Toward a Solution for Acid Mine Drainage Treatment: Role of Electron Donors in Sulfate Reduction at Low pH

Abstract

Sediment historically impacted by acid mine drainage was exposed to different initial pH and electron donors to investigate the effect that both conditions had on the performance and fingerprint of the community from naturally acidic sediments. Batch experiments were fed with either acetate, lactate, or glycerol at initial pH of 5, 4, or 3, under sulfate-reducing conditions. The performance results indicated that sulfide production efficiency was above 85% in the treatments fed with lactate and glycerol at pH 5 and 4. However, acetate consumption efficiency was greater than 85% only in the treatments with acetate at pH 5 and lactate at pH 5 and 4. Glycerol fed treatments successfully produced sulfide even at initial pH = 3. Sulfide production rates were related to the initial pH in treatments fed with lactate and acetate and independent of the pH in the glycerol fed treatments. 16S rRNA gene T-RFLP analysis of the enriched communities indicated that the initial pH could explain the differences of the microbial community fingerprint obtained after 90 days. This study points out the fact that acidic stress is a heavy burden for the development of sulfate-reducing microorganisms, especially for those that use acetate as substrate.