Optimization of molecular hydrogen production by Rhodobacter sphaeroides O.U.001 in the annular photobioreactor using response surface methodology

Photofermentative H-2 production at higher rate is desired to make H-2 viable as cheap energy carrier. The process is influenced by C/N composition, pH levels, temperature, light intensity etc. In this study, Rhodobacter sphaeroides strain O.U 001 was used in the annular photobioreactor with working volume 1 L, initial pH of 6.7 +/- 0.2, inoculum age 36 h, inoculum volume 10% (v/v), 250 rpm stirring and light intensity of 15 +/- 1.1 W m(-2). The effect of parameters, i.e. variation in concentration of DL malic acid, L glutamic acid and temperature on the H-2 production was noted using three factor three level full factorial designs. Surface and contour plots of the regression models revealed optimum H-2 production rate of 7.97 mL H-2 L(-1)h(-1) at 32 degrees C with 2.012 g L-1DL malic acid and 0.297 g L-1 L glutamic acid, which showed an excellent correlation (99.36%) with experimental H-2 production rate of 7.92 mL H-2 L-1 h(-1). Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.