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© 2021 Evelyn Herrera | Alexander Meneses-Jácome
The current dominant approach of the “networkedcity” reinforced by local governments, practitioners and multilateral agencies has failed to close the sanitation gap in countries of the Global South. Nature-based wastewater treatment technologies are increasingly considered are silient and adaptable alternative with lower investment costs that could complement current centralised approaches, minimize resource consumption and growing pressures on fresh water resources through enabling recycling and reuse of treated wastewater. This chapter focuses on nature-based wastewater treatment systems with an emphasis on those installed in countries of the Global South: septic tanks, waste stabilisation ponds (WSPs), constructed wetlands and vermifilters. While the performance of nature-based solutions can be comparable to conventional wastewater treatment systems, two or more solutions usually have to be combined in order to meet stringent discharge standards. In particular, the reduction of nutrients by individual technologies can be limited, although nutrient removal may not be a requirement where the effluent shave value for irrigation purposes. Nature-based solutions can share some of the same issues as conventional centralised approaches, such as overloading, underloading, lack of de-sludging, improper operation and maintenance, and lack of dedicated financial/human resource. Further adoption and robust implementation of nature-based solutions in the Global South will require appropriate governmental/institutional/communal interventions, including realistic and enforceable discharge and water reuse standards, and exchange among practitioners from the Global South and technology providers from the Global North to provide better solutions adapted to the realities and contexts of the Global South.