GREEN TECHNOLOGIES FOR REMEDIATING ACID MINE DRAINAGE (AMD) AND AMD IMPACTED SOIL

Acid mine drainage (AMD), produced when exposed pyrite (FeS₂) reacts with air and water to form sulfuric acid and dissolved metals, contaminate surface water and soil if not treated. Existing remediation technologies are mostly expensive and environmentally unsustainable. This study aims to develop lower cost, green alternatives for passive treatment of AMD water and affected soils at an abandoned mine site. The concept applies the metal binding and acid neutralizing capacity of water treatment residues (WTR), a waste material generated from drinking water treatment facilities, and the phytoextraction potential of some known grass/plants to develop a green, cost-effective AMD remediation technology. An abandoned Illinois coal mine site that generates approximately 20 gallon per minute of AMD (pH_average =2.6) was selected as the host site. Batch adsorption tests, and lab-scale flow-through study of a newly designed filter column that employs WTRs as media has proven applicable in reducing the high iron, aluminum, manganese and sulfate concentrations in the influent acidic water to concentrations that meet their respective discharge levels. A preliminary 3-month laboratory column leaching study has been conducted with different rates of WTR amendment for pH control and metal immobilization. Complementary phytoextraction potential of known metal hyperaccumulators has also been investigated. Geochemical models have been used to better understand the geochemical conditions of the leachate composition.