US Patent 8480902 Biofilm remediation of acid mine drainage

A method of prevention of acid rock drainage excludes oxygen from waste rocks that contain ferrous sulfides by building an oxygen bio-barrier over exposed surfaces of the waste rock. The bio-barrier may be formed by applying a slurry to the rock. The slurry may contain several components such as microbial material, one or more nutrients, water or another fluid, and optionally water-absorbent material. The microbial material may include bacteria, algae, fungi or a combination thereof. Additionally, the slurry may contain one or more acid-neutralizing compounds, one or more cellulose-containing substances, and one or more UV protecting agents.