Alternative sanitary concepts for rural and urban areas

Abstract

This paper describes how conventional wastewater treatment is state of the art in Middle Europe. Most of the nutrients in wastewater are removed in wastewater treatment plants, but a part of them is discharged out to our rivers and lakes and can effect eutrophication. In other areas, such as Africa, Asia and South-America, there is little or no treatment of wastewater at all. In particular, rapidly growing megacities have problems with the collection and treatment of incoming wastewater. Sewage systems, if existent, are overloaded. The insufficient sewage purification causes diseases and environmental pollution. Furthermore, there is a scarcity of fresh water and there is not enough fertilizer for agriculture. Alternative sanitary concepts are able to close the loop of water and nutrients and give sanitary comfort to citizens. Novel sustainable wastewater treatment systems take care of the different flows of wastewater, such as grey water, brown water and yellow water, in a special and verified way. By using brown water, it is possible to produce biogas for heating, cooking and power. Grey water can be treated to obtain water for laundry and to flush toilets. Urine is full of nutrients and a perfect substitute for mineral fertilizer. In a project near Berlin, some no-mix toilets are installed in an office and an apartment building. The results of the tests with a biogas plant show good production of biogas and there is a possibility of using bio-waste from households as a co-substrate. The measured values in the treated sludge show that it is possible to use it as a soil conditioner in agriculture. The implementation of such novel sanitary concepts in urban areas is more difficult than in low-density areas, but in general is not impossible.