Abstract:

In order to understand the micro-behavior and mass transfer of photosynthetic bacteria (PSB)in an immobilized granule, a visualized microchannels photo-bioreactor was designed to observe the adsorption and film forming of PSB named as Rhodopseudomonas palustris CQK 01. And the effects of substrate concentration and flow rate on hydrogen production and substrate degradation of microchannels photo-bioreactor were investigated. The results showed that the PSB behavior in the microchannels can be divided into four stages: initial diffusion and adsorption, diffusion-adsorption and initial splitting and reproducing of bacteria, dividing-increasing and morphological transformation, and gathering and biofilm forming. With the increase of substrate concentration and flow rate, the rate and yield of hydrogen producing rised first and then fell down, but the substrate conversion monotonically went up with its rate slowed down. The substrate degradation efficiency increased first and then decreased with increase of substrate concentration,and reduced with increase of solution flow rate. At higher substrate concentration and flow rate, substrate inhibition and the loss of biofilm were the main reasons for lower rate and yield of hydrogen production. In the range of present experiments, the optimum substrate concentration and flow rate were 50mmol·L^-1 and 2.1ml·h ^-1 respectively, the maximum rate and yield of hydrogen production were 2.4mmol·(g cell dry mass)^-1 ·h ^-1 and 0.78 mol H₂·(mol sub)^-1 respectively.