Due to the constant use of plastics in daily life, plastic waste in the environment is becoming more and more common. Particles of microplastics (MP) are of major concern due to their size and some other properties. They have various adverse effects on organisms and the entire ecosystem. Poly(vinyl-chloride) (PVC) microparticles have particularly adverse effects because their degradation releases chlorides into the environment, which can form various toxic substances. Conventional water treatment methods are not efficient enough to remove MP PVC from polluted waters, so the application of advanced removal technologies has been considered. Advanced oxidation processes (AOPs) are processes based on the in situ formation of highly reactive radicals capable of degrading organic pollutants from aqueous media. AOPs are not economically feasible, so a combination of AOPs and biological processes is being considered as a treatment approach. In this study, the degradation of PVC particles with size between 25 and 100 μm by UV-C/H2O2 and UV-C/S2O82– processes was tested. The objective was to determine which of the tested AOPs caused more degradation of MP PVC and which conditions were optimal. The PVC microparticles were characterized by FTIR analysis and the aqueous medium was analyzed by TOC and MS. According to the research results, it was found that both AOPs did not cause complete mineralization of MP PVC under the applied conditions. More fragmentation of MP PVC was observed after UV-C/S2O82– treatment. Moreover, it is considered that the UV-C/S2O82– process is the better choice as a pretreatment for biological processes of waters contaminated with PVC microparticles. Of course, the degradation efficiency depends on the applied degradation time, oxidant concentration and pH. The UV-C/S2O82- process has the potential to increase the biodegradability of PVC. The combination of these two processes is a contribution to the development of sustainable water treatment technologies that are in line with the idea of green chemistry.