Study On The Remediation And Mechanism Of Antimony Pollution By Sulfate Reducing Bacteria

Due to the massive mining and utilization of antimony resources,the surrounding water bodies and soils have been seriously polluted.The sulfate-reducing bacteria（SRB）method has the advantages of high efficiency,low cost and no secondary pollution,and is highly advantageous in the treatment of antimony-contaminated waters and soils.In this study,we investigated the effect of SRB on the removal of Sb（Ⅲ）/Sb（Ⅴ）by using SRB to treat antimony-contaminated wastewater,and analyzed its removal mechanism in terms of chemical elemental composition and molecular structure.The functional composition,molecular ecological network and ecological assembly mechanism of soil microbial community in the remediation of antimony-contaminated soil by SRB（T1）,SRB mixed with humic acid（T2）,and SRB mixed with sodium sulfate（T3）were studied.Genome developmental relationships,functional annotations,and genes related to metal reduction characteristics were analyzed by gene mining,and the sulfate reduction and metal reduction characteristics of Desulfovibrio desulfuricans strains used in the study were analyzed.It provides some theoretical and technical basis for the practical application of SRB to repair antimony polluted environment.The main conclusions of the thesis are as follows:（1）Under anoxic conditions,the removal rate of Sb（Ⅲ）wastewater treated by SRB reached over 91.02%when Sb（Ⅲ）concentration was 30mg/L,temperature was 30°C,p H value was 7.13,C/N ratio was 10:1 and SO₄^2-concentration was 1600 mg/L.The SRB achieved over 94%removal of Sb（Ⅴ）from the wastewater when the Sb（Ⅴ）concentration was45 mg/L,the temperature was 35°C,the p H value was 7.24,the C/N ratio was 40:3 and the SO₄^2-concentration was 2000 mg/L.Containing N,S₂^2-and S_n^2-and their surface functional groups acted as electron donors,reducing part of Sb（Ⅴ）to Sb（Ⅲ）and combining with the functional groups,mineralization occurred on the surface of SRB cells,generating Sb₂S₃ and Sb₂S₅ solid precipitates,thus achieving the removal of Sb（Ⅲ）/Sb（Ⅴ）from the wastewater by SRB.（2）In the remediation of antimony-contaminated soil,the effects of T1,T2 and T3 treatments on day 28 were 56.38%,74.21%and 46.89%,respectively,with the best effect of T2 treatment with humic acid addition.The SRB treatment group significantly altered the functional structure of the antimony-contaminated soil microbial community,with a significant increase in the abundance of genes related to the metabolism of biosulfate,sulfur monomers,thiosulfate and sulfur-containing compounds.SRB treatment was suggested to directionally shape the community structure of soil microorganisms and the functional groups of sulfate-reducing bacteria during the phylogenetic sub-box community ecological assembly of microbial communities and sulfate-containing reducing bacteria.（3）Desulfovibrio desulfuricans species were capable of exchanging genetic material with other species in a variety of ways in different environments to acquire new genes,but the gene family gradually decreased with genome accession.The upstream and downstream regions of the Desulfovibrio desulfuricans genome containing molybdenum redox proteins were not conserved,with the potential for acquisition by horizontal gene transfer.Genes encoding members of the P-type ATPase cation transport protein family such as Cop A,which relied on ATP as an energy source to pump monovalent copper to regulate dynamic intracellular copper homeostasis,conferred heavy metal resistance to bacteria.Their genomes were not conserved and might have been transferred several times during evolution.