Pharmaceutical Residues in Drinking Water - A Case Study on Pharmaceutical Concentration in Rådasjön and Its Impact on Human and Environmental Health

Abstract

In recent years, the occurrence of anthropogenic persistent substances, such as pharmaceuticals, in aquatic environments has attracted global attention to find solutions that both mitigate measured concentrations and address the significant challenges they pose to public health and aquatic ecosystems. This study aimed to identify and quantify pharmaceuticals in Lake Rådasjön, western Sweden, which act as a primary drinking water source for Mölndal’s inhabitants. The study identified metformin (MET) and gabapentin (GBP) as the main pharmaceuticals in the lake water using Liquid Chromatography-Mass Spectrometry (LC-MS) analytical method. The analysis showed that only MET was detected at high concentrations in the drinking water treatment plant (DWTP) effluent, while GBP was below the detection limit, indicating that the current treatment methods at Mölndal's DWTP achieved high removal efficiency. MET, on the other hand, remained high, indicating that current treatment processes were insufficient and other advanced processes needed to be adapted. This thesis was based on a literature review evaluating several treatment methods, followed by laboratory experiments aimed at estimating the removal efficiency of multiple treatment combinations, including ozonation alone, the combination of ozonation and chlorination, and ozonation combined with Granular Activated Carbon (GAC). The results showed that ozonation alone reduced MET concentrations by 52.5%, while the combination of ozonation and chlorination resulted in a similar reduction of 52.9%. The most effective combination to reduce MET concentration, promote human health, and improve the environment was ozonation followed by GAC, which gave a reduction of up to 88.4%. The calculation of the risk assessment showed that the MET concentration found in DWTP effluent posed no risk to human health. Similarly, the MET concentration in the lake did not pose any risk to fish. However, GBP posed a moderate risk to fish and potentially caused oxidative damage. Finally, further research is necessary to better understand the impacts and risks of GBP and MET and to ensure safe water quality.