Starch degradation and biohydrogen generation by Bacillus sp. SSA

Abstract

Population increase has also increased the need for energy. The use of nonrenewable fossil fuels as the main energy supply has decreased its resources and hydrogen become an attractive substitute for it. Besides, environmental pollution has always accompanied the use of fossil fuels. Hence, simultaneous treatment of wastes and energy generation is desirable. Starch-containing cassava wastewater has the potential to be used as the feedstock for biohydrogen production via dark fermentation process. In the present study, effective starch utilization and biohydrogen production by Bacillus sp. SSA was investigated. It was observed that Bacillus sp. SSA produced hydrogen as early as 12 hours after batch culture fermentation starts. In order to find the optimum conditions for biohydrogen production, batch experiments were conducted at various temperature (30-40ºC), initial medium pH (4.5-5.5) and initial substrate concentrations (0.5-1.5 g/L). The maximum biohydrogen production was obtained at temperature 30ºC, pH 5.5 and initial substrate concentration 1.0 g/L with a total value of 0.141 mL. The biohydrogen production rate, starch utilization, specific growth rate, maximum specific growth rate and yield of product on cell at this condition were the highest with a total of 0.008 mL/h, 23.9%, 0.013 h-1, 0.026 h-1 and 2.104 mL/g, respectively. This study supports the potential of simultaneous cassava wastewater treatment and biohydrogen production using Bacillus sp. SSA strain as the biological agent.