Performance evaluation of urban wastewater treatment plants: The case of Antalya province

This thesis evaluates the performance of three urban wastewater treatment plants Lara, Göynük, and Gazipaşa located within the administrative boundaries of Antalya Province, through statistical analyses covering the period from 2021 to 2024. The primary objective of the study is to assess the treatment efficiency of these selected facilities, determine inter-plant and seasonal variations using appropriate statistical methods, and evaluate the overall effectiveness of the treatment processes based on the analyzed data. Statistical evaluations were conducted using SPSS software, focusing on the removal efficiencies of key pollutant parameters, namely Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Total Nitrogen (TN), and Total Phosphorus (TP). Following assessments of data normality and homogeneity, non-parametric statistical tests such as the Wilcoxon signed-rank test, Kruskal–Wallis H test, and Mann–Whitney U test were applied. Initially, the study assessed the statistical significance of differences between influent and effluent concentrations of the selected pollutant parameters. Subsequently, the temporal (annual and seasonal) distribution of influent and effluent values was analyzed. Statistically significant differences were observed in both inter-plant and seasonal comparisons. The results indicated a marked decline in biological treatment performance during the winter months. Among the facilities, the Gazipaşa WWTP demonstrated the highest removal efficiency, while the Göynük WWTP showed comparatively lower performance. In contrast, the Lara WWTP exhibited a more stable and consistent treatment efficiency throughout the study period. The findings underscore the critical role of treatment process type, seasonal variability, and operational parameters in determining wastewater treatment performance. In conclusion, seasonal fluctuations significantly influence treatment efficiency, and this effect appears to be closely linked to the specific biological treatment processes implemented at each facility.