Tuning extracellular polymers in sludge for better sludge dewatering
Changing the properties of extracellular polymeric substances to better remove water and reduce the use of flocculants
Sludge dewatering is a major challenge in wastewater treatment. Optimizing this process can lead to significant reductions in expenses, chemical use, and greenhouse gas emissions—all key goals for future water management.
Flocculants, such as polyelectrolytes (PE), are commonly used to improve dewatering. However, they are expensive and have a large environmental footprint.
In this research project, we explore how dewaterability of sewage sludge can be improved by actively controlling the composition of extracellular polymeric substances (EPS). EPS play a key role in sludge dewatering as they are capable of forming hydrogels in the sludge matrix. Actively shaping the EPS composition will lead to an optimization, potentially even omission of flocculant dosing.
Research challenges
Sludge dewatering is a major challenge in wastewater treatment, largely due to the presence of extracellular polymeric substances (EPS). These biopolymers strongly bind water, making it difficult and costly to separate water from the solid sludge matrix. Conventional aids like flocculants only partly help, while thermal processes such as hydrolysis can improve dewaterability but are energy intensive and underlying mechanisms remain poorly understood.
At Delft University of Technology, researchers have shown that EPS can also be recovered as a valuable resource (Kaumera), where its water-binding capacity becomes an asset rather than a problem. New characterization methods now offer deeper insight into EPS composition and its link to dewatering performance.
This project will build on that foundation to actively influence EPS properties, aiming to make sludge dewatering more efficient and sustainable while exploring opportunities for resource recovery. The research offers the chance to contribute to both fundamental understanding and practical innovations in wastewater treatment.
Your assignment
As a PhD researcher, you will take on the challenge of tuning the EPS in sewage sludge so that it will be easier to dewater, ideally without the use of any chemicals. Building on earlier research you will explore ways to induce changes to the EPS via biological, chemical or thermal treatments. This will involve thorough characterisation of the EPS using advanced analytical tools, such as NMR, FT IR and other means.
Based on the developed insights it is the ultimate goal to provide a proof of principle for a novel approach to change sewage sludge EPS to improve the dewatering performance. This research will help reduce costs, improve sustainability, and support more efficient wastewater management.
Your profile
We are looking for a highly motivated and curiosity driven recent master graduate with a background in either (environmental) biotechnology, chemical engineering, process engineering or a related field. Ideally you have previous experience with biopolymers research and characterization of biopolymers.
During your PhD, you will be part of and connected to top research groups working on extracellular polymeric substances while also having the opportunity to collaborate with representatives from the water authorities and technology providers and also learn how sludge dewatering is taking place in practice.
Keywords: Organic chemistry; physical chemistry; microbiology; sludge treatment; process engineering
Professor/University group/Wetsus supervisor(s):
University promotor: Prof. dr. ir. M.C.M. Van Loosdrecht, Delft University of Technology;
University supervisor: Dr. P. Wilfert, Delft University of Technology, Lubeck University of Applied Sciences
Wetsus supervisor(s): ir. Leon Korving, Wetsus
Project partners: This project is part of a new research theme that is intended to cover three to four different projects on sludge dewatering. We will work closely with water authorities and technology providers from Europe and China.
Only applications that are complete, in English, and submitted via the application webpage before the deadline will be considered eligible.
Guidelines for applicants: https://phdpositionswetsus.eu/guide-for-applicants/
