Department Process Engineering

Source Separation and Urine Treatment

Today's gold standard for wastewater management is a sewer system with a centralised wastewater treatment plant. However, this system has its limits, because it requires large amounts of water and an extensive infrastructure. An alternative are small, highly efficient decentralised reactors, which allow a more flexible wastewater management. We develop processes, which can be used for such wastewater treatment plants. We use the following three principles as guidelines:

Separation at the source: Waste streams with different compositions should be treated separately according to their properties.

Decentralisation: The waste streams should be treated as closely to the source as possible, thereby minimising resource consumption and environmental pollution.

Resource recovery: The treatment should focus on recovering the resources contained in the waste streams.

The three most important domestic wastewater streams are urine, faeces and greywater. So far, our research has been mainly focused on urine, because it contains most of the nutrients. A careful management of nutrients not only reduces environmental pollution (e.g. eutrophication), but it also allows closing the nutrient cycle with agriculture.

We work closely together with the other research groups within the ENG department in order to develop optimal resource recovery processes. Strong links also exist with other Eawag departments and national and international research units to cover the various aspects, which have to be considered when implementing new wastewater treatment and sanitation systems.


Prof. Dr. Kai UdertTel. +41 58 765 5360Send Mail

Selected projects

RTTC – Reinvent the Toilet Challenge
The new toilet model will provide a sanitary solution that ensures human dignity and hygiene, while also being environmentally-friendly and economically feasible. A project in cooperation with EOOS and Makerere University in Uganda, funded by the Bill & Melinda Gates Foundation.

By recovering nutrients from urine, we develop a sanitation system, which produces a valuable fertiliser
We develop reactors for the separate treatment of urine, feces and water directly in the toilet.
Sustainable urban water and wastewater management applied and implemented in the modular NEST building.

Completed Projects

  • STUN - Struvite recovery from urine in Nepal.
  • Partial nitritation/anammox - Nitrogen removal from urine with partial nitritation / anammox.
  • Electrochemical ammonia removal
  • Urine collection - Long-term observation of a urine collection system
  • Wastewater in alpine areas - Decentralised treatment and reuse of toilet wastewater in alpine areas
  • Single house - Single house wastewater treatment with water reuse
  • SELF - Greywater treatment in the living module SELF [pdf 0.7 MB]

Selected Publications

Fumasoli, A.; Etter, B.; Sterkele, B.; Morgenroth, E.; Udert, K. M. (2016) Operating a pilot-scale nitrification/distillation plant for complete nutrient recovery from urine, Water Science and Technology, 73(1), 215-222, doi:10.2166/wst.2015.485, Institutional Repository
Zöllig, H.; Remmele, A.; Fritzsche, C.; Morgenroth, E.; Udert, K. M. (2015) Formation of chlorination byproducts and their emission pathways in chlorine mediated electro-oxidation of urine on active and nonactive type anodes, Environmental Science and Technology, 49(18), 11062-11069, doi:10.1021/acs.est.5b01675, Institutional Repository
Zöllig, H.; Morgenroth, E.; Udert, K. M. (2015) Inhibition of direct electrolytic ammonia oxidation due to a change in local pH, Electrochimica Acta, 165, 348-355, doi:10.1016/j.electacta.2015.02.162, Institutional Repository
Zöllig, H.; Fritzsche, C.; Morgenroth, E.; Udert, K. M. (2015) Direct electrochemical oxidation of ammonia on graphite as a treatment option for stored source-separated urine, Water Research, 69, 284-294, doi:10.1016/j.watres.2014.11.031, Institutional Repository
Fumasoli, A.; Morgenroth, E.; Udert, K. M. (2015) Modeling the low pH limit of Nitrosomonas eutropha in high-strength nitrogen wastewaters, Water Research, 83, 161-170, doi:10.1016/j.watres.2015.06.013, Institutional Repository
Udert, K. M.; Buckley, C. A.; Wächter, M.; McArdell, C. S.; Kohn, T.; Strande, L.; Zöllig, H.; Fumasoli, A.; Oberson, A.; Etter, B. (2015) Technologies for the treatment of source-separated urine in the eThekwini Municipality, Water SA, 41(2), 212-221, doi:10.4314/wsa.v41i2.06, Institutional Repository
Larsen, T. A.; Gebauer, H.; Gründl, H.; Künzle, R.; Lüthi, C.; Messmer, U.; Morgenroth, E.; Niwagaba, C. B.; Ranner, B. (2015) Blue Diversion: a new approach to sanitation in informal settlements, Journal of Water Sanitation and Hygiene for Development, 5(1), 64-71, doi:10.2166/washdev.2014.115, Institutional Repository
Udert, K. M.; Wächter, M. (2012) Complete nutrient recovery from source-separated urine by nitrification and distillation, Water Research, 46(2), 453-464, doi:10.1016/j.watres.2011.11.020, Institutional Repository
Etter, B.; Tilley, E.; Khadka, R.; Udert, K. M. (2011) Low-cost struvite production using source-separated urine in Nepal, Water Research, 45(11), 852-862, doi:10.1016/j.watres.2010.10.007, Institutional Repository