Experimental Study Of Bio-hydrogen Production By Photoferm Entation Of Chlorella

With the progress of science and technology and economic development,global energy shortage and unreasonable utilization of fossil energy have led to increasingly serious problems such as environmental pollution-It is the general trend to find new alternative energy sources.Hydrogen energy has been paid attention to because it is clean and renewable.In the production of hydrogen energy,photosynthetic biological hydrogen production technology has prominent advantages.It can not only combine the utilization,development and treatment of solar energy,hydrogen energy and organic waste,but also has the characteristics of low cost and low energy consumption.In this paper,heterotrophic concentrated Chlorella solution is used as the raw material,and photosynthetic bacteria(HAU-M1)is used as the hydrogen-producing bacteria.The potential of Chlorella as the hydrogen-producing raw material is discussed,and the technological parameters of photosynthetic biological hydrogen production of Chlorella are optimized.Firstly,the composition of Chlorella was analyzed to explore the possibility of its application in hydrogen production by photosynthetic organisms.Then,different substrate concentrations were set up for hydrogen production experiments of photosynthetic organisms to explore the best hydrogen production substrate concentration.Then,under the optimal substrate concentration,cellulase,neutral protease,cellulase and neutral protease were used to carry out hydrogen production experiments on Chlorella,and the optimal enzyme load under different enzymolysis conditions was explored.Finally,under the optimal enzyme load for hydrogen production by enzymatic hydrolysis,the effects of initial pH and inoculum size on hydrogen production by photosynthetic bacteria simultaneous saccharification were investigated.The purpose of this study is to explore the potential of Chlorella biomass as a raw material for photosynthetic biological hydrogen production,to further expand the source of raw materials for photosynthetic biological hydrogen production process,and to provide scientific reference for the research and development of efficient and low-cost microalgae biomass photosynthetic hydrogen production technology.The results showed that:(1)Biomass contains 47.2±0.2%carbon,6.5±0.0%hydrogen,30.2±0.1%oxygen,8.4±0.1%nitrogen and 0.6 ± 0.0%sulfur[17],and is suitable as a raw material for hydrogen production by photosynthetic organisms.(2)When the substrate concentration was 25g/L,the hydrogen production effect was the best,the cumulative hydrogen production could reach 16.65mL,and the hydrogen concentration could reach 32%.(3)Enzymatic hydrolysis of Chlorella biomass was beneficial to hydrogen production by photosynthetic organisms.When cellulase and neutral protease were used for separate enzymatic hydrolysis and mixed enzymatic hydrolysis respectively,hydrogen production was increased.When cellulase and neutral protease were hydrolyzed separately,when the enzyme load was 15%,the cumulative hydrogen production was the highest with 29.44mL and 43.62mL respectively,and the hydrogen content was the highest with 35.3%and 48%.When the two enzymes were mixed to hydrolyze Chlorella to produce hydrogen,when the ratio of cellulase to neutral protease was 3:2,the cumulative hydrogen production was 56.12mL and the hydrogen content was 45.1%.(4)When cellulase was used for enzymolysis to produce hydrogen,the optimal initial pH was 7.0,the cumulative hydrogen production was 129.92mL,and the hydrogen content was 46.2%at the highest.When neutral protease was used for enzymolysis to produce hydrogen,the best initial pH was 8.0,the highest hydrogen production was 82.36mL,and the highest hydrogen content was 54.2%.When the two enzymes were mixed for enzymolysis to produce hydrogen,the optimal initial pH was 7.0,the cumulative hydrogen production was 137.12mL,and the hydrogen content was 45.8%at the highest.(5)When cellulase and neutral protease were used for separate enzymolysis and mixed enzymolysis of Chlorella biomass for light fermentation to produce hydrogen,the hydrogen production effect was the best when the inoculation amount was 10%,the cumulative hydrogen production amount was 204mL,90.5mL and 260.8mL respectively,and the highest hydrogen content was 48.8%,39.5%and 49.8%respectively.