Study for the Bio-CNG Recovery of Methane Gas in the Anaerobic Co-digestion Using Malaysian POME (Palm Oil Mill Effluent).

Palm oil mill industry generates a large amount of POME (palm oil mill effluent) and EFB (empty fruit bunch) as a byproduct. Biogas production from anaerobic co-digestion of POME with EFB was investigated under mesophilic condition. High methane yield and high biodegradability were achieved as mixing POME with EFB material applied into an alkaline pretreatment method. The raw biogas from anaerobic co-digestion of POME and EFB contained 60% CH4, 34% CO2, and 200 ppm H2S and was available at 1.013 bar with a production rate of 48–65 m3/h. The biomethane has not utilized as a bio-CNG gas in Southeast Asian region yet. This paper aims to identify the potential of POME biogas into purified bio-CNG gas. The location, capacity and technology of biogas refinery plant were identified based on biogas production of Malaysian palm oil mill plant. The chelate-iron (EDTA-iron solution) process as a pre-treatment method of raw biogas is among the most promising techniques for the hydrogen sulfide (H2S) removal of 99%. The energy contents of biogas could be significantly enhanced by upgrading it to CNG fuel. A pilot-scale separation plant based on cellulosic spiral wound membrane for upgrading biogas to CNG fuel quality was constructed as having a capacity of 30 m3/h and operated at the biogas plant. The result shows that purifying yield contained 98% CH4, 2% CO2, 0.004% H2O, and 1 ppm H2S. [ABSTRACT FROM AUTHOR]