The Characteristics And Mechanism Of Fe???/NO₂^--Dependent Anaerobic Methane Oxidation

Anaerobic methane oxidation?AOM?has the potential to control greenhouse gas methane.It has been reported that NO2^-/Fe?III?-dependent anaerobic methane oxidation N/Fe?III?-DAMO)occurred widely in natural environment.However,the process of AOM is hardly developed to technique becauseits function microbial grows very slowly and difficult to enrich and cultivate.Hence,the paper investigated the microbial community structure and metabolic characteristics of N-DAMO by metagenomics and macroproteomics methods,using the enriching microbial reactorwith reservoir sediment as inoculum,screened out the better landfill cover soil from three different landfill by assessing anaerobic methane oxidation potential and analyzing functional gene,observed the characteristicsthat synergistic coupling of different forms of Fe?III??FeCl₃/ferric citrate/chelated iron/Fe?OH?₃?with N-DAMO to remove CH₄.The results showed as follows:?1?N-DAMO process did occur in the reactor with lake sediment as inoculum.The removal rate of CH₄ in reactor accerlated with the increase of continued operating time,and its reduction with time could be described quantitatively by the first-order kinetic equation.The dominant genus obtained is Methylocystis and Hyphomicrobiumin the reactor.Furthermore,the processes of enery production and conversion,amino acid transport and metabolism and inorganic ion transport and metabolism changed significantly in N-DAMO reactor.?2?The anaerobic methane oxidation potential of different landfills was followed as X landfill>L landfill>P landfill.The methane oxidation potentials at different sites in the same location were followed as upper?low-middle>upper-middle>lower layers.Functional gene analysis showed NC10 Phylumper formed N-DAMO existed in landfill cover soil from three landfills.However,the anaerobic methane oxidation potentialis not related to the number of pmoA genes copies.?3?All forms Fe???promoted the process of N-DAMO in reactor with landfill cover soil as inoculum.The N₂ production and CH₄ removal were all improved after adding Fe???intoreactors.The promoting effect of four different forms Fe???was followed asferric citrate>Fe?OH?₃>FeCl₃>chelate iron.The removal of CH₄ and N₂production over time from all reactors could be described quantitatively by the zero-order kinetic equation.The CH₄ removal rate of reactor,which was added ferriccitrate and operated for 160 days,was faster than that of reactor without ferric and being operated for 730 days.