<![CDATA[Mass transit stations generate domestic wastewater from passenger, employee, and food tenant activities; therefore, wastewater treatment plants need to be evaluated to ensure process performance and compliance with environmental quality standards. This study aims to evaluate the technical and environmental performance of four wastewater treatment plants, consisting of three underperforming units, namely I1, M5-2, and L1, and one best-performing unit, C1, used as a comparison. The technical evaluation was conducted through field observation, design criteria analysis, operational analysis, and evaluation of standard operating procedures. The environmental evaluation was carried out through inlet-outlet laboratory testing, removal efficiency calculation, and daily pollutant load calculation. The technical evaluation results showed that WWTP I1, M5-2, and L1 still had parameters that exceeded the quality standards, particularly ammonia, TSS, COD, and total coliform. The main causes included unstable aeration, excessive hydraulic loading, short detention time, insufficient biofilter media, sludge and scum accumulation, and the lack of detailed procedures for abnormal conditions. The environmental evaluation showed that WWTP M5-2 had the lowest environmental performance due to an increase in TSS load by 0.02 kg/day and ammonia load by 1.14 kg/day at the outlet, with effluent values exceeding the quality standards. Short-term recommendations focus on process control and operational improvement, while long-term recommendations are directed toward increasing WWTP capacity for L1 and M5-2.]]>
