This fully funded PhD position at Wageningen University & Research focuses on the sorption and biodegradation of surface-active chemicals (SACs) in anaerobic granule-based bioreactors, specifically within the recycled cardboard industry. The project aims to understand how commonly used SACs behave at the solid-liquid interface of microbial biofilms, such as anaerobic granular sludge, and to identify which chemicals contribute to process instabilities. By combining expertise in surface rheology, material science, food physics, and environmental process engineering, the research will systematically screen SACs through batch sorption-biodegradation experiments and continuous expanded granular sludge bed (EGSB) investigations. The goal is to assess the accumulation potential and impact of these chemicals on process performance under continuous flow conditions.

Key activities include investigating sorption kinetics and isotherms of SACs in solution and when attached to colloids, studying biodegradation kinetics, analyzing sorption and biodegradation in EGSB reactors, and performing particle image velocimetry in shear-controlled experiments. The project will also develop guidelines for controlling negative effects of SACs in anaerobic wastewater treatment. The research is embedded within the chair of Environmental Technology and the group of reusable water, led by Prof. Adriaan Mels, with co-supervision from Dr.

Dainis Sudmalis and collaboration with Dr. Mehdi Habibi and Dr. Leonard Sagis.

The project is funded by an NWO Open Technology Programme grant and involves close collaboration with industry partners such as Kemira, Paques B.V., DS Smith Kemsley, and Smurfit Westrock Roermond. Candidates should have an MSc in a relevant field, strong background in rheology, fluid dynamics, or bioprocess engineering, and be fluent in English at C1 level. Experience with programming (Python), sorption behavior of surfactants/polymers, and anaerobic bioreactors is a plus.

The position offers excellent employment terms, including a competitive salary, pension scheme, year-end bonus, and tailored training opportunities. Wageningen University & Research provides a supportive international environment, assistance with immigration procedures, and a focus on diversity and inclusion. Applications are open until November 25, 2025, with interviews scheduled for December 2, 2025.

Applicants must submit a CV, motivation letter, and complete a mandatory qualification form via the university's vacancy page.