Nanoplastics in sand filters
The increased use of plastics in everyday life and inadequate waste management practices conducted to the accumulation of plastic debris in the natural environment, especially in the aquatic systems used for drinking water production. Nanoplastics resulting from the fragmentation of microplastics are considered as the most hazardous fraction and the question has been raised whether conventional treatment processes, including filtration, are able to retain these pollutants.
The present study investigated adsorption of polystyrene nanoplastics to quartz sand used as a filtration medium in the main drinking water treatment plant of Geneva. The obtained results enabled to estimate sand adsorption capacities and percentage of sand surface covered with nanoplastics. Moreover, they enabled to identify adsorption mechanisms under ideal laboratory conditions and to follow their changes under environmental conditions. These outcomes are very important for drinking water providers as they help to better understand processes taking place inside filtration units and improve operational conditions and maintenance procedures.
This research was conducted in close collaboration between the department F.-A. Forel for environmental and aquatic sciences, (Gabriela Hul, Serge Stoll; Environmental Physical Chemistry Group), the Department of Earth Sciences (Agathe Martignier) and the Services Industriels de Genève (SIG).