Biogas production enhancement by co-digestion of empty fruit bunch (EFB) with palm oil mill effluent (POME): Performance and kinetic evaluation

Abstract

The palm oil industry is gearing itself towards sustainability by implementing mandatory biogas capture for all palm oil mills in the effort to reduce greenhouse gases. This action also indicates that the anaerobic digestion of palm oil mill effluent (POME) will be one of the essential sources of biogas for energy generation. However, the availability of POME is limited during the low crop season due to the lower palm oil production. Concurrently, the solid wastes known as empty fruit bunches (EFB) are also produced from the oil mill. EFB has vast potential for power generation, though it is currently not being fully utilized. Therefore, this work aims to enhance the biogas production from anaerobic co-digestion (ACD) of EFB with POME by evaluating the effect of alkaline pretreatment of EFB, EFB-to-POME ratio, and temperature on the methane yield. The optimum EFB:POME ratio is 0.6:1 as the methane production of this ratio at both thermophilic and mesophilic conditions are relatively high (up to 74.02 ml CH4/g VS). Results show that ACD performs 2.36 times better than mono-digestion of POME at mesophilic conditions. The modified Gompertz model could predict the process behavior of the ACD of EFB with POME with high R2 (>0.95). Further investigation on other potential pretreatment methods and synergism analysis of co-digestion, which provides a balance between efficiency and economy could be carried out. The impact of this work will be towards a sustainable environment, which will significantly reduce the environmental impacts of palm oil production.