Research On Performance And Environmental Factors Of Hydrogen Production By Attached-growth Photosynthetic Bacteria

The problems of energy shortage and environmental pollution stimulated humans to search clean and renewable energy. Hydrogen is brought out as such a high calory and cleaning energy to replace the fossil. A couple of hydrogen production methods were put forward, whatever, the style of bio-hydrogen production was paid more attention to because it was produced with less cost and pollution. Phototrophic fermentation is a kind of bio-hydrogen production method which product hydrogen by heterotrophic photosynthetic bacteria with the light energy. So far, these researches are majorly about the hydrogen production of the pure suspended photosynthetic bacteria with the single carbon resource. Although a few studies have given an idea of carrier addition to increase the hydrogen producing velocity by immobilized photosynthetic bacteria, most of these were conducted with pure photosynthetic bacteria. This study aimed to develop the hydrogen production of photo fermentation and the endurance of bacteria at unfavorable factor by immobilized photosynthetic bacteria consortium with the mixed carbon source of acetate and butyrate.Firstly, this study seeks to get a proper carrier to stimulate the hydrogen production, and the activated carbon fiber is tested to be effective for immobilizing the photosynthetic bacteria. The test was carried out at the concentration of 10 m M acetate and butyrate respectively, the light intensity of 6000 lux, and the temperature of 30 ?. The highest hydrogen production of 1904.21 m L/L was got at a ratio of 0.4g/L activated carbon fiber for immobilized photosynthetic bacteria, which is increased by 24.33% for the suspended photosynthetic bacteria. However, the hydrogen production was inhibited when the dosage increased to 0.8g/L and 1.2g/L.Then, at the same condition, this study took a test for the endurance of p H and [NH4+-N] with a dosage of 0.4g/L activated carbon fibers. It concluded that the best p H for the immobilized photosynthetic bacteria hydrogen production is 6.0, which get a cumulative hydrogen production of 1155.9m L/L. This result is developed by 21.6% than p H7.0 hydrogen production by immobilized photosynthetic bacteria. What's more, is still get an increasing of 135.8% compared with suspended photosynthetic bacteria at p H7.0. The immobilized photosynthetic bacteria seemed to be more endurable to the acid condition. On another side, the perfect [NH4+-N] for immobilized photosynthetic bacteria hydrogen production is 1m M. This result seemed did not give a good proof of endurance at high ammonia concentration for immobilized photosynthetic bacteria hydrogen production. Otherwise, the attached-growth bacteria performed better at ammonia concentration of 0~1m M, and acetate removal was also increased.A molecular biochemistry analysis is brought out in this study. The result showed that the photosynthetic bacteria named Rhodobacter blasticus played an important role in hydrogen producing process. It also found that the immobilized bacteria population was much different from the suspended one. What's more, the immobilized photosynthetic bacteria system keeps more stable in the hydrogen production process.