PhD Sorption and biodegradation of surface-active chemicals in anaerobic granule-based bioreactors Wageningen • Wageningen University & Research

Interested in studying surface-active chemicals' behavior at the solid-liquid interface of microbial biofilms in the recycled cardboard industry? This PhD opportunity might be for you! You will focus on identifying problematic chemicals and redesign the biological process to prevent instabilities. Key benefits include partially paid parental leave, flexible working hours, access to sports facilities for a small fee, an 8.3% year-end bonus, and a fully funded PhD position with a tailored course program. Join an international team in a collaborative environment. Take a closer look at why this opportunity stands out.

Your job

Are you interested in studying how commonly used surface-active chemicals in recycled cardboard industry behave at the solid-liquid interface of microbial biofilms, i.e., anaerobic granular sludge? Then this PhD vacancy might be something for you! At Wageningen University & Research we are looking for two candidates to join our teams.

This project combines expertise and techniques from surface rheology and material science in food physics and from environmental process engineering. We will investigate which ones of these chemicals are the problem source and redesign the biological process to avoid process instabilities. New insights into biodegradability and accumulation of surface-active chemicals on microbial biofilms and relations to mass transfer and process stability can be used to rationally design the water treatment in recycled cardboard making or to reassess the types of chemicals that the industry uses.

You will focus on elucidating which surface active chemicals (SACs) used in recycled cardboard production or their combinations thereof have the tendency to form viscoelastic films on microbial biofilms. Since the wastewater matrix of papermaking may contain e.g., surfactants and polyelectrolytes at the same time, it is very likely that complexes of these SACs ultimately are interacting with the biofilm surface. Furthermore, they can be attached to colloids in wastewater before reaching the anaerobic treatment.

Hence, a systematic screening of SACs in small scale batch sorption-biodegradation experiments will be combined with continuous expanded granular sludge bed investigations to assess their accumulation potential and impact on process performance under continuous flow. Results of biodegradation kinetics, adsorption behaviour and interfacial behaviour (performed at WUR-FPH) will be exploited to design a continuous process with improved stability, when exposed to SAC containing wastewater streams. Here e.g., hydrodynamic shear effects can be exploited, when response to stresses of these SAC-films at the interface is known. These results will provide essential information for anaerobic process design in recycled cardboard industry under water-saving scenarios.

This PhD project comprises the following activities:

1. Sorption kinetics/isotherm investigation of SACs in solution/attached to colloids;
2. Biodegradation kinetics of SACs in solution/attached to colloids;
3. Sorption and biodegradation of SACs in EGSB reactors in relation to process performance;
4. Perform and Analyse Particle Image Velocimetry data in shear controlled continuous experiments;
5. Developing guidelines for controlling negative effects of SACs in anaerobic wastewater treatment.

The second PhD position is Mechanisms of surface-active chemical film formation and their mechanical properties (at FPH – WUR). Both PhDs will be performed in close collaboration with Kemira, Paques B.V., DS Smith Kemsley and Smurfit Westrock Roermond. The project is funded by an NWO Open Technology Programme (OTP) grant. 
 
You will work here
The research is embedded within the chair of Environmental Technology, the group of reusable water, which is led by Prof. Adriaan Mels. You will be co-supervised by Dr. Dainis Sudmalis, and you will collaborate with a PhD candidate supervised by Dr. Mehdi Habibi and Dr. Leonard Sagis.
Your qualities

We are looking for highly motivated candidates holding an MSc. degree in physical chemistry, food physics, applied physics or mechanics, material science, chemical engineering, environmental engineering or biotechnology with a strong background in rheology, fluid dynamics or bioprocess engineering, and a strong desire for multi-disciplinary work. The candidates should be fluent in written and spoken English, enjoy working within the interface between curiosity-driven and application-inspired research. A key success factor of this project is intensive collaboration between the two PhD projects, which means that candidates should enjoy collaboration with other PhD-students and the experts from the industry involved in this project.

You also possess:

• An English proficiency certificate in case your MSc degree was not obtained in the Netherlands and/or English is not your mother tongue;
• Official, stamped MSc degree certificate;
• Good command of programming languages like Python will be considered as a plus;
• Experience with sorption behavior of surfactants/polymers will be considered a plus;
• Experience with anaerobic bioreactors will be considered a plus.

For this position your command of the English language is expected to be at C1 level. Sometimes it is necessary to submit an internationally recognised Certificate of Proficiency in the English Language. More information can be found here.
We offer you

Wageningen University & Research offers excellent terms of employment. A few highlights from our Collective Labour Agreement include:

• Partially paid parental leave;
• working hours that can be discussed and arranged so that they allow for the best possible work-life balance;
• there is a strong focus on vitality and you can make use of the sports facilities available on campus for a small fee;
• a fixed year-end bonus of 8.3%;
• excellent pension scheme.

In addition to these first-rate employee benefits, you will receive a fully funded PhD position and you will be offered a course program tailored to your needs and the research team.

The gross salary for the first year is € 3.059,- per month rising to € 3.881,-  in the fourth year in according to the Collective Labour Agreements for Dutch Universities (CAO-NU) (scale P). This is based on a full-time working week of 38 hours. We offer a temporary contract for 18 months which will be extended for the duration of the project if you perform well.

There are plenty of options for personal initiative in a learning environment, and we provide excellent training opportunities. We are offering a unique position in an international environment with a pleasant and open working atmosphere.

You will work on the greenest and most innovative campus in the Netherlands, in an international and open working environment. For 20 consecutive years, we have been voted the "best university" in the Netherlands! A place to be proud of.

Coming from abroad
Wageningen University & Research is the university and research centre for life sciences. The themes we deal with are relevant to everyone around the world and Wageningen, therefore, has a large international community and a lot to offer to international employees.

Because we expect you to work and live in the Netherlands our team of advisors on Dutch immigration procedures will help you with the visa application procedures for yourself and, if applicable, for your family.

Feeling welcome also has everything to do with being well informed. We can assist you with any additional advice and information about for example helping your partner to find a job, housing, or schooling. Finally, certain categories of international staff may be eligible for a tax exemption on a part of their salary during the first five years in the Netherlands.
Do you want more information?

For more information about this position, please contact Dainis Sudmalis, assistant professor of environmental process engineering and water treatment (via de button "Solliciteer nu" op deze pagina.).

For more information about the procedure, please contact Evelien Janssen, corporate recruiter, by email via de button "Solliciteer nu" op deze pagina.. 

Ready to apply?
You can apply directly using the apply button on the vacancy page on our website which will allow us to process your personal information with your approval. Only applications submitted through our website will be considered.

To apply, please send the following documents (max. 3 pages in total for both documents):

• Complete and up-to-date curriculum vitae;
• Motivation letter

The maximum length of the documents must not exceed 3 pages. If it exceeds, applications will not be considered. Additional files such as grades and transcripts are not required during this stage and will not be considered.

You can apply until Monday, November 25th, 2025. The first interviews are scheduled for Tuesday, December 2nd , 2025.

Additional information form
For this position, you must fill in a mandatory form which will allow us to have a comprehensive view of your qualifications and better assess your fit for it. You can access the form using the link below:

Your prompt response will ensure that your application continues to move forward in the evaluation process. We assure you that the information provided will be kept confidential and used solely for this application process.

Welcome, safe, and valued
Wageningen University & Research (WUR) highly values diversity and inclusion because we believe that different insights lead to innovative solutions. We create a work environment where everyone feels welcome, safe, and appreciated, regardless of background, identity, or experience. Together, we are building a culture where everyone's unique contribution adds to the success of our organization.
We are

The mission of Wageningen University & Research is ‘To explore the potential of nature to improve the quality of life’.

We pursue this mission through a synergistic approach between Wageningen University and Wageningen Research Foundation (applied research). Our research focuses on questions within the domains of food, living environment, and society. With approximately 30 locations, 7,700 staff members, 2,500 PhD candidates, and over 13,000 students, Wageningen University & Research is among the world’s leading knowledge institutions in its domain. The integral approach to challenges and the collaboration across various disciplines form the core of the unique Wageningen approach.

Read the 5 reasons why your future colleagues enjoy working at WUR.

We will recruit for the vacancy ourselves, so no employment agencies please. However, sharing in your network is appreciated.