Abstract
The effect of NH4+ concentration on hydrogen production from volatile fatty acids (acetate, propionate and butyrate) by the mixed culture of photosynthetic bacteria was investigated by batch experiments. The initial NH4+ concentrations in the batch cultures ranged from 0 to 12mM. The concentrations of acetate, propionate and butyrate in the medium were 1500, 500 and 1500mg/l, respectively. Hydrogen production was observed at NH4+ concentrations ranging from 0 to 6mM. The hydrogen content in the produced gas (H2 and CO2) was 88% at NH4+ concentrations of 4 and 6mM. The hydrogen conversion efficiency was between 12.6 and 42.7%. The maximum hydrogen production rate was 42.3μl/mg dry wt/h. At NH4+ concentration above 8mM, no hydrogen was detected
