Process Optimization And Mechanism Study Of Hydrogen Production With Anaerobic Digestion Coupled Syngas And Organic Wastewater

Syngas is used in production and life.It is chemically used in the industry to synthesize high value-added chemical products such as methanol,alkanes and acetic acid.It can also be used as a synthetic fuel for power generation(synthetic natural gas),as well as for petroleum synthesis and purification.Hydrogen production,etc.However,the chemical method usually requires high temperature and high pressure,and has high energy consumption,and the chemical reaction may cause secondary pollution and the catalyst is easily deactivated.In recent years,the use of synthetic biochemical methods to convert high value-added products has attracted great attention due to its mild reaction conditions and strong specificity of biological enzymes.Hydrogen does not cause pollution when used as a fuel,and its calorific value is as high as 142.35 kJ/g,so the synthesis gas produced by syngas can support energy demand and industrial production.This topic explores the feasibility of coupling hydrogen production from syngas and organic wastewater to produce hydrogen,and optimizes its fermentation process and its fermentation mechanism.Firstly,the effects of different initial pH(pH4-pHll,8 groups)on the hydrogen production of synthesis gas and organic wastewater coupled fermentation were investigated.The maximum hydrogen production in the stable phase was obtained at a constant temperature of 55? and initial pH6,which was 196.13 mL./d.At this time,the composition of the VFA in the liquid phase is mainly acetic acid and butyric acid.Later,the strength of homoacetogenics was investigated.It was found that in the initial pH5-pH9 range,the isoform acetogenic effect increased with the increase of pH.The homoacetogenics effect at the initial pH9 was the strongest,the pH was further enhanced,and the activity was weakened.Then,the coupling mechanism of the reaction process was explored.It was found that the addition of glucose had no obvious inhibition on the hydrogen production of carbon monoxide.The effect of pH change on the hydrogen production of carbon monoxide was the increase of pH,and the gas production trend first increased to the maximum value and then decreased.Small,the initial pH6 conversion rate is the largest,53%;the addition of carbon monoxide inhibits the hydrogen production of glucose,and the inhibition increases with increasing pH,and the inhibition is weakest under the initial pH of 5,and the coupling is combined under the initial pH6.Hydrogen production works best.Then,high-throughput sequencing was used to detect the microbial community composition and diversity.The dominant bacteria were Thermoanaerobacterium,and the known carbon monoxide hydrogen producing bacteria were Thermosinus and Moorella,which were the best initial pH6 in hydrogen production.The content of the former is 5%,the content of the latter is 2%,and the content of hydrogen monoxide producing carbon monoxide under other pH conditions is lower than this level.In all reactors,6%-49%of the microorganisms are unclassified,indicating that the research on carbon monoxide anaerobic hydrogen producing bacteria is limited and further research is needed.Secondly,the effects of different carbon monoxide loads(0.5L/d,1L/d,2L/d,4L/d)in the volumetric reactor on hydrogen production were investigated under different constant pH5,pH6,pH7 and pH8 conditions.At a constant pH of 5,the maximum hydrogen production at a carbon monoxide load of 2 L/d is 5132.12 mL/d.The hydrogen production decreases with constant pH increase,the maximum hydrogen production is obtained at 2L/d.Subsequent investigations on the strength of homoacetogenics revealed that in the range of constant pH5-pH8,homoacetogenics activity increased with the increase of pH.Afterwards,the coupling mechanism of the reaction process was explored.It was found that the addition of glucose did not significantly inhibit the hydrogen production of carbon monoxide.The effect of pH change on the hydrogen production of carbon monoxide was increased pH,the hydrogen production decreased,and the maximum value was obtained at constant pH 5.The conversion rate was 90.6%.The addition of carbon monoxide inhibits the hydrogen production of glucose.With the increase of pH,the inhibition is enhanced.Under the condition of constant pH5,the inhibition is the weakest,and the coupling hydrogen production is the best.High-throughput sequencing of 16SrRNA was then performed on the microorganisms.The results showed that the known hydrogen monoxide producing bacteria were Thermosinus and Moorella.In the former,the constant pH 5 with the best hydrogen production effect was 14%,and the latter content was 0.6%.The content of carbon monoxide producing hydrogen bacteria under other pH conditions was lower than this level.The presence of Clostridium sensu stricto was also detected in the microbial samples obtained in this study.Studies have shown that this genus is associated with the hydrogen production process of carbon monoxide.Then qPCR analysis of 16S,FTHFS and CODH showed that the activity of isoforms of acetogens increased with the increase of pH before the addition of carbon monoxide,and the activity was the strongest at constant pH8.After the addition of carbon monoxide,the total amount of bacteria increased,and the activity of carbon monoxide oxidizing bacteria It decreases with increasing pH and is most active at constant pH 5.At the same time,the addition of carbon monoxide significantly enhanced the homologous acetogenic activity of constant pH 7-8.Finally,the ADM1 model was used to simulate the effect of constant pH on the hydrogen production by coupled anaerobic fermentation of syngas and organic wastewater.The results showed that the goodness of the original ADM1 for coupled hydrogen production was insufficient.The pH of the constant pH7 and pH8 groups were respectively good.It is 0.57 and 0.56,and the hydrogen goodness of fit is 0.24 and 0.03,respectively,which needs to be improved for the model.Therefore,by extending the homoacetogenic process of ADM1 and the addition of syngas components,a model with good fit of each component greater than 0.9 was obtained.Subsequently,the model was used to verify the initial pH effect on the hydrogen production by coupled anaerobic fermentation of syngas and organic wastewater.The simulation results are good,indicating that ADM1 after the addition of the isoform acetogenic process and the modification component of the syngas component have good simulation,prediction and calculation functions for the anaerobic fermentation hydrogen production process in coupled fermentation.