edited by Joop Steenvoorden & Theodore Endreny

An integrated approach to the groundwater resource–wastewater production–wastewater (pre-)treatment–wastewater re-use chain is required to find optimal solutions with respect to food security, cost-effectiveness, environmental load and health risks.

Re-use of (pre-)treated wastewater, especially in agriculture, could considerably contribute to water resource conservation, recycling of nutrients, and prevention of surface water pollution. Water quality guidelines are necessary for wastewater irrigation, but they are rather strict and developing countries cannot afford the expensive treatment.

Joop Steenvoorden provides an overview and broad perspective concluding that decentralized collection and anaerobic treatment of wastewater and use of the treated water and by-products has many merits, whilst Jules Van Lier and Frans Huibers call for a paradigm shift with respect to sanitation and treatment.