Ind. Eng. Chem. Res. 2010, 49, 7093–7101
7093
Effects of Temperature on Aerobic Treatment of Anaerobically Digested Palm Oil Mill Effluent (POME) Yi Jing Chan, Mei Fong Chong,* and Chung Lim Law School of Chemical and EnVironmental Engineering, Faculty of Engineering, The UniVersity of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia
Aerobic treatment of wastewater under thermophilic conditions has received growing interest in recent years. Because of the high discharge temperature (75 to 85 °C) of palm oil mill effluent (POME), it would be more economical if POME were treated thermophilically, as then cooling facilities prior to biological treatment can be eliminated. In the present investigation, the feasibility of thermophilic aerobic biological treatment as a suitable post-treatment system for anaerobically treated POME was examined. Also, the effects of temperature on the treated effluent quality were investigated by using sequencing batch reactors (SBRs) under mesophilic (28 °C) and thermophilic (45, 50, and 55 °C) conditions. The average total COD (TCOD) removal efficiencies varied from 55 to 98% at organic loading rates (OLR) of 2.6 to 4.5 kg COD/m3 · day, dissolved oxygen (DO) concentrations of 2.9-4.5 mg/L, and mixed-liquor suspended solids (MLSS) concentrations of 22500-24200 mg/L. The results show that the thermophilic aerobic treatment was capable of achieving promising treatment efficiencies in terms of TCOD and biochemical oxygen demand (BOD) removals, which exceeded 72% and 76%, respectively, at an OLR of 2.8 ( 0.3 kg COD/m3 · day. The thermophilic sludge also showed good settling characteristics, as reflected by the low sludge volume index (SVI) values (
