Integrated Submerged Membrane Bioreactor Anaerobic/Aerobic (ISMBR-A/O) for Nitrogen and Phosphorus Removal During Oil Refinery Wastewater Treatment

Abstract

Nitrogen and phosphorus removal from oil refinery wastewater using an integrated submerged membrane bioreactor anaerobic/aerobic (ISMBR-A/O) was investigated in this laboratory study. The objectives were to demonstrate suitability of the membrane bioreactor (MBR) technology to the treatment of refinery wastewater and its ability to achieve nitrogen and phosphorus removal effectively. IMBR-A/O comprised four reactor tanks: an influent tank, anaerobic tank, aerobic tank, and effluent tank. The IMBR-A/O was operated in cycles of four phases: fill, anaerobic, aerobic, and draw. During the fill phase, the influent tank was half-filled with oil refinery wastewater. During the subsequent anaerobic phase, most of the phosphorus release took place from the submerged biofilm in this reactor. In the aerobic phase, the wastewater was circulated by pumps between the influent tank and the anaerobic tank, resulting in denitrification at the start of the aerobic phase due to low oxygen concentrations, followed by nitrification and luxury uptake of phosphorus when oxygen concentrations increased. Ultimately, the treated water flowed from the effluent tank. The results show that the chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD₅), oil, NH⁺ ₄-N, total nitrogen (TN), and total phosphorus (TP) removal efficiencies were 91, 90, 91, 99, 80, and 66%, respectively.