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In this master thesis project, the removal of micro-pollutants (MPs) from water and wastewater were investigated by ozonation and the peroxone process O3/H2O2. Themain aim of the study was to compare the degradation efficiency of the two processes for a selection of organic biocides and active pharmaceutical ingredients (APIs) in wastewater and synthetic water. Synthetic water and wastewater effluent were spiked with fifteen compounds including twelve biocides and three APIs and samples were taken at different time points to determine degradation kinetics in treatment by the two processes, respectively. Most of the biocides tested in this study showed moderately reactivity, or were non-reactive, with O3 (e.g., Carbendazim, 1H-Benzotriazole, 1, 2-Benzisothiazol-3(2H)-one, 2, 4-Dinitrophenol, 4-nitrophenol) and some of the biocides and APIs were readily reactive with ozone (O3) and were removed from the water by direct O3 oxidationduring both processes. Trimethoprim was found to be an ozone reactive micropollutants and showed highest reactivity with O3. In the abatement mechanism, these micro-pollutants are removed based on the ozone-based processes and with hydroxyl radical •OH in peroxone process. Comparing the two processes, the peroxone process showed highest percentage removal of compounds (90-100%) within moderate time periods (30 s - 2 min) in synthetic water and (30 s to 10 min) in wastewater. The results revealed that the peroxone process showed highest removal efficiency and with higher reproducibility. Further, generally