Effect Of Hydrogen Partial Pressure On Fermentative Hydrogen Production From Organic Wastewater

Dark fermentative bio-hydrogen production from organic wastewater can treat wastewater and produce clean energy at the same time.At present,dark fermentative bio-hydrogen production is not commercially exploited due to several factors hindering its production,making the process unfeasible on large scale.The hydrogen partial pressure is one of the key factors affecting hydrogen production process.High hydrogen partial pressure produces inhibition on fermentative hydrogen production system in the engineering application and process of hydrogen production.To solve these problems,an ethanol-type and a butyric-acid-type hydrogen production system have been studied.The effects of hydrogen partial pressure on the hydrogen production of different fermentation types were investigated and the related factors were discussed.The microorganism community structure was analyzed by high-throughput sequencing analysis technique.And the effect of hydrogen partial pressure on the structure of hydrogen producing microorganism of different fermentation types was studied.The CSTR reactor was used to produce hydrogen production by continuous flow fermentation.The start-up and operation conditions of the reactor were controlled respectively.The ethanol and butyric acid type fermentation hydrogen production system was formed.The sludge in the stable operation of CSTR reactor was selected to carry out the intermittent test of hydrogen partial pressure on the hydrogen production process of different types of fermentation.The hydrogen production system of ethanol and butyric acid type fermentation was studied by shaking flask experiment.The effect of hydrogen partial pressure,CO₂ and negative pressure on two kinds of hydrogen production systems under the three conditions of negative pressure suction filling N2,negative pressure suction filling CO₂ and negative pressure suction were investigated.The modified Gompertz model was used to reduce the fermentation under different hydrogen pressure conditions.The cumulative hydrogen production of hydrogen system was fitted by function,and the fundamental reason for the enhancement of hydrogen production by hydrogen partial pressure reduction was studied.The effects of different pressure gradient on the enhancement of hydrogen production were set up,and the effect of the end product of liquid phase was analyzed and the effect of the low pressure drop on VFAs was studied.The main achievements of this paper are as follows:The experimental study on ethanol fermentation showed that the maximum cumulative hydrogen production was 3.63 L/L when the hydrogen partial pressure was reduced by 30%,and the hydrogen production was positively moved by the reduction of hydrogen partial pressure;the best pumping frequency was reduced by 10% per 2H and the maximum hydrogen production rate was 3.62 L/L,and the production of different hydrogen partial pressure was produced by the modified Gompertz model.When the cumulative gas yield of the hydrogen system is fitted,the system Pmax and R Max are 3.85 L/L and 0.127L/?L·h?when the hydrogen partial pressure is reduced by 30%,and the negative pressure has a strengthening effect on the ethanol type hydrogen production.When the pressure of the top space gas pressure is 0.4 bar,the hydrogen production in the fermented hydrogen production system is up to 3.21 L/L.When the 40 m L CO₂ is filled to the system,the hydrogen production is reduced to the time of decreasing to the time of the 40 m L CO₂.The minimum value decreased from 2.63L/L of the control group to 1.28L/L,and CO₂ mainly affected the acetic acid production in the fermentation hydrogen production system,the competition of the bacteria group and the p H value of the system.The experimental study of butyric acid fermentation showed that the reduction of hydrogen partial pressure and negative pressure on the hydrogen production of butyric acid type was less.The supplementation of CO₂ could obviously strengthen the fermentation of butyric acid type.When the 40 m L CO₂ was added to the system,the hydrogen production reached the maximum value of 2.56 L/L,which was 39% higher than that of the control group.The improved Gompertz model is used to fit the cumulative gas production of hydrogen production system with different CO₂.When 40 m L CO₂ is filled,the system Pmax and R Max are 2.70 L/L and 0.081L/?L·h?,and the high concentration CO₂ partial pressure has little influence on the butyric acid producing bacteria,but it can inhibit the hydrogen producing acetic acid bacteria and the lactic acid producing bacteria and promote hydrogen.At the same time,the consumption of hydrogen is reduced by HCB,thus improving the hydrogen production efficiency of the system.The microbial community structure in the hydrogen production process of different fermentation types was further analyzed.It was found that the top community of ethanol type fermentation was Ethanoligenens and Acetanaerobacterium,and the abundances of the hydrogen partial pressure producing ethanolic bacilli increased,while the abundances of Acetanaerobacterium decreased with the decrease of hydrogen partial pressure,and the efficiency of hydrogen production was improved.It is mainly based on the increase of Ethanoligenens abundance;the top community of butyric acid type fermentation is Clostridium.The results show that the increase of hydrogen production efficiency is related to the increase of the abundance of the community.