MICROPLASTICS IN THE DRINKING WATER TREATMENT PROCESS: A CASE STUDY OF GISLAVED, SWEDEN

Abstract

The production and subsequent pollution of plastics has reached staggering levels in recent decades, leading to the ubiquitous presence of microplastics in Earth’s environmental systems, including aquatic resources used for drinking water. The consumption of microplastics is a risk to human health and microplastics have been found in a variety of drinking water sources worldwide, including in larger cities in Sweden with complex treatment processes. This study examines a simpler drinking water treatment plant in Gislaved, Sweden which uses the river Nissan as a source and removes contaminants using natural and artificial slow sand filtration in addition to a bioreactor employing polypropylene-based biofilm carriers. The aims are to assess the presence of microplastics in the drinking water produced, the effectiveness of the treatment process, and the possibility of contamination from the plant itself. Samples representing various stages of the treatment process were collected, processed and analyzed using micro-Raman spectrometry, with minimum examined particle size 5µm. Microplastics were found in the drinking water at significantly higher rates than in more advanced drinking water treatment plants in Sweden in all examined size fractions. The full effectiveness of the treatment plant was not possible to assess due to technical and time-related difficulties, but the artificial sand filtration showed an >95% removal rate of microplastic particles in the >50µm range. Contamination from the bioreactor was determined to be likely, with more than half of detected plastic particles in the drinking water showing corresponding Raman spectra to the polypropylene biocarrier material. The results highlight the possible health risks of drinking water from simpler treatment plants, especially those employing plastic components; further research is recommended for a complete assessment of the studied water treatment plant as well as other comparable facilities.