Biochemical methane potential of palm oil mill effluent (POME) co-digested with rubber latex effluent (LTE): Effect of POME/LTE ratio and temperature

Abstract

Single anaerobic digestion of rubber latex effluent (LTE) is known to be difficult and low yield which produces biogas containing high sulfur dioxide and ammonia. This article investigates the potential of co-digestion of palm oil mill effluent (POME) and LTE both in terms of synergistic, inhibitory effects and process stability particularly in inferring what would happen in an industrial-scale biogas plant if this type of co-digestion is to be used. The article focuses on the biochemical methane potential (BMP) of POME-LTE at different mixing ratio within the temperature range of 30-45 °C, the range which is used in most commercial biogas power plants in Thailand. It was found that proper co-digestion between POME and LTE provided a good opportunity to optimize the bio-methane yield because of their synergistic effect. All mixing ratios provided stable biogas production up to at least 45 days. Co-digestion of POME and LTE had a synergistic effect that when mixing 80-90 % of POME with 10-20 % of LTE, it enhanced the BMP by 25-35 %. It is also recommended that, in mesophilic range, 45 °C would be the best for both methane yield and high methane content in the biogas. We also have illustrated that 2-substrate models (in this case the Gompertz 2 substrate (GTS) model) is very suitable for representing and describing co-digestion data because of their inherently multiple substrate tendency. In most cases, Gompertz-type equations for single substrate did not represent the accumulated biogas/methane data adequately.