Field-scale demonstration of the potential for sewage to remediate acidic mine waters

Abstract

Pit lake waters are often contaminated by acid mine drainage (AMD) from weathering of pyritic materials exposed by mining operations, leading to low pH, and high solute and heavy metal concentrations. Few cost-effective engineering solutions exist for large-scale environmental remediation of AMD-contaminated pit lakes. However, various studies have demonstrated that biological remediation strategies for remediating AMD-contaminated waters, including microbially-mediated sulphate reduction, show promise at the laboratory-scale. The addition of acidic mine water to raw sewage and workshop wastewaters in an evaporation pond provided an opportunity for a field-scale experiment as essentially a reversal of suggested in-situ treatment of acidic pit lakes by addition of organic carbon. The hyper-eutrophic evaporation pond initially contained high concentrations of nutrients, a pH [ 8, high levels of sulphate (500 mg L -1 ), and had regular algal blooms. Soon after the addition of the AMD pit water, the evaporation pond pH fell to 2.4, and electrical conductivity (EC) and most metal concentrations were elevated by one to two orders of magnitude. Over the following 18 months, the pH of the pond increased and the EC and metal concentrations decreased. After only 18 months of addition of AMD, pond water quality had returned to a level similar to that before AMD addition. These observations suggest that addition of low-grade organic materials shows promise for remediation of acid mine waters at field scale and warrants experimental investigation.

The Potential Use of Exhausted Open Pit Mine Voids as Sinks for Atmospheric CO2: Insights from Natural Reedbeds and Mine Water Treatment Wetlands

“…Geller and Schultze 2013) or mixing with organic-rich sewage (e.g. McCullough et al 2008). These approaches may well be more costeffective than the method proposed here when the only aim is water treatment.…”

Alkalinity Generation in a Novel Multi-stage High-strength Acid Mine Drainage and Municipal Wastewater Passive Co-treatment System

“…In laboratory microcosm studies, Van Hille et al (1999) used MWW to create algae-rich high pH water, which was mixed with AMD. McCullough et al (2008) documented water quality improvement due to BSR in an evaporation pond in which high-strength AMD was accidentally introduced to secondary MWW. Strosnider and Nairn (2010) found that incubating AMD with MWW, with and without limestone, could decrease acidity and create alkalinity.…”

“…Waybrant et al (1998) observed that sewage sludge encouraged higher levels of SO 4 2-reduction than seven other commonly used organic carbon sources. However, studies have noted that mixtures of MWW sludge with multiple organic carbon sources generally promote higher SO 4 2-reduction rates than single sources (McCullough et al 2008;Waybrant et al 1998). MWW contains a wide variety of organic compounds ranging from simple sugars to more recalcitrant compounds, such as cellulose (Metcalf and Eddy, Inc 2002).…”

Heterotrophic Microbial Stimulation through Biosolids Addition for Enhanced Acid Mine Drainage Control

“…Techniques like the co-treatment of municipal wastewater (with biosolids as byproducts) and AMD has recently gained popularity following its introduction by Roetman [39], when it was proposed to remove pathogens in sewage [40]. Results from studies to date have shown the removal of metals, certain nutrients, increases in pH and alkalinity, and overall water/leachates quality improvements [41][42][43][44][45][46][47][48][49][50].…”