Yi Jing Chan*, Foo Seng Hue, Mei Fong Chong, Denny K.S. Ng, David Lian Keong Lim

Abstract
Integrated anaerobic-aerobic bioreactor (IAAB) is a bioreactor technology which operates as a single treatment unit for the removal of organic matter and generation of biogas from Palm Oil Mill Effluent (POME). It is a single reactor configuration with compartmentalization in which the first, second and last compartments are designed for anaerobic, aerobic and settling processes respectively. A pre-commercialized IAAB (3000 m3) was built at Havys Oil Mill Sdn Bhd which is located at Palong, Malaysia, with the objective of investigating its long-term performance under variable organic loads and environmental conditions with respect to effluent quality and methane yield. The pre-commercialized IAAB system was directly fed with raw POME from the palm oil mill. Based on the results, at the steady state operation of over five months, the IAAB achieved a total removal efficiency which was up to 99% for chemical oxygen demand (COD), and biochemical oxygen demand (BOD) and methane yield up to 0.26 L CH4/g COD at organic loading rate (OLR) of 2.0 – 20.0 kg COD/m3 day. The achievement of BOD <100 mg/L throughout the 150 operational days with 45% of compliance was reported. The system could significantly reduce 70% of footprint and 78% of hydraulic retention time (HRT) compared with current conventional treatment systems. Further work on optimization for the recirculation flow rate in the anaerobic zone with consideration of fluid dynamics and microbiology is required to achieve 100% compliance of BOD <100 mg/L.