Construction And Mechanism Of Sulfate-type Methane Anaerobic Oxidation Syste

Microbial reduction is one of the most effective methods in the treatment of sulfate-containing wastewater.Sulfate reducing bacteria（SRB）will use organic matter or inorganic matter in water as electron donor,transfer electrons to SO₄^2-under anaerobic conditions,and then reduce SO₄^2-to S^2-,so as to achieve the removal of SO₄^2-.Sulphate-dependent anaerobic methane oxidation,（SAMO）is a process in which CH₄is used as an electron donor to achieve SO₄^2-reduction under the joint action of methane oxidizing bacteria and sulfate reducing bacteria.Sulfate wastewater is taken as the object of this study,Firstly,the SAMO system was constructed,and then the material changes of the reaction process were analyzed by Fourier infrared spectroscopy（FTIR）and stable isotope analysis.The morphology of microorganisms was analyzed by scanning electron microscopy（SEM）and fluorescence in situ hybridization（FISH）,and further combined with the results of real-time fluorescence quantitative PCR,metagenomic,proteome and metabolome analysis.To explore the microbial action mechanism of SAMO.The main findings are as follows:（1）Our used Sequencing batch biofilm reactor（SBBR,A:quartz sand、B:granular active carbon）to enrich SAMO functional bacteria.The rate of sulfate reduction（SR）,average consumption of methane,and CO₂production were all lower in the low methane concentration mode（phase I）and high methane concentration mode（phase II）.After adding nano zero-valent iron（n ZVI）（Stage III）,when SO₄^2-concentration was 11.59 mmol/L,the average SR rate of group A was 1.37 mmol/（L·d）,the average methane consumption was 1.43 mmol/（L·d）,and the average SR rate of group B was2.13 mmol/（L·d）.The average methane consumption was 1.17 mmol/（L·d）.In addition to n ZVI mode,the Sulphate-dependent anaerobic methane oxidation system was successfully constructed.（2）Fourier infrared spectroscopy（FTIR）analysis results showed that substances containing hydroxyl and amide functional groups were produced in the system,and sulfate removal was realized.The stable isotope analysis results show that theδ13C_VPDB‰values of CO₂detected in the gas are positive（906.39‰～3597.76‰）,and a large amount of ¹³CO₂is produced in the system.The results of scanning electron microscope（SEM）analysis showed that the microorganisms on the filler were mainly rod-shaped bacteria and globular bacteria with irregular overlapping distribution.Fluorescence in situ hybridization（FISH）analysis showed that the microflora of ANME and DSS were less than 30μm in size and relatively dispersed.ANME and DSS were wrapped in each other.（3）In the low methane concentration mode,the system successfully enriched sulfate reducing bacteria and methane oxidizing bacteria.The identified methanooxidating bacteria include Methylobacter,Methylococcus,Methylomonas,Methylocystis,ANME-1 and ANME-2 clusters,etc.Sulfate reducing bacteria include Desulfococcus and Desulfosarcina,etc.In addition of n ZVI mode,the methane oxidation archaea ANME-1、ANME-2 abundance increased in the system,Sulfate reducing bacteria into unclassified＿f＿＿Desulfobacteraceae,Desulfovibrio,Desulfosarcina,Desulfovibrio,Desulfobacula and Desulfobulbus,The system gradually changed to be dominated by SAOM reaction.（4）Quantitative real-time PCR analysis results showed that the number of functional genes of dsr B belonging to SRB and Mcr A belonging to ANME in activated carbon filler group B was higher than that in quartz sand filler group A.A total of 228 related proteins were annotated by proteomic analysis.Compared with the inoculated sludge,the proteins in sulfur metabolism,methane metabolism,quorum sensing and ABC transport pathway in SAMO system were significantly up-regulated.Metabolomics analysis showed that,compared with inoculated sludge,the different metabolites in SAMO system were mainly fatty acids and conjugated compounds,and the difference multiple of Methimazole was the most obvious.In addition,there are 6 classes of metabolites related to methane metabolism and sulfur metabolism,most of which are related to microbial sulfate assimilation.