Continuous mode of carbon dioxide sequestration by C. sorokiniana and subsequent use of its biomass for hydrogen production by E. cloacae IIT-BT 08

The present study investigated to find out the suitability of the CO2 sequestered algal biomass of Chlorella sorokiniana as substrate for the hydrogen production by Enterobacter cloacae IIT-BT 08. The maximum biomass productivity in continuous mode of operation in autotrophic condition was enhanced from 0.05 g L−1 h−1 in air to 0.11 g L−1 h−1 in 5% air–CO2 (v/v) gas mixture at an optimum dilution rate of 0.05 h−1. Decrease in steady state biomass and productivity was less sensitive at higher dilution and found fitting with the model proposed by Eppley and Dyer (1965). Pretreated algal biomass of 10 g L−1 with 2% (v/v) HCl–heat was found most suitable for hydrogen production yielding 9 ± 2 mol H2 (kg COD reduced)−1 and was found fitting with modified Gompertz equation. Further, hydrogen energy recovery in dark fermentation was significantly enhanced compared to earlier report of hydrogen production by biophotolysis of algae.