Feasibility & Microbial Mechanisms Of Compacted Sewage Sludge As A Barrier For Tailings

This dissertation aimed permeability coefficient, heavy metals speciation, total organic carbon content(TOC), sulfate reducing bacteria(SRB) quantity, total bacteria quantity, microbial community functional diversity, and microbial community structure diversity in the compacted sewage sludge, trying to assess the tailings reducing barrier environmental risk and finding the functional microbial mechanisms through the flexible wall permeating experiment with 3 different seepage liquids: deionized water(DW), pH 2.1 sulfuric acid water(SA) and the pH 2.1 simulated acid mine drainage(AMD), during 75 days process. The main conclusions were as follows:1)The permeability coefficient of compacted sludge samples in the present research conditions fully met the standard requirements of liner permeability in landfill site. It was found that lower environmental risks resulted from relatively minimal heavy metals potential mobility.2) Compared with DW seepage conditions to SA and AMD, the latter had lower AWCD, S, H, and E values, which explained the inhibition of the latter seepage conditions was stronger.3) SRB was not the only bacteria and only mechanism of the sludge reducing barrier.4) There were no correlations between deposition of Cd and Cu, Fe, Ni, Zn content.5) At the seepage starting point(SP), the 41 st day(T1) and 75th(T2), under different seepage conditions, Clostridiales, Bacillaceae and Carnobacteriaceae were dominants, whose relative abundance ranged from 46.26 %-10.25 %. The redundancy analysis(RDA) showed that bacteria such as Carnobacteriaceae, Bacillaceae, Clostridiales Family XI. Incertae Sedis, Clostridiaceae, Lactobacillaceae, Peptoniphilaceae, Ruminococcaceae, Moraxellacea, Caulobacteraceae and Corynebacteriaceae were positively correlated with Zn potential mobility and pH; while the Carnobacteriaceae, Bacillaceae 、 Clostridiales Family XI. Incertae Sedis, Clostridiaceae, Micrococcineae, and uncertain family Moraxellaceae bacteria were positively correlated with Fe potential mobility; Carnobacteriaceae, Clostridiaceae and Corynebacteriaceae were positively correlated with Cd and Ni potential mobility; Ruminococcaceae was positively correlated with Cu potential mobility.