This fully funded PhD position at Wageningen University & Research focuses on the mechanisms of surface-active chemical (SAC) film formation and their mechanical properties, particularly in the context of recycled cardboard industry and microbial biofilms (anaerobic granular sludge). The project integrates expertise from surface rheology, material science, food physics, and environmental process engineering to investigate how SACs interact with biofilm surfaces, their rheological properties, and the implications for process stability in water treatment. The research aims to identify problematic chemicals, understand their biodegradability and accumulation, and redesign biological processes to avoid instabilities. Key activities include preparation and rheological characterization of SAC films, development of surface rheology protocols, use of colloidal probe atomic force microscopy (AFM) and super resolution microscopy to visualize and quantify film structure, and assessment of mass transfer of biogas through these films using microfluidics.

The project is embedded within the chair of Physics and Physical Chemistry of Foods, led by Prof. Erik van der Linden, and co-supervised by Dr. Dainis Sudmalis, Dr. Mehdi Habibi, and Dr.

Leonard Sagis. Collaboration with industry partners and another PhD project at Environmental Technology is central. Candidates should have an MSc in a relevant field, strong background in rheology, fluid dynamics, or bioprocess engineering, and be fluent in English (C1 level).

Experience with Python, rheology, and AFM is a plus. The position offers a competitive salary, excellent benefits, and a supportive, international research environment.

Applications are open until November 25, 2025, and must include a CV and motivation letter (max 3 pages), plus a mandatory information form. Wageningen University & Research provides assistance for international staff, including visa support and integration services.