Enhanced photo-H2 production of R. faecalis RLD-53 by separation of CO2 from reaction system

The effect of different gases, CO2 concentration, and separation of CO2 from reaction system on photo-fermentation H2 production was investigated by batch culture in this study. Experimental results showed that different gases (Ar, N2, CO2, and air) as gas phase have obviously affected on photo-H2 production and a high concentration of CO2 can inhibit the growth and H2 evolution of Rhodopseudomonas faecalis RLD-53. When CO2 concentration at 5%, cell increased most rapidly the specific growth rate of 0.489 g/l/h and the specific growth rate fell to be 0.265 g/l/h when CO2 concentration at 40%. However, the growth of RLD-53 at CO2 concentration of 60–100% was almost completely inhibited. At CO2 concentrations of 5% and 10%, the maximum H2 yield was 2.54 and 2.59 mol-H2/mol acetate, respectively, and it was similar with the control (2.61 mol-H2/mol acetate). H2 not produced when CO2 concentration at 60–100%. In conclusion, separation of CO2 from reaction system can stimulate H2 production in the entire photo-H2 production process and H2 yield increased about 12.8–18.85% than the control.