Bioreactors are devices used by sewage treatment plants to process sewage and which produce active sludge, and sediments separated by solid-liquid are treated in anaerobic digestion tanks. In anaerobic digestion tanks, the volume of active sludge deposits is reduced and biogas is produced. After dehydrating the digestive sludge generated after anaerobic digestion, anaerobic digested wastewater, which features a high concentration of organic matters, is generated. In this study, the decomposition of organic carbon and nitrogen was studied by advanced oxidation process. Ozone-microbubble flotation process was used for oxidation pretreatment. During ozonation, the TOC decreased by 11.6%. After ozone treatment, the TOC decreased and the removal rate reached 80.4% as a result of the Ultra Violet-Advanced Oxidation Process (UV-AOP). The results with regard to organic substances before and after treatment differed depending on the organic carbon index, such as CODMn, CODCr, and TOC. Those indexes did not change significantly in ozone treatment, but decreased significantly after the UV-AOP process as the linkage treatment, and were removed by up to 39.1%, 15.2%, and 80.4%, respectively. It was confirmed that biodegradability was improved according to the ratio of CODMn to TOC. As for the nitrogen component, the ammonia nitrogen component showed a level of 3.2×102 mg/L or more, and the content was maintained at 80% even after treatment. Since most of the contaminants are removed from the treated water and its transparency is high, this water can be utilized as a resource that contains high concentrations of nitrogen.