Master Thesis / Internship in Modelling of Densified Activated Sludge in Sequencing Batch Reactor at Eawag, Switzerland

Are you interested in advanced wastewater treatment technologies, biological process modelling, data analysis, and environmental engineering? Eawag, the Swiss Federal Institute of Aquatic Science and Technology, is offering a Master thesis / internship opportunity in modelling of Densified Activated Sludge in Sequencing Batch Reactor (DAS-SBR).

The project is based within Eawag’s Department of Process Engineering (ENG) and focuses on developing a mathematical model that better represents the biological and physical processes taking place in densified activated sludge systems.

The project is particularly relevant to students interested in wastewater treatment, environmental engineering, process modelling, biological processes, data science, and sustainable water technologies. The preferred starting period is September or October 2026 onward, with a latest possible start by March 2027. Applications are accepted until the position is filled and will be evaluated on a rolling basis.

About Eawag

Eawag is the Swiss Federal Institute of Aquatic Science and Technology, an internationally networked aquatic research institute within the ETH Domain. The institute combines research, education, and expert consulting to address major challenges related to water. Its work aims to meet human needs for water while protecting the function and integrity of aquatic ecosystems.

The Master thesis/internship is hosted by the Department of Process Engineering (ENG), where the research addresses advanced technologies and processes relevant to water and wastewater treatment.

What Is Densified Activated Sludge?

Densified Activated Sludge (DAS) is a hybrid biological wastewater treatment system consisting of conventional flocs together with small granules, typically around 200–500 μm in diameter. DAS is being investigated as a promising approach for meeting increasingly stringent wastewater effluent standards while also intensifying biological treatment processes.

One of its major advantages is the potential to increase treatment capacity without requiring a larger plant footprint. Improved settling properties can enable greater biomass retention and consequently increase the volumetric treatment capacity of wastewater treatment systems. DAS can also promote the enrichment of slow-growing microorganisms, particularly nitrifying bacteria. This can support microbial activity and provide greater flexibility when optimizing aeration strategies for improved nutrient removal.

The DAS-SBR Research Challenge

The use of Densified Activated Sludge in Sequencing Batch Reactors (SBRs) is increasingly being investigated and implemented worldwide. Research has produced valuable experimental results and practical operational experience, but important questions remain about the long-term performance of DAS-SBR systems under dynamic operating conditions.

Existing mathematical models do not yet fully represent all of the relevant biological and physical processes and characteristics of DAS-SBR systems. In addition, these models have not been sufficiently calibrated and validated against real-world operational datasets. This creates an important opportunity for modelling research that can bridge the gap between experimental observations and process simulation.

About the Master Thesis / Internship Project

The main objective of this project is to develop a DAS-SBR model in Sumo that better represents the key biological and physical processes observed in real-world wastewater treatment systems. The model will be calibrated and validated using real-world datasets. By comparing model predictions with operational data, the project aims to improve understanding of DAS-SBR performance and establish a reliable modelling tool for future applications.

The resulting model could support:

• Process analysis
• Treatment-process optimization
• Understanding of biological and physical mechanisms
• Evaluation of operational strategies
• Future DAS-SBR system design

This makes the project particularly suitable for students who want to combine environmental engineering with mathematical modelling and practical wastewater treatment research.

Research Focus

The thesis or internship will focus on the development and evaluation of a process model capable of representing DAS-SBR systems under realistic conditions. A major component will be the calibration of the model against real-world datasets. Model validation will then be used to assess how accurately the simulated system reflects observed operational behavior.

Through this approach, the student will gain experience connecting experimental or operational wastewater-treatment data with mathematical and computational models. The exact scope of the project can be developed around the student’s interests and existing skills while remaining within the objectives of the research programme.

Ideal Candidate

Eawag is looking for a motivated Master’s student or intern with an interest in advanced biological wastewater treatment and process modelling. Applicants must be enrolled at a university for the entire duration of the thesis or internship.

The ideal candidate should have a strong interest in:

• Biological wastewater treatment
• Environmental engineering
• Mathematical and process modelling
• Data analysis
• Sustainable wastewater technologies
• Biological treatment processes
• Process optimization

Fluent spoken and written English is essential. Strong data-analysis and programming skills are highly desirable. Previous experience with Sumo modelling is also strongly recommended.

Skills and Experience

The preferred candidate will have:

• Current university enrollment throughout the thesis/internship period
• An academic background relevant to environmental engineering, wastewater treatment, biotechnology, chemical engineering, or a related discipline
• Interest in advanced biological wastewater treatment technologies
• Strong analytical and quantitative skills
• Good programming or computational skills
• Excellent written and spoken English
• Interest in process modelling and simulation

Experience with Sumo is particularly valuable, while strong programming and data-analysis abilities can also support the modelling work.

What You Will Learn

The project provides an opportunity to develop practical research skills at the intersection of wastewater treatment and computational modelling. Depending on the project scope, the student will gain experience with concepts related to:

• Densified activated sludge
• Sequencing batch reactors
• Biological wastewater treatment
• Mathematical process modelling
• Model calibration
• Model validation
• Real-world operational datasets
• Data analysis
• Programming and simulation
• Process optimization

The combination of modelling and wastewater-treatment research can be valuable preparation for further academic research, environmental engineering careers, water-technology positions, or a future PhD.

Research Environment at Eawag

The student will work within Eawag, an internationally recognized aquatic research institution that combines scientific research with practical water-management expertise. Eawag promotes a working environment where people with different experiences, strengths, and perspectives can contribute and develop professionally. The institute emphasizes participation, collaboration, mutual understanding, and reducing barriers within the workplace. Flexible solutions concerning workplace arrangements, working hours, and job design may be available depending on individual requirements.

Key Details

Detail	Information
Position	Master Thesis / Internship
Research Topic	Modelling of Densified Activated Sludge in SBR
Abbreviation	DAS-SBR
Institution	Eawag – Swiss Federal Institute of Aquatic Science and Technology
Department	Department of Process Engineering (ENG)
Research Area	Biological Wastewater Treatment
Main Tool	Sumo
Research Focus	Process modelling, calibration, validation, and optimization
System	Densified Activated Sludge in Sequencing Batch Reactors
Candidate Status	Master’s student / Intern
Enrollment	University enrollment required throughout the project
Language	Fluent English
Preferred Start	September/October 2026 onward
Latest Start	March 2027
Application Deadline	Until position is filled
Selection	Rolling evaluation
Application Documents	Short letter, CV, university lectures/transcripts

How to Apply:

Applications should include a short letter of motivation of no more than one page explaining the applicant’s interests and why their background is relevant to the project.

Applicants should also submit:

• Curriculum vitae (CV)
• List of university lectures/courses
• University transcripts or records
• The application form is available through Apply now. 
• Applications are accepted until the position is filled and are evaluated on a rolling basis. 
• Applications submitted through other channels will not be considered 
• Apply now

Important Start-Date Information

The preferred starting period is September or October 2026 onward. The latest stated starting point is March 2027. Students should ensure that they will remain enrolled at a university for the entire duration of their Master’s thesis or internship.

Frequently Asked Questions

What is the topic of this Master’s thesis?

The project focuses on modelling Densified Activated Sludge in Sequencing Batch Reactors (DAS-SBR) and aims to develop a model that better represents biological and physical processes observed in practice.

What is Densified Activated Sludge?

Densified Activated Sludge is a hybrid wastewater-treatment system containing conventional flocs and small granules, typically around 200–500 μm in diameter.

What is the purpose of the research?

The project aims to develop a reliable DAS-SBR model that can be calibrated and validated using real-world operational data and subsequently used for process analysis, optimization, and future system design.

Which modelling software will be used?

The project will develop the DAS-SBR model using Sumo.

Is Sumo experience required?

Experience with modelling in Sumo is highly recommended, although the source does not state that it is an absolute mandatory requirement.

Who can apply?

The position is intended for a Master’s thesis student or intern who remains enrolled at a university throughout the entire thesis or internship period.

What academic background is suitable?

The source emphasizes an interest in advanced biological wastewater treatment and biological-process modelling. Students from relevant environmental, engineering, biological, or related disciplines may be suitable depending on their background.

Is programming experience important?

Yes. Strong data-analysis and programming skills are highly recommended for this project.

What language is required?

Applicants must have fluent spoken and written English.

When can the thesis or internship start?

The preferred starting period is September/October 2026 onward, with the latest stated start date being March 2027.

What is the application deadline?

There is no fixed closing date. Applications are accepted until the position is filled and are evaluated on a rolling basis.

What documents are required?

Applicants should submit a short motivation letter of no more than one page, a CV, and a list of university lectures/courses and transcripts of records.