Master thesis / Internship in modelling of densified activated sludge in sequencing batch reactor (DAS-SBR)

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 Department of Process Engineering (ENG) has a vacancy for a

Master thesis / Internship in modelling of densified activated sludge in sequencing batch reactor (DAS-SBR)

Densified Activated Sludge (DAS), a hybrid system consisting of flocs and small granules (typically 200~500 μm in diameter), is a promising solution for the increasing stringent effluent quality standards and the intensification of biological processes in wastewater treatment. Compared to conventional activated sludge, DAS offers significant advantages to “do more with less” – increasing treatment capacity without expanding the plant footprint. The improved settleability enables high biomass retention, thereby substantially increasing volumetric treatment capacity. The enrichment of slow-growing bacteria, particularly nitrifiers, promotes microbial activities and provides greater flexibility for optimizing aeration strategies for enhancing nutrient removal.

The application of DAS in sequencing batch reactors (SBR) is being increasingly investigated and implemented worldwide, yielding many new valuable experimental findings and operational experience. However, a comprehensive understanding of long-term performance of DAS-SBR systems under dynamic conditions remains limited. Existing mathematical models do not yet adequately represent all relevant processes and characteristics, nor have they been calibrated and validated using real-world operational data.

This project aims to develop a DAS-SBR model in Sumo , which can better represent the key biological and physical processes observed in practice. By calibrating and validating the model against real-world datasets, the project seeks to improve the understanding of DAS-SBR system and to provide a reliable tool for process analysis, optimization, and future design.

We are looking for a motivated master thesis student or intern, who needs to be enrolled in a university for the entire thesis/internship duration, with interests in advanced technologies for biological wastewater treatment and modelling biological processes. Fluent spoken and written English are essential. Strong data analysis and programming skills and experience with modelling in Sumo are highly recommended. The preferred starting date is September/October 2026 onwards, not later than March 2027. 

At Eawag , we have a working environment in which people with different experiences, strengths, and perspectives can fully contribute and further develop. Here, you can help us advance! We promote genuine participation, exchange, and mutual understanding. We create structures that enable the compatibility of work and other areas of life, such as care work, and continuously make efforts to reduce barriers. 

Do you have specific requirements regarding the application process or the position, or do you need additional information? Talk to us about it—we will be happy to support you with possible flexible workplace, working hours, and job design solutions. For further information about Eawag and its conditions of employment, please visit and .

Applications can be submitted until the position is filled and will therefore be evaluated on a rolling basis. Applications should include a short letter (max. one page) describing your interests and their relevance to this position, a CV, and a list of lectures/transcripts of records from the university. 

For further information, please contact Mengqi Zhu or Dr Nicolas Derlon .

We look forward to receiving your application. Please send it through this webpage, as any other way of applying will not be considered. A click on the link below will take you directly to the application form.

Eawag: Swiss Federal Institute of Aquatic Science and Technology