Isolation Of Fermentation Hydrogen Producing Bacteria And Its Hydrogen Production Research

The increasing crisis of global fossil fuels shortage, climate change, environmental pollution and associated health problems are all driving the need of a clean and alternative energy. Hydrogen, a high combustion value, clean, safe and renewable energy carrier, is considered as a preferred resource. Nowadays, people concentrate their attentions on the development of hydrogen energy, and more and more researches have focused on this field. Among the numerous hydrogen production methods, dark fermentation appears to be the most attractive method because it can utilize a variety of cheap carbon sources such as organic wastewater and crops straw,and this method can clean environment and obtain energy. The isolation of fermented bacteria can contribute to study the mechanism of producing hydrogen, spawning transformation and co-culturing hydrogen production.In this work, bio-hydrogen technological skills have been researched, such as screening and identifying the hydrogen producing strains; the influence of inoculation quantity and vaccination time on cumulative hydrogen yield and the average production rate of hydrogen; effect of initial pH on the cumulative hydrogen yield and the average hydrogen producing rate. Surveying the influence of inorganic nitrogen source on hydrogen production, with three kinds of inorganic nitrogen source NH4Cl, CH3COONH4 and (NH2)2CO in glucose and apple pomace for carbon sources; influence of pure strains (CP) and the mixed bacteria (MB) hydrogen production on fermentative time, with apple pomace, cornstalk and glucose as carbon sources; change of accumulate hydrogen production and average hydrogen production rate from glucose on time in different concentration (0.5,1.0,2.0 and 3.0,4.0 and 5.0 g·L-1); change of accumulate hydrogen production(ml·L-1-glu and ml·g-1-glu) on time with initial pH value as 7 and controlling fermentative process pH in 4.7-5.0,5.5-5.8 and 6.3-6.6 range; change of accumulate hydrogen production (ml·L-1-glu and ml·g-1-glu) on the concentrations (0.5,1.0,2.0 and 3.0,4.0 and 5.0 g·L-1), with initial pH value as 7 and comparison of no adjustment and adjusting the pH by NaOH as well as ammonia solution; putting the strains isolated from the sludge back to pure hydrogen production environment (sterilization) and pure strains as well as sludge (processed produce hydrogen sludge produced hydrogen experiment) co-culturing to investigate the hydrogen productive effect.The the genetic traits 16 SrRNA gene sequencing experimental results show that the isolated bacteria gets the 16SrRNA genetic similarity as 99% with Clostridium perfringens ATCC13124 (CP), which recognize the strains isolated from sludge. The strains static training achieved the best concentration when cultivate strains for 8h., In dynamic training, bacteria number increased 1～9 hours, and declined in 9～11 hours. The hydrogen production experiments substantiate that CP appears to be the high efficient hydrogen production bacteria. The best quantity and vaccination time prove to be 1/50 (v/v) and 8 h respectively,and the optimal initial pH for hydrogen producing appears to be 7; The production cost can be effectively reduced when utilizing CH3COONH4 as inorganic nitrogen source and apple pomace as carbon source. In addition, the analysis of experiment results suggest that CP has the ability to utilize cellulose. And CP utilizes biomass to producing hydrogen is no better than mixed bacteria, but it favors to use simple sugars, which suggest that pure bacteria should be chosen to utilize simple sugars. The hydrogen production by CP from glucose suggests that the lower the substrate concentration is, the higher the substrate utilizing effect. And unit volume cumulative yield as 2g·L-1 is the largest, so it is chosen to be the optimal hydrogen production substrate concentration considering the productive cost. When the initial pH value is 7, fermentation process controlling pH in 4.7-5.0 proves to be the optimal control range, and the higher the substrate concentration is, the more hydrogen production increases in the process of on-line controlling pH.With using 3g·L-1 glucose as the fermentation substrate, replacing the CP to sludge environment results in two different phenomenon. If the sewage sludge are sterilized, the weight and domestication in fermented liquid hydrogen production time affects the quantity of accumulation, and the best sludge weight is 15 g, the best domesticated time is 12 h. If CP is co-cultured with the mixed bacteria in sewage sludge, the accumulated hydrogen production elevated at first and then decreased with the increase of domesticated time, and the best domesticated time appeared to be 3 h.