This master's thesis investigates the wastewater treatment process in the City of Vinkovci. An analysis of the wastewater treatment process in the city of Vinkovci was conducted over the period from 2015 to 2021. The central aim of this research is to analyze the effectiveness and progress of wastewater treatment procedures and their impact on the environment and the quality of life of the residents of the City of Vinkovci. The research is based on continuous collection of wastewater samples at the inlet and outlet of the treatment facility during the analyzed period. The samples underwent detailed physicochemical and biological analyses to determine changes in the concentrations of various parameters, including suspended particles, chemical compounds, and biological oxidation. The research findings indicate a gradual improvement in the efficiency of the wastewater treatment facility over the analyzed period. Reductions in pollutant concentrations at the facility's outlet, better removal of suspended particles, and more successful biological treatment represent positive trends. Through this analysis, the obtained data provide valuable insights into the progress of wastewater treatment processes in the City of Vinkovci. These results have significant implications for environmental preservation and water quality in the area, contributing to a higher standard of living for the residents and a better future for the environment."