Application of Flowback Water and GOPS on the Prevention of Acid Mine Drainage in the Mather Mine

摘要

Acid mine drainage (AMD) is an environmental pollutant that degrades water bodies and harms aquatic life. In the Appalachian Mountains of the eastern U.S., over 7,500 miles of streams are impacted by AMD. Current methods of active treating AMD such as neutralization with limestone are labor-intensive and costly. Passive treatments with lower maintenance and management costs are the more sustainable alternatives for AMD management. The research reported herein explores the possibility of applying flowback water from natural gas drilling operations and the chelating agent 3-glycidoxypropyltrimethoxysilane (GOPS) as additive to passively treat AMD. The hypothesis is that chemicals present in the flowback water will form insoluble salts with those in the mine residue and precipitate on the mine rock to passivate the surface.. Additionally, GOPS will improve upon the passivation process by complexing with metal ions in the precipitate to form a multilayer hydrophobic coating.udIn order to develop a protocol for measuring the optimal dosage of flowback water and GOPS for AMD prevention, several preliminary batch tests were conducted. These tests evaluated the reaction time and volumes of flowback water and GOPS appropriate for further column testing, as measured by concentrations of Fe, Ba, and SO42-. From batch studies, it is observed that when 55 mL of flowback water was added to 500 mg of mine residue, the contaminants of major concern, Fe and SO42- reached their lowest levels. Meanwhile, a dosage of 0.0001 M GOPS is optimum to improve the microencapsulation. Results from the test column were compared to an identical control column, which was treated with deionized water. The results suggest that, for the experiment duration of one month, flowback water and GOPS have done an effective job in curbing the release of Fe and SO42- from mine residue. After 15 days of treatment, the concentration of Fe was 0.6 ppm, reduced by 96% relative to the control, and the concentration of SO42- was 90 ppm, reduced by 83%. However, trace metals including Mn were not reduced to within the requirements set by the Environment Protection Agency. As a result, more studies are needed to improve the performance of this technique. ud