Affinity adsorption

Roberta Hofman PhD MSc

  • Start date
    01 Jan 2016
  • End date
    31 Dec 2017
  • Principal
    TKI Watertechnologie
  • collaborating partners
    Hoogheemraadschap de Stichtse Rijnlanden (HDSR), Sibelco, Waterschap Limburg, Waterschapsbedrijf Limburg (WBL),Universitair Medisch Centrum Utrecht

The presence of pharmaceuticals and degradation products in surface water represents a threat to ecological water quality and drinking water sources. The removal of pharmaceuticals and organic micropollutants is also becoming more and more topical. Many pharmaceuticals end up in wastewater through urine. The most effective way of controlling the emission of pharmaceuticals is by tackling them at-source, that is, in the toilet. In this project adsorption materials will be made which can adsorb the pharmaceuticals at-source. The loaded adsorbent can then settle in the WWTP, and be disposed of and processed together with the sludge. This would prevent the pharmaceuticals from ending up in the surface water and drinking water sources.


A substantial part of the pharmaceuticals we use end up, via urine, in wastewater. But the WWTPs are not usually designed for the removal of this type of substance, so that a high proportion of them ultimately reach surface waters and drinking water sources. It is difficult to remove these substances at this point, because a wide range of substances are involved and they are extremely diluted. In contrast, in the toilet their range is limited and their concentration is relatively high. Pharmaceutical molecules have specific functional groups. The idea is now to develop adsorbents that can interact with precisely these functional groups, so that specific categories of pharmaceuticals can be adsorbed from the water. Because the interaction is specific, the presence of other substances does not pose a problem.


In the first instance, the appropriate adsorbents are being developed for specific, frequently-occurring and difficult-to-remove pharmaceuticals. These adsorbents are tested in the laboratory in drinking water and artificial urine. A method will then be developed for the easy use of these adsorbents in a toilet – e.g., in the form of a small bag. Subsequently, a pilot project will be conducted at the University Medical Center Utrecht. The acceptance of such a system by patients will be studied, as will the question of whether the amount of these pharmaceuticals in the wastewater actually decreases.


Together with their medication, patients are given an adsorbent – e.g., a small paper bag or a toilet block– which they have to place in the toilet before using it. The pharmaceuticals are adsorbed from the urine in the toilet and as they travel to the sewer. The loaded adsorbent settles in the WWTP and can be disposed of and incinerated together with the sludge. All that is left over is the carrier material of the adsorbent, which is a harmless substance such as silica oxide or sand.