Technologies for the treatment of source-separated urine in the eThekwini Municipality

Authors

  • Kai M Udert Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • Chris A Buckley Pollution Research Group, School of Chemical Engineering, University of KwaZulu-Natal, Durban 4041, South Africa
  • Michael Wächter 1. Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; 2. Enswico AG, 8132 Egg, Switzerland
  • Christa S McArdell Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • Tamar Kohn Ecole Polytechnique Fédérale de Lausanne (EPFL), Environmental Chemistry Laboratory, School of Architecture, Civil and Environmental Engineering (ENAC), 1015 Lausanne, Switzerland
  • Linda Strande Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • Hanspeter Zöllig Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • Alexandra Fumasoli Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • Astrid Oberson Swiss Federal Institute of Technology (ETH) Zurich, Institute of Agricultural Sciences, 8315 Lindau, Switzerland
  • Bastian Etter Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland

DOI:

https://doi.org/10.4314/wsa.v41i2.06

Keywords:

sanitation, source separation, nutrient recovery, eutrophication, hygiene, human health

Abstract

In recent years, a large number of urine-diverting dehydration toilets (UDDTs) have been installed in eThekwini to ensure access to adequate sanitation. The initial purpose of these toilets was to facilitate faeces drying, while the urine was diverted into a soak pit. This practice can lead to environmental pollution, since urine contains high amounts of nutrients. Instead of polluting the environment, these nutrients should be recovered and used as fertiliser. In 2010 the international and transdisciplinary research project VUNA was initiated in order to explore technologies and management methods for better urine management in eThekwini. Three treatment technologies have been chosen for the VUNA project. The first is struvite precipitation, a technology which has already been tested in multiple projects on urine treatment. Struvite precipitation is a simple and fast process for phosphorus recovery. Other nutrients, such as nitrogen and potassium, remain in the effluent and pathogens are not completely inactivated. Therefore, struvite precipitation has to be combined with other treatment  processes to prevent environmental pollution and hygiene risks. The second process is a combination of nitrification and distillation. This process combination is more complex than struvite precipitation, but it recovers all nutrients in one concentrated solution, ensures safe sanitisation and produces only distilled water and a small amount of sludge as by-products. The third process is electrolysis. This process could be used for very small on-site reactors, because conversion rates are high and the operation is simple, as long as appropriate electrodes and voltages are used. However, nitrogen is removed and not recovered and chlorinated by-products are formed, which can be hazardous for human health. While urine electrolysis requires further research in the laboratory, struvite precipitation and nitrification/distillation have already been operated at pilot scale.

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Published

2015-03-31

How to Cite

Kai M Udert, Chris A Buckley, Michael Wächter, Christa S McArdell, Tamar Kohn, Linda Strande, Hanspeter Zöllig, Alexandra Fumasoli, Astrid Oberson, & Bastian Etter. (2015). Technologies for the treatment of source-separated urine in the eThekwini Municipality. Water SA, 41(2 WISA 2014 Special Edition). https://doi.org/10.4314/wsa.v41i2.06