Alkaline hydrogen peroxide pretreatment of cladodes of cactus (opuntia ficus-indica) for biogas production

Abstract

The alkaline hydrogen peroxide (AHP) pretreatment of cladodes of cactus (Opuntia ficus-indica) for biogas production was evaluated based on the delignification of cladodes of cactus. The effects of alkaline hydrogen peroxide concentration (30% w/w solution) and the pretreatment time (3, 6, 9, and 12 h) were evaluated at pH 11.5, temperature of 30 C, and 180 rpm for removal of lignin. A batch of anaerobic digestion experiments were conducted at mesophilic temperature conditions (37 1 C) with the pretreated biomass. The feed stock (cladodes of cactus) used in this study contained 12.51 1.25 cellulose, 16.34 2.93% hemicellulose, and 10.45 2.31% lignin, and the balance were (carbohydrate, protein, lipid, and ash). After AHP pretreatment, the lignocellulosic content of the feed stock was changed to 12.50 1.84%, 13.63 3.23%, and 7.49 3.05% for cellulose, hemicellulose, and lignin respectively. The AHP pre treatment of cladodes of cactus highly affected the lignin structure relative to cellulose and hemicellulose. The alkaline hydrogen peroxide pretreatment resulted in a higher amount of biogas produced from 877.9 15.12 ml biogas/g VS to 1613.5 10.76 ml biogas/g VS which is an 83.4% increment and decreased after 9 h treatment to 1398.8 17.8 ml biogas/g VS. In addition, the measured methane yields range from 302.48 0.33 to 602.65 3.24 ml CH4/g VS. The results showed that alkaline hydrogen peroxide pretreatment of cladodes of cactus is an effective strategy for enhance biogas yield