Evaluation of the effectiveness of wastewater treatment in meeting the effluent quality standard - a case study in Balongan, Indonesia

Wastewater discharged from oil and gas operations contains harmful pollutants, including COD, oil and grease, H2S, NH3, and total phenol, which cause environmental risks if not adequately treated. This study evaluates the wastewater treatment at the MGS WTP in Balongan, West Java, Indonesia. This assessment integrates pollutant efficiency, pollutant load reduction, and correlation analysis between water quality parameters. A total of two samples (inlet and outlet) were collected daily from January to December 2024. Wastewater samples were analyzed according to SNI and APHA methods. The results of the study achieved high removal efficiencies for COD (94%), NH3 (88%), and total phenol (76%). While oil and grease, and H2S achieved moderate removal efficiencies of 68% and 65%, respectively. Pollutant load analysis showed a substantial reduction in COD (262 kg/day), oil and grease (31.1 kg/day), H2S (0.06 kg/day), NH3 (12.2 kg/day), and total phenol (2.36 kg/day). The paired t-test showed statistically significant reductions for all pollutants (p < 0.001). The treated wastewater complied with Indonesian Regulation of wastewater quality, resulting in the treatment system effectively reducing pollutant loads and supporting sustainable management of wastewater.