Development of an Integrated Biorefinery System for Bioconversion of Lignocellulosic Biomass to Polyhydroxyalkanoates and Biohydrogen
S. Kavitha, Yukesh Kannah Ravi, M. Gunasekaran, Indranil Chattopadhyay, P. Sivashanmugam, Vinod Kumar, Gopalakrishnan Kumar, Rajesh Banu Jeyakumar
Abstract
A sustainable lignocellulosic biomass-based biorefinery requires complete utilization and valorization of the biomass components. In the present study, a phase-separated pretreatment (chemo mechanical─delignification followed by bacterial pretreatment) was performed to fractionate lignin and cellulose-rich residue from rice straw biomass (RSB) to utilize lignin for polyhydroxyalkanoates (PHA) and cellulose-rich residue for biohydrogen production. A higher lignin removal of 81.4% was obtained through combined H 2 O 2 –homogenizer pretreatment. The lignin was utilized as a substrate by Bacillus cereus for PHA production. The cellulose-rich delignified RSB was hydrolyzed with cellulase-secreting bacteria. A higher chemical oxygen demand solubilization of 38.2% was achieved in delignified and bacterially (Delig-Bac) pretreated RSB than bacterially pretreated (Bac) alone (22.9%) and control (3.43%). A higher cellulose solubilization of 35.8% was obtained in Delig-Bac pretreated RSB than Bac alone (21.5%). A higher PHA concentration, content, and yield of 480 mg/L, 56%, and 561 mg/g were obtained from 2.970 g/L of lignin. Higher biohydrogen production of 66 mL/gVS was achieved in Delig-Bac pretreated RSB. The economic analysis revealed that Delig-Bac was found to be economically feasible with a net profit of 4.18 USD/m 3 when compared to Bac (−457.4 USD/m 3 ).