothetical market context. Thus both of
these approaches attempt to evaluate human behavior in economic terms but they differ in the
sense that the former is based on actual or observed behavior while the latter is based on
potential or likely behavior (Hussain et al., 2002).
2.8 Public Health Aspects
The use of untreated wastewater for irrigation poses a high risk to human health in all age
groups. However, the degree of risk may vary among the various age groups. Untreated
wastewater 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). The
DFID-sponsored research in North-east Brazil has shown that bacterial pathogens such as
Vibrio cholera, Salmonella species and Campylobacter species are present in wastewater
(Mara, 1998).
With many guidelines dealing with water quality for irrigation purposes, the microbiological
aspects have always predominated perhaps, because of their immediate human health
consequences. Chang et al (1996), notes that, few of the irrigation water quality criteria were
developed specifically for wastewater irrigation. The public health risks associated with
wastewater reuse include increased exposure to infectious diseases, trace organic compounds
(Cooper, 1991), and heavy metals. Wastewater contains the full spectrum of enteric pathogens
endemic within a community (Scott et al., 2000). Many of these can survive for weeks when
discharged on the land, notwithstanding the presence of infective organisms, however,
epidemiological studies have shown that the mere presence of pathogen does not necessarily
increase human diseases. Of particular interest from a public health perspective are the
helminthes (Ascaris and Trichuris), which have both a relatively long persistence and a small
infective dose. The risks of intestinal nematodes in untreated wastewater are recognized as
important, both for consumers and irrigators (Shuval, 1991).
According to Rose (1999), the most recent guidelines directing the reuse of wastewater to a
level 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 Agriculture
and Aquaculture’’. According to Mara and Cairncross (1989) the WHO guidelines outline
acceptable microbial pathogen levels for treated wastewater for reuse in unrestricted and
restricted irrigation. In practice, most developing countries use untreated wastewater for
agriculture for a variety of reasons. These include the cost of treatment and the loss of precious
nutrients. 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 religious
beliefs (Mara, 2000). According to Hussain et al (2002) in view of these requirements, water
scarcity, dry land farming, hot climatic conditions and the high economic value of fresh water
resources, a great deal of research and development effort has been undertaken particularly in
Israel, for the reuse of wastewater. Furthermore, in the absence of too high a concentration of
waste from industrial sources, an efficient treatment option for conventional wastewater
treatment is to use primary sedimentation followed by secondary biological treatment using
high-rate biological processes.
9

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, hotel
lawns, and tourist areas. The criteria for unrestricted irrigation, contain the same helminthes
criteria for restricted irrigation, in addition to a restriction of no more than a geometric mean
concentration of less than or equal to 1000 faecal coliforms per 100ml treated effluents. These
guidelines as noted by Mara and Cairncross (1989) have been introduced to protect the health
of consumers who may eat uncooked crops such as vegetables and salads (Table 2.2). In
order 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 it
is discharged into the environment.
Restricted irrigation refers to the irrigation of crops not intended for direct human consumption
and there should be no more than one viable human intestinal nematode egg per liter implying
a greater than 99% treatment level (Table 2.2). This guideline has been introduced to protect
the health of field workers and to indirectly protect consumers and grazing cattle (Hussain et
al., 2002). Restricted irrigation can be applied to industrial crops (e.g., cotton, sisal, and
sunflower, wheat, barley, oats); and fruit trees, fodder crops and pastures (WHO, 1989). The
wastewater retention in stabilization ponds should be 8-10 days or equivalent helminthes and
faecal coliform removal (Hussain et al., 2002). The human intestinal nematodes include,
roundworm (Ascaris lumbricoides); hookworm (Ancylostoma duodenale and Necator
americanus); and whipworm (Trichuris trichiura) Mara (2000).
Apart from the biological considerations, nitrates and trace organic chemicals leaching to the
groundwater are considered to pose a potential health risk. However, there is very limited
documented evidence that these chemicals have been the cause of human disease (Cooper
1991). The leaching of salts, nitrates and microorganisms would be of little concern anyway in
areas where groundwater cannot be utilized because of high fluoride, iron, arsenic or salt
levels. 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 the
Shikoswe stream which passes through the Nitrogen Chemicals of Zambia (NCZ) plant and
finally into the Kafue river. The washing from the ammonium plant contain ammonia and
nitrates. These are not allowed to go in the storm water drains but go to the balance tank where
the effluent is neutralized by addition of lime before pumping to the ponds located 2 kilometers
out the plant. Some of the results from the study which was conducted in 1996 to 1997 by
Sinkala et al noted that the concentration of nitrates from NCZ were higher than the ECZ limit
of nitrate levels found in the effluents (Appendix XIII).
The effluent from Lee Yeast is used by the community between the factory and the Kafue
River, for vegetable growing. The effluent is known to contain low nutrient level except for high
Chemical 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 100ml
compared to ECZ limit. The Total Dissolved Solids (TDS) and Total Solids (TS) were also
higher than the ECZ limit for effluents and wastewater (Appendix XIV).
10

32. 2.9 Environmental Aspects
Mara (1977) and United States environmental protection agency (USEPA) (1992) indicated that
one of the negative environmental impacts associated with wastewater use is groundwater
contamination through high concentrations of nitrates, salts and micro-organisms. Faruqui et al.
(2002) indicated that environmental issues associated with untreated wastewater reuse are
contamination and clogging of soil particles. Egziabher et al., (1994) noted that environmental
contamination could be mitigated by treatment of domestic wastewater for unrestricted use.
WHO (1989) and Cornish et al. (1990) emphasized that unrestricted irrigation should have no
more than one thousand fecal coliform bacteria per hundred milliliter.
Eutrophication of water bodies would be one of the ecological impacts related to nutrient rich
drainage water, in the vicinity of wastewater agricultural areas and apart from those related to
buildup of heavy metals and toxic contamination of ecosystem components. Eutrophication
affects fish species and fish populations and so commercial fishing at such places is affected
(income loss). Another consequence of eutrophication is the disappearance of popular fish
species important for recreational fishing (welfare loss to general public) (Hussain et al., 2002).
2.10 Sociocultural Aspects
Peri-urban and urban agriculture is understood to be the agricultural activities undertaken
within the area immediately surrounding the city, where the presence of the city has an impact
on land use, property rights and where proximity to the urban market and urban demand drive
change in agricultural production (Hide et al., 2001). Furthermore, urban agriculture is one of
the several strategies used by the urban and peri-urban dwellers to cope with poverty. It is
mainly carried out by, but not restricted to, the urban and peri-urban poor in their efforts to meet
the food needs of their households. The sale of the produce is an integral part of the food
production and acts as a source of cash without cutting the household’s food supply. Revenue
accruing from sale of the produce is used for various purposes, such as purchase of household
requirements, education of children and health expenses.
The argument for reuse of wastewater is carried further by Khouri et al (1994) who indicated
that a physical, natural resources-oriented survey complemented by a socio-economic study of
the community affected by the reuse project would reveal the need for reuse. However, the
acceptance of wastewater reuse and the adoption of practices for its safe implementation will
be influenced by the sociocultural makeup of the people involved (that is the values, beliefs,
and customs that are concerned with water supply, sanitation, hygiene and other activities
related to water use). Khouri et al (1994) observed that there are few reconnaissance-type
studies that describe sociocultural aspects of reuse.
Furthermore, Hussain et al (2002) indicated that the social concerns about the potential risk of
wastewater irrigation originate from concerns regarding impacts on environmental quality,
public health and safety. These concerns may be addressed with appropriate educational and
public awareness programs. The cost of public education, awareness and demonstration
programmes can be used as a choice for the valuation of social impacts of wastewater
irrigation programmes, using awareness and sensitization educational models.
11