Optimization of Moving Bed Sequencing Batch Reactor for the Treatment of Oil Refinery Wastewater

Abstract

The oil refinery wastewater, distinguished by a high organic load and oil content, was effectively treated using a moving bed sequencing batch reactor (MBSBR). MBSBR integrates the benefits of both sequencing batch reactors (SBR) and moving bed biofilm reactor (MBBR) techniques, operated in sequencing batch mode, resulting in improved treatment performance. The performance of lab-scale aerobic MBSBR was investigated for an oil refinery wastewater with a chemical oxygen demand (COD) concentration of 810 ± 30 mg/L. The study aims to explore the performance of carrier media filling ratios (FRs) and hydraulic retention time (HRTs) on treating oil refinery wastewater as well as to determine the optimal value for both the parameters. The experimental investigation included optimization of parameters by adjusting the filling ratio ranging from 10 to 40% and hydraulic retention time from 6 to 24 h. The optimization was done by examining the organic pollutant concentration in the effluent. Higher media FR and HRT show higher pollutant removal efficiencies from wastewater. The COD, BOD, oil and Ammonium-N (NH4-N) removal efficiencies were determined to be 88.43, 88.50, 86.21 and 88.72%, respectively at the optimum filling ratio of 30% and hydraulic retention time of 18 h. The morphology of biofilm shows that the biofilm thickness was larger at lower HRT as compared to higher HRT. Overall, this study highlights that a media filling ratio of 30% and HRT of 18 h gives the optimal treatment efficacy, providing a better understanding of how to treat oil refinery wastewater by using this hybrid treatment technology.