Regulation Of Photo Fermentative Hydrogen Production Enhanced By Biofilm

There is an obstacle before industrialization for photo fermentative biological hydrogen production that the photo-fermentive bacteria have a bad flocculation property so the active bacteria flow away with the outlet leading to the low and unstable hydrogen production. Biofilm will be a proper solution to this problem. At first the thesis studied the impact of biofilm formed above the carrier added into the reactor on the bacteria and hydrogen production. The parameters effecting the biofilm forming and reactor operating were also optimized. Then this paper studied how biofilm promotes the reactor to produce hydrogen from various aspects. This research will support the techniques and theoretical foundation for the following way of the amplified industrialized production.The carrier didn’t promote the growth of the bacteria in the simulated waste water. However, the biofilm formed on the carrier greatly improved the biofilm reactor hydrogen producing activity by expanding the run time from 2-5d to 1-10 d. It increased biogas from 2120 m L/L to 4300 m L/L with a 100% increase, hydrogen concentration of from 60% to 70% and hydrogen production from1060 mLH2/L to 2580 mL H2/L with a 180% increase and a more stable and continuous operating process compared to the control group. The biofilm also helped the bacteria degrade waste form 74mg/L to 320mg/L with the substrate conversion from 24% to 58%.It was confirmed 4 g/L carbon concentration, 0.5 g/L L-cysteine concentration and the kind of carrier with 10 cm wide and number of 1 was the best optimized reactor conditions considering the hydrogen production, run time, rate and the use rate of waste synthetically. The results showed the biofilm could help the reactor resist to the adverse condition and maintain the reactor performance. The biofilm reactor could make the more use of substrates and produce the hydrogen with efficiency and effectivenessThe appearance of the biofilm could micro-regulate the whole reactor. After the form of the biofilm, the nitrogenase and hydrogenase the key enzymes activity of the experimental group were higher than the controlled group such the hydrogen production was increased. The biofilm doesn’t change the relative amounts of the EPS but change the structure especially phenyl structure and hydrogen bond thus made the bacteria low surface energy. Also the biofilm helped the bacteria aggregated in couples thus the bacteria could degrade the EPS to transform more energy and substance to hydrogen. Since the biofilm supported two living strategies: the fixed and free form, the bacteria could choose to distribute the energy and substances to live and produce hydrogen simultaneously.