Improved methods and systems for treating wastewaters produced in mining and/or subterranean well bore operations are provided. In one embodiment, the systems comprise: an electro-coagulation unit that receives wastewater from a wastewater source, performs an electro-coagulation treatment on the wastewater using one or more EC cells, and produces a first fluid stream that comprises one or more solid materials and a liquid effluent; a solids separation unit coupled downstream of and in fluid communication with the electro-coagulation unit that separates at least a portion of the solid materials in the first fluid stream from the liquid effluent; and a filter comprising a metal-bearing filtration media coupled downstream of and in fluid communication with the solids separation unit that filters the liquid effluent from the solids separation unit to produce a treated water stream.