Text: Clarice Sivesgaard Abacan, AAU Communication and Public Affairs
Photos: Sonsoles Quinzanos Lobo

So far, simple groundwater treatment based on aeration and sand filtration has been enough to provide high-quality drinking water in Denmark.  The presence of PFAS, or per- and polyfluoroalkyl substances, together with pesticide residues and other organic micropollutants in Danish groundwater might call for advanced water treatment at Danish waterworks in the future, and there is a need to investigate treatment technologies in Danish groundwater, before implementation at full-scale.

To address this, HOFOR, Greater Copenhagen Utility Company, and Aalborg University have launched a new industrial PhD project funded by the Innovation Fund Denmark and established collaboration with the Hamburg University of Technology. The project focuses on investigating and optimizing membrane filtration with reverse osmosis membranes (RO-membranes) to remove groundwater contaminants from Danish groundwater.

Sonsoles Quinzanos Lobo, the industrial PhD candidate at HOFOR and Aalborg University’s Department of Chemistry and Bioscience, leads the project, emphasizing the importance of effective technologies to protect water supplies

Innovations in Reverse Osmosis Membrane Filtration

This innovative project focuses on two main research areas within RO-membrane filtration. Sonsoles Quinzanos Lobo explains:

 “First, we’re studying the impact of antiscalants - the chemicals added to RO-membranes to prevent scaling. There’s a concern that some compounds from these antiscalants could pass the RO-membranes and end up in the drinking water, introducing a new health risk. Experiences from Germany and Denmark suggest that certain contaminants can pass RO-membranes and enter treated water, so understanding how antiscalants might affect water quality is essential.”

“The second part of our research focuses on the challenge of managing the concentrate produced by RO-membranes. This concentrate, which comprises a large part of the treated water volume, can contain PFAS and other micropollutants from the groundwater at concentrations up to four times higher than in the original groundwater. The options for disposal of this concentrate are limited, and therefore managing the concentrate is currently the largest barrier to the implementation of the technology. Our goal is to identify and test technologies to treat PFAS-rich concentrate efficiently, thus reducing its environmental impact, especially before any large-scale implementation.”

A Collaborative Effort for Clean Drinking Water in the Future

Since its beginning in January 2024, the project has shown promising results at HOFOR’s Hvidovre Waterworks, where RO-membrane filtration is being tested and optimized at an RO-pilot plant rented from Holland. A collaboration with the University of Copenhagen is established to analyze antiscalants through non-target screening to identify their composition and fate through the membranes, strengthening the knowledge needed for safe, effective water treatment practices.

In the next steps of the project, the team will focus on treating PFAS in the concentrate from the RO-pilot plant, initially testing granular activated carbon (GAC) filtration to assess its effectiveness in removing PFAS and other micropollutants, with its first results expected soon.

The project aims to improve our knowledge on implementation and optimization of RO-membrane filtration in Danish groundwater, to increase the technological know-how to manage trace contaminants in the groundwater in Denmark in the future.