Investigation of the Effects of Initial Substrate and Biomass Concentrations and Light Intensity on Photofermentative Hydrogen Gas Production

摘要

Biohydrogen, which can be produced by dark fermentation and photofermentation processes, is a renewable and clean approach for hydrogen production. In this study, it was aimed to determine the operational conditions which satisfy the highest photofermentative hydrogen production rate in batch reactors. To that purpose, the effects of initial substrate concentration, initial volatile suspended solids (VSS) concentration and light intensity on photofermentation process were investigated by using Response Surface Methodology (RSM). The photofermantative process was followed by using pure strain of purple non-sulfur (PNS) bacteria: Rhodobacter capsitlatus DSM1710. Results indicated that, under the studied conditions, hydrogen production yields and rates varied in the range of 0.27 mmol H_2/L.h and 0.91 mmol H_2/L.h, respectively. RSM results revealed that the highest hydrogen production rate of 1.04 mmol/L_(reactor).h can be obtained when acetate concentration, initial R.capsulatus concentration and the light intensity values were 35.35 mM, 0.27 g VSS/L and 263.6 W/ m~2 (3955 lux), respectively. Optimum Substrate/Initial biomass concentration ratio (S/X_o), leading to the maximum hydrogen production rate, was found as 7.7 g Acetate/g VSS (8.3 g Chemical Oxygen Demand/g VSS). Moreover, the light intensity was found to be an important factor affecting the hydrogen production rate as well as S/X_o ratio.