Need for cost-effective and robust treatment technologies: the anaerobic alternative

Shortages in irrigation water in and around urban areas calls for alternative sources in particularly the (sub)tropical zones. Domestic sewage represents such alternative source and its nutritional value is known by the farmers since long times. In many situations, even diluted raw domestic sewage is used for agricultural purposes, especially in those areas that cannot afford sewerage and treatment systems. However, discharge or reuse of non-treated effluents, give rise to serious environmental problems, including human health threats. Anaerobic pre-treatment might (partly) fill this gap owing to its cost-effectiveness in construction and operation and the possibility to implement the system in a decentralised mode, i.e., reducing the required sewerage. Moreover, the local farmers can beneficially use the products of anaerobic treatment, such as nutrient-rich effluent and the stabilised sludge, whereas the produced biogas can be used on the site if it is produced in sufficient quantities. The cost-effectiveness of anaerobic treatment may lead to a more rapid implementation of productive sewage reclamation, while the environmental problems are concomitantly addressed.