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.

No abstract

No abstract

A high about 3% H 2 S concentration in the biogas produced from concentrated latex process wastewater needs to be removed before further utilization. Water scrubbing is appropriate for the latex factory having plenty of recycled water available. Effects of liquid to gas (L/G) ratios at 0.5-4.0 on H 2 S removal were tested at 0.06 m 3 /h biogas flow rate using a pilot scale scrubber. The experimental results were then simulated to validate the scale-up for the factory, using the process simulation software Aspen HYSYS (HYSYS, Hyprotech and Systems). The highest 99.71% H 2 S removal was obtained by using L/G ratio 4.0. Interestingly, using L/G ratio 1.0 provided 96.01% H 2 S removal, which is slightly lower than on using L/G ratio 4.0, but is more practically appropriate for the real volumes of recycled water and biogas generated from the factory. The experimental data agree with the simulations well. The packed column diameter and height were estimated as 0.5 and 3 m for 40 m 3 /h biogas. Key characteristics of the scrubber effluent were analyzed for further discharge management. The scrubber effluent qualified for direct discharge to the post-treatment ponds. This work shows that using recycled water for desulfurization of the H 2 S-rich biogas is feasible at atmospheric pressure operation.

No abstract