The Study On Co-production Of Hydrogen And Methane From Glucose Using Anaerobic Baffled Reactor

The co-production of hydrogen and methane is a kind of anaerobic digestion technology for organic wastewater treatment,which had the advantages of strong anti-shock function and high energy recovery efficiency.Using two-phase or more than two-phase systems for anaerobic digesters can improve load resistance,increase gas yield and composition,but the practical operation was not convenient and the running cost was too high.However,we could achieve phase separation by anaerobic baffled reactor(ABR)and get hydrogen and methane production separately,which was one of the most popular methods in the field of co-production hydrogen and methane.At present,some progress had been made in the production of hydrogen and methane from ABR,but the relationship between the dominant flora and the operating parameters had not been clearly reported.Therefore,we discussed co-production of hydrogen and methane in four compartment ABR at room temperature by artificial glucose solution as raw material.The main research contents are as follows(1)A co-production of hydrogen and methane coupling in ABR.In other words,geting the best operating parameters by testing different organic loading rate in the ABR.(2)The stability of dominant flora in activated sludge.Through acclimating of activated sludge of co-production of hydrogen and methane,we could get a correlation between dominant flora and regulatory factors.(3)The effect of organic loading on the succession of microbial community and the relationship between microbial community and volatile organic acids were investigated.The results show that:(1)By artificial glucose solution as raw materials in ABR,when inlet COD concentration was 4500mg/L,HRT=3d,the production of hydrogen and methane was perfect station,which the degradation rate of COD was 56% and the energy recovery efficiency reached 25%.In contrast,when the organic load rate was more than 2kg/m3.d,methane production system became acidific,COD removal efficiency was lower than 25%,energy recovery rate was less than 10%,which the degradation rate of COD and energy recovery efficiency in hydration production respectively accounted for 80% of the total.Therefore,the methanogenic phase played a vital function for co-production of hydrogen and methane in ABR.With the increasing of organic loading rate,the concentration and composition of volatile organic acids in ABR also changed regularly.At the end of the production stage,the main VFA s in the stage of hydrogen production was acetic acid,but the VFAs were increased rapidly,and the serious acidification occurred.Through the analysis of each compartment of hydrogen and methane content and the removal rate of COD,we could find that improving the HRT could alleviate the "acid drowning" phenomenon in a certain extent and restore the compartment 3 and compartment 4 methane production capacity.Compared with the single hydrogen production system,theenergy recovery efficiency of the co-production of hydrogen and methane in ABR was higher,which was 3.19 times and 1.46 times respectively.(2)There was a rich microbial community in co-production of hydrogen and methane in ABR,The bacterial community diversity was much higher than that of archaea.For the microbial community abundance,the ABR system has finished the phase separation,the difference of OTU between the hydrogen production system and the methane production system was obvious.The dominant bacteria in hydrogen production system were Firmicutes,Proteobacteria and Bacteroidetes and the dominant geneus were Clostridium,Enterobacter.Methane production system was also the same with the advantages of hydrogen production system in bacteria,but also the Euryarchaeota was found,the dominant geneus were Clostridium and Methanosaeta.From the hydrogen and acidogenic bacteria of compartment 1,compartment 2 to methanogen,it produced methane by acetate cleaves.Under the influence of organic loading rate,the dominant flora may change into non-dominant.The different raw materials and non-biological factors,may affect the microbial changes.In addition,the content of acetic acid and butyric acid was proportional such as Clostridium and Enterobacteriaceae in the hydrogen-producing phase.However,the methanogenic phase can not be controlled because methanogen can produce methane by acetic acid and methane is produced by hydrogen reduction of carbon dioxide.