Improvement of Biohydrogen Fermentation by Co-digestion of Crude Glycerol with Palm Oil Decanter Cake

Abstract

This study focuses on enhancement the efficiency of biohydrogen production from co-digestion of crude glycerol (GLC) with palm oil decanter cake. Decanter cake with the characteristic of high biodegradable organic contents and nutrient rich compositions is an attractive feedstock for biogas production. The biochemical methane potential tests, the applied method to determine hydrogen production, were conducted to evaluate the effect of crude glycerol in decanter cake fermentation at the varying glycerol concentration of 0.25-2% wv^-1 under thermophilic condition (55°C). The results revealed that the maximum hydrogen potential production (P) (562 mL) and hydrogen yield (871mL/gTSremoval) were observed at the 2% wv^-1 crude glycerol. Decanter cake was used as 2 functions 1) feedstock and 2) microbial source in hydrogen fermentation. Crude glycerol displayed strong effect on the pH maintenance for the overall process including hydrolysis and fermentation process. The final pH > 5 was obtained for all cases. Waste utilization based on TS and COD removal trended to decrease at the increase of crude glycerol loading (0.75 and 2% wv^-1). This study displayed the feasibility of waste to energy from palm oil industry and biodiesel production besides the biogas plant from POME. Semi-continuous fermentation in 20 L bioreactor expressed the optimal HRT of 2 days could be maintain to dilute the acidity condition. The maximum yield of hydrogen production of 43.33 L/kgTS_added, hydrogen production rate of 0.89 L/L.d and energy recovery of 0.11 kWh/kgTS_added were obtained from the HRT of 2 days with 1.5% GLC co-digestion. However, better performance in both hydrogen production and waste utilization from decanter cake and crude glycerol fermentation could be more effectively improved by using two-stage fermentation.