Marijn Timmer researches the use of aeration membrane technology in decentralized wastewater for enhanced circularity in water usage schemes. His aim is to integrate a membrane aerated bioreactor for urine treatment to recover water and (N2-)gas in space-stations in the framework of the MELiSSA-project from the European Space Agency. Furthermore, he researches integration of these bioreactors in decentralized wastewater-treatment schemes on earth, for local, cost-effective recovery and reuse of water, as to decrease the usage of tap water.