Initial Evaluation of a Large Multi-Cell Passive Treatment System for Net-Alkaline Ferruginous Lead-Zinc Mine Waters

Abstract

Artesian discharges of net-alkaline, ferruginous waters from abandoned underground lead-zinc mines cause considerable surface water degradation at the Tar Creek Superfund Site, part of the historic Tri-State Mining District of Oklahoma, Kansas and Missouri. At the study site, perennial borehole discharges have flowed unabated for almost 30 years and considerably degraded the physical, chemical, and biological integrity of a first-order tributary to Tar Creek. Based on a comprehensive water quality and quantity characterization study, a large multicell passive treatment system was designed to receive approximately 1000 L/minute of mine water flowing from these abandoned boreholes (pH 5.95±0.06, total alkalinity 393±18 mg/L CaCO 3 , total acidity 364±19 mg/L CaCO 3 , Fe 192±10 mg/L, Zn 11±0.7 mg/L, Cd 17±4 ug/L, Pb 60±13 ug/L and As 64±6 ug/L). The passive treatment system (~ 2 ha total surface area) includes an initial oxidation pond followed by parallel treatment trains consisting of aerobic wetlands, vertical flow bioreactors, re-aeration ponds, and horizontal-flow limestone beds. Waters from the parallel trains are recombined in a polishing wetland prior to final discharge. In the first year of operation, mean final effluent waters had pH >7, were net alkaline and contained < 1 mg/L total Fe and < 0.1 mg/L total Zn, and had concentrations of Cd, Pb and As below detectable limits. The treatment system is successfully removing nearly 107 kg Fe/d, 5 kg Zn/d, 42 g Pb/d, 11 g Cd/d and 38 g As/d and is addressing approximately 20% of the contaminant mass loading from artesian mine pool discharges in the Tar Creek watershed.

Stream Water Quality Improvements After Installation of a Passive Treatment System

“…In addition, the system effluent no longer exceeds the National Recommended Water Quality Criteria for any of the metals of concern. A more thorough explanation of these improvements is reported in Nairn et al (2010).…”

Assessment of Bed Hydraulics and Metal Loadings in a Passive Vertical Flow Bioreactor in Commerce, Oklahoma

“…The gravel is underlain by a low permeability geotextile liner. The overall PTS was designed to accommodate flows of up to 1000 L/min (Nairn et al , ), corresponding to a maximum flow capacity of 500 L/min in C3S. The water residence time in the pond surface water is estimated to be on the order of 3 days.…”

Using Periphyton Assemblage and Water Quality Variables to Assess the Ecological Recovery of an Ecologically Engineered Wetland Affected by Acid Mine Drainage after a Dry Spell

“…The passive treatment processes in wetlands are characterized by ion exchange and adsorption by plants and their substrates; bacterial and abiotic metal oxidation; precipitated metals settling; carbonate dissolution and processes associated with microbial enabled acid neutralization; and filtration and sulfate reduction and metal sulfide precipitation. The performance of such a passive system is influenced by initial water quality as an inflow determinant, site-specific conditions, minimal human intervention, and the nature of operations in specific climatic conditions [5,[10][11][12][13][14][15][16][17][18]. According to Zedler [7], the need to provide specific and unique hydrological conditions (e.g., water quality and quantity) complicates wetland restoration because of the potential effect on microtopography and biogeochemistry from the degree of wetland wetness.…”