The Process Optimization And Equipment Research Of Dark Fermentation Biological Hydrogen Production Process

In recent years,hydrogen as eco-friendly clean energy has received the widespread attention.In numerous hydrogen production methods,dark fermentation bio-hydrogen production has become a research hotspot in the field of renewable energy because it can utilize biomass raw materials effectively,reduce the agricultural waste pollution to the environment and other characteristics.The corn straw biomass is the main agricultural waste of crop production in our country,and the cellulose content in maize straw?about 36%?is higher than wheat straw,soybean straw and sorghum straw,the research of cellulose energy efficient transformation in maize straw has important scientific significance and practical value,and the research for using corn straw biomass as the raw material of biological hydrogen production technology has become one of the research hotspots at domestic and overseas.At present,the biological hydrogen production research work is most in the laboratory research stage,and the design scale and operation mode of hydrogen production reactor are only limited to small batch operation stage,which is few involved in the productive operation of large volume of the reactor.This subject adopts the test way combining the small biomass dark fermentation hydrogen production and the dark fermentation reaction unit in the 10m3 hydrogen production reactor combining of dark and light fermentation,looking athydrogen production as investigation target,optimizing the parameters such as fermentation temperature?initial pH valueand hydraulic retention time whendark fermentation hydrogen production system running with activated sludge and enterobacter aerogenes as hydrogen producing bacteria source.This will play an important role for improving the biological hydrogen production efficiency,the maximum using of agricultural waste resources and the protecting of the ecological environment and have a great importance to achieve the low-cost,large-scale biological hydrogen production.?1?Dark fermentation experiments were performed for bio-hydrogen production from enzymatic hydrolyzate of corn stover powder?its granularity less than 0.088 mm?using heat pretreated activated sludge?its TS% is 6.77%,VS% is 47.90%,COD is 36665mg/L?as fermentation microorganism.Effects of heat pretreated time?water bath is 100 ??,initial pH value,enzymatic hydrolyzate concentration,and fermentative temperature on yield and rate of hydrogen production were investigated.Modified Gompertz Model was adopted to predict the bio-hydrogen production process.The results of one-factor experiments showed that each factor had significant effect on bio-hydrogen production process,and the optimum parameters were chosen from the selected levels.All the results fit well to the Modified Gompertz Model.The highest cumulative hydrogen yield?653.98 m L?and hydrogen production rate?15.89 m L/h?were obtained with a heat pretreated time of 15 min,initial pH value of 5.0,enzymatic hydrolyzate concentration of 22.34 mg/m L and fermentative temperature of 40 ?.?2?Dark fermentation experiments were performed for bio-hydrogen production from enzymatic hydrolyzate supernatants of corn stover powder?its granularity less than 0.088mm?using heat pretreated activated sludge as fermentation microorganism,choosing cumulative amount of hydrogen production as main experiment parameter,the influences of different factors on dark fermentation bio-hydrogen production of corn stover's enzymatic hydrolysate supernatants were studied based on Box-Behnken model of response surface method,the significance of interactions between different factors during the dark fermentation bio-hydrogen production process was examined and the dark fermentation bio-hydrogen production process of corn stover's enzymatic hydrolysate supernatants was optimized.The results show that the effect of temperature and reducing sugar concentration on the corn stover's enzymatic hydrolysate supernatants darkfermentation bio-hydrogen production process are the most comparing with initial pH value,the interaction of two factors on the effect of hydrogen yield are all significant.Box-Behnken model is adopted to obtain the optimal conditions of hydrogen production,temperature of 38.32 ?,the initial pH value of 4.93 and the reducing sugar concentration of 20.70mg/m L,the maximum hydrogen yield is 685.59 m L and the maximum hydrogen production rate is 57.13 m L/g.The model is validated through experiment,the actual maximum hydrogen yield can reach 659.24 m L and the hydrogen production rate is 54.94 m L/g,with the prediction error of 3.84%,which proves that this model has a good fitness.?3?According to the anaerobic baffle reactor?ABR?design principle,designing the dark fermentation reaction unit in the 10m3 hydrogen production reactor combining of dark and light fermentation,namely feed tube?discharge tube?heating cover layer?the size of the baffle plate?plate in the dark fermentation reactor and the design of automatic control system of thedark fermentation reaction unit,the total volume reaches 3m3.To establish a complete set of biological hydrogen production system,which will have a great importance to achieve the low-cost,large-scale biological hydrogen production.?4?Respectively based on activated sludge and enterobacter aerogenes as hydrogen producing bacteria source in the dark fermentation reaction unit in the 10m3 hydrogen production reactor combining of dark and light fermentationfor continuous experiments,using activated sludge as bacteria source,the best hydraulic retention time is 24 h,dark fermentation 144 h producing gas 6.6 m3,hydrogen content is 31.07%,hydrogen production is 2.05 m3,hydrogen production rate is 11.4 m LH₂ / g(C₆H₁₂O₆),the largest amount of hydrogen production of 222.46 L/d appearing in the 2# compartment;using enterobacter aerogenes as bacteria source,the best hydraulic retention time is 48 h,dark fermentation 144 h producing gas 3.4 m3,hydrogen content is 35.18%,hydrogen production is 1.19m3,hydrogen production rate is13.2m LH₂ / g(C₆H₁₂O₆),the largest amount of hydrogen production of 128L/dappearing in the 2# compartment,which laying the foundation for the industrialization development of dark fermentation hydrogen production.