4.6 Ecological sanitation: Innovative sanitation systems for urban and peri-urban areas, high- and low-tech options with resources recovery (Otterpohl & Oldenburg)
Ecological sanitation: Innovative sanitation systems for urban and peri-urban areas, high- and low-tech options with resources recovery: Resources Management Sanitation is a term introduced during the IWAWorld Water Congress in Marrakech 2004. It covers systems that are designed for the reuse of nutrients, soil conditioners and water. Freshwater use can be reduced by up to 80% while nutrients can be recovered to a large extent. In many cases this is achieved through source separation at least of urine, that contains most of the soluble nutrients in very high concentrations. It can also be advantageous to separate the blackwater flow (toilet wastewater) with little or no water – small volumes are far easier to sanitise and reuse. New toilet systems with very low dilution factors, ranging from vacuum- over urine diverting (UD) flush to UD-dry toilets, have been introduced in hundreds of projects and proven feasible. New ideas as vacuum-biogas-systems, the blackwater-cycle systems and urinediverting vermi-composting systems are presently realized in different locations mainly in middle and northern Europe. Source separation technology in municipal wastewater treatment does often lead to decentralised or semicentral systems, but combinations with conventional sewerage do make sense as well, as future strategy studies of the Hamburg wastewater utility have shown. However, especially for new construction there are often clear economic advantages of integrated decentral systems. Such modular, flexible and small-scale systems have become feasible through the recent advances in membrane technology. Both high- and low-tech options are available; both can achieve very high efficiencies. The low-tech range of UD dry systems has been successfully implemented around the world, mostly called Ecological Sanitation. This type of sanitation is essential to extend services to the neglected part of the world population as it was promised in the Millennium Development Goals with very high hygienic standards, water efficiency and resources recovery. The high-tech range is needed to change the technological paradigm and to allow prices getting down through mass production. All systems are essential to deal with limited resources in an intelligent way according to the given situation.