Sustainable Small Community Wastewater Treatment: Evaluating the Efficacy of DEWATS

Abstract The study investigates the effectiveness of the decentralized wastewater treatment system (DEWATS) in managing and treating domestic wastewater. In this study, the performance of DEWATS located at Wazir Bagh Peshawar, Pakistan was assessed through water quality parameters, namely biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, and temperature. The DEWATS mainly comprises a settler, anaerobic baffled reactor (ABR), and anaerobic filter (AF). Wastewater samples were collected and tested according to American Public Health Association Guidelines (APHA) guidelines on a weekly basis from September 2023 to July 2024. A total of 80 samples of influent and effluent were collected during the aforementioned period. The efficacy of DEWATS was assessed through various statistical tests and efficiency equations. Shapley additive explanations (SHAP) technique was used to render the most important physiochemical parameter that can play a vital role in the treatment process. Both Mann−Whitney U test and t-test produced p-values (<0.05) for BOD, COD, and TSS, showing a statistically significant difference between influent and effluent levels. The average efficiency of DEWATS in removing BOD, COD, and TSS was 76, 83, and 68% respectively. For BOD and COD effluent, SHAP analysis rendered influent BOD and sample temperature respectively as the most important parameters that can enhance the treatment process. Effluent BOD, COD and TSS have been compared with the permissible limits of National Environmental Quality Standards (NEQS) standards which suggest that the effluent water from DEWATS can be used for gardening purposes. The results concluded that DEWATS is an efficient system that can be used to treat water and can be a good alternative treatment option for small communities, schools, and hospitals. The treated water can be used for gardening purposes to reduce stress on groundwater and pumping energy consumption.