Potential for Passive Treatment of Coal Mine-derived Acid Mine Drainage in Abandoned Stream Channels

Abstract

Passive treatment of coal mining derived acid mine drainage (AMD) utilizes natural processes to neutralize acidity and remove dissolved metal contaminants. In some cases, microbial communities develop without human intervention that can induce the removal of harmful AMD components. To better understand how these beneficial processes might develop, we studied the Huff Run system in eastern Ohio, where a portion of the stream was artificially diverted to prevent direct entry of AMD into the stream. There are now two abandoned stream channels that receive raw AMD and we hypothesized that the increased residence time of the AMD in these abandoned channels could reduce the adverse effects of AMD on Huff Run. We tracked seasonal changes in the aqueous chemistry and microbiology in the two abandoned channels, referred to as Farr and Lyons. The Fe, Al, and Mn were partially removed from solution as AMD moved through the Farr channel, with net alkaline water, and abundant Bacillus and Paenibacillus phylotypes. Dissolved Fe was partially removed in the Lyons channel, but neither Al nor Mn were, and the sediments contained abundant phylotypes attributable to Alicyclobacillus sp., which are capable of oxidative precipitation of Fe(II) under acidic conditions. Our results indicate that enhanced AMD retention in abandoned channels can induce contaminant removal and that abiotic and biotic reactions in the channels are influenced by the AMD chemistry.