Effects Of 5-hydroxymethylfurfural On Removal Performance And Microbial Community Structure Of Aerobic Activated Sludge

Anaerobic digestion is a clean production process that can recover resources and energy from a variety of agricultural and industrial organic wastes.In the process of anaerobic fermentation,the presence of various inhibitors usually leads to low efficiency or even failure of anaerobic digesters.5-hydroxymethylfurfural(HMF)is an important intermediate product in the anaerobic fermentation process using biomass(such as lignocellulose),and it has also been shown to be an obstacle to anaerobi c fermentation of hydrogen and methane.Inhibition of alcohol production.In addition,in recent years,with the development of the livestock and poultry breeding industry,wastewater discharged from intensive pig farms has become a serious pollutio n problem.If the digested swine wastewater is directly discharged into the nearby water body without any effective measures,it will cause serious environmental problems,such as eutrophication of the water body,pollution of groundwater and loss of soil fertility.Among them,the treatment technology of pig-raising biogas slurry includes zeolite ion exchange method,magnesium ammonium phosphate crystallization method,microalgae method,aerobic activated sludge method and duckweed treatment technology.At present,most researches basically focus on the effect of heavy metals and antibiotics on the removal of nutrients in aquaculture wastewater.Whether HMF has an inhibitory effect on the aerobic activated sludge treatment of aquacultu r e wastewater remains to be studied.First,this article reviews various production methods of HMF and their effects on hydrogen production by fermentation,methane and ethanol production,and strategies to reduce the inhibitory effect of HMF on anaerobi c fermentation.These provide new ideas and methods for reducing the inhibitory effect of HMF on biomass anaerobic fermentation and restoring the performance of anaerobi c fermentation.At the same time,the performance of activated sludge in the treatment of swine biogas slurry,activated sludge characterist ics and microbial communit y structure under the condition of HMF concentration of 0 to 400 mg/L was also studied.The main results are as follows:(1)The production method of HMF.The results show that although the yield of HMF converted from fructose is higher than that of glucose,it is expensive and has a lower natural abundance;Corn stalks,potato stems,girasol,foxtail weed,wood,Catalpa,Indian Rosewood,Babool,Chinaberry,bread crumbs,starch,straw,wood chips and cellulose can all be converted into HMF.(2)The influence of HMF on anaerobic fermentation.The results show that:HMF in the range of 0.6–2.0 g/L can inhibit hydrogen production in the fermentati o n process to varying degrees,and can affect the community structure of fermentin g microorganisms;when a higher HMF concentration has a negative effect on fermentation,it is very likely Resulting in lower anaerobic digestion rate,longer fermentation time and lower methane yield;on the contrary,when the HMF concentration is low,anaerobic sludge may use it as a carbon source for utilization and conversion,although it will Causes fermentation delays,but will eventually increase methane production;(3)Strategies to reduce the inhibitory effect of HMF on anaerobic fermentati o n.The results show that pretreatment and physical and chemical methods can effective l y reduce the inhibitory effect of HMF;genetically engineered microorganisms that convert HMF into other valuable products are the direction of future work;we can know that many microorganisms have high tolerance to HMF,including Comamon a s testosterone SC1588,Acinetobacter oleivorans S27,Gluconobacter oxydans DSM50049,S.stipitis KCTC 7228,Pseudomonas putida KT2440,Bordetella sp.BTIIT R,Enterobacter sp.FDS8 and Amorphotheca resinae ZN1.(4)The effect of HMF on the removal of nutrients(COD,N,P)in wastewater by activated sludge.The results showed that:HMF inhibited the removal performance of activated sludge.Compared with the control group,the removal rates of chemical oxygen demand(COD),total phosphorus(TP)and ammonia nitrogen(NH4~+-N)in each treatment group increased from 95.7%,respectively.84.6%and 80.0%decreased to46.5%,77.6%and 21.0%.(5)The influence of HMF on the properties of activated sludge.The results show that:HMF increases the EPS content of activated sludge,thereby reducing the settling and dewatering capacity of activated sludge;HMF has a significant inhibitory effect on DHA in activated sludge.The higher the concentration of HMF,the more obvious the inhibitory effect.(6)The influence of HMF on the microbial community structure of activated sludge.The results showed that:HMF changed the structure of the activated sludge microbial community and increased the richness and diversity of the microbial community.The dominant bacteria gradually changed from Enterobacteriaceae to Bacillaceae;HMF can interfere with microbial functions,inhibit the transmission and metabolism of carbohydrates and lipids,and reduce energy conversion,which may be the main reason for the decline in nitrogen,COD and phosphorus removal performan c e.