Research On The Cascade Utilization Of Corn Stalks For Butanol Production And Hydrogen Production By MEC

China is a large agricultural country and there is a high production of stalks each year.However,the utilization rate of them is low.Corn stalks,as a high quality bioenergy,containing a lot of cellulose and hemicelluloses,can provide an adequate carbon source for the production of bioenergy.Butanol and hydrogen are important renewable energy sources that can be applied to energy,transportation fuels and other areas,helping to solve today’s energy crisis and environmental problems.The use of cellulose-based biomass production of bio-energy and straw resource utilization has aroused widespread concern in the community.Microbial electrolysis cell(MEC)is a new bio-hydrogen production technology,which can be used in the treatment of organic wastewater with the efficient production of hydrogen at the same time.In this study,the method of improving the yield of butanol in corn stover hydrolysate fermentation was studied.Additionally,the feasibility of using MEC to convert butanol fermentation wastewater into hydrogen was studied.Microbial fuel cell(MFC)was applied to treat with MEC hydrogen production wastewater,and we put forward the pathway which is the straw hydrolyzate to produce butanol-MEC hydrogen production to improve the utilization of biomass.The pretreatment method and the cellulose enzymolysis buffer were selected and the hydrolysate inhibitor concentration was decreased by the lime method and FeSO4 treatment.When detoxified with lime,5.19 g/L butanol was obtained.0.4 g/L FeSO4 was added to the hydrolysate and the final butanol yield was 4.9 g/L,which was 54.69 % higher than that of the untreated hydrolysate.In addition,the addition of an appropriate amount of exogenous electron carrier(benzyl violet,methyl blue,etc.)can significantly increase the yield of butanol.The yield of butanol and solvent was 6.49 g/L and 8.14 g/L,respectively.And the yield of butanol was increased to 0.41 g/g when the hydrolysate contained 20 mg/L benzyl benzene.The addition of 50 % by volume of oleyl alcohol to the hydrolysate to extract the fermentation butanol from solution is beneficial to increase the concentration of butanol.MEC utilized butanol fermentation solution to produce hydrogen,and different concentrations of fermentation solution have an effect on the final hydrogen production and COD removal.When the concentration of organic matter was 4272 mg/L,the maximum hydrogen production rate reached 3.58 ± 0.47 m3 H2/m3/d.The hydrogen yield was 16.34 mmol H2/g COD and the Coulomb efficiency was 110.60 ± 9.11%.There were 71.63 ± 2.29% COD removal rates.When the applied voltage increased from 0.5 V to 0.8 V,the maximum hydrogen production rate and hydrogen yield of MEC were improved.The highest COD removal efficiency was obtained under 0.8 V applied voltage.After that,MFC was used to treat hydrogen production wastewater from MEC,and the production characteristics and COD removal efficiency of MFC anode microbes were investigated.When the COD concentration of the hydrogen-producing waste is 1277 ± 103.1 mg/L,the maximum voltage in MFC is 553 mV and the power density is 0.607 W/m2.The COD removal rate of the low concentration substrate was 93.63 ± 0.23%,and the effluent COD was only 39 ± 1.41 mg/L.The macromolecules of MEC were analyzed by 454 high-throughput sequencing method,and the communities contained more Geobacter bacteria.Compared with the single substrate sodium acetate running in the reactor,the fermentation waste liquid contains ethanol,acetone,acetic acid,butyric acid and other organic matter.Using fermentation wastewater as the substrate of the MEC,the microbial community diversity is higher and the type of bacteria is complex.Therefore the hydrogen production effect and microbial community structure are closely linked.