Response surface analysis on the effect of cell concentration and light intensity on hydrogen production by Rhodopseudomonas capsulata

A mixture of acetate, propionate and butyrate was used as a carbon source to produce H-2 by Rhodopseudontonas capsulata. The specific H-2 production rate, H-2 yield and light efficiency were evaluated at various levels of initial cell concentration and light intensity by applying response surface methodology. The mixture of 1.8 g/l acetate, 0.2 g/l propionate and 1.0 g/l butyrate could be readily utilized by R. capsulata for H-2 production. Their consumption rate followed the order of acetate > propionate > butyrate. The response surface methodology results demonstrated the effects of initial cell concentration and light intensity as well as their interactive effects on H-2 production. The optimum R-H2 was achieved at an initial cell concentration of 0.77 g/l and a light intensity of 4170 lux. Initial cell concentrations of 0.6-1.2 g/l and light intensities of 3000 lux or higher were suitable for H-2 yield and light efficiency. (c) 2004 Elsevier Ltd. All rights reserved.