English

Abstract

Biochemical reactors (BCRs) are a passive treatment technology used to reduce metals concentrations and increase the pH of mining influenced water (MIW). The practice of mixing municipal wastewater with MIW is known to remove metals from the MIW, destroy pathogens, and lower the biochemical oxygen demand of the wastewater. (Strosnider et al. 2009). Characteristics of typical BCR effluent, including a near neutral pH and elevated concentrations of sulfide, alkalinity, biochemical oxygen demand, and residual nutrients (i.e., nitrogen and phosphorus) are similar to typical municipal wastewater water characteristics. Mixing MIW with BCR effluent may have several synergistic effects, including reducing the metals and acidity load associated with the MIW, reducing the biochemical oxygen demand and sulfide concentrations of the BCR effluent, and ultimately reducing the footprint requirements for a passive treatment system utilizing BCRs. In July 2009, a field study was conducted to evaluate the treatment accomplished by mixing BCR effluent with MIW generated at the Standard Mine Superfund Site near Crested Butte, Colorado. The field demonstration included batch and continuous flow mixing tests. The study results suggest mixing MIW and BCR effluent can accomplish metals removal rates greater than 90% for cadmium, copper, lead, and zinc