Effect of oil and derivative in palm oil mill effluent on the process imbalance of biogas production

Abstract

The effect of oil and its derivative (long-chain fatty acids (LCFAs), and glycerol) in palm oil mill effluent (POME) on methane production and the microbial community were investigated. POME with oil concentration >1.6 g⋅L−1 could cause the imbalance of the anaerobic digestion (AD) process by decreasing methane yield, accumulation of volatile fatty acid (VFA), and increasing foaming tendency. POME containing oleic acid and stearic acid >10 g⋅L−1 caused an imbalanced AD process via accumulation of propionic acid, butyric acid, and oleic acid. Glycerol >5 g.L−1 in POME strongly inhibited on the AD process by a decrease of pH, accumulation of butyric acid, acetic acid, propionic acid, and LCFAs. The cooperation of fatty acid degrading bacteria (Syntrophomonas sp., and Acinetobacter sp.) with H2-consuming methanogens (Methanococcus sp.,and Methanogenium sp.) was found in the normal AD process and played an important role during the degradation of oil and derivatives containing in POME. The concentrations of propionic acid, butyric acid, and biogas production could be the main state indicators for monitoring the AD process performance in POME biogas reactors.