Characteristics of sulfate-reducing bacteria and organic bactericides and their potential to mitigate pollution caused by coal gangue acidification

Abstract

High-salinity acid drainage and spontaneous combustion caused by the oxidation of coal gangue piles are one of the pollution sources that seriously harm the environment in coal mine areas. Using sulfate-reducing bacteria, Bacillus subtilis S-19, isolated and identified in the laboratory, a bactericide, which can be used in cooperation with S-19, was screened from sodium dodecyl sulfate (SDS), Kathon (isothiazolinones), and triclosan. Subsequently, the degradation rate of S-19 with respect to organic bactericides was analyzed and a column leaching experiment was conducted to determine the effect of the cooperative repair by organic bactericides and S-19 of the acidification of weathered coal gangue and the inhibition effect on the oxidation of newly generated gangue The results show that: (1) At the minimum inhibitory concentration of Thiobacillus ferrooxidans, the use of only SDS has no inhibitory effect on the growth of S-19. The S-19 strain uses SDS as the carbon source and the degradation rate of SDS reaches 86.90% after 7 d; (2) The SO42− concentration in the leaching solution decreases by 72.19% and the pH increases from 3.15 to 5.21 after 21 d of adding 50 mg⋅ L−1 SDS and S-19 to the weathered gangue filling column, representing a significantly better effect than the treatment with S-19 alone; and (3) S-19 inoculation reduces the concentration of SO42− and soluble salts in the newly produced gangue leaching solution, but it does not increase the pH. There is no significant difference between the effects of the treatments with the combination of S-19 and SDS and S-19 alone.