On Tuesday 17 May, the University of Twente (UT) opened a membrane filtration pilot unit at the Enschede wastewater treatment facility. This is part of the research being carried out by the Applied and Engineering Sciences department of the Dutch Research Council into new technology for the filtration of organic micro-pollutants. One of the things that PhD research scientist Hans David Wendt is studying is the process that breaks down the contaminated water that is left from the membrane filtration in a bioreactor.
When you take medicines, you expel a lot of the active substances when you urinate. Those small, organic molecules are examples of micro-pollutants. When they get into the water, these drug residues are harmful not only to humans but also to life in and around the water. “We aren’t talking about just one substance but a large cocktail of possibly thousands of different substances”, says UT researcher Hans David Wendt.
The University of Twente has been carrying out research for many years into the development of membranes for purifying water and removing the cocktail of micro-pollutants. A membrane – a sort of very fine sieve – allows only water and some minerals to pass through. However, the residual water that remains has a higher concentration of drug residues, which requires further treatment. “In this project we aim to tackle this residual water by sending it back to a bioreactor, where the drug residues are broken down”, says Wendt. “A bioreactor is frequently already installed at wastewater treatment facilities but is unable to break down the drug residues adequately. Sending the water back increases the time available to the bioreactor to break down the substances. That will therefore enable total removal.”
Wastewater treatment facility in miniature
The pilot is a miniature version of the present wastewater treatment facility in Enschede, with the addition of the new membrane filtration unit. The entire system was designed in partnership with Nijhuis Saur Industries, which subsequently built it. This plant will filter one thousand litres per hour. That is substantially more than in the laboratories at UT. “Along with all the partners we want to find out whether the technology works in practice on a larger scale”, Wendt adds, “We’re working with genuine wastewater, so we hope to get results that you cannot see in the laboratory.” The plant is based on membranes for which the basis was developed at the UT, and which are being deployed globally by NX Filtration.
Picture 1: Opening of the pilot. Picture by Jaap Eijsker
The project partners started the pilot on 17 May 2022 with a gala opening at WWTP Enschede. The pilot is part of the wider research being carried out by the Applied and Engineering Sciences department of the Dutch Research Council into the filtration of organic micro-pollutants, headed by Prof. Wiebe M. de Vos of the Membrane Science and Technology Cluster. Alongside the PhD project of Hans David Wendt, PhD researcher Wendy Jonkers is developing a new generation of membranes that she can also test in the pilot. A third PhD researcher, Claudia Rodriguez, at the Environmental Technology department of Wageningen University & Research is studying in detail how the drug residues break down in the bioreactor. In these projects, UT is cooperating actively with Wageningen University & Research, Nijhuis Saur Industries, NX Filtration, Vechtstromen Water Authority, Rijn en IJssel Water Authority, Aa en Maas Water Authority, Vallei en Veluwe Water Authority, STOWA, Oasen, Saxion and KWR.