Department Sanitation, Water and Solid Waste for Development

Understanding governing mechanisms for dewatering

This research focuses on elucidating the mechanisms that control settling and dewatering of faecal sludge. The effect of extracellular polymeric substances, particle properties, surface charge and microbial community on the settling and dewatering properties of faecal sludge is being investigated. The outcome of the investigation will provide the basis for the modelling and prediction of solid-liquid separation of faecal sludge based on influent sludge characteristics. Online measurements of the influent sludge characteristics can be used to predict conditioner dosages to enhance faecal sludge dewatering.


Globally, 40% of the population is served by onsite sanitation, and the management of faecal sludge from onsite sanitation are desperately needed. Onsite sanitation is only recently acknowledged as a viable long-term solution, and consequently research lags substantially behind wastewater treatment. Solid-liquid separation is one of the greatest obstacles in developing management solutions, as faecal sludge consists of over 95% water. Identifying and understanding the mechanisms regulating solid-liquid separation is required prior to the development of solutions for adequate treatment, and cost-effective transportation.


The goal of this project is to understand the governing mechanism of solid liquid separation in faecal sludge. Improved dewatering of faecal sludge will enhance collection and transport in urban settlements and ensure the development of high throughput and low footprint technologies.

For examples of the applications of this fundamental research, including the Sludge Snap app and the applied research on up-scaling treatment technologies.




  • Prof. Eberhard Morgenroth, Eawag and ETH Zurich, Zurich, Switzerland
  • Dr. Amadou Gueye and Dr. Bécaye Sidy Diop, Delvic Sanitation Initiatives, Dakar, Senegal
  • Dr. James Tembo and Prof. Joel Kabika, University of Zambia, Lusaka, Zambia
  • Prof. Charles Niwagaba, Makerere University, Kampala, Uganda
  • Naomi Korir, Sanivation, Naivasha, Kenya
  • Prof. Ruixin Niu, Prof. Robert Dahlberg, and Prof. Bennett Ward, Virginia Commonwealth University, Richmond, USA


  • Swiss National Science Foundation (SNF)
  • Engineering for Development (E4D) Doctoral Scholarship Programme, supported by the Sawiris Foundation
  • Swiss Agency for Development and Cooperation (SDC)
  • Eawag discretionary funding


Ward, B. J.; Andriessen, N.; Tembo, J. M.; Kabika, J.; Grau, M.; Scheidegger, A.; Morgenroth, E.; Strande, L. (2021) Predictive models using "cheap and easy" field measurements: can they fill a gap in planning, monitoring, and implementing fecal sludge management solutions?, Water Research, 196, 116997 (12 pp.), doi:10.1016/j.watres.2021.116997, Institutional Repository
Ward, B. J.; Traber, J.; Gueye, A.; Diop, B.; Morgenroth, E.; Strande, L. (2019) Evaluation of conceptual model and predictors of faecal sludge dewatering performance in Senegal and Tanzania, Water Research, 167, 115101 (13 pp.), doi:10.1016/j.watres.2019.115101, Institutional Repository
Moto, N.; Esanju, M.; Andriessen, N.; Kimwaga, R.; Strande, L. (2018) Use of chitosan and Moringa oleifera as conditioners for improved dewatering of faecal sludge, (6 pp.), Institutional Repository
Gold, M.; Harada, H.; Therrien, J.-D.; Nishida, T.; Cunningham, M.; Semiyaga, S.; Fujii, S.; Dorea, C.; Nguyen, V.-A.; Strande, L. (2018) Cross-country analysis of faecal sludge dewatering, Environmental Technology, 39(23), 3077-3087, doi:10.1080/09593330.2017.1374472, Institutional Repository
Gold, M.; Dayer, P.; Faye, M. C. A. S.; Clair, G.; Seck, A.; Niang, S.; Morgenroth, E.; Strande, L. (2016) Locally produced natural conditioners for dewatering of faecal sludge, Environmental Technology, 37(21), 1-13, doi:10.1080/09593330.2016.1165293, Institutional Repository
Ward, B. J.; Sam, S.; Andriessen, N.; Morgenroth, E.; Strande, L. (2018) Research priorities and progress in faecal sludge dewatering, Sandec News, 19, 10-11, Institutional Repository
  • The trials of developing a biomethane potential method for faecal sludge Sandec News No 21, Sam, S., Kapanda, K., Ward, B.J., Tembo, J., Morgenroth, E., Strande, L.
  • Research strategy for overcoming the faecal sludge dewatering bottleneck Sandec News No. 21, Ward, B.J., Sam, S., Kapanda, K., Tembo J.M., Morgenroth, E., Strande, L.
  • Predicting faecal sludge dewatering performance for improved treatment Sandec News No. 20, Ward, B.J., Sam, S., Gueye, A., Diop, B., Morgenroth, E., Strande, L.