Natural Wastewater Treatment Gains Favor in Nepal, With Nearly 30 Plants

Wastewater managers in Nepal are increasingly turning to natural, decentralized wastewater treatment to prevent the mass discharge of raw sewage into urban water bodies and rivers. Almost 30 systems have been constructed in the last 15 years, and recent efforts to institutionalize decentralized treatment may see these numbers rise. The pervasive plant design in Nepal is a constructed wetland — a shallow bed of gravel, stone, and specialized reeds that filter contaminants. Some of the treated wastewater is reused for toilet flushing, and the dried sludge applied as fertilizer on land. More recently, biogas reactors affixed to treatment plants have provided additional energy recovery. The plants can serve communities of up to 2,000 people. Experts with the Asian Development Bank say decentralized systems are well suited for developing countries that often cannot afford larger, centralized sewage treatment plants, but note that the natural treatment wetlands require sizeable amounts of land and may not be suitable for densely populated urban areas.
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