DEUS 21 – Successful paradigm shift

Semi-decentralized water and wastewater management

For more than a hundred years now, industrialized countries have been used to flushing feces together with valuable drinking water over long distances from urban areas to central wastewater treatment plants. This scheme has two costly drawbacks. It is expensive to build and maintain large sewer networks, and drinking water is a scarce resource, much too valuable to use for transporting waste.

In the DEUS 21 project (Decentralized Urban Water Infrastructure Systems), the Fraunhofer IGB was looking for more sensible alternatives to established water management systems – in order to save both resources and costs.

Maximum recycling of water, energy and nutrients

DEUS 21.
DEUS 21.
Vacuum plant.
Vacuum plant.

The innovative concept developed at the Fraunhofer IGB for semi-centralized urban water and wastewater management encompasses:

  • Using treated rainwater as high-quality water of reliable standards
  • A new form of transport for wastewater (vacuum canalization)
  • Semi-central, sustainable anaerobic wastewater purification

Vacuum suction systems for sanitary installations are already common in airplanes, on boats and on trains and are available for municipal wastewater too. Drastic reductions in water consumption and its costs can be obtained by using vacuum systems and by treating rainwater to become suitable for domestic use. Another advantage of the semi-central concept is that wastewater channel pipes are smaller in diameter and can be buried closer to the surface. Plants for purifying wastewater can be built more accurately in size as they only have to treat wastewater, with no additional rainwater. Central wastewater plants and rainwater storage reservoirs are no longer necessary.

The main aim of the new technologies developed and established for purifying wastewater is to close the cycle of materials by converting the ingredients of wastewater into usable substances e.g. carbon compounds into methane, nitrogen compounds into ammonia fertilizers and phosphorous compounds into a phosphate fertilizer.


We would like to thank the German Federal Ministry of Education and Research (BMBF) for funding the project "Decentralized Urban Infrastructure Systems DEUS 21", promotional reference 02WD0850.

Federal Ministry of Education and Research.