A study of pharmaceutical residues in wastewater from small municipalities in Northern Sweden : E-peroxone as a complementary tertiary removal technique

Abstract: The conventional treatment processes used in Swedish sewage treatment plants (STPs) are not designed to remove micropollutants such as pharmaceuticals and biocides. This leads to STPs being a major source of pharmaceuticals in the environment including surface waters, coastal waters, and groundwaters all over the world. The occurrence of these compounds combined with their adverse ecological effects makes them problematic. This study aims to investigate the removal of pharmaceuticals and biocides from six conventional STPs from small municipalities in Northern Sweden. It also aims to evaluate the suitability and potential of an advanced treatment process called electro-peroxone (E-peroxone) as an additional tertiary treatment step complementing the current STPs configurations, through batch experiments. The removal of pharmaceuticals and biocides in the studied STPs showed great variability. The occurrence of pharmaceuticals was mainly in line with previous research apart from caffeine and paracetamol concentrations. Several pharmaceuticals were detected above their respective critical environmental concentration (CEC) in effluent wastewaters. The removal of pharmaceuticals was heavily influenced by paracetamol. When excluding paracetamol, the total removal of pharmaceuticals ranged from -23% to 80% in the conventional processes. After E-peroxone treatment, removals, excluding paracetamol, ranged from 61% to 93%, and no average effluent concentrations exceeded their respective CEC. In this study, E-peroxone was conducted in not optimized batch-experiments due to time constraints, but still with promising results. In a full-scale application, water matrix specific optimizing should be performed. Therefore, the removal efficiencies of pharmaceutical residues by the E-peroxone process in a plant-specific configuration would most likely be significantly increased.