Effects Of COD/N On Fermentation Hydrogen Production By UASB Reacter

Energy was the power of economic and social development. In recent years, as people’s pursuit of higher living standards, the demand of the energy also increased. The statistical review of world energy by the British Petroleum(BP) in June2010shows that oil and natural gas were the main. However, the environmental issues such as global warming of extensive use of fossil fuels have begun to surface already. So it is urgent to seek a new renewable energy. Hydrogen as a clean and efficient energy has become the focus of attention of the world. With the Brown sugar as substrate. This paper studies the change of the run-time arguments when changes the content of organic nitrogen and inorganic nitrogen sources by up flow anaerobic sludge blanket (UASB) as a reactor. Compared the effects of different COD/N on hydrogen production, and determine the best value of COD/N.The significant effects of gas production and the removal rate of COD when added organic nitrogen sources(beef extract and yeast extract) was increased from0.5to2.5g. When the reactor operation from21to30d. The maximum gas production and the removal rate of COD of beef extract were15.30L/d and35.10%. And the maximum gas production and the removal rate of COD of yeast extract were18.06L/d L/d and38.81%at the same time. The hydrogen content could reach the balance between50%to60%. During the whole operation, the pH range was4.0～4.5and ORP stably remained at the range of-250mV to-500mV. The liquid end products were always mainly ethanol and acetate in the system for a typical ethanol-type fermentation type.The same added inorganic nitrogen which has been used in former study was organic nitrogen, the system was stable within50d. Results showed that, improve the concentration of inorganic nitrogen has the ability to enhance the gas production, but the fluctuation margin was narrower. There were no obvious effects on hydrogen content, pH, ORP and the removal rate of COD. Liquid end products were predominated by ethanol and acetate, with smaller quantities of propionate, butyrate. The feature of ethanol-type fermentation was maintained with the sum of ethanol and acetate concentration ratio of70%.Comparing with inorganic nitrogen source, organic nitrogen source(specifically yeast extract) was beneficial to hydrogen production on operation of anaerobic fermentation system for hydrogen production was beneficial. And the best value of COD/N was53.3. Therefore, this paper proved that organic nitrogen source could improve the efficiency of hydrogen production through appropriate adjustment of COD/N when the UASB reactor for anaerobic fermentative biohydrogen production. But it was a long distance to mass production in the factory, and the stability of the system and the structure of the UASB reactor should be studied in the further.