A robust and efficient bioprocess of hydrogen production from crude glycerol by Clostridium beijerinckii G117

Clostridia can produce hydrogen (a renewable-biofuel) from crude glycerol (CG). Reportedly, the indigenous CG-impurities (eg.methanol, soap and salt) interfere with clostridial-process, and reduces hydrogen production. Thus, it is important to develop a robust bio-process to directly utilize native-CG for hydrogen production. In this study, among four Clostridia tested, Clostridium beijerinckii G117 is selected based on its high hydrogen (>290 mL/g) production from CG. Furthermore, optimization of process-parameters en-hances hydrogen production from strain G117 by-5 fold from 1195 +/- 45 to 5893 +/- 25 mL/L with 2.16 mol/mol yield. The order of impact of process-parameters (optimum value in parenthesis) on hydrogen production is: CG concentration (12.5 g/L)>inoculum size (10%v/ v)>inoculum age (12 h)>temperature (39 degrees C)>initial medium-pH (6.4)>L-cysteine (1 g/L) >operational volume (30 mL)>agitation rate (150 rpm). Notably, this optimized bioprocess records >90% efficiency by determining total mass and electron balances. Interestingly, this optimized bioprocess retains adequate robustness to yield 1.94-2.02 mol/mol hydrogen with elevated CG-impurities including alcohols/salts/surfactants.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.