Experimental Study Of Corn Straw By Anaerobic Fermentation Of Biological Hydrogen Production

Biohydrogen production process with anaerobic fermentation resolves the organic waste by the biological technology to produce H₂,simple equipments,easy manipulation,not only environment friendly and low cost but also sufficient supply,being considered a promising way of producing H₂.The hydrogen production of cornstalk wastes was systematically investigated through anaerobic fermentation by using the natural sludge as inoculant.The effects of pretretment,enzymatic hydrolysis,substrate concentration and fermentation initial pH value on hydrogen production potential of cornstalk were discussed in this work.Cornstalk was pretreated by dilute acid and sodium hydroxide,respectively,for enhancing the yield and the rate of hydrogen production of substrate.The optimal pretrcatment is that the substrate was soaked with a HCl concentration of 0.6%at 90℃for 2h.Batch experiments investigated the effects of hydrogen production from the fermentation substrate at different enzymatic hydrolysis conditions(temperature,time and pH).The results indicate that HCl pretreatment and enzymolysis for cornstalk wastes could obviously increase the H₂ yield form the fermentation substrate.A maximum cumulative H₂ yield of 104.30 ml·g^-1-CS was obtained at HCl concentration of 0.6%when the enzymatic hydrolysis condition was fixed at 50℃,time 72 h and initial pH 4.8.The yield was much larger than the corresponding H₂ yield of 58.69 ml·g^-1-CS only pretreated by acid at 0.6%previously, increasing by about 77.7%.and by about 3-fold as compared with the un-pretreated raw cornstalk wastes.The comprehensive influence of pretreatment and fermentation condition for fermentative H₂ production was investigated using orthogonal design method and the optimum conditions were obtained.An orthogonal experimental design of L₉(3⁴) was used in this experimental design,considering four important parameters(enzymatic temperature,enzymatic time, substrate concentration and fermentation initial pH) and the cumulative hydrogen yield was the optimization criteria.The results indicate that:(1) Substrate concentration had the largest influence on hydrogen production,and fermentation initial pH was more influential than enzymatic temperature and enzymatic time.(2) When the pretreated substrate with the concentration of 10 g·L^-1 was fermented at 36℃,a maximum cumulative H₂ yield of 141.29 influence on hydrogen production,and fermentation initial pH was more influential than enzymatic temperature and enzymatic time.(2) When the pretreated substrate with the concentration of 10 g·L^-1 was fermented at 36℃,a maximum cumulative H₂ yield of 141.29 ml·g^-1-CS and the average H₂ production rate of 12.31 ml·g^-1-CS·h^-1 were obtained through an optimal pretreatment process:the substrate pretreated by a HCl concentration of 0.6%for 2 h at 90℃(the ratio of solid to liquid was 1g:10 ml),as well as subsequently degraded by cellulase catalysis(the ratio of substrate to enzyme was 100:1) for 72 h at 50℃and the initial pH of 4.8.