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

2

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