Study On Biohydrogen Production From Organic Wastewater Fermentation Enhanced By Redox Mediator

With the rapid development of industrialization and urbanization,a large amount of domestic wastewater and industrial wastewater are discharged.The wastewater discharged from the food industry contains a large amount of sugars,amino acids,proteins and vitamins,which provides a large amount of cheap organic substrates for biological hydrogen production,especially high concentration organic wastewater,whose dissolved oxygen is easily consumed by aerobic and facultative anaerobic microorganisms to form an anaerobic environment,which is conducive to the anaerobic fermentation of microorganisms to produce hydrogen.In this study,the biological catalytic function and electron transfer function of redox mediator(ROMs)were used to enhance biological hydrogen production from organic wastewater fermentation.The effects of initial p H,substrate concentration and methane production inhibitor on ROMs-mediated anaerobic biological hydrogen production from organic wastewater were investigated.Firstly,anthraquinone-2,6-disulfonic acid sodium(AQDS),anthraquinone-2-sodium sulfonate(AQS),graphene oxide(GO),henna quinone and humic acid were selected as ROMs in this thesis.Organic wastewater was used as substrate,and the effects of different ROMs on hydrogen production efficiency of organic wastewater anaerobic fermentation were investigated at 35?.The results showed that AQS and humic acid could enhance the hydrogen production efficiency of anaerobic fermentation of organic wastewater,and humic acid had the best enhancement effect.Its cumulative hydrogen production was 59.3% higher than the control,while the other three ROMs inhibited the hydrogen production efficiency of anaerobic fermentation.The analysis of microbial community structure showed that in the fermentation system of humic acid as ROMs,Thermomarinilinea,Longilinea and Ottowia were the dominant flora.Further research shows that when the concentration of humic acid is 80 mg/L,it isthe best to promote the anaerobic fermentation of organic wastewater to produce hydrogen.When ROMs is not contained in the anaerobic fermentation system,0.02% chloroform,0.04% chloroform,BES and tinidazole as methane-producing inhibitors can effectively inhibit the activity of methanogens.Except tinidazole,the cumulative hydrogen production is higher than that of the control group(without methane-producing inhibitor),which is 6.3 m L,6.9 m L and 3.8 m L respectively.When AQS is used as ROMs in the anaerobic fermentation system,0.02% chloroform and 0.04%chloroform can significantly improve the hydrogen production capacity of anaerobic sludge,and the cumulative hydrogen production is 41.3% and8.7% higher than the control.When BES and tinidazole were used as methane-producing inhibitors,the hydrogen-producing activity of anaerobic sludge was also inhibited.When humic acid is used as ROMs in anaerobic fermentation system,0.02% chloroform,0.04% chloroform and BES can promote hydrogen production,and their cumulative hydrogen production are7.0 m L,5.8 m L and 4.5 m L respectively,which is 2.0~3.2 times higher than the control.Analysis of microbial community structure shows that the dominant bacteria in the 0.02% chloroform+humic acid fermentation system are Saccharibacteria_genera_incertae_sedis,Ignavibacterium,Terrimonas and Ottowia.But the dominant genus under the condition of 0.04%chloroform is Ottowia?Saccharibacteria_genera_incertae_sedis?Terrimona and Ilumatobacter The effects of different substrate concentrations and initial p H on bio-hydrogen production from organic wastewater fermentation showed that when COD was 2,000 ~ 10,000 mg/L,the cumulative hydrogen production from humic acid-mediated anaerobic fermentation of organic wastewater gradually increased with the increase of COD concentration.Under the condition of initial p H 4.0~p H 7.0,the hydrogen production efficiency of humic acid-mediated anaerobic fermentation of organic wastewater increases with the increase of p H.The analysis of microbial community structure showed that the dominant genera had obvious succession with the increase ofp H,and the succession from Thermocarilinea,Clostridium sensu stricto,Nitrospira and Ottowia(p H 4.0 and 4.5)was Thermocarilinea,Nitrospira and Thauera(p H 5.0),Thermocarilinea,Ottowia and Thauera(p H 5.5),Thermocarilinea and Ottowia(p H 6.0,6.5 and 7.0).