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.

The environmental risk assessment of substances is introduced and the various controls used to protect the environment are outlined. The European notification system and the risk assessments required as part of the system are detailed. Through an examination of the existing European Union System for the Evaluation of Substances tool and sensitivity analyses based on variability in the measurement of physico-chemical properties for a substance, a spreadsheet model was developed to allow multiple risk assessments for the same substance to be calculated simultaneously. The development and testing of the NECXES spreadsheet tool are documented in detail. Data for the capacity and dilution factor at Sewage Treatment Plants (STPs) in England and Wales were collated and statistically analysed and compared to European default values used for generic risk assessments. The default capacity value for STPs (10,000 population equivalents) was protective of 70% of the STPs sampled. The remaining 30% however, a small number of large works, contributed 94% of the total effluent discharged from STPs in England and Wales. The STP data were used with the NEXCES tool to perform and compare probabilistic risk assessments to those calculated using deterministic methods for a number of test substances. The probabilistic calculations produced a lower median exposure concentration for water than the generic assessment for all of the test substances. Regression analysis allowed the probability of adverse effects to be quantified for the various deterministic risk values. The NEXCES tool was also used to develop a rapid assessment tool for new substances in the form of contour plots, which can be used to assess the risk of substances using minimal data. The main conclusions and contributions to the academic and industrial fields, as well as the field of environmental technology are presented. Areas where there are opportunities for further research are also outlined.

Recently, the presence of illicit drugs in effluents from Wastewater Treatment Plants (WWTPs) and the aquatic environment has raised concern over their possible negative effects on aquatic organisms. In this study, therefore ecotoxicological data was retrieved through a literature survey and by using the software ECOSAR. Predicted No Effect Concentrations (PNEC) of five types of illicit drugs and their metabolites including 1. Cocaine (COC) and its metabolite Benzoylecgonine (BE), 2. Amphetamine (AMPH), 3. Methamphetamine (METH), 4. Cannabis ((delta 9 tetrahydrocannabinol (THC), 11-Nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-CCOH)) and 5. 3,4-Methylenedioxymethamphetamine (MDMA) for species of three trophic levels in aquatic ecosystems derived. Predicted Environmental Concentrations (PEC) of above-mentioned drugs in twelve WWTPs’ influent and two effluents in Halland County have been measured by Swedish Toxicology Research Center (SWETOX co). Acute and chronic Risk Quotients (RQ) of the mixture of illicit drugs based upon two novel approaches calculated for the effluents of two WWTPs. Wastewater treatment plant in Ängstorp found with better removal efficiency of above- mentioned illicit drugs and the lower total RQs of (0.01<MRQacute<0.1; MRQchronic = 0.13) in comparison with that of Västra Stranden with the total RQs of (0.1<MRQacute <1; MRQchronic = 1.4). Although the RQ of WWTPs’ effluent was higher than 1 in Västra Stranden, there was no potential of risk on aquatic organisms in surface waters receiving that effluent. AMPH and Cannabis found as the most degradable substances through the WWTPs with (90-100%) of removal efficiency. Moreover, the results revealed that Cannabis (THC-COOH) was the most hazardous illicit drug on aquatic species in case of acute and chronic effects while, in terms of genotoxicology, a mixture of Cocaine metabolites found the most dangerous mixture of illicit drugs on zebrafish embryos.