Application of the UV-C assisted persulphate/peroxymonosulphate process for the mineralization of organic substances in drinking water

Abstract

The aim of this study was to evaluate the high oxidation potential of hydroxyl and sulphate radicals generated by UV-C assisted persulphate (PS) and peroxymonosulphate (PMS) processes in natural water. The effects of initial oxidant concentration on degradation processes were investigated using TOC, PS, pH, and UV254 measurements in samples taken at specific time intervals. The particle size distribution profiles were also determined for the raw water and effluent samples from the PS/UV-C and PMS/UV-C. Accordingly, the final removal rates were 19%, 40%, and 55% for PS/UV-C doses of 0.2 mM, 0.5 mM, and 1.0 mM, respectively, while the TOC removal was 20%, 35%, and 64% for 0.2 mM, 0.5 mM, and 1.0 mM PMS/UV-C, respectively. The results showed that the rate constants of TOC removal followed first-order kinetics for both PS and PMS. The general assessment of energy consumption during the PS/UV-C and PMS/UV-C processes showed that the time required for the same amount of TOC removal decreased as the initial PS/PMS concentration increased, so that the energy required decreased in relation to volume and mass. Overall, the obtained results were used for a comparative analysis of the oxidation process, and the recommended process was evaluated with samples taken from the effluent of each unit of the drinking water treatment plant to determine the correct location for the treatment process. The results showed that the PS/UV-C process should be designed after filtration, rather than after sedimentation, and the end of the treatment plant.