Wastewater Re-use and Groundwater Quality (Proceedings of symposium HS04 held duriim IUGG2003 al Sapporo. July 2003). IAI IS Publ. 285. 2004." 5 Agricultural use of treated wastewater: the need for a paradigm shift in sanitation and treatment JULES B. VAN LIER Subdepartment of Environmental Technology, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands
[email protected] FRANS P. HUIBERS Irrigation and Water Engineering Group, Wageningen University, Nienwe Kanaal If 6709 PA Wageningen, The Netherlands Abstract Shortages in irrigation water in and around urban areas call for alter native sources, particularly in the (sub)tropical zones. Domestic sewage represents such an alternative source and its nutritional value has been known by farmers for a long time. In many situations even raw (diluted) domestic sewage is used for agricultural purposes, especially in those areas that cannot afford extensive sewerage and treatment systems. However, discharge or re use of non-treated effluents gives rise to serious environmental problems, including threats to human health. Whenever agricultural use of urban effluents is considered, an integrated approach should be pursued, taking into account the agricultural requirements as well as the possible technological solutions for cost-effective sanitation and treataient. Such an integrated set-up questions the existing paradigms in sanitation and treatment and will call for a more decentralized approach, minimizing the requirements for large-scale infra-structural investments, such as sewerage systems. Also, with respect to the available treatment techniques, economic sustainability is often disregar ded in making the final choices. Amongst the available compact technologies for wastewater treatment, the anaerobic (pre-)treatment is seen as an appropriate technology, but so far, its potential has hardly been utilized.