Article // Designing Sustainable Wastewater Reuse Systems: Towards an Agroecology of Wastewater Irrigation

By Philipp Weckenbrock (International Development Consultant), Graham Alabaster. — One of the challenges of population growth and rapid urbanization processes is how to deal with the ever-increasing volumes of wastewater. Because of high costs of conventional technical wastewater treatment facilities, only the wealthiest countries can treat most of their wastewater. The largest part of the world’s wastewater enters the environment untreated. Centralized wastewater collection and treatment also impacts downstream use. New opportunities for decentralized treatment and reuse, particularly in smaller urban centres can increase reuse opportunities significantly. Recently, more emphasis has been put on potential benefits of wastewater reuse in agriculture. However, what works and what doesn’t depends on a range of factors concerning the general context of each scheme (including soil, climate, etc.), as well as on the specific crops chosen. More research is therefore needed on crop types and combinations of crops suitable for wastewater irrigation. No single plant can flourish in varying degrees of water quality while at the same time resisting pests and diseases, absorbing contaminants from wastewater and soils and producing abundant harvests. Only a variety of plants grown in combination can fulfil all these functions. A sustainable agricultural system under wastewater irrigation must therefore be a multicropping system. In order to design such a sustainable wastewater reuse scheme, agroecological principles and methods should be used.