Research

New Geometries and materials for low salt retention nanofiltration

Introduction
The increasing draught in the Netherlands has put more stress on the water system and new water sources will be needed in the near future. A solution to this problem would be to implement a cyclic water system where wastewater is reused. The problem with this is that many waste streams contain so called organic micropollutants (OMPs). OMPs are small compounds originating from industrial, medical and agricultural waste streams (among others) and are harmful to the environment and potentially humans. Nanofiltration (NF) membranes have proven to be able to filter out OMPs, while having a low salt retention preventing a concentrated brine from being formed. However, the salt concentration of the permeate still has to be tuned for some applications. A possible solution would be to couple electrodialysis (ED) to a NF system to control the salt content. Therefore, in this research, an affordable fit-for-purpose NF/ED system will be designed in collaboration with Wageningen University & Research. This to both filter out OMPs and fine tune the salt concentration of the permeate to minimize the formation of a brine to be able to reuse waste streams to create a cyclic water net.

Keywords
New geometries, Nanofiltration, Polyelectrolyte multilayer membranes, abrasion, module design

Technological challenges
In this research, hollow fiber NF membranes with alternative geometries will be designed that allow for more sustainable and effective processes, specifically in combination with downstream ED. Next to this, the existing NF transport models need to be coupled to ED models to be able to design a fit-for-purpose NF/ED system.