Utilization of Lampung Natural Zeolite as Immobilization Media on Biogas Production from Palm Oil Mill Effluent (POME)

Lampung is one of provinces with wide area of palm oil plantations and processing industries in Indonesia. Each palm oil mill produces 0.7-1 m3 of POME per ton of fresh palm bunches and pollutes the environment when untreated. Furthermore, Lampung is also a region with abundant Natural Zeolites (ZAL) availability. This research was performed to study the influences of modified ZAL as the microorganisms immobilization media (Biocarrier) in biogas production of POME. Hereafter, ZAL as Biocarrier will be applied on Anaerobic Fluidized Bed Reactor (AFBR). AFBR with biocarrier will have higher efficiency than conventional biogas reactor. Furthermore the vertical design of the AFBR does not require excessive land. Modification of ZAL was conducted to provide appropriate place for microorganisms, especially methanogen. This research was started by physical modification of ZAL (CV. Minatama, Lampung), followed by impregnation of ZAL by Fe2+ and Mg2+. Each of the modified ZAL was analyzed by XRF, then characterized by XRD and FTIR before used. Based on XRF analysis, SiO2/Al2O3 mol ratio of physical activated ZAL was 8.913, while ZAL-Fe2+, and ZAL-Mg2+ were 9.957 and 8.8, respectively. The anaerobic process took place in a 2.8 L batch anaerobic digester by adding POME and an active digester effluent of cattle manure as microbial inoculum and 280 grams of each type of the modified ZALs to each digester. Result showed that that impregnated ZAL decreased the organic content of POME more rapidly than the physically treated ZAL. Besides, impregnated zeolite also resulted in higher methane concentration than the digester using physical activated.