Key parameters governing biological hydrogen production from benzoate by Rhodopseudomonas capsulata

Combination of toxic contaminant degradation with hydrogen production has been regarded as a promising but challenging approach in wastewater treatment. In this work, the effects of benzoate concentration, pH and type of nitrogen source on photo-hydrogen production from benzoate by Rhodopseudomonas capsulata were explored. The experimental results show that both benzoate concentration and pH significantly affected the photo-hydrogen production. Taking into account the specific hydrogen production rate and hydrogen yield simultaneously, a benzoate concentration of 5 mM and pH of 7.0 were favorable for hydrogen production by R. capsulata with 0.2 g L−1 glutamate as the nitrogen source. To further improve the economic viability of this process, NH4Cl could be used to replace the expensive glutamate as nitrogen source, and its desired concentration for hydrogen production was in a range of 0.2–0.4 g L−1.