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Passive Biological Treatment of Mine Water to Reduce Conductivity: Potential Designs, Challenges, and Research Needs
Author(s) -
Smyntek Peter M.,
Wagner Rachel C.,
Krometis LeighAnne,
Sanchez Sergio Carvajal,
WynnThompson Theresa,
Strosnider William H. J.
Publication year - 2017
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2016.06.0216
Subject(s) - conductivity , environmental remediation , environmental science , dissolution , water quality , contamination , chemistry , engineering , ecology , chemical engineering , biology
The remediation of mine water to preserve receiving water quality has advanced substantially over the past half century, but prospective regulations to limit the conductivity of mining‐impacted waters pose a significant new challenge. Conventional approaches to reduce high levels of conductivity in these mine waters are often costly, requiring high levels of maintenance and significant inputs of energy and refined chemicals. In contrast, passive biological treatment (PBT) systems are a relatively low‐cost, low‐maintenance treatment technology for mine waters that have been used for over three decades. However, their practical ability to reduce conductivity is unclear, given previous research reports focused on the removal of metals, acidity, and solids. A systematic literature review to identify previous reports of PBT systems at the laboratory or field scale that include evaluations of changes in conductivity suggests that decreases in conductivity of 30 to 40% are achievable. Substantial variability in performance is common, however, and conductivity increased markedly in some systems. This variation may be associated with the dissolution of limestone, which is a key treatment material in some systems. Although the development of PBT to serve as pre‐, post‐, or stand‐alone treatment systems targeting conductivity may reduce overall treatment cost in some settings, optimization of these designs requires an increase in the number of published conductivity datasets from similar systems, detailed reports on the key ions contributing to elevated conductivity region to region, and further investigation of the underlying biochemical processes responsible for conductivity reductions. Core Ideas Passive treatment of mine waters is a low‐maintenance option for conductivity reduction. Passive treatment systems can reduce conductivity by 30–40%, but efficacy is variable. The use of limestone in passive treatment systems may prevent conductivity reduction. More datasets on conductivity reduction by passive treatment systems are needed. Regional ionic profiles of conductivity will improve passive treatment system design.