Dark Fermentative Biohydrogen Production From Rice Mill Wastewater

Hydrogen (H-2) is one of the most promising fuels for sustainable energy production. Microbial bio-H(2)fermentation is considered to be one of the environment friendly alternatives for satisfying the demand for fossil fuels. The study has aimed to isolate the effective bio-H(2)producing microbes from rice mill wastewater (RMWW) using various pre-treatment enrichment methods. Among the 27 enriched isolates, three isolates produced higher H(2)utilizing rice mill wastewater as the substrate. Molecular level identification revealed that the three bacterial strains wereBacillus thuringiensis-RH1,Bacillus aerophilus-RH2, andBacillus beringensis-AARAT1. Optimization studies revealed thatB. thuringiensis-RH1 would be a promising bio-H(2)producing bacterium with a yield of 0.96 +/- 0.06 mol H-2/ mol glucose utilizing 50% of rice mill wastewater at pH 5.5. Furthermore, the obtained optimized substrate concentration (50%) and pH (5.5) from batch fermentation were used in the 3 L batch bioreactor experiment usingB. thuringiensis-RH1.A higher hydrogen yield (HY) of 1.63 +/- 0.14 mol H-2/mol glucose usingB. thuringiensis-RH1 at 72 hours was obtained in the extensive scale up process.