| Anaerobic degradation of organic matter is the key of anaerobic biological treatment technology.Complex organic matter is degraded to CH4 and CO2 by the co-operation of anaerobic microorganisms of several metabolic guilds involving the syntrophic oxidation of short-chain fatty acids like propionate,butyrate and acetate.Previous research results showed that iron oxide can promote production in anaerobic digestion of organic matter,but the mechanism of iron oxide promoting methane oxidation by short chain fatty acid interaction is not yet clear.Therefore,according to the environmental microbial community of system that added iron oxide minerals in short chain fatty acids to produce of methane and treatment of mining wastewater with constructed wetland as the research object,using SPSS statistical analysis software and multiple linear regression model to research whether there is a linear relation between microorganisms in the system,to sort these relations of anaerobic microbial competition or syntrophic interaction,in order to improve the methane production rate and efficiency in anaerobic digestion of organic matter in the process of methane production.In this paper,the abundance and correlation of bacteria and archaea in the short chain fatty acid methanogenic system under the action of iron oxides are analyzed.Among them,bacteria are divided into Enterococcus et.fermentation bacteria(62%),Pseudomonas(15%)with the function of Mn?Fe reduction nitrification?denitrifying bacteria(15%)Bacillus(15%)and Clostridium(8%),sulfur reducing bacteria Petrimonas(8%)and Mesotoga(10%),sulfate reducing bacteria Desulfovibrio(14%),fatty acid oxidizing bacteria Treponema(5%),hydrogen consumption of Acetoclastic methanogens Acetobacterium(10%).The main Archaea are Acetoclastic methanogens producing Methanothrix and Hydrogenotrphic methanogens Methanosarcina et.The results of statistical analysis showed that Pseudomonas has negative correlation with the electron and substrate competition of Hydrogenotrphic methanogens and Acetoclastic methanogens.Bacillus,Mesotoga,Enterococcus,Desulfovibrio,Treponema and Petrimonas to Acetoclastic methanogens were negatively correlated,of which Pseudomonas,Bacillus,Mesotoga,Desulfovibrio,Petrimonas and methanogens were competitive with substrates and electrons,and positively correlated with the Hydrogenotrphic methanogens.Bacillus and Treponema produce fatty acids that are oxidized to H2 and CO2 used by Hydrogenotrphic methanogens.Petrimonas,Mesotoga and Desulfovibrio can generate CO2.Clostridium and Acetobacterium have positive correlation to Methanothrix.Clostridium and methanogens compete with the electrons and substrates,but at the same time ferment acetic acid to Methanothrix utilization.Acetobacterium can oxidize H2 and restore CO2 to acetic acid used by Acetoclastic methanogens.Therefore,there is a negative correlation with Hydrogenotrphic methanogens and positive correlation with Acetoclastic methanogens.The physical and chemical indexes of the constructed wetland in Ma'anshan showed that the p H of wetland is 6.32~6.67,and TOC was less than that of vegetable fields and reed fields is 0.06~0.17g/g.The sulfate and total Fe in the upper reaches of the wetland were higher than those in the middle and lower reaches.The sulfate concentration is 79.213~219.438g/kg and the total iron concentration is0.53~0.78mg/g.Microbial community analysis showed that the main species in the constructed wetland were Pseudomonas(7%~10%),fermentative acid producing bacteria Lactococcus(80%),Bacillus(10%),and methanogenic archaea were all Hydrogenotrphic methanogens.The results of regression analysis showed that the concentration of TOC and total iron had a positive correlation with the abundance of methanogens in the physical and chemical indexes,while the sulfate concentration and p H had a negative correlation with the abundances of methanogens.Bacillus and Pseudomonas had positive correlation and negative correlation with hydrogen methanogens. |
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