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Eawag, the Swiss Federal Institute of Aquatic Science and Technology, is an internationally networked aquatic research institute within the ETH Domain (Swiss Federal Institutes of Technology). Eawag conducts research, education and expert consulting to achieve the dual goals of meeting direct human needs for water and maintaining the function and integrity of aquatic ecosystems.

The departments Sandec and Process Engineering are seeking a highly motivated and qualified individual for a

PhD Position on faecal sludge dewatering and settling for improved global sanitation

This PhD position is part of a research project funded by the Swiss National Science Foundation (SNF). The project aims to better understand the mechanisms governing the solid-liquid separation of faecal sludge during collection and treatment.

Project Summary: Globally, 40% of the population is served by onsite sanitation, and in low-income countries entire urban areas are not served by sewers. Methods for the management of faecal sludge from onsite sanitation are desperately needed, as in low-income countries it is mostly discharged untreated in the urban environment, placing a huge burden on public and environmental health. Solid-liquid separation is one of the greatest obstacles in developing management solutions, as faecal sludge consists of over 95% water. Direct transfer of solid-liquid separation experience from wastewater treatment is not possible due to the lack of understanding of governing mechanisms for faecal sludge, much different characteristics, and 1-2 orders of magnitude of variability. However, wastewater research provides insights into possible mechanisms. For example, extracellular polymeric substances (EPS) excreted by microorganisms governs solid-liquid separation in wastewater sludge, and therefore microbial community plays a large role in determining separation performance. Faecal sludge is contained onsite in oxygen-limited conditions, which leads to EPS degradation, especially at long residence times. With lower concentrations of EPS, particle properties and environmental conditions affecting surface charge are expected to more likely govern solid-liquid separation. The objective of this research is to understand governing mechanisms of solid-liquid separation of faecal sludge, specifically, the role of microbial community, EPS, surface charge and particle properties.Ultimately, the goal is to translate this fundamental understanding into improved faecal sludge treatment, by linking with ongoing field research in Tanzania.