Effect of Partial Ozonation and Thermal Pretreatment on Biogas Production from Palm Oil Decanter Cake

Abstract

In the present work, the effect of partial ozonation and thermal pretreatment on the CH4 production by the anaerobic digestion of palm oil decanter cake was studied. Decanter cake is an attractive feedstock because of high biodegradable organic contents (50 and 31 %ww-1 cellulose and hemicellulose). Partial ozonation with 250 mg/hr O3 loading for 20 and 60 minutes increased total sugar releasing and finally improved the performance of anaerobic fermentation based on the CH4 yield and maximum biogas production potential (P). Xylose was the main pentose sugar hydrolyzed on hemicellulose structure for the partial ozonation pretreatment. Thermal pretreatment achieved higher total sugar releasing compared with the partial ozonation pretreatment for most cases. Besides, thermal pretreatment displayed strong effect on short lag time (1.8 d) for microbial adaptation in the fermentation system compared with ozonation pretreatment and non- pretreatment (2.6 and 4.3 d). However, the maximum methane yield (581 mL CH4/g TSadded) and energy recovery (2.9 kJ) were obtained from the partial ozonation pretreatment for 60 min. Similarly, the maximum waste reduction based on TS removal was about 33% observed from the partial ozonation pretreatment for 60 min. Therefore, to improve the biogas production in overall process and enhance the waste utilization, integrating ozonation pretreatment with two stage fermentation would be suggested.