SCST Sanitation Concepts for Separate Treatment

Projectpartners: KWB, BWB, Veolia
Consultant: Otterwasser GmbH
Subcontractors: TUHH, TUB, HUB
Project volume: 2,22 Mio €
Project duration: January 1st, 2003 – December 31st, 2006

This project was funded in the framework of the LIFE programme of the European Union (LIFE03 ENV/D/000025).


Centralised, conventional water provision and wastewater treatment concepts that have been developed and implemented for decades in industrialised countries are not sufficiently sustainable as they involve high costs, high water consumption, and a low reuse of nutrients. This is particularly true for their implementation in developing countries. Sustainable concepts aim to reuse as much as possible the treated wastewater and the nutrients while at the same time aiming to lower the overall energy consumption or even to produce energy. Alternative concepts and technologies have been around for a long time and have been implemented; however, further developments and plausibility checks are necessary.

Operation premises of the WWTP in Stahnsdorf
Operation premises of the WWTP in Stahnsdorf
Residential buildings at WWTP Sahnsdorf
Residential buildings at WWTP Stahnsdorf
Retrofit Roediger No-Mix-Toilet
Retrofit Roediger No-Mix-Toilet

For this reason, the Berlin Centre of Competence for Water (KompetenzZentrum Wasser Berlin, KWB), together with the Berliner Wasserbetriebe (BWB) and Veolia Water carried out an EU-demonstration project in this field (Sanitation Concepts for Separate Treatment (SCST). In this project, two different sanitation concepts were tested in buildings of the BWB on the grounds of the wastewater treatment plant Stahndsdorf.



Constructed wetland
Constructed wetland
Gravity separation toilet (Roediger No-Mix-Toilet)
Gravity separation toilet (Roediger No-Mix-Toilet)
Waterless collection of urine
Waterless collection of urine


The project goal was to test if these new sanitation concepts prove to have significant advantages over conventional sanitation systems with water-borne sewage system and sewage plant (end-of-pipe-system) in terms of environmental impact as well as economic efficiency.


The new sanitation concepts for the separate discharge and treatment of yellowwater (urine), brownwater (faeces without urine but with flushing water), and greywater (wastewater from kitchen and bathroom) were installed and implemented in previously existing buildings (one office building and one residential building) on the grounds of the wastewater treatment plant Stahnsdorf nearby Berlin. The new sanitation concept in the office building was installed in 2002 / 2003, when the building was being renovated. In spring 2005, the new concept was extended to the residential building.

New Sanitation Concepts (left: gravity separation toilets, right: vacuum separation toilets)
New Sanitation Concepts (left: gravity separation toilets, right: vacuum separation toilets)


The most important findings are:

  • Overall, the tested sanitation concepts are functional and working;
  • Only 30 - 40 % of the urine could be separated with the tested toilets, not the expected 70 - 80 %;
  • Some technologies (toilets, faeces separator etc.) have to be improved;
  • The treatment of greywater with a constructed wetland is as effective as anticipated;
  • Urine has the same fertilising efficiency as mineral fertiliser;
  • The results of consumer and farmer surveys regarding agricultural use are motivating;
  • Pharmaceuticals and steroids in the products (urine, composted faeces, digested faeces) could be an obstacle to their use as fertilisers. However, many actors dealing with new sanitation concepts estimate that the benefits of these products outweigh the damages that could possibly be caused by these micro pollutants.
  • Steam stripping plus magnesia-ammonium-phosphate-precipitation is the favoured process for nutrient concentration in the urine;
  • The results of the life-cycle-assessment show that the tested sanitation concepts are advantageous;
  • Costs for the new sanitation concepts depend very much on the given circumstances and can be advantageous (compared to conventional systems);
  • There is a very strong interest in this project. Based on the internet presentation and the many national and international presentations given on this project, approx. 500 national and international visitors have come to learn about it on-site.


The results prove that the new sanitation concepts have potential for further development. In order to introduce them on a larger scale, further developments, in particular in the area of sanitation technology, are necessary. Given the increasing importance of topics such as saving water and energy, water reuse, and nutrient recycling, further endeavours in these areas need to be undertaken, which is what is happening in many places. In 2005, the DWA (German Association for Water Management, Wastewater and Waste) e.g. founded a special commission of experts called “Neuartige Sanitärsysteme / Innovative Sanitation Systems”, which collects and publishes up-to-date knowledge on the topic. Examples of the application of innovative sanitation systems are Solar City in Linz (Austria), House Griesbach of the EAWAG (Water Research Institute of Switzerland) and, in Germany, apart from the SCST-project, the settlement Flintenbreite (Lübeck) of the family Hans-Huber (Berching), the Lambertsmühle (Burscheid), and the German Agency for Technical Cooperation (GTZ, Eschborn). In some of these projects, efforts are undertaken to advance the topic of new sanitation concepts. At present, no applications are planned in Berlin, mainly because the problems and uncertainties detailed above (for details see the SCST final report).


Dr.-Ing. Anton PETER-FRÖHLICH (Berliner Wasserbetriebe)