Biogas Production from Oil Palm Empty Fruit Bunches and Palm Oil Decanter Cake using Solid-State Anaerobic co-Digestion

Abstract

Oil palm empty fruit bunches (EFB) and palm oil decanter cake (DC) were used to investigate biogas production by using solid-state anaerobic co-digestion (SS-AcoD) with 15% total solid (TS) content. Solid state anaerobic digestion (SS-AD) using substrate to inoculum (S:I) ratio of 3:1, methane yields of 353.0 mL-CH4/g-VS and 101.5 mL-CH4/g-VS were respectively achieved from mono-digestion of EFB without oil palm ash (OPA) addition and of DC with 10% OPA addition under mesophilic conditions 35 °C. By adding 5% OPA to SS-AD using 3:1 S:I ratio under thermophilic conditions (55 °C), mono-digestion of EFB and DC provided methane yields of 365.0 and 160.3 mL-CH4/g-VS, respectively. Furthermore, SS-AcoD of EFB:DC at 1:1 mixing ratio (volatile solid, VS basis), corresponding to carbon to nitrogen (C:N) ratio of 32, gathering with S:I ratio of 3:1 and 5% ash addition, synergistic effect is observed together with similar methane yields of 414.4 and 399.3 mL-CH4/g-VS, achieved under 35 °C and 55 °C, respectively. According to first order kinetic analysis under synergistic condition, methane production rate from thermophilic operation is 5 times higher than that from mesophilic operation. Therefore, SS-AcoD could be potentially beneficial to generate biogas from EFB and DC.

Study of Biogas Production From Palm Oil Solid Wastes: A Review

“…The temperature affected the methane production of DC based on the literature by SJ Malik (29) that around 46% more methane was yielded during 38 o C compared to 26oC. It was further supported by Muthita Tepsour's research (22) which uses the temperature of 55 oC and 35 o C where DC digested at 55 o C resulted in a higher methane yield compared to 35 o C by 110%. This shows that an increase in temperature can increase the methane production.…”

“…Based on the study of Suwimon and Nipon's research (26) DC has the potential to produce methane as an individual feedstock/substrate. Muthita Tepsour's research (22) supported that anaerobic mono-digestion of DC has the potential to produce methane of 160 ml CH4/g VS. By codigesting it with EFB the methane yield increased to 353.8 ml CH4/g VS, which is a 121% increase in methane yield. Other co-digestion of DC with EFB, POME, waste water and sewage sludge have the potential to increase methane production.…”

“…The main substrate used for study is EFB. Based on Muthita Tepsour and friends (22) and Vincentius' research shows that anaerobic digestion of EFB alone has the potential to produce methane. Co-digestion of EFB with other substrates can result in synergism or antagonism.…”

“…Co-digestion of EFB with other substrates can result in synergism or antagonism. From Muthita Tepsour's research (22), it showed that the co-digestion of DC and EFB caused antagonism in the biogas production; resulting in lower methane yield. Although when EFB was co-digested with POME it resulted in synergism which increased the methane production based on Sittikorn Saelor's research (23).…”

“…When these inoculums were used during anaerobic digestion, sufficient amount of substrate to inoculum is required to avoid excessive pH spikes especially during the acidification stage. Muthita Tepsour's research (22), as can be seen in table 2.3.1 shows that EFB digested at the temperatures of 55 o C and 35 oC were compared and concluded that the anaerobic digestion at higher temperatures of 55 o C performed better and resulted in higher methane production. The effect of the temperature on methane yield varied depending on the S:I ratio studied and percentage of OPA studied.…”