Study The Key Factors And Kinetic Characteristics Of The Anaerobic Hydrogen Fermentation

With the growth of biomass waste, the recycling and harmless of biomass waste is ahot focus in environmental and energy field. The biological hydrogen production has beenwidely applied for low cost and abundant sources compared to other resource utilizationmethods. However, the lower efficiency of biological hydrogen production is the keyfactor in this field. Therefore, this study focused on improving the utilization efficiency ofhydrogen fermentation.Firstly, the availability of different fermentation raw material was investigated. Theresults showed that the sucrose was suitable as the substrate, and the pretreated cow dunghad a better ability to produce hydrogen. Digestion conditions were optimized byorthogonal experiment and the single factor experiment with the cumulative hydrogenproduction as a response. The optimized substrate concentration, initial pH, vomule ofbacteria source were15g/L,6.0, and200mL, respectively. Secondly, the kinds andconcentration of metal element were also optimized by the single factor experiment, anddynamics of hydrogen produce were carried out in detail., The best added concentration ofFe2+, Mg2+and Ni2+were10mg/L,100mg/L and0.6mg/L, respectively. At the same time,the yield of hydrogen increased43.53%,41.77%and105.3%compared to the control,respectively. The reaction with Ni2+was an uncompetitive inhibition. The critical Ni2+concentration was15.58mg/L, which suppressed hydrogen production completely. At last,the accelerating effect of five similar structure redox mediators was compared in anaerobichydrogen fermentation. The yield of hydrogen was increased at the best addedconcentration of structure redox mediators compared to the control. The results suggestedthat the optimal concentration of AQDS was0.06mmol/L. The relationship between theconcentration of AQDS (LnC) and average hydrogen production rate (Y) wasY=1.7679LnC+10.39for0-0.06mmol/L AQDS. Then, the accelerating mechanism of theredox mediators on hydrogen production was speculated by comparing and combining thehydrolysis rate constant, pH, ORP, VFAs and other indicators.