Utilization of hydrogen gas production for electricity generation in fuel cell by Enterobacter aerogenes ADH 43 with many kinds of carbon sources in batch stirred tank reactor

Abstract

Enterobacter aerogenes ADH-43 is a hydrogen gas (H₂) producing mutant bacterium and a facultative anaerobic microbe. This double mutant was obtained by classical mutagenetically treated in order to enhance H₂ production. In addition, this mutant has ability to degrade molasses from sugar factory as well as other carbon sources. The main goals of this research were to use E. aerogenes ADH-43 for fermentation in order to decide the best carbon sources and optimum concentration from molasses, glucose, cassava sugar, glycerol and biodiesel waste media in vial bottle. Moreover, to stabilize H₂ production, it was operated at 37°C and an initial pH 6.8. Performing the research in batch and fed-batch culture, utilizing it by converting to electricity using fuel cells in 50 ml vial bottle, 2% total sugar concentration of sugar cane molases was found to be the highest H₂ production (9.38 L H₂/L medium) during 24 h fermentation. It was also observed that in batch culture at 12 h fermentation, the volume, flow rate maximum, and the yield of H₂ production were 1.6 L H₂/L sugar molases, 73.4 ml H₂/min, and 2.99 mol H₂/mol sugar molases, respectively. Both sugar was consumed perfectly, colony count was 1.7 10⁷ cfu/ml, pH was nearly constant at 6.0, and finally the H₂ was drifted to fuel cell to generate electrical power until 4 V 0.25 A. Moreover, the volume, flow rate maximum, and the yield of H₂ production were 2.12 L H₂/L sugar molases, 107.7 ml H₂/min, and 3.84 mol H₂/mol sugar molases, respectively when the fed-batch culture was performed. This means nearly 1.3- fold yield of H₂ as compared to batch culture was obtained by adding 0.5 L of 2% sugar cane molasses at 5 and 12 h of fermentation in order to reach 7.0 V, 5.3 W and 0.38 A by a fuel cell.

Keywords: Enterobacter aerogenes ADH-43, H₂ production, molasses and fuel cell