ENHANCEMENT STRATEGY OF METHANE PRODUCTION FROM ANAEROBIC DIGESTION START-UP PROCESS OF GREASE TRAP WASTE

Anaerobic digestion is one of the potential processes of waste lipid recovery for beneficial use to produce methane (CH 4 ). In anaerobic digestion, the utilization of grease trap waste for mono digestion is less reported. This might be due to high lipid content in grease trap waste that may cause inhibition effects which resulted from long chain fatty acids (LCFA) accumulation during the degradation process. This study is intended to investigate the effects of lipid acclimated biomass (LAB) and non-acclimated biomass (NAB) in the anaerobic treatment of grease trap waste over increasing organic loading rate (OLR) in continuous stir tank reactor. The results showed that the resistance of grease trap waste toxicity was higher in LAB while in inhibited reactor (NAB), 9 days lag phase occurred during the start-up process and affected the overall CH 4 production. At OLR of 2.2 gCOD/L.day, high CH 4 was yielded of 0.22 LCH 4 /gCOD removed at standard temperature and pressure with 11% CH 4 enhancement in LAB. The inoculum acclimatization is one of the strategy to improve CH 4 production and the purpose is to provide favorable condition to the methanogens towards build-up of volatile acids and inhibitive components such as LCFA. Thus, the overall enhancement for acclimated to LCFA inoculum strategy was 42%. The induction during the start-up had promoted and enhanced CH 4 production when semi-continuous feeding was introduced and remain higher than the other reactors throughout the entire experiment. This indicates that the use of biomass consortium acclimated to long chain fatty acids compounds is a reliable strategy to speed up the start-up of anaerobic digestion process and to enhance the overall CH 4 yield.