technical note f.3 environment department - world …...3. categories of municipal wastewater reuse...

Series EditorsRichard Davis

Rafik Hirji

Series EditorsRichard Davis

Rafik Hirji

Water Resources and EnvironmentTechnical Note F.3

Wastewater Reuse

Water Resources and EnvironmentTechnical Note F.3

Wastewater Reuse

Environment DepartmentThe World Bank1818 H Street, N.W.Washington, D.C. 20433, U.S.A.www.worldbank.orgFor information on these publications contact theESSD Advisory Service at [email protected] call 202.522.3773

Environment DepartmentThe World Bank1818 H Street, N.W.Washington, D.C. 20433, U.S.A.www.worldbank.orgFor information on these publications contact theESSD Advisory Service at [email protected] call 202.522.3773

The World BankThe World Bank

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The World BankWashington, D.C.

WATER RESOURCES

AND ENVIRONMENTTECHNICAL NOTE F.3

Wastewater Reuse

SERIES EDITORS

RICHARD DAVIS, RAFIK HIRJI

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A. Environmental Issues and LessonsNote A.1 Environmental Aspects of Water Resources ManagementNote A.2 Water Resources Management Policy Implementation: Early Lessons

B. Institutional and Regulatory IssuesNote B.1 Strategic Environmental Assessment: A Watershed ApproachNote B.2 Water Resources Management: Regulatory DimensionsNote B.3 Regulations for Private Sector Utilities

C. Environmental Flow AssessmentNote C.1 Environmental Flows: Concepts and MethodsNote C.2 Environmental Flows: Case StudiesNote C.3 Environmental Flows: Flood FlowsNote C.4 Environmental Flows: Social Issues

D. Water Quality ManagementNote D.1 Water Quality: Assessment and ProtectionNote D.2 Water Quality: Wastewater TreatmentNote D.3 Water Quality: Nonpoint-Source Pollution

E. Irrigation and DrainageNote E.1 Irrigation and Drainage: DevelopmentNote E.2 Irrigation and Drainage: Rehabilitation

F. Water Conservation and Demand ManagementNote F.1 Water Conservation: Urban UtilitiesNote F.2 Water Conservation: IrrigationNote F.3 Wastewater Reuse

G. Waterbody ManagementNote G.1 Groundwater ManagementNote G.2 Lake ManagementNote G.3 Wetlands ManagementNote G.4 Management of Aquatic Plants

H. Selected TopicsNote H.1 Interbasin TransfersNote H.2 DesalinationNote H.3 Climate Variability and Climate Change

Water Resources and Environment Technical Notes

Copyright © 2003

The International Bank for Reconstruction and Development/THE WORLD BANK

1818 H Street, N.W., Washington, D.C. 20433, U.S.A.

All rights reserved.

Manufactured in the United States of America

First printing March 2003

3

AuthorHugo van Gool

Technical AdviserStephen Lintner

EditorRobert Livernash

Production StaffCover Design: Cathe Fadel

Design and Production:The Word Express, Inc.

NotesUnless otherwise stated,all dollars = U.S. dollars.All tons are metric tons.

Cover photo byWalter Ochs, World BankReuse of drainage water,

near Fresno, California

This series also is available on theWorld Bank website

(www.worldbank.org).

CONTENTSForeword 5

Acknowledgments 7

Introduction 8As demand for water increases and new sources ofsupply become increasingly expensive to develop,there is a growing need to use water more than onceduring the hydrological cycle.

Reclaimed Wastewater Quality 9Because of the potential dangers to public health fromwastewater reuse, many countries have developedwater quality standards for different reuse purposes.These country standards are usually based on WHOstandards.

Reuse Applications 11Wastewater can be reused for irrigation, industrial re-cycling, groundwater recharge, recreational andenvironmental uses, nonpotable urban uses, and po-table reuse.

The Planning Process for Wastewater Reuse 19Planning for water reuse projects should be integrated,involving a number of disciplines, institutions, andbeneficiaries. Special emphasis should be given tomarket assessment for reuse options, and to publicacceptance of the reuse project.

Awareness and Education 22Public awareness and education programs are animportant aspect of water reuse project managementbecause of the potential sensitivities about reusingwater.

Economic and Legal Aspects of Wastewater Reuse 25Even when there appears to be a commercially ac-ceptable rate of return on the investment, there arelarge risks associated with water reuse schemes, partlybecause of the limited experience with these schemesand partly because of public perceptions. In thesecases, the government may need to accept part ofthe risk in order to attract private investment.

To be effective any legal regime should be accom-panied by appropriate standards and enforcementmechanisms, including financial incentives, sanctions,and ultimately possibilities of criminal prosecution.

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WATER RESOURCES AND ENVIRONMENT • TECHNICAL NOTE F.3

Conclusion 30Wastewater reuse is a potentially viable component of integrated waterresources management along with demand-side management and supplyaugmentation.

Further Information 31

Boxes1. Definitions 92. Agricultural use of treated wastewater in Jordan 113. Aquaculture in San Juan, Lima, Peru 144. Recycling of industrial effluents, Jamaica 145. Reclaimed city sewage as industrial water in Chennai, India 156. Groundwater recharge in Israel 167. Wastewater reuse in Cyprus 178. Wastewater reclamation for drinking water purposes in Windhoek, Namibia 189. Public evaluation of reuse alternatives in San Diego, California 21

10. Reuse of wastewater in the Gulf region 2311. Water education program, Queensland, Australia 2412. Managing the risks in the Virginia Pipeline Scheme, South Australia 2613. Collection of urban stormwater for potable water supply, Singapore 30

Figures1. Public participation program for water reuse 22

Tables1. Microbiological criteria for different applications of wastewater reclamation 102. An overview of various national standards for wastewater reused 10

for irrigation of food crops for human consumption3. Categories of municipal wastewater reuse and potential constraints 124. Summary of key elements in the planning of wastewater reuse 205. Percentage of respondents opposed to various types of water reuse (USA) 246. Examples of parameters for estimating construction costs of water supply 27

and reclaimed wastewater systems7. Examples of parameters for estimating operation and maintenance costs 28

of water supply and reclaimed wastewater systems

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WASTEWATER REUSE

FOREWORD

The environmentally sustainable development andmanagement of water resources is a critical andcomplex issue for both rich and poor countries. Itis technically challenging and often entails difficulttrade-offs among social, economic, and political con-siderations. Typically, the environment is treatedas a marginal issue when it is actually key to sus-tainable water management.

According to the World Bank’s recently approvedWater Resources Sector Strategy, “the environmentis a special ‘water-using sector’ in that most envi-ronmental concerns are a central part of overallwater resources management, and not just a partof a distinct water-using sector” (World Bank 2003:28). Being integral to overall water resources man-agement, the environment is “voiceless” when otherwater using sectors have distinct voices. As a con-sequence, representatives of these other water us-ing sectors need to be fully aware of the importanceof environmental aspects of water resources man-agement for the development of their sectoral in-terests.

For us in the World Bank, water resources man-agement—including the development of surface andgroundwater resources for urban, rural, agriculture,energy, mining, and industrial uses, as well as theprotection of surface and groundwater sources, pol-lution control, watershed management, control ofwater weeds, and restoration of degraded ecosys-tems such as lakes and wetlands—is an importantelement of our lending, supporting one of the es-sential building blocks for sustaining livelihoods andfor social and economic development in general.Prior to 1993, environmental considerations of suchinvestments were addressed reactively and prima-rily through the Bank’s safeguard policies. The 1993Water Resources Management Policy Paper broad-ened the development focus to include the protec-tion and management of water resources in anenvironmentally sustainable, socially acceptable,and economically efficient manner as an emerging

priority in Bank lending. Many lessons have beenlearned, and these have contributed to changingattitudes and practices in World Bank operations.

Water resources management is also a critical de-velopment issue because of its many links to pov-erty reduction, including health, agriculturalproductivity, industrial and energy development,and sustainable growth in downstream communi-ties. But strategies to reduce poverty should not leadto further degradation of water resources␣ or eco-logical services. Finding a balance between theseobjectives is an important aspect of the Bank’s in-terest in sustainable development. The 2001 Envi-ronment Strategy underscores the linkages amongwater resources management, environmentalsustainability, and poverty, and shows how the 2003Water Resources Sector Strategy’s call for usingwater as a vehicle for increasing growth and re-ducing poverty can be carried out in a socially andenvironmentally responsible manner.

Over the past few decades, many nations have beensubjected to the ravages of either droughts or floods.Unsustainable land and water use practices havecontributed to the degradation of the water resourcesbase and are undermining the primary investmentsin water supply, energy and irrigation infrastruc-ture, often also contributing to loss of biodiversity.In response, new policy and institutional reformsare being developed to ensure responsible and sus-tainable practices are put in place, and new predic-tive and forecasting techniques are being developedthat can help to reduce the impacts and managethe consequences of such events. The Environmentand Water Resources Sector Strategies make it clearthat water must be treated as a resource that spansmultiple uses in a river basin, particularly to main-tain sufficient flows of sufficient quality at the ap-propriate times to offset upstream abstraction andpollution and sustain the downstream social, eco-logical, and hydrological functions of watershedsand wetlands.

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With the support of the Government of the Nether-lands, the Environment Department has preparedan initial series of Water Resources and Environ-ment Technical Notes to improve the knowledgebase about applying environmental managementprinciples to water resources management. TheTechnical Note series supports the implementationof the World Bank 1993 Water Resources Manage-ment Policy, 2001 Environment Strategy, and 2003Water Resources Sector Strategy, as well as theimplementation of the Bank’s safeguard policies.The Notes are also consistent with the MillenniumDevelopment Goal objectives related to environmen-tal sustainability of water resources.

The Notes are intended for use by those withoutspecific training in water resources managementsuch as technical specialists, policymakers andmanagers working on water sector related invest-ments within the Bank; practitioners from bilateral,multilateral, and nongovernmental organizations;and public and private sector specialists interestedin environmentally sustainable water resourcesmanagement. These people may have been trainedas environmental, municipal, water resources, ir-rigation, power, or mining engineers; or as econo-mists, lawyers, sociologists, natural resourcesspecialists, urban planners, environmental planners,or ecologists.

The Notes are in eight categories: environmentalissues and lessons; institutional and regulatory is-sues; environmental flow assessment; water qual-ity management; irrigation and drainage; waterconservation (demand management); waterbodymanagement; and selected topics. The series maybe expanded in the future to include other relevantcategories or topics. Not all topics will be of inter-est to all specialists. Some will find the review ofpast environmental practices in the water sectoruseful for learning and improving their perfor-mance; others may find their suggestions for fur-ther, more detailed information to be valuable; whilestill others will find them useful as a reference onemerging topics such as environmental flow assess-ment, environmental regulations for private waterutilities, inter-basin water transfers, and climatevariability and climate change. The latter topics arelikely to be of increasing importance as the WorldBank implements its environment and water re-sources sector strategies and supports the next gen-eration of water resources and environmental policyand institutional reforms.

Kristalina GeorgievaDirector

Environment Department

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WASTEWATER REUSE

ACKNOWLEDGMENTS

The Bank is deeply grateful to the Government ofthe Netherlands for financing the production of thisTechnical Note.

Technical Note F.3 was drafted by Hugo van Goolof DHV Water, Amersfoot, The Netherlands. It wasreviewed by David Hanrahan and Hans Olav Ibrekkof the World Bank. Safwat Abdel-Dayem providedcomments and information for the case studies.

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INTRODUCTION

and is a feature of the new Rural Development Strat-egy. Technical issues associated with wastewaterreuse are explored in a number of World Bank pub-lications, such as Technical Papers 51 and 64. TheBank has invested in projects that contain a waterreuse component, and will continue to support so-cially and environmentally acceptable and economi-cally efficient reuse projects.

This document is one in a series of Water Resourcesand Environment Technical Notes that have beenprepared by the Environment Department to applyenvironmental management principles to waterresources management.

This Note provides an overview of water reuse ap-plications, the planning of water reuse projects, thedevelopment of public education programs, and theeconomics of reuse schemes. However, every indi-vidual country has its own legislation, cultural re-strictions, and financial opportunities, so this generalinformation needs to be customized for each cir-cumstance.

This Note begins with a definition of terms usedin water reuse management and an overview ofreclaimed wastewater quality criteria and stan-

dards. It then discusses pos-sible reuse applications,including irrigation, indus-trial use, groundwater re-charge, and potable use. Itdescribes a planning pro-cess for wastewater reuseand discusses public aware-ness and education pro-grams. The Note concludeswith discussions about theeconomics of wastewater re-use and some legal aspects.

As the demand for water increases and new sourcesof supply become more expensive to develop, thereis an increasing need to use water more than onceduring the hydrological cycle. Wastewater from pointsources—such as sewage treatment plants, indus-tries, and thermal power stations—can provide anexcellent source of reusable water because thiswater is usually available on a reliable basis, canbe accessed at a single point, and has a known qual-ity. These sources can be reused within the sameindustry or for completely different purposes. Waste-water reuse can not only help maintain upstreamenvironmental quality by reducing the demand fornew water sources, but can also offer communitiesan opportunity for pollution abatement by reduc-ing effluent discharge to surface waters.

In many parts of the world, wastewater has longbeen used in an unplanned way for agriculture. Theplanned reuse of wastewater is less common butincreasing, particularly in water-short regions.However, there are financial and social impedimentsto both planned and unplanned reuse. Treatmentto a desired quality and transport of the water tothe reuse location can make the project uneconomic;lack of social acceptance, particularly of reused sew-age flows, can also limit the adoption of reuse tech-nologies in countries wherethese technologies have notbeen traditionally applied.

The World Bank supports wa-ter reuse where it is an ap-propriate strategy. Thepotential of water reuse strat-egies for promoting waterconservation was recognizedin the Bank’s 1993 Water Re-sources Management Policy

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Wastewater irrigation fields, Hanoi, VietNam

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WASTEWATER REUSE

RECLAIMED WASTEWATER QUALITY

where wastewater is used to irrigate crops for hu-man consumption without any treatment or admin-istrative oversight. All these occurrences are termedunplanned reuse. In this Note, we will primarily beconcerned with planned wastewater reuse, wherethe water is diverted to a specific use in a controlledway, including management of water quality.

Unplanned reuse can sometimes act as an impedi-ment to planned reuse because water managersargue that there is no need to invest in wastewatertreatment and management when unplanned re-use is already occurring. However, the unplanneduses may not be the most efficient uses of the dis-charged water, particularly when environmentalimpacts are considered. There can also be obvioushealth and environmental implications from un-planned activities.

Wastewater reuse is closely related to water con-servation. Both approaches aim at making maxi-mum use of existing water supplies in order toreduce the need to tap new sources of high-qualitywater for both financial and environmental reasons.Municipal and agricultural water conservation aredescribed in Notes F.1 and F.2.

Many countries have developed guidelines and stan-dards to establish an appropriate level of treatment

Wastewater reuse (see Box 1 for terminology) is ac-cepted in principle in most industrialized and de-veloping countries, as well as in urban and ruralareas. In developing countries, almost all wastewa-ter reuse is applied to agricultural purposes. In gen-eral, planned reuse of municipal or industrial waste-water occurs in regions where the demand for wateris high and the supply is limited because of eitherlimited rainfall or environmental or health restric-tions on development of further water resources. Thebest-known regions are the Middle East, the south-western United States, Namibia, northern Africa, andAustralia. In large, dense urban areas where spaceis precious, wastewater is reused for nonpotablepurposes such as toilet-flushing, and stormwater isstored and used later for irrigation of lawns and parks.This occurs in Japanese cities such as Tokyo and inseveral counties in the greater Los Angeles area.

Wastewater has been reused in an unplanned wayin many parts of the world for centuries. For example,wastewater that is discharged to streams or infiltratesgroundwater systems without deliberate manage-ment activities is often reused for other purposes.There are many examples of river water being usedfor municipal purposes, discharged (often treated tosome extent) back to the river, and later withdrawnfor water supply for cities further down the sameriver. There are also many places, particularly in Asia,

BOX 1.DEFINITIONS

Wastewater reuse. Use of reclaimed wastewater for a beneficial use such as agricultural irrigation or industrial cooling.

Planned reuse. Direct or indirect use of reclaimed wastewater without losing control over the water during delivery.

Unplanned reuse. Use of wastewater after surrendering control of the water after discharge (including incidental use ofwater from a river downstream of a treated wastewater discharge point).

Wastewater reclamation. Treatment or processing of wastewater to make it reusable.

Direct reuse. Use of reclaimed wastewater without intervening discharge to a natural body of water.

Indirect reuse. Use of reclaimed wastewater with intervening discharge to a natural body of water.

Wastewater recycling. Use of wastewater that is captured and redirected back to the water-use scheme from which itoriginates. This technique is applied particularly in industry.

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TABLE 1.MICROBIOLOGICAL CRITERIA FOR DIFFERENT

APPLICATIONS OF WASTEWATER RECLAMATION

Application Fecal coliforms(geometric mean; no. per 100 ml)

Irrigation (restricted) No standards recommended

Irrigation (unrestricted) ≤ 1000*

Aquaculture ≤ 1000*(measured in the fish ponds)

Landscape irrigation ≤ 200*

Groundwater recharge 23**

Non-potable urban use 3-1000**

Recreation 2.2-1000**

Drinking water Must not be detectable*

* WHO standards** USA-EPA standards

TABLE 2.AN OVERVIEW OF VARIOUS NATIONAL STANDARDS FOR WASTEWATER REUSED FOR IRRIGATION OF FOOD CROPS

FOR HUMAN CONSUMPTION

Parameter Unit Saudi Arabia Jordan USA WHO1989 1985

ChemicalBOD mg/l 10 150 30 naCOD mg/l — 500 na naTSS mg/l 10 200 30 naOil and grease mg/l absent 8 na napH 6.0 - 8.1 na 6 – 9 6 – 9Chlorine residual mg/l na 0.5 1 na

HealthFecal coliforms MPN/100ml 2.2 1,000 200 1,000Nematodes eggs/l 1 < 1 na < 1

Saudi Arabia: Draft Standard, MAW 1989 na = not availableJordan: Jordan Standard 893/95USA: EPA recommendations

for wastewater reuse. In developing countries,where wastewater is often reused without treatment,any treatment of untreated wastewater represents asignificant health improvement. Applications rangefrom irrigation of crops not intended for human con-sumption (for which the criteria are absence of gross

solids and significant removal of parasite eggs) topotable reuse. In the latter application, secondarytreatment followed by filtration, nitrification, deni-trification, chemical clarification, carbon adsorption,ion exchange or membrane filtration, and disinfec-tion is recommended. Many countries base theirstandards on those published by the World HealthOrganization (WHO).

The WHO guidelines emphasize microbiologicalsafety because more than half of the world popula-tion is still exposed to waters that contain pathogenicorganisms to some degree. Chemical contaminantsnormally cause health effects after prolonged peri-ods of exposure. Of particular concern are chemi-cals that have cumulative toxic properties, like heavymetals and carcinogenic substances, for which sev-eral countries have developed their own standards.

Table 1 summarizes some microbiological criteriafor different wastewater reuse applications accord-ing to the WHO guidelines. Apart from health con-cerns, use of wastewater for irrigation of crops canlead to the buildup of toxicants-such as heavy met-als-in the soil, eventually rendering it unsuitablefor crop use. Table 2 provides an overview of somenational standards for selected chemical and mi-crobial parameters for wastewater reused for irri-gation of food crops for human consumption.

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WASTEWATER REUSE

Wastewater can be reused in many different ways.Table 3 provides a summary of the most commonpossibilities.

IRRIGATION

Worldwide, crop and landscape irrigation is themajor reuse purpose for domestic and municipalwastewater. Health risks and soil damage are mini-mal if the wastewater is treated and the necessaryprecautions are taken (see Box 2). However, inad-equate funding for operations and maintenance(O&M) in treatment plants in developing countriesmeans that irrigation with ostensibly treated waste-water carries many of the same risks as irrigationwith untreated effluent. In these circumstances,wastewater quality can be highly variable, and ag-ricultural workers and nearby communities can beexposed to pathogens and other contaminants whenthey believe they are safe.

The WHO guidelines for viable intestinal nema-tode eggs are set at less than 1 per liter for restrictedand unrestricted irrigation (arithmetic mean), andat less than 1,000 per 100 ml (geometric mean) forfecal coliform bacteria for unrestricted irrigation.A more stringent guideline—less than 200 fecalcoliforms per 100 ml—is appropriate for landscapeirrigation such as public lawns or schoolgrounds, where frequent direct contact by the publicis expected.

Treatment in wastewater stabilization ponds willproduce effluent complying with the WHO micro-biological guidelines with high reliability and at lowcost, although a relatively large area of land is re-quired. Another possibility is disinfection such aschlorination, although this will leave most helm-inth eggs unharmed and is costly. If the WHO guide-lines are not fully met, it may still be possible togrow selected crops without risks to the consumer,but protection for field workers is needed.

REUSE APPLICATIONS

BOX 2.AGRICULTURAL USE OF TREATED WASTEWATER IN JORDAN

In Jordan, the demand for water is high and sources are limited. Consequently, wastewater reuse is a central part ofnational water policy. The use of wastewater has grown rapidly from 4 percent of total water supply in 1990 to 6.5percent in 1995, and was projected to increase to 9 percent in 2000 and 16 percent in 2020. Groundwater abstrac-tions will be reduced during this period to eliminate over-abstraction and protect highland aquifers from salinization.

Treated wastewater has been used for agricultural irrigation in the Jordan River Valley since 1968. If current plans arefulfilled, the share of treated wastewater in the valley is projected to increase from 18 percent in 1998 to 34 percent in2020. This water is used to produce an additional winter crop and contributes to the irrigation of perennial crops. Inaddition, treated effluent—about 18,000 m3 per day from the Mafraq, Aqaba, Ramtha, Al-Samra, and Kufranjatreatment plants—is used to irrigate 600 ha of forage crops, forests, olives, and palm trees.

Health and environmental standards are a critical part of this program. Existing water quality standards have beenreassessed and N and BOD targets have been made more stringent. Wastewater treatment plants are being up-graded as part of the reuse activities. Water quality is now monitored independently of the treatment facilities by theRoyal Scientific Society. Laboratories have been upgraded and an early warning system has been instituted. In addi-tion, treated effluent is mixed with freshwater from the Talal dam before delivery to the irrigation districts to help mangewater quality.

There is widespread public support for wastewater reuse, although debate continues about the best agricultural usesfor the wastewater.

Sources: UNDP/FAP/World Bank/WHO. 1998. Wastewater treatment and reuse in the Middle East and North Africa Region: Unlocking thepotential. Report of a Joint mission to the Middle East Region. Subramanian, A. 2001. The Hashemite Kingdom of Jordan Water SectorReview Update. World Bank Report 21946-JO. Washington: The World Bank.

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Nutrients—such as nitrogen and phosphorus—inwastewater are beneficial to the plants and reducethe need for artificial fertilizers. However, mostnonindustrial wastewater streams contain nutrientsin excess of plant needs. Environmental problems,such as eutrophication of surface waterbodies (seeNote G.4) from agricultural run-off and infiltrationof nitrate to groundwater (see Note G.1), can occur

Irrigation with wastewater can result in soil andgroundwater pollution. The quality of irrigationwater is of particular importance in arid zones withhigh rates of evaporation because of the accumula-tion of salts in the soil profile. The salinity of thewastewater must be low enough to maintain favor-able osmotic pressures for plants to take up water(different crops have different salt tolerances).

TABLE 3.CATEGORIES OF MUNICIPAL WASTEWATER REUSE AND POTENTIAL CONSTRAINTS

Wastewater reuse categories Potential constraints

Agriculture and landscape irrigationCrop irrigation Surface- and groundwater pollution, if not properly managedCommercial nurseriesPark/School yards Marketability of crops and public acceptanceFreeways (median strips)Golf courses Effect of water quality, particularly salts, on soils, grasses, and cropsCemeteriesGreenbelts Public health concerns related to pathogens (bacteria, viruses, andResidential areas parasites)

Industrial recycling and reuseCooling Constituents in reclaimed wastewater cause scaling, corrosion,Boiler feed biological growth, and foulingProcess waterHeavy construction Public health concerns, particularly aerosol transmission of pathogens in

cooling water

Groundwater rechargeGroundwater replenishment Organic chemicals in reclaimed wastewater and their toxicological effectsSalt water intrusion controlSubsidence control Total dissolved solids, nitrates, and pathogens in reclaimed wastewater

Recreational/environmental usesLakes and ponds Health concerns from bacteria and virusesMarsh enhancementStreamflow augmentation Eutrophication due to nitrogen and phosphorus in receiving watersFisheriesSnowmaking Toxicity to aquatic life

Nonpotable urban usesFire protection Public health concerns on pathogens transmitted by aerosolsAir conditioningToilet flushing Effects of water quality on scaling, corrosion, biological growth, and fouling

Potable usesBlending in water supply reservoirs Constituents in reclaimed wastewater, especially trace organic chemicalsPipe-to-pipe water supply and their toxicological effects

Aesthetics and public acceptance

Health concerns about pathogen transmission, particularly viruses

Source: Metcalf & Eddy, Inc. (1991)

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WASTEWATER REUSE

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Wastewater ponds

if these sources are not diluted with other, lower-nutrient sources of water.

Heavy metals, persistent organics, and ions suchas boron, chloride, and sodium can harm crops andsoils. Heavy metals pose the greatest long-term en-vironmental risk because they accumulate in theupper soil. If a soil is highly permeable or if thegroundwater table is close to the surface, pollutionof groundwater can also occur. Many heavy metalsand pollutants such as chlorinated hydrocarbonsmay accumulate in sufficient concentrations in cropsto pose a serious hazard to the health of livestockand humans. In most cases, harmful levels of chemi-cals can be prevented by avoiding the use of un-treated wastewater and by pre-treatment ofindustrial discharges to the wastewater reclama-tion system. References providing guidance on man-aging harmful chemical constituents are providedin the Further Information section of this Note.

The health risk depends on the method of applyingthe irrigation water. Flooding involves the least in-vestment, but the greatest risk to field workers ifthe wastewater is not fully treated. Sprinkler irri-gation should be avoided if the WHO guidelines arenot fully met. Even with treated wastewater, sprin-kler irrigation may promote aerosol transmissionof viruses, although this is likely to be rare. Sub-surface irrigation gives the greatest degree of healthprotection, more efficient water use, and often higher

production yields. However, it is expensive, requiresprevention of clogging, and may cause soil salin-ization in arid climates unless sufficient freshwa-ter is added to leach the salts below the root zone(see Note E.1). This leachate fraction can be inter-cepted in sub-surface drains. Health protection re-quires regular monitoring of wastewater quality,crop quality, and medical surveillance of farmworkers.

Although the above discussion focuses on theplanned reuse of wastewater for agriculture, the re-ality is that in many parts of Asia, Central America,and Africa wastewater is used in an unplanned wayfor raising crops. These crops, which are central tothe livelihoods of farmers and of considerable im-portance to local communities, could not be grownwithout this source of water and nutrients. It is un-realistic to expect that these wastewaters will re-ceive treatment, so the issue is to understand howto continue to apply the effluent at minimal riskto both human health and soil productivity.Although research is under way in this area, thereare currently no well-founded guidelines for thesepractices.

AQUACULTURE

About two-thirds of the world yield of farmed fishis produced from ponds fertilized with wastewater.These fish represent a cheap source of animal pro-tein for poor people. Box 3 describes an economi-cally successful and safe example of wastewaterreuse for fish production. With a few exceptions,health aspects, treatment processes, and monitor-ing are comparable to those for irrigation. Some sub-stances may accumulate in the fish or aquatic plantsmore readily than in agricultural plants. However,few standards have been set for chemical contami-nants in wastewater reused for aquaculture.1 Keep-ing fish in clean water for at least 2 to 3 weeks beforeharvest will remove residual odors and reduce con-

1 Zweig, R.D., J.D. Morton and M.M. Stewart. 1999. Source

water quality for aquaculture: A guide for assessment.

Washington: World Bank.

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BOX 3.AQUACULTURE IN SAN JUAN, LIMA, PERU

Between 1985 and 1990, CEPIS (Centro Panamericano de Ingeniería Sanitaria y Sciencias del Ambiente, a researchcentre of WHO) ran a test program on the use of effluent from the San Juan wastewater treatment plant, 15 km south ofLima, for aquaculture. The effluent had a coliform concentration between 1,000 and 10,000 per 100 ml. It was used togrow tilapia (Oreochromis niloticus) in tanks designed for aquaculture.

No pathogenic bacteria or viruses could be detected in the fish as long as the concentration of coliforms in the aquac-ulture tanks was less than 10,000 per 100 ml. Production of tilapia is influenced strongly by temperature. In the warmestfour months of the year, tilapia could be produced with a final commercial weight of 250 g, at a density of 2 fishes/m2,from an initial weight of 60 g. In this way, an initial fish biomass of 1,000 kg/ha could be increased to 4,400 kg/ha duringfour warm months.

The revenues from the tilapia production were such that the investment in the aquaculture tanks proved to be aneconomically viable operation. Much of the cost of wastewater treatment could be recovered by this reuse option.

tamination from fecal microorganisms. When plan-ning or managing aquaculture, considerationshould be given to the effects of the discharge fromthe ponds on surface waterbodies and on ground-water.

INDUSTRIAL REUSE

Wastewater reuse is increasingly used to supple-ment or replace freshwater demands from indus-try. Industrial reuse has the twin advantages of agenerally continuous demand and the ability to uti-lize secondary treated wastewater. The major fac-tors that influence industrial wastewater reuseinclude availability and reliability of the watersource, the industry’s discharge requirement, andthe required water quality and quantity. Membranetechnologies (ultra filtration and reverse osmosis)

are being used increasingly, opening the possibil-ity of producing high quality water from conven-tionally treated wastewater.

Major uses in industry are cooling system augmen-tation, once-through cooling systems, process wa-ter, boiler feedwater, washdown water, andmiscellaneous applications such as fire protectionand dust control. Reclaimed water for industrial usemay be derived from recycling within the plant it-self (Box 4) or from secondary effluent from mu-nicipal wastewater treatment plants (Box 5).

Quality requirements for cooling towers are set bythe build-up of impurities in these closed-loop sys-tems as water is evaporated from the cooling tower.If concentrations of impurities are too high, scaledeposits will form on heat exchanger surfaces, low-ering the heat transfer capacity. Excessive impu-

BOX 4.RECYCLING OF INDUSTRIAL EFFLUENTS, JAMAICA

Bauxite/alumina companies have spearheaded the recycling of industrial effluent in Jamaica. The bauxite/aluminaindustry produces a waste product known locally as “ red mud,” which consists of over 70 percent water enriched withcaustic soda and organics. The waste is thickened to 28 percent solids and sprayed on a sloping dr ying bed. The dryingbeds are sealed to prevent infiltration of effluent to the groundwater. The liquid fraction is collected at the toe of thedrying bed and is channeled to a sealed holding pond. Pumps move the effluent from the holding pond back to theplant via a pipeline, where it is recycled through the process. The technology is now used at four bauxite/alumina plantsin Jamaica.

The system is very effective at reducing contamination of groundwater resources. Moreover, the project reduces annualfreshwater consumption by 4 to 5 million cubic meters. The main disadvantage is the large area required for the dryingbeds.

15

WASTEWATER REUSE

the wastewater stream is used for food process-ing, water quality must also meet potable waterstandards.

rity concentrations may cause accelerated corro-sion, sliming, or clogging. Chemical additives areused to control these problems. Control of Legionellabacteria is an increasingly important issue in cool-ing systems. These bacteria are not introduced spe-cifically by the reuse of wastewater, but may bepromoted by, for example, nutrients from reclaimedwater, which may accelerate the growth of theLegionella bacteria.

Once-through cooling involves substantial watervolumes, but does not require as stringent qualityrequirements as does cooling tower augmentation.The primary water quality concerns are slime andsuspended solids. Scaling and corrosion are usu-ally not a problem. Discharge water quality is es-sentially unchanged, except for a temperatureincrease.

Boiler feedwater has similar but more stringentquality requirements to cooling tower augmenta-tion. Removal of hardness is required to preventscale formation and deposits in boilers.

Process water quality requirements are highly de-pendent on the particular industry involved.Generally it is desirable to minimize the suspendedsolids concentration, water turbidity, and color.Other concerns are silica, aluminium, hardness,microorganisms and pH. Generally, the water qual-ity must meet near-potable water standards. If

BOX 5.RECLAIMED CITY SEWAGE AS INDUSTRIAL WATER IN CHENNAI, INDIA

The Chennai Metropolitan area, with scant rainfall, no river sources, and no major nearby watersheds, has long beenchronically short of water. Demand is increasing substantially due to increases in population and industrial development.Lately, water shortages have resulted in several stoppages of water supplies to industries, leading to cessation of produc-tion and related financial losses to industries. As a result, a fertilizer company has explored alternative sources, includingthe use of desalinated seawater and treated wastewater to provide process and cooling water for its operations. Thecompany has decided to reclaim water from city sewage using advanced wastewater treatment followed by reverseosmosis (RO) as an additional purification step. Wastewater used by the plant is treated to tertiary standards using anactivated sludge process, with the treated water being further reclaimed through excess lime addition, ammoniastripping, recarbonation, chlorination, multimedia filtration, activated carbon filtration, cartridge filtration, and reverseosmosis.

The capital cost of the entire project is estimated at $18 million. Due to the sewage reclamation project, 13,700 m3/dayof potable water, previously supplied to the fertilizer company, has been redirected to domestic use in the city.

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Spinach fields, wastewater irrigation

16


soil, although very soluble contaminants such asnitrate will still enter the groundwater. The effec-tiveness of this treatment is affected by tempera-ture, rainfall characteristics, and the physical andmechanical characteristics of the soil. In specialcases, some soils—such as those with high arsenicconcentrations—may contribute contaminants to theleachate. Direct injection to groundwater bypassesthis “natural soil treatment,” but there is evidencethat contaminants are removed from wastewater inthe aquifer matrix.

There are several advantages to ASR. The cost ofartificial recharge may be less than the cost of us-ing surface reservoirs; the aquifer serves as an even-tual distribution system, reducing the need forpipelines and canals; and the aquifer is not sub-jected to evaporation, to taste and odor problems,or to ambient pollution. The physical transition be-tween reclaimed wastewater and the water’s lateremergence as groundwater also provides an impor-tant psychological and aesthetic barrier for even-tual potable uses. However, AS R is sensitive toleakage or poor placement of injection wells. Fre-quent monitoring of groundwater quality is essen-tial, because it takes as much as 100 years for soiland groundwater to recover once it has been con-taminated.

RECREATION AND ENVIRONMENT

There are three broad uses of reclaimed water forrecreational purposes, each with their own specificquality requirements: primary body-contact suchas swimming and water-skiing; secondary body-

GROUNDWATER RECHARGE

Groundwater recharge is used to preserve ground-water levels, to prevent land subsidence, to protectcoastal aquifers against saltwater intrusion, and tostore reclaimed wastewater and surface runoff forfuture use (called aquifer storage and recovery, orASR). Recharge methods commonly used are sur-face spreading in basins, direct injection intogroundwater aquifers, and riverbank infiltration(Box 6).

A problem with recharge is that boundaries betweenpotable and nonpotable aquifers are rarely well-defined (see Note G.1). Recharging “nonpotable”aquifers carries the risk of contaminating high-qual-ity potable groundwater sources. Therefore, thehealth effects from prolonged exposure to low lev-els of contaminants must be considered, as well asthe acute health effects from pathogens or toxicsubstances. The lack of knowledge about the fateand long-term health effects of contaminants foundin reclaimed water—together with the extreme dif-ficulty of rectifying water quality problems once thegroundwater has been contaminated—means thata conservative approach should be taken when re-charging a nonpotable aquifer.

Because recharged water may be an eventual sourceof potable water, pre-treatment is necessary beforegroundwater recharge. Particular attention has tobe paid to contamination by pathogenic microor-ganisms. If the reclaimed wastewater is being in-troduced through soil infiltration, many constituentswill be removed during their passage through the

BOX 6.GROUNDWATER RECHARGE IN ISRAEL

Partially treated effluent has been used to recharge aquifers in the Dan region (Greater Tel Aviv) of Israel for almost 20years. The effluent is discharged into spreading basins, from which it percolates through the unsaturated zone until itreaches the groundwater system. Most of the remaining contaminants are removed from the effluent during this Soil-Aquifer Treatment (SAT) process. The water then moves laterally until it reaches a series of recovery wells that surroundthe recharge area. The recovered effluent is pumped to the Negev Desert and used for irrigation. With proper design,the zone between the recharge area and the recovery wells can be separated hydrologically from the rest of theaquifer, which can then continue to be used for potable supply.

Source: UNDP/FAP/World Bank/WHO. 1998. Wastewater treatment and reuse in the Middle East and North Africa Region: Unlocking thepotential. Report, Joint mission to Middle East region.

17

WASTEWATER REUSE

contact such as boating and fishing; and non-contact such as ornamental fountains and aquac-ulture.

The water quality criteria for primary body-con-tact are the most stringent. The water has to be aes-thetically attractive, and have acceptable physicalparameters such as color, taste, and odor. Most im-portantly, the water must be free of toxic compoundsand hygienically and microbiologically safe. Mostnational standards range from 100 to 1,000 fecalcoliforms per 100 ml. Water quality requirementsare less strict for secondary body-contact. The re-quirements for non-contact recreational water area reasonable temperature to sustain aquatic life, asuitable concentration of dissolved oxygen, a suit-able chemical quality, the absence of nutrients toavoid eutrophication, and reasonable microbiologi-cal quality. The fundamental concern is publichealth, but the biological health of receiving watermust also be considered in recreational/aestheticreuse. Cyprus illustrates a special case where thesensitivity of tourists to wastewater reuse had to beconsidered (Box 7).

NONPOTABLE URBAN USES

Wastewater has long been used for nonpotable ur-ban reuse in Japan. For example, treated wastewa-ter is used in 19 buildings in a development in theShinjuku District of Tokyo for toilet flushing. Notonly does this reduce the need for water supply for

this high-density urban renewal, but it reduces thepressure on existing sewerage and wastewater treat-ment facilities, which were not designed to handlethe increased flow of wastewater.

Similar uses of wastewater are being investigatedin several pilot projects in Europe and China, mostlyas locally treated “grey” water (that is, all house-hold wastewater except that from toilets) for toiletflushing and washing machines. Special attentionis given to the possibility of biological contamina-tion through aerosols, with tentative microbiologi-cal standards being established for Cryptosporidium(< 2 organisms per 10 litres), Giardia (< 5 organ-isms per 10 litres), and entero-viruses (< 1 organ-isms per 10 litres).

POTABLE WATER

Potable water can be reused directly or indirectly.Direct potable water reuse is a “pipe to pipe” con-nection between the reclaimed water treatment fa-cility and the potable water distribution system. Inindirect potable water reuse, the highly treated re-claimed water is introduced to a surface water orgroundwater system that is ultimately used as apotable water supply. The reclaimed water isblended with water from the natural system, andthere may be a significant delay between the pointof reclaimed water discharge and the point of with-drawal into the potable water treatment facility. Thechoice of direct or indirect potable reuse is based

BOX 7.WASTEWATER REUSE IN CYPRUS

By 2010, the Republic of Cyprus expects to have developed all readily available ground and surface water resources.The government has ambitious plans to use wastewater for agricultural production, particularly around Limassol, Nicosia,Larnaca, and AyiaNapa/Paralimni. However, the countr y’s economy is heavily dependent on tourism, an industry wherereuse is also widely practiced. More than 250 package treatment plants service hotels and tourist sites. About 75percent of these use tertiary treatment and reuse the water for landscaping around the tourist sites. Tourists are particu-larly sensitive to health and aesthetic issues, and great care is taken to make sure that wastewater is used safely andwith minimal environmental impact around the tourist sites.

For this reason, the tourist industry opposed the introduction of the discharge of treated wastewater in coastal areas. Thisopposition led to the delay and eventual cancellation of a proposed treatment plant and ocean outfall for wastewaterfrom Larnaca. The wastewater was eventually collected, treated, and reused for nonpotable uses around tourist areas

Source: UNDP/FAP/World Bank/WHO. 1998. Wastewater treatment and reuse in the Middle East and North Africa Region: Unlocking thepotential. Report, Joint mission to Middle East region. See also World Bank. 1996. Environmental Assessment Sourcebook Update 13.Washington: World Bank.

18


on technical factors—such as quality criteria, costs,distribution requirements, treatment technologies,and necessary reliability—and nontechnical factorssuch as public acceptance, and legal requirements.

The most serious problem of direct potable reuse ispublic acceptance of water with a wastewater ori-gin, particularly chronic health effects that mightresult from ingesting the mixture of inorganic and

organic (bacteria, viruses, protozoa, and helminths)contaminants that remain in the water, even afterthe most advanced treatment methods. Box 8 pro-vides an example of direct reclamation in a water-deficient environment.

There are several means for indirect, reclaimedwater to be introduced into water supplies. The mostcommon are ASR (as discussed earlier), and sur-

BOX 8.WASTEWATER RECLAMATION FOR DRINKING WATER PURPOSES IN WINDHOEK, NAMIBIA

In the 1960s, the city of Windhoek was approaching the limit of its conventional drinking water sources (groundwaterand surface water) and was forced to implement direct reclamation of wastewater for potable use in 1968. Twenty-fiveyears later, the existing capacity of 4,800 m3/d was exceeded by the demand, and the existing plant was extended to21,000 m3/d in 1998. From the start, it was clear that reclamation could only be successful if three important matterscould be controlled: diversion of industrial and potentially toxic wastewater; wastewater treatment to produce anadequate and consistent effluent quality; and effluent treatment to produce acceptable potable water. As a safe-guard against pathogens, a maturation pond and multiple chlorination steps were applied. As shown in the schematicbelow, the wastewater is treated in two separate treatment plants—a conventional biological wastewater treatmentplant (activated sludge) and a wastewater reclamation plant.

Wastewater reclamation plant in Windhoek, Namibia

The cost of reclaimed potable water is high compared to potable water from conventional sources due to the highcosts of chemical dosage. For this reason, the reclamation plant was operated on an intermittent basis. For the 1968-91 period, the average production was 27.3 percent of the plant capacity, contributing only 4 percent to the totalwater supply in Windhoek. In 1982, after a series of dry years, the plant ran at 80 percent of its capacity.

From the start of the project, an extensive monitoring program, representing 20 percent of the total production cost,was conducted. Samples were taken at different points—varying from the treatment plant to consumer taps—andepidemiological research on the health effects of the consumption of water focused on diarrheal disease and hepatitisA. The study showed that a marginally lower incidence of diarrheal disease was found in the population receiving directpotable reuse water. The hepatitis study concluded that consumption of direct potable reuse water did not result in theoccurrence of hepatitis A infections.

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secondaryeffluent

tertiaryeffluent

Reactor

alum lime

Dissolvedair flotation

Sandfiltration

Reactor Settling

Drying bedsActivated

Carbon

CI2 CI2

Breakpointcombination

19

WASTEWATER REUSE

face water augmentation by direct discharge to araw water storage reservoir or an intervening streamfollowed by withdrawal for use. Surface water aug-mentation with reclaimed wastewater must be donecarefully and with thorough evaluation of severalimportant considerations, such as the proximity ofa reclaimed water discharge point to the supply in-take. The attenuation of pollutant concentrationsfrom biological degradation, adsorption, sedimen-

tation, and exchange of contaminants needs to beassessed between these two points, preferablythrough water quality models. Short-circuiting ofreclaimed water to the water supply intake shouldbe avoided. The amount of effluent relative to theambient water flows has to be considered for bothaverage and extreme conditions, such as those thatoccur during drought periods.

THE PLANNING PROCESS FOR WASTEWATER REUSE

Wastewater reuse plans, programs, and projects notonly include technical implications, but can haveimportant environmental, economic, social andpublic health impacts. Planning water reuse projectsshould be integrated, involving a number of disci-plines, institutions, and beneficiaries. Special em-phasis should be given to market assessment forreuse options, and to public acceptance of the re-use project.

Because of the complexity and sensitivity of waste-water reuse, the planning process should occur ina number of phases from a broad “rough-sketch”stage to the technical design and construction:n Scope, objectives and area boundaries of the

projectn Preliminary investigationsn Screening of potential marketsn Detailed evaluation of selected alternativesn Implementation plan for most feasible alterna-

tive(s)n Agreements with users and institutionsn Designn Constructionn Operation and evaluation.

The first four phases define the feasibility of the re-use project. The remaining five phases cover theactual implementation of the project, following moreor less the normal process of technical facilities plan-ning. This section of the Note includes guidelinesfor the first four phases. Table 4 summarizes theelements to be addressed in these phases; Box 9provides an example of the operation of these steps.

SCOPE, OBJECTIVES, ANDBOUNDARIES OF THE PROJECT

Reuse projects can be incorporated in nationalmasterplans, basinwide programs, to locally de-fined projects. Every project should start with adefinition of its scope and objectives. This shouldinclude a sketch of the present and desired futuresituation in order to clarify the priorities of theobjectives. In principle, a water reuse project ismulti-purpose, because it is at least both a pollu-tion control project and a water supply project (po-table or nonpotable). However, one objective maybe more important than the others. For example,public health will be the dominating issue with re-use of raw sewage in and around many cities indeveloping countries. A clear definition of the mainobjectives simplifies the screening and evaluationphases. Nevertheless, to enable a broad perspec-tive in the following phases, it is recommended thatsecondary effects be identified in the first phase asmuch as possible, including possible effects out-side the project area.

PRELIMINARY INVESTIGATIONS

This phase is dedicated to gathering backgroundinformation, gaining insight into the present situa-tion, and listing all potential wastewater sources forreuse and all potential markets for the reclaimedwater. Typically the following elements need to beaddressed in a general way:

20


for which specific technical, social, legal and envi-ronmental data are all necessary. This phase is alsoused to establish contact with relevant institutions,define the level of involvement of the different in-stitutions (partnership, influence on decisions, ad-visory, to be informed only), and draft a plan forpublic participation and communication. In somedeveloping countries, this phase may also includethe development of specific institutions or a regu-latory framework.

SCREENING OF POTENTIAL MARKETS

In this phase, the options identified in the preced-ing phase are reduced to a limited number, prefer-ably between two and four, to reduce the cost of thedetailed evaluation in the following phase. If thenumber of options identified is large (greater than10), a first quick screening should be done by a teamof experts, based on their evaluation of the generalinformation gathered in the preceding phase. Thenext screening should be based primarily on a com-

n Local sources of (treated) wastewater suitablefor reuse

n Potential local markets for reclaimed watern Present uses of other (fresh) water resources in

the arean Present and future water costs of freshwater in

the arean Public health considerations associated with re-

usen Potential environmental impacts of reusen Laws, regulations, and legal liabilities affecting

reuse optionsn Identification of local and national institutions,

involved in regulation, permits and/or advicen Sources of funding available to support the re-

use programn General survey of attitudes, (potential) support

and opposition of the public, as well as culturaland religious concerns.

The information gathered should support thescreening of alternatives in the following phases,

TABLE 4.SUMMARY OF KEY ELEMENTS IN THE PLANNING OF WASTEWATER REUSE

Planning phase Technical Institutional Social Environmental Marketassessment

Scope and objectives nMain objectives nPositive nPositivenProject area effects effects

Preliminary investigations nPresent situation nLaws and nSurvey of nPotential nPotentialnWastewater regulations attitudes of impacts markets for

sources suitable n Institutions and the public reclaimedfor reuse their level of water

involvement

Screening of potential nEstimation and nPublic nRequirementsmarkets comparison information of user groups

of costs program matchingnStakeholders with

and their level reclaimedof involvement water

Detailed evaluation nOptimization of nOwnership and nStart of public nEnvironmental nRequirementsalternatives management education impact and interest

assessment of each usergroup

21

WASTEWATER REUSE

be used in the screening process (for example, thepossibility for future expansion, technical and/orinstitutional complexity, reliability, use of energy,production of wastes, and expected user accep-tance).

A public participation and information program hasto be defined, based on the survey information fromthe preceding phase (Box 9). This is discussed ex-tensively later in this Note.

DETAILED EVALUATION OFSELECTED ALTERNATIVES

The most promising alternatives from the preced-ing phase are evaluated in more detail, including adetailed survey of potential users, technical opti-mization, more refined calculation of investmentsand operational costs, and a more refined compari-son between costs of reclaimed water and costs offreshwater systems. As far as possible, the follow-ing information should be obtained from each po-tential user:

parison between the cost of freshwater delivery toa market and the cost of reclaimed water to the samemarket, for which the following steps have to bemade:n Estimation of the water quality and quantity re-

quired for each type of applicationn Expectation of the regulatory requirements for

each type of applicationn Estimation regarding probable reclaimed wa-

ter quality that would be available in the futurewith various levels of treatment, and compari-son with regulatory and user requirements

n Estimation of the quantity of reclaimed wateravailable and the ability to meet fluctuatingdemand for each type of application

n Estimation of the present and future cost offreshwater for each user or group of users

n Estimation of the cost of reclaimed water treat-ment and distribution for each type of appli-cation.

Apart from the comparison of costs, other criteriaderived from the technical, social, and environ-mental data gathered in the preceding phases can

BOX 9.PUBLIC EVALUATION OF REUSE ALTERNATIVES IN SAN DIEGO, CALIFORNIA

Planning of a wastewater reclamation and reuse project in the San Diego Clean Water Program included publicinvolvement from the early stages of assessing the system options to ratifying the selected alternative.

The initial technical evaluation identified 21 alternatives, which were reduced through further analyses to seven beforepresentation to the public. A survey of the general population in the greater metropolitan area of San Diego wasconducted in 1989. A total of 600 respondents, selected to represent the area’s residents, were interviewed to assessattitudes toward various forms of reuse, assess the seven alternatives and their associated costs, and obtain an assess-ment and ranking of each alternative.

Concurrent with the interview process, technical planners per formed a comprehensive analysis of the seven alterna-tives. The technical and public rankings agreed on four alternatives, with both groups ranking the same alternative astheir first choice.

Based on these results, the Clean Water Program proceeded with development of plans and specifications for thepreferred alternative. Two more surveys were conducted, each using 600 new respondents and focusing only on theselected alternative. These surveys confirmed the favorable evaluations of the first survey, and indicated a stronginclination to support public ratification of the program.

The San Diego survey illustrates several interesting points:n Technical findings and public opinion may be in concert with one another when reuse alternatives are being

considered.n Preliminary surveys reliably predicted project acceptance for the reuse program.n When the public is involved in the planning process in a substantial way from an early stage, it is more likely that

funding will be obtained for the project.

22


n Interest in using reclaimed watern Potential uses of reclaimed water (e.g. type of

crops, type of process)n Present and future quantity needsn Timing and reliability of needsn Quality needs and constraints on specific usesn Modifications to on-site facilities necessary to

convert to reclaimed water, and estimate of as-sociated costs

n Fraction of current demand that could be re-placed by reclaimed water.

This detailed information is used in the basic de-sign and technical optimization of the alternatives.The technical aspects should include reliability of

systems, application of multiple barriers in the re-moval of substances, and functioning duringemergencies. During this phase, ownership andmanagement of installations, sale of reclaimedwater, and competition elements have to be dis-cussed by the institutions involved. The public in-formation program starts implementation with thefirst steps of targeted education activities for thegeneral public. Also, the process of environmentaland/or public health impact assessment is identi-fied, which may be necessary for obtaining permits.A first outline of the elements to be discussed inthe impact assessment process can be used in theevaluation of alternatives and the final assessmentof the feasibility of the reuse project.

Public awareness and education programs are aparticularly important aspect of water reuse projectsin both industrialized and developing countries.There is a close association in the public’s mindbetween water quality and health, while there is ageneral lack of knowledge of wastewater treatmentprocesses. Modern public information, education,and participation programs should be designed to

FIGURE 1.PUBLIC PARTICIPATION PROGRAM FOR WATER REUSE

GeneralSurvey

Specific UsersSurvey

AlternativesIdentification &

Evaluation

Plan ofStudy

Plan Selection

ProjectImplementation

PublicMeetings

CustomerSpecific

Workshops

Customer-SpecificInformation

Program

Public Notification/Involvement

Public Notification/Involvement

AWARENESS AND EDUCATION

meet direct and obvious needs of the public. More-over, accountability and transparency of agenciesand agency activities instills public trust and im-proves public perceptions; this is essential to over-come major social and cultural barriers.

Figure 1 shows a flowchart of a general public par-ticipation program. Education and information is

23

WASTEWATER REUSE

not a single intervention, but an ongoing processthat runs through all stages of the project. Publicmeetings and workshops provide a way to educatethe public about a project, obtain information, andascertain the level of support. A general survey maybe helpful in identifying the level of interest, poten-tial customers, and any initial concerns that thepopulation might have. Specific surveys can serveto confirm earlier results and monitor the effective-ness of the ongoing education program. After aproject is completed and is technically successful,the goal of education activities is to influence theusers to maximize benefits by making full use ofthe facilities (Box 10).

Surveys in the United States over the last two de-cades indicate a high degree of public support forwater reuse programs, although the public’s reluc-tance to support reuse increases as the degree ofhuman contact with the reclaimed water increases.Several surveys also indicate that socioeconomic andenvironmental factors play a role in the perceptionof water reclamation. Acceptance tends to increase

with income and education. Table 5 provides anoverview of average responses from the differentsurveys.

The results from San Diego, described above in Box9, have been found to be true elsewhere. Water re-use projects show that the best results are obtainedwhen communities are involved early in the plan-ning and execution of projects and are encouragedto play an active and decisive role. Since social, eco-nomic, educational, and other conditions differ fromone community to another, the form and degree ofpeople’s involvement may vary. Nevertheless, it isimportant to encourage all relevant groups withina community to participate, irrespective of ethnicorigin, religion, social or economical status, orgender.

In many countries, it will require significant changesin policy, together with the reorganization and re-orientation of agency staff, to switch from centrallymanaged projects to community-based projects. Italso requires considerable effort and funding to

BOX 10.REUSE OF WASTEWATER IN THE GULF REGION

In the arid countries of the Middle East, where water demand outstrips supply, conserving existing water resources andusing innovative technologies to tap new sources is a priority. Although desalination has long been accepted as a newsource of potable water, the reuse of treated wastewater for agriculture and industr y has met with regulatory and culturalresistance.

Stringent water quality standards have been established, which many suppliers feel are so restrictive they discourage thereuse of treated effluent. Even when wastewater reuse has been permitted, problems have arisen. Inadvertent or unin-tended uses of wastewater have occurred, sometimes when the public is unaware of the meaning of signs indicatingwastewater transport and points of discharge. Also, the hot dr y climate encourages the aerosol transmission of virusesand disease when inadequately treated wastewater is used for sprinkler irrigation. These health hazards are a particularconcern during pilgrimage times, when the Holy Shrines of Mecca and Medina are visited by millions of worshippers,.

Islamic religious beliefs, which require cleanliness and “purity” of water, also affect attitudes toward wastewater reuse.Since the introduction of wastewater reuse programs, the fulfillment of religious requirements for water purity has been anissue of debate among religious scholars in the Islamic world. After a thorough investigation, including both scientists andspecialists, the Council of Leading Islamic Scholars of Saudi Arabia expressed its approval in 1978 of wastewater reuse,after proper treatment, for all purposes. However, they stated that they preferred to avoid using treated wastewater fordrinking purposes.

Faced with the extent of the water shortage and reassured by this ruling, wastewater is now used for a wide range ofpurposes in Saudi Arabia. For example, 9,000 ha of date palms and forage crops near Riyadh and municipal parks inJeddah, Jubail, Riyadh, and Taif are now irrigated with treated wastewater

Source: Abderrahman, W.A. 2001. “Water demand management in Saudi Arabia,” in Faruqui, N.I., A. K. Biswas, and M. J. Bino, eds., WaterManagement in Islam. Tokyo: UN University Press.

24


engage the community in a participatory approach,and to support them so they are able to participateeffectively. It is clear that political commitment atthe highest level is required to make such impor-tant changes in project approach. Early commu-nity participation will provide an insight intocommunity attitudes regarding a water reuse projectand, if necessary, allow time for education to in-crease awareness of the benefits of the project.

Some communities participate only in advisorycommittees, while others may make a financial con-tribution or contribute labor to the implementationof a project. A citizen advisory or participation com-mittee may help ensure that a project’s technicalstaff has not neglected an aspect of the project thatcould build public confidence.

Media coverage may be important to a project, de-pending on the degree of development of a coun-try. Background information should be providedto the media. It is important that community lead-ers are made aware of a proposed reuse projectand its benefits prior to the media being informed.Stakeholder briefings may be a useful strategy toaccomplish this objective, especially for those whomay be contacted by the media for comments aboutthe proposed project. Further, in a stakeholderinterview other individuals in the communitywho have a logical interest in the project can beidentified.

THE IMPORTANCE OFTERMINOLOGY

It is important to use water reuse terminology care-fully with the public. For example, “water” and“wastewater” suggest radically different propertiesand are perceived differently by the general public.One should not hide the fact that recycled water is

BOX 11.WATER EDUCATION PROGRAM, QUEENSLAND, AUSTRALIA

The Australian Water & Wastewater Association, together with the Sunshine Coast Environment Council, has developed aWater Education Program. The program will try to improve public knowledge of wastewater, including what is in it, andhow it can be treated and monitored. It will not “market ” the concept of reuse as potable water, but rather providepeople with knowledge and understanding, so they have an informed opinion.

The program will avoid describing the quality of effluent by the amount of treatment it receives; its quality is whatmatters, not its history. It will be aimed at all ages and groups in the community and recognize all learning styles. Only asmall proportion of residents are sufficiently motivated to come to meetings; all others have to be reached in moresubtle ways. Two of the problems that will need to be addressed are the reluctance of water managers to consult withthe community about future water supplies, which results in the community being unaware of the need for reuse, andgaps in knowledge about some of the health issues.

Terminology is of critical importance. In the past, the water industry seems to have had a penchant for negativeterminology. Now, the word “disposal” has almost disappeared from the vocabulary. Water is now discharged if it can’tbe reused.

TABLE 5.PERCENTAGE OF RESPONDENTS OPPOSED TOVARIOUS TYPES OF WATER REUSE (USA)

Type of reuse percent opposed to reuse

Drinking water 55

Food preparation 50

Bathing at home 35

Swimming 21

Laundry 21

Irrigation of vegetablecrops, vineyards etc. 12

Toilet flushing 5

Irrigation of lawns, parks,golf courses etc. 4

25

WASTEWATER REUSE

produced from wastewater (Box 11), but public dis-cussions should carefully distinguish between“wastewater reuse” and “treated wastewater reuse.”Omission of the latter term could give rise to theimpression that raw sewage will be used, when infact the wastewater will be treated to a high stan-dard, making it comparable to freshwater.

In general, professionals implementing water re-use schemes need to be aware of the perceptions oftheir target audience. Technical people often play

it safe by using conservative, worst-case scenarioswith likely risks couched as deaths-per-million. Thiscan give a wrong impression to many people, be-cause they wonder if that one case could apply tothem. Personal control over risks is an importantfactor. People are willing to assume more risk if theyperceive that they have control, such as when driv-ing an automobile. Risks that are outside anindividual’s control are met with considerablygreater resistance, even if the risks are much lowerin comparison with voluntary risks.

ECONOMIC AND LEGAL ASPECTS OF WASTEWATER REUSE

BENEFITS AND COST FACTORS

Wastewater reuse projects are diverse and can in-volve improvements in sanitation such as waste-water collection, water pollution control such asreduction of waste discharges in streams, alterna-tive water production, and social or economic im-provements such as the development of anagricultural area. The benefits to be included in aneconomic analysis will depend on the purpose ofthe project. For example, in a project where nowastewater infrastructure is present and where thegoal is to use the wastewater for agricultural pro-duction in an area where freshwater sources arescarce, the cost of the wastewater reuse systemwould include all elements of the wastewater col-lection system, wastewater treatment, transport, anddistribution to the users. The benefits would includehealth improvements (for example, reduction ofmedical costs), environmental benefits such as re-duction of oxygen depletion in streams, social/eco-nomic benefits, an increase in agriculturalproduction, and a reduction in the cost of fertilizer.

In developing countries, part of the wastewater col-lection system may often be present, but wastewa-ter treatment typically is absent or inoperative dueto lack of funds. Wastewater treatment may not befelt by the government to be a priority, if direct short-term benefits are not obvious. However, if the waste-water can be reused for agriculture or aquaculture,then the costs of wastewater treatment can be in-

cluded as part of irrigation/aquaculture costs (seeBox 2). The complete wastewater treatment plantcan be defined as a production unit for irrigationwater, and can be designed and built to meet thestandards for the proposed use rather than for dis-charge into receiving waters. In most other cases(for example, wastewater reuse as potable or non-potable urban water, or for industrial purposes), al-ternative freshwater sources will be present orplanned, and so the evaluation of costs and ben-efits will involve a comparison of alternatives. Toprevent overestimation of the cost of the wastewa-ter reuse alternative, the following costs should beincluded when assessing the alternative:n Wastewater treatment and dischargen Collection and transport of wastewater to the

wastewater treatment plantn Wastewater treatment to standards for disposal

to receiving watersn Transport of effluent to discharge locationn Cost of effluent discharge (pollution taxes should

be set by government).

The following should be included when assessingthe reuse scheme:n Wastewater reuse alternativen Wastewater treatment to reclaimed water stan-

dardsn Transport and distribution to the users.

In this way, any savings on effluent transport to thereceiving waters, in discharge taxes, and in (addi-

26


tional) treatment to meet increasingly stringent dis-charge limits are measured as benefits. An exampleis the use of advanced wastewater treatment to re-move nutrients before discharge into surface wa-ter susceptible to eutrophication. Such advancedtreatment can be avoided if effluent is reused, es-pecially for agriculture or aquaculture, where thenutrients are beneficial. If the treated water is in-tended for potable use and drinking water or otherfreshwater infrastructure is already present, thenthe cost of the reuse system should be compared tothe cost of the expected increase in capacity of thepresent water system if the reuse system is notimplemented.

Increasingly, the role of governments is seen ascoordinating and regulating water infrastructureprojects; private sector finance is sought to buildand operate these schemes. This is also true withwastewater reuse schemes. However, even whenthere appears to be a commercially acceptable rateof return on the investment, there are large risksassociated with water reuse schemes, partly becauseof their novelty and partly because of public wari-

ness of wastewater reuse. Where the treated waste-water is intended for agriculture, there is the addi-tional risk because of the inter-annual variabilityin demand from agricultural users. In these cases,the government may need to accept part of the riskin order to attract private investment. Box 12 pro-vides an example of public-private sector coopera-tion in a wastewater reuse scheme.

ECONOMIC AND FINANCIAL ANALYSES

The economic evaluation of wastewater reuseprojects seeks to determine the net benefit to soci-ety of the proposed investment. The tools commonlyused are:n Net-Present Value (NPV). If all or most of the ben-

efits can be expressed in financial terms (as de-scribed in the preceding paragraph), the netpresent value represents the present value ofthe benefits minus the present value of the costs.If NPV is greater than zero, the activity has anet economic value. It is also possible to com-pare the NPVs of different alternatives (Maxi-

BOX 12.MANAGING THE RISKS IN THE VIRGINIA PIPELINE SCHEME, SOUTH AUSTRALIA.

The Virginia area near Adelaide, Australia, has used groundwater for horticulture for over 50 years. In recent years, wateryields have been dropping and salinity has been increasing. At the same time, the operators of the major wastewatertreatment plant for the nearby city of Adelaide (1 million people) were required by the Environmental ProtectionAuthority to reduce nitrogen concentrations in their discharges to coastal waters. They decided that the most cost-effective solution was to sell their wastewater to the horticulturalists at Virginia, 120 km away.

The government took the roles of promoting and demonstrating large-scale wastewater recycling and providing start-upfinance. A private sector operator, who was granted the rights to build and operate the project, supplied the capitalinvestment. The operator, Euratech, a pipe manufacturer, was selected early in the project to give them the opportunityto negotiate agreements with all parties from the beginning. Euratech assumed the construction, financing, andoperations risks. The horticulturalists faced risks from the unknown effects of the wastewater quality on their crops. Bothoperator and horticulturalist risks were reduced by the government, which provided some of the project developmentcosts, assisted with the necessary approvals, and undertook research into the suitability of the water for horticulture. Thewastewater plant operators faced the risk that, if the reuse scheme did not achieve its targets, they would have to incurthe additional expense of constructing nitrogen removal facilities. The contracts between the parties specified the waterquality standards for pathogens, metals, and salinity, and the responsibilities for maintaining the standards.

Once the scheme was operational, the horticulturalists were able to obtain contracts with the major Australian super-market chains to accept produce grown with recycled wastewater. They are also selling their produce to Asia.

Source: Croke, G., B. Kracman, and C. Wright. 1999. “The Virginia Pipeline scheme, Adelaide South Australia - Commercialsolutions to environmental problems,” in Medina, J. A., Proceedings of the 17th International Congress on Irrigation andDrainage, Granada, Spain, pp. 93-106.

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WASTEWATER REUSE

mum Net-Present Value Criterion).n Cost-Effectiveness Analysis. Cost-effectiveness

analysis can be used if it is difficult to expressthe benefits in financial terms. It is a system-atic method to compare the costs of alternativesthat produce the same result. This technique re-quires a single base criterion for the evaluation.

n Impact Analyses or Multi-Criteria Analysis. Ifbenefits are difficult to express in financial termsand impacts and results of projects are diverseand difficult to express as a single base crite-rion, impact analysis or multi-criteria analysiscan be used. A number of positive and negativeimpacts are compared qualitatively, includingcosts, and weighed in a more or less subjectivemanner.

Financial analysis refers to the cost and benefits fora specific user or participant, and determines thefeasible price of the product. Even if the reuse projectproves to be economically feasible, compared to thecost of developing new freshwater sources, it may

be necessary to set the price of the water lower thanthe price needed to cover costs. In most instances,the price should be set lower than the (sometimessubsidized) drinking water price in order to makethe reuse water attractive for the potential users,particularly during the first few years of operation.Grants, subsidies, and support from national or in-ternational organizations can be employed. For long-term sustainability, however, prices shouldeventually be raised to ensure that capital and op-erating costs are covered.

ESTIMATION OF COSTS

The estimated costs for reclaimed wastewater andreuse projects can be divided into capital costs (Table6) and operation and maintenance costs (Table 7),and include the following costs:n Additional treatment required to meet reuse

standardsn Conveyance and distribution of the treated

wastewater

TABLE 6.EXAMPLES OF PARAMETERS FOR ESTIMATING CONSTRUCTION COSTS OF WATER SUPPLY AND RECLAIMED WASTEWATER SYSTEMS

Item Main factors influencing cost Key parameters of cost functions

Water pipes Diameter, material, class of pipe Diameter of pipe, length

Ground storage Storage capacity, construction materials, shape Storage capacityreservoir and structure of reservoir, soil conditions

Elevated storage Storage capacity, height, construction Storage capacity and height ofreservoir materials, shape and structure, wind and reservoir above ground level

earthquake loadings, soil conditions

Pumping station Pump capacity, pump head, no. and type of Pump capacity and pumping headpumps used, construction material forstation, class and material for pressure pipe

Water treatment Plant capacity, type of process and treatment Plant capacityfacilities, construction materials, topographyof plant site, soil conditions, raw water intake

Sewers Diameter of sewer, depth of sewer, materials, Diameter of sewer, mean sewershape of trench, type of soil, water table level, invert depth, lengthstatic and dynamic loading on sewer

Wastewater Type of treatment, construction material, area, Area, population equivalent,treatment plant capacity, influent BOD standard

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TABLE 7.EXAMPLES OF PARAMETERS FOR ESTIMATING OPERATION AND MAINTENANCE COSTS OF WATER SUPPLY

AND RECLAIMED WASTEWATER SYSTEMS

Item Main factors influencing cost Key parameters of cost functions

Water pipes Total length of pipes, material and quality of Total length of pipes, or percentageconstruction, topography of area, pressure in of construction costpipes

Sewers Total length of pipes, materials and quality of Total length of sewers, orconstruction, topography of area percentage of construction cost

Storage tank Quality of construction, size of structure Percentage of construction cost

Water treatment Plant capacity, type of process and facilities, Plant capacityquality of raw water

Wastewater Plant capacity, designed efficiency of plant Population equivalent, or BODtreatment type of process and facilities, quality of of influent wastewater

construction

Pumping station Pump capacity, pumping head, no. and type of Percentage of construction costpumps, pump efficiency, quality of and pumping headconstruction, energy cost

n Storage to accommodate diurnal and/or sea-sonal fluctuations

n Connection, additional on-site treatment and usen Operation, maintenance, and replacementn Monitoring reclaimed water quality and health

and environmental impactsn Customer billing, administration, and overhead.

Normally capital cost is a large part (50-80 percent)of total costs. The capital cost is directly related tothe transport, distribution, and storage of the re-claimed water. Strong seasonal fluctuation in de-mand for, or production of, reclaimed waternecessitates very large storage reservoirs. The costof constructing these facilities may render the re-use scheme economically less feasible. Economi-cal feasibility can be expected to be high if a fewlarge continuous users can be identified close tothe origin of the wastewater, such as an existingwastewater treatment plant.

It is difficult to provide general guidelines for waste-water reuse costs. Total costs vary greatly, becausethey strongly depend on the local physical and eco-

nomic situation, local reuse options, and abundanceof alternatives. Nevertheless, the following examplesprovide indicative costs of wastewater treatment:n In The Netherlands, the cost for wastewater col-

lection is around $0.50 per m3. The cost for trans-port to the wastewater treatment plant andadvanced biological treatment (including nu-trient removal) amounts to another $0.50 perm3 (2000).

n In Egypt, the costs for wastewater collection andwastewater treatment were reported at $0.40 perm3 (1990).

n In Middle Eastern countries, the cost of ad-vanced wastewater treatment was reported be-tween $0.20 and $0.50 per m3 (1997).

Indications for the cost of wastewater reuseschemes:n In the Middle East, the use of treated wastewa-

ter as a source for drinking water (high leveltreatment by reverse osmosis) was calculatedat $0.40 to $1.00 per m3. This was cheaper thanreverse osmosis of seawater at $1.50 to $2.00per m3 (1980).

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WASTEWATER REUSE

LEGAL ASPECTS

Legislation for wastewater management usuallyconsists of a water management component and apublic and environmental health component. Con-sequently, different departments of government maybe involved, so water supply planners and manag-ers must address the legal aspects of water reuse ina coordinated way. Depending on the legal require-ments of different countries and states, the follow-ing items may need to be regulated:n Protection and creation of water rights and al-

location of water among competing users. Wa-ter abstraction from a system may result in netloss of water as a consequence of return flowsnot reaching the water system. As a result, therights of legitimate users who rely on such re-turn flows need to be protected.

n Ensuring adequate protection of public healthand the environment from changes in flows aswell as changes in water quality.

n A permit system for authorizing wastewater dis-charges.

n Controls over land uses and activities in thecatchment area (see Box 13).

n Water quality standards appropriate to varioususes.

To be effective, any legal regime should be accom-panied by appropriate standards and enforcementmechanisms, including financial incentives, sanc-tions, and ultimately possibilities of criminal pros-ecution (see Note B.2).

n CEPI S (see Box 3) reported the cost of waste-water treatment by a series of disinfection la-goons, followed by fish breeding lagoons in Peru,at $0.10 to $0.20 per m3. The cost was more thanbalanced by the revenues from the productionof fish (1985).

n A large chemical industry in the Netherlandsstudied the production of demineralized waterfrom effluent from their own biological waste-water treatment plant, instead of producing itfrom drinking water. Drinking water cost was$1.00 per m3, and demineralized water fromdrinking water cost $0.50 per m3, resulting in atotal cost of $1.50 per m3. Demineralized waterfrom effluent by ultra-filtration followed by re-versed osmosis cost $1.00 per m3 (1998).

n In India, a petrochemical company decided toreuse secondary treated municipal effluent forcooling water (15,000 m3/d). Additional treat-ment included coagulation by iron, sedimenta-tion, filtration, ion-exchange, and chlorination.Total cost of the additional treatment was $0.15per m3 (1990).

n In Japan, secondary treated municipal effluentwas used for toilet flushing in a business areawith high-rise buildings (4,000 m3/d). Additionaltreatment included filtration and chlorination.Total cost was $3.00 per m3, with a large part ofthe cost attributed to the extensive distributionsystem.

n In Clayton County (USA), secondary treatmentof municipal wastewater was reported to cost$0.25 per m3. The effluent was then reused in anature conservation area at a cost of $0.10 perm3. Via groundwater flow and streams, the wa-ter finally reaches the area where potable wa-ter is abstracted (1987).

30


such high-quality uses as potable supply to lower-quality requirements such as toilet flushing andcooling water. However, reuse is not a pancea; costsof treatment can be high, adequate sources of wa-ter may be remote from the needs, and the volumesrequired may not match the supply. Nevertheless,there are enough economically successful examplesof reuse schemes to show that it is a viable optionthat should be considered in water supply projects.

CONCLUSION

BOX 13.COLLECTION OF URBAN STORMWATER FOR POTABLE WATER SUPPLY, SINGAPORE

Singapore has reached a point where around half its total land area is harnessed for water resources. The recent LowerSeletar / Bedok Water Scheme utilizes runoff from residential areas as the main source of raw water. The schemecollects surface runoff and transfers it to two new raw water storage reservoirs. The reservoirs are connected by pipelineto the Bedok waterworks, where there are extensive pre-treatment and treatment processes. The design and operationof the stormwater collection systems also ensures that only the cleaner part of the stormwater is abstracted andpumped into the reservoir. This prevents the low-quality dry weather flow and the first flush during storms from enteringthe reservoirs.

Since its commissioning in 1986, the scheme has delivered raw water comparable in quality to raw water obtainedfrom an upland reservoir with a largely forested catchment.

The use of urban stormwater as a raw water source for potable water supply implies that the runoff should not containexcessive concentrations of organic matter and other urban pollutants. Consequently, pollution control measures areincorporated into the spatial planning of the urban area, especially regarding potentially polluting industries. Pollutioncontrol measures are imposed where necessary as a condition for planning approval. This is made possible by closeand continuous consultations between government agencies to ensure that all new developments in the catchmentare non-polluting and that suitable measures are implemented to prevent pollution of the stormwater.

Reuse of wastewater is one of a number of waterconservation measures that are increasingly beingimplemented in water-scarce regions. Reuse of con-taminated effluent can also provide the additionalbenefit of protecting sensitive downstream environ-ments from damage. The source of the wastewatercan vary-from industrial discharges to urban efflu-ent to thermal power stations. The treated waste-water can be used for a range of purposes, from

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WASTEWATER REUSE

FURTHER INFORMATION

General information on wastewater reuse can befound in:

U.S. Environmental Protection Agency/Agency for Inter-national Development. 1992. Guidelines for Wa-ter Reuse. Washington: U.S . EnvironmentalProtection Agency/Agency for International De-velopment.

Water Pollution Control Federation. 1989. Water Reuse,Manual of Practice SM-3. Alexandria, VA: WaterPollution Control Federation.

Metcalf & Eddy Inc. 1991. Wastewater Engineering - treat-ment, disposal, and reuse. New York: McGraw-Hill

Rowe, D.R. and I.M. Abdel-Magid. 1995. Handbook ofWastewater Reclamation and Reuse. Boca Raton,FL: Lewis Publishers.

Water Environment Federation/American Water WorksAssociation. 1998. Using Reclaimed Water to Aug-ment Potable Water Resources. Alexandria, VA:Water Environment Federation/ Denver, CO:American Water Works Association.

World Health Organisation. 1986. Guidelines for PlanningCommunity Participation Activities in Water Sup-ply and Sanitation Projects. Geneva: World HealthOrganisation.

Khouri, N., J.M. Kalbermatten, and C.R. Bartone. 1994.The reuse of wastewater in agriculture: a guidefor planners. Water and Sanitation Report No. 6.UNDP-World Bank Water and Sanitation Pro-gram. Washington: World Bank.

Information on handling harmful chemical contami-nants in wastewater can be found in:

Chang, A.C., A.L. Page, T. Asano, and I. Hespanhol. 1996.“Developing Human Health-related ChemicalGuidelines for Reclaimed Wastewater Irrigation.”Water Science & Technology 33 (10–11): 463–472

Mara, D. and S. Cairncross. 1989. Guidelines for the SafeUse of Wastewater and Excreta in Agriculture andAquaculture. Geneva: World Health Organisation(WHO).

León, G. and J.M. Cavallini. 1996. Curso de tratamiento yuso de aguas residuales. Lima: Centro Panamer-icano de Ingeniería Sanitaria y Ciencias delAmbiente (CEPIS)/Organización Panamericanade la Salud (OPS/PAHO/WHO).

Some case studies of reuse schemes are describedin:

Rosenblum, E. 1999. “Selection and implementation ofnon potable water recycling in “Silicon Valley”(San Jose area) California.” Water Science & Tech-nology 40 (4–5): 51–57.

Fong, L.M. and H. Nazarudeen. 1996. “Collection of ur-ban stormwater for potable water supplyin Singapore.” Water Quality InternationalMay/June: 36–40.

Husain, T. and A.H. Ahmed. 1997. “Environmental andeconomic aspects of wastewater reuse in SaudiArabia.” Water International 22: 108–112.

Asano, T., M. Maeda, and M. Takaki. “Wastewater recla-mation and reuse in Japan: Overview and imple-mentation examples.” Water Science andTechnology 34 (11): 219–226.

Mansour, M. and F.J. McNeill. 1998. “Wastewater reuseis key to solving Jordan’s water problems.” Wa-ter Environment & Technology 10 (11): 44–48.

The International Water Management Institute(IWMI) maintains contact information on waste-water reuse at the following address:

Citations: http://www.iwmi.org/library/dbsearches/wwcitations.htm

Contacts: http://www.iwmi.org/library/dbsearches/wwcontacts.htm

Organizations: http://www.iwmi.org/library/dbsearches/wworganizations.htm

Projects: http://www.iwmi.org/library/dbsearches/wwprojects.htm

technical note f.3 environment department - world …...3. categories of municipal wastewater reuse...

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