Evaluation of SBRP and BRP at various process conditions for the removal of pollutants from dairy effluent: optimization and kinetic studies

This research describes the impact of hydraulic retention time (HRT) and bacterial mass concentration (MLSS) in sequencing batch reactor process (SBRP) and batch reactor process (BRP) for the removal of pollutants from the dairy wastewater. The operational conditions used were variable volume exchange ratio up to 75%, hydraulic retention time (4–8 h), and initial MLSS concentration up to 5150 mg/L. It was found that the SBRP increased the removal efficiencies of biological oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solids (TSS). The higher percent removals of BOD, COD, TP, TN, and SS were obtained in the bacterial mass concentration (MLSS) of 2100 mg/L which were in the order of 88, 96, 82, 92, and 75% for SBRP and were in the order of 84, 93, 70, 91, and 70% for BRP, respectively. The optimum level of MLSS was found to be 2100 mg/L at the retention time of 6 h for both SBRP and BRP. Compared to the conventional process, the SBR reduced the aeration step and achieved higher removal efficiency. Moreover, it reduced the excess sludge by about 25%. Interestingly, the results revealed that lower MLSS brought about better removal efficiencies for both SBRP and BRP.