Study On The Effect Of Biotrickling Filter On The Purification Of Methane And High Ammonium Nitrogen Wastewater From Farms

Due to the anaerobic fermentation of microorganisms,a certain concentration of greenhouse gas methane(CH4)will be produced in the closed storage tank of livestock and poultry breeding manure.As an effective measure to control low concentration of CH4,biological method needs to add nitrate nitrogen to maintain efficient and stable CH4 purification efficiency.The manure storage tank wastewater contains high concentration of ammonium nitrogen.Whether it can be used as a nitrogen source for CH4 biotrickling filter,and then realize the synergistic purification of CH4 in the manure storage tank and high ammonium nitrogen wastewater is still unclear.Therefore,in this study,two biotrickling filters BF_no(control,no nitrogen source)and BF_A(ammonium nitrogen as nitrogen source)were successfully started and operated by natural biofilm formation method.The CH4 purification performance of the two biotrickling filters under different residence time(EBRT)was compared and analyzed,and the microbial mechanism of ammonium nitrogen affecting the CH4 purification performance of biotrickling filters was analyzed by metagenomic technology.On this basis,the CH4 removal efficiency of two biotrickling filters BTF1(control,nutrient solution as nitrogen source)and BTF2(simulated aquaculture wastewater as nitrogen source)and the variation of ’three nitrogen’ and chemical oxygen demand(COD)in the influent and effluent were compared and analyzed.The purification effect of biotrickling filter synergistic purification of CH4 and high ammonium nitrogen wastewater was preliminarily verified.Finally,in order to further improve the water-gas synergistic purification effect of the biotrickling filter,the biotrickling filter BTF2 was used as the research object,and the mixed bacteria of heterotrophic nitrification-aerobic denitrification bacteria Paracoccus pantotorphus ATCC 35512 and methanotroph Methylosinus trichosporium OB3b were used for bioaugmentation.The effect of bioaugmentation on the synergistic purification efficiency of CH4 and high ammonium nitrogen wastewater by biotrickling filter was studied.The specific research results are as follows:(1)Ammonium nitrogen as a nitrogen source can change the microbial population structure and functional gene expression of the biotrickling filter,thereby improving the CH4 removal performance of the biotrickling filter.When EBRT was 44 min,the CH4 removal efficiency of biotrickling filter BF_A with 138 mg·L-1 ammonium nitrogen as nitrogen source was stable at more than 80%,while the CH4 removal efficiency of biotrickling filter BF_no was less than 70%.The results of metagenomic analysis showed that ammonium nitrogen as nitrogen source could significantly change the microbial community structure and function in the biotrickling filter for CH4 removal.Nitrospirae was the unique genus in the biotrickling filter BF_A.The relative abundances of amoA and hao genes related to nitrification process,and fae,mtdA and fmdA genes related to CH4 oxidation in the biotrickling filter BF_A were significantly higher than those in BF_no(P<0.05),which proved that the biotrickling filter BF_A with ammonium nitrogen as nitrogen source not only had high nitrification ability.It also has high CH4 oxidation capacity.(2)The feasibility of co-purification of CH4 and high ammonium nitrogen wastewater by biotrickling filter was preliminarily proved.The biotrickling filter BTF2 with high ammonium nitrogen wastewater as nitrogen source also had certain CH4 and wastewater removal efficiency,but its CH4 removal efficiency and wastewater purification capacity were lower than those of the control biotrickling filter BTF1.The CH4 removal efficiency of the control biotrickling filter BTF1 was always above 99%,while the CH4 removal efficiency of the biotrickling filter BTF2 was only about 40%.In addition,the removal efficiencies of NH4+-N and TN by BTF2 were 35%and 25%,respectively,which were significantly lower than those of BTF1(77%and 75%),and the effluent of BTF2 had higher concentrations of NO3--N and NO2--N accumulation.(3)Using heterotrophic nitrification-aerobic denitrification bacteria Paracoccus pantotorphus ATCC 35512 and methanotroph Methylosinus trichosporium OB3b for bioaugmentation technology can significantly improve the purification efficiency of biotrickling filter synergistic purification of CH4 and high ammonium nitrogen aquaculture wastewater.The removal efficiency of CH4 increased from 40%to more than 99%,and the average removal efficiency of NH4+-N and TN in water increased from 35%and 23%to more than 95%.The concentrations of NO3--N and NO2--N in the effluent also decreased from 1.7 mg·L-1 and 8 mg·L-1 to 0.5 mg·L-1 and 2 mg·L-1,respectively.In summary,this paper clarified the effect of ammonium nitrogen as a nitrogen source on the CH4 removal performance of the biotrickling filter and the influence of microbiology.The bioaugmentation technology was used to achieve the synergistic removal of CH4 and high ammonium nitrogen wastewater from the manure storage tank.This study can provide theoretical support and technical reference for the synergistic control of CH4 and high ammonium nitrogen wastewater in the manure storage facilities of farms.