Study On Microbial Communities And Distribution Characteristics Of Sulfur Speciation Of Coal Gangue Dump

During the coal ore mining and utilization process, coal and its associatedminerals have been discharged as coal gangue. Under the interaction with the water,air and microbial oxidation, the harmful heavy metals and sulfides in coal gangue willcause serious sulfur pollution. Making use of sulfur oxidizing bacteria (SOB) orsulfate reducing bacteria (SRB) to oxidize and remove the sulfides in coal gangue orfix heavy metal ions in acid waste water is one of the most important methods toachieve the goal of the remediation of sulfur pollution. Therefore, to carry out basicstudy related to the treatment of sulfur pollution caused by coal gangue dumpcontaining high sulfur with microbes has important guiding significance to ecologicalrestoration of mining areas.In present work, the microbial community structure, sulfur and heavy meteralspeciation and distribution characteristics in coal gangue dump were analyzed withPCR-16S rRNA gene clone library, sulfur K-edge XANES and Tessier’s extractionscheme. Then the SOB and SRB microorganism were isolated and identified and itscharacteristics of leaching coal gangue and processing acid mine drainage wereinvestigated.Research results showed that the soil surrounding the coal gangue dump was acidand contained high levels of heavy metals, which were polluted by a certain extent ofdispersionof heavy metals. The Tessier’s sequential extraction results showed that Crand Mn was mainly associated with the resident fraction (RES), however, Fe wasmainly associated carbonate-bound fraction (CAR) and resident fraction (RES). Themineral composition of soil samples was mainly quartz and kaolinite and a smallamount of metal minerals. Sulfurspeciation in soil samples was associated with sulfate、sulfite and thiosulfate， including a small amount of metal minerals. Principalcomponent analysis (PCA) results showed that the ten soil samples could be dividedinto four categories.A total of63OTUs (operational taxonomic units) were obtained in fourrepresentative sample, fell into six putative phylogenetic divisions, which wereNitrospira,Actinobacteria, Firmicutes, Proteobacteria,Deferribacteres andKtedonobacteria, respectively. And the main dominant bacteria species in foursamples were Moorella glycerini，Escherichia coli，Leptospirillum ferriphilum，Ferrimicrobium acidiphilum，Sulfobacillusbenefaciens， Desulfomonile tiedjei. Inaddition, the correlation between physic-chemical characteristics and sulfur speciation and the distribution of microbial communities have been inverstigated by PCAin thisstudy. The results showed that oxidation-reduction potential (ORP) was corrleated tobacteria populations Proteobacteria, and pH was corrleated to Ktedonobacteri.Correlation between sulfate、 thiosulfate and Deferribacteres、 Nitrospira andActinobacteria was particularly significant.On the other hand,and the correlationbetween sulfite, glutathione and Ktedonobacteria,Proteobacteria was particularlysignificant.Two sulfur oxidizing bacteria named SOB-1and SOB-2and a sulfate-reducingstrain named SRB-7were isolated from surrounding soil of a coal gangue dump. The16S rRNA gene analysis showed that the strain SOB-1and SOB-2had99%phylogenic similarity with Acidithiobacillus thiooxidans and Acidithiobacillusferrooxidans, and the strain SOB-1had99%phylogenic similarity withDesulfuromonasalkenivorans. XRD showed that there was no significant change inphase composition in coal gangue after leaching by SOB-1. XPS and XANES resultsshowed that sulfurspeciation in original gangue samples were associated with sulfateand a small amount of sulfide. After leaching wtih SOB-1, there was no significantsulfurspeciation transformationin coal gangue. While leaching with SOB-2andmixture, the reduced sulfides in coal gangue were oxidized into sulfate. The SRB-7strain had better processing ability on Fe, Mn, Pb and Zn ions in the acid minedrainage of coal gangue dump, and the remove rate of which followed Pb>Fe>Zn>Mn.Among of them, the removal rate of Pb was up to100%after7d processing.