Biotreatment of Mn2+ and Pb2+ with Sulfate-Reducing Bacterium Desulfuromonas alkenivorans S-7

Abstract

Biotreatment of heavy metals in acid mine drainage (AMD) with sulfate-reducing bacteria (SRB) is considered the most promising technique in the ecological restoration of mines. In the present work, the authors evaluated the ability of bioprocessing acidic water (pH=6.) containing different concentrations of Mn2+ (ranging from 1. to ∼12.28 mg/L) and Pb2+ (ranging from 1. to ∼11.6 mg/L) and coexisting with sulfate (.8–1.1 g/L) with a native SRB Desulfuromonas alkenivorans S-7 obtained from a coal gangue dump. Furthermore, the organic functional groups and sulfur components involved in the bioprocess mediated with SRB were investigated with Fourier transform infrared spectroscopy (FT-IR) and detailed in a Peakfit analysis. The results showed that the S-7 strain could remove 93.1% Mn2+ and 9.% Pb2+ from acid mine drainage after 7 days’ culture, respectively. Three clear stages of biotreatment of Mn2+ and Pb2+ were identified as initial rapid precipitation, subsequent absorption, and a final equilibrium state. The removal of heavy metals included chemical precipitation and biosorption. FT-IR spectroscopy results showed that the OH, NH2, C═O, and amide group might play an important role in the absorption of Mn2+ and Pb2+ by extracellular polymeric substances. Furthermore, the intermediate sulfite products of the sulfate-reducing process were also identified in the cell samples. The present study proves that biotreatment of heavy metals with a native SRB S-7 is possible, and thus provides potential information for its future application in the ecological restoration of coal gangue dumps.