flocculants production from wastewater

Background: Fossil-based, potentially-toxic polymers such as polyacrylamide (PAM) are widely employed as flocculants in, for instance, drinking water production, (waste)water treatment, soil conditioners, microbial biomass harvesting. This is a still-growing global market in the order of several millions of tons per year. After application, a fraction of the flocculants end-up in the aquatic environment, raising serious environmental concerns since PAM degradation leads to acrylamide formation, which is neurotoxic, suspected carcinogenic and inhibits reproduction. Alternative, ‘greener’ polymeric flocculants are available (e.g. tannines, chitosan, alginate), but are not competitive with synthetic flocculants. A new biotechnological alternative to obtain competitive flocculants is through open-culture microbial conversion of waste(water) into extracellular polymeric substances (EPS), natural biopolymers excreted by microorganisms. These natural flocculants are biodegradable, do not pose environmental risks and have a lower carbon footprint than synthetic flocculants. Since they are produced from low-value residual streams, EPS can compete with current expensive flocculants while achieving both waste(water) treatment and recovery of valuable products.

Research objective and hypothesis: Microbial EPS have been obtained from synthetic wastewater in lab-scale experiments at high yields. These EPS showed high potential for flocculation and heavy metal recovery in preliminary tests. The objective of this research is to produce EPS from synthetic and real wastewater. Bioreactor design and operating conditions will be optimized to maximize EPS production. We hypothesize that EPS will be produced at high efficiencies, displaying competitive flocculation performance in real-life conditions.

1. Background in Bioprocess Engineering/ Environmental Technology/ Chemical Engineering or equivalent.
2. Great interest in bioreactors, bioprocesses, biopolymers.
3. Good practical and experimental skills.
4. Experience with bioreactors, wastewater treatment.

Duration, salary and location:
1. At least 4 – 6 months working at Wetsus.
2. Allowance: €200,- per month.
3. Start: January – February 2023.

Please upload your CV (max 2 pages) and motivation letter (max 1 page) using the form below. Do not hesitate to contact me in case you have any further questions or if you need more information (

  • Max. bestandsgrootte: 128 MB.
  • Max. bestandsgrootte: 128 MB.