Biological nutrient removal of palm oil mill effluent (POME) hybrid sequencing batch reactor (H-SBR)

Abstract

Recently, one of the alternative technologies applied in treating POME is the combined anaerobic-aerobic system such as conventional sequencing batch reactor (SBR). However, the conventional SBR requires sophisticated technology with high maintenance and multiple tanks. In this study, a modified SBR system with combination of both anaerobic and aerobic condition, named as hybrid sequencing batch reactor (H-SBR), was introduced which combine all of the treatment phases (fill, react, settle, decant, idle) in a single tank. The experiment was set up using automatic bioreactor with a combination of 50 % inoculum (anaerobic/aerobic) and in fresh POME. Preliminary study on single aerobic and anaerobic conditions in treating POME was carried out to investigate combination of anaerobic-aerobic sequences for the best biological nutrient removal of POME and the optimum operational sequence of the lab-scale H-SBR system. The hydraulic retention time (HRT) was 12 hours consisting of 11 hours reaction, 20 minutes filling, 10 minutes settling and 20 minutes discharging. The priority was for the removal of COD, nitrogen and phosphorus. It consisted of 6 different types of sequences where three of them were initiated by anaerobic condition, name as Anae and the other three were initiated by aerobic condition, named as Aerob. From all of the experiments, Anae2 (8 hours anaerobic-3 hours aerobic) results showed that the optimum removal efficiencies were 92.7 %, 94.6 %, and 77.9 % for biological nitrogen removal (BNR), COD removal and biological phosphorus removal (BPR), respectively. Optimization experiment was done with HRT was 20 hours for reaction (8 hours anaerobic, 3 hours aerobic, 8 hours anaerobic) and the removals of BNR, COD and BPR achieved were 95.0 %, 94.1 % and 97.8 % respectively.