Passive Treatment of Manganese at Coal and Metal Mine Sites

Event Format: Hybrid (Zoom Access)

Speaker: Robert Hedin, Hedin Environmental

Abstract:

Manganese (Mn) is a common water contaminant at mining sites that is limited in effluent permits to 0.5 — 2.0 mg/L. Its treatment with conventional mine drainage technologies relies on chemical oxidants or caustic reagents that are costly, hazardous, and produce copious wastes. Passive treatment technologies, which utilize natural materials and processes to remediate mine water, provide an alternative treatment strategy. One method for passively treating Mn contaminated water is oxic limestone beds that promote a heterogeneous Mn oxidation process that is operative at circumneutral pH and creates dense Mn oxide solids. The performance of existing OAB systems that treat mine waters with flow rates ranging 10 — 1000 gpm and Mn concentrations ranging 6 — 32 mg/L will be presented. The operation and performance of an experimental OLB unit, installed in 2022 to treat effluent of an existing chemical treatment plant, will also be presented. Opportunities to optimize the passive treatment technology will be discussed.