Africa Water, Sanitation & Hygiene Africa Water & Sanitation & Hygiene Nov-Dec 2017 | Page 23

Wastewater Use cant economic benefits . Environmental quality is often an important benefit of reuse programs because poorquality water is used in agriculture instead of being discharged into cleaner surface water bodies or groundwater . Finally , water reuse may reduce the investment costs of developing new resources for agriculture or other uses for which it is substituted .

Figure 1 : Urban Water Supply Growth , 1980 — 2015

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Based on international experience , it is increasingly apparent that economic win-win solutions are not easy . Instead , potential Bank investments in the water sector need to address alternatives and consider the economic tradeoffs , for example :

• Should a sea outfall be built to discharge wastewater from a coastal city , if permitted by national and regional regulations and treaties , or should wastewater be reused , possibly incurring much higher costs for the treatment , storage , and especially the transfer of reclaimed water ?

• Should a reservoir for reclaimed water be built to increase its availability during the irrigation season or should treated water be discharged during the wet season ?

• Are more expensive treatment and unrestricted irrigation preferable to simpler treatment and crop restrictions ?

POLICY AND IMPLEMENTATION

Planned reuse is not just about treatment ; it requires an integrated approach . Where the Bank lends for wastewater treatment , the planned reuse of effluent should be integrated into the decision to invest in intensive ( for example , activated sludge ) or extensive ( for example , stabilization ponds ) technologies , or centralized versus decentralized systems .

Because collection and treatment of wastewater are usually under the jurisdiction of a different sector ( such as urban water supply and sanitation ) from the reuse sectors ( such as agriculture and municipalities ), intersectoral coordination in planning and management is extremely important . The World Bank Country Water Assistance Strategies offer an opportunity to ensure such coordination . On the demand side , users should be involved in planning and monitoring the quality of the supplied effluent . Effective advisory / extension services are also extremely important .

Table 1 : Water Treatment Gaps

Region

Percentage of sewered population in large cities

Percentage of sewered wastewater that is treated to secondary level

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