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Banks, S. B. (2003). The UK coal authority minewater-treatment scheme programme: Performance of operational systems. Jciwem, 17(2), 117–122.
Abstract: This paper summarises the performance of minewater-treatment schemes which are operated under the Coal Authority's National Minewater Treatment Programme. Commonly-used design criteria and performance indicators are briefly discussed, and the performance of wetland systems which are operated by the Coal Authority is reviewed. Most schemes for which data are available remove more than 90% iron, and average area-adjusted iron-removal rates range from 1.5 to 5.5 g Fe/m(2). d. These values, which are based on performance calculations, can be distorted by several factors, including the practice of maximising wetland areas to make best use of available land. Removal rates are limited by influent iron loadings, and area-adjusted iron-removal rates should be used with caution when assessing wetland performance. Sizing criteria for all types of treatment system might be refined if more detailed data become available.
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Ziemkiewicz, P. F., Skousen, J. G., & Simmons, J. (2003). Long-term Performance of Passive Acid Mine Drainage Treatment Systems. Mine Water Env., 22(3), 118–129.
Abstract: State and federal reclamation programs, mining operators, and citizen-based watershed organizations have constructed hundreds of passive systems in the eastern U.S. over the past 20 years to provide reliable, low cost, low maintenance mine water treatment in remote locations. While performance has been reported for individual systems, there has not been a comprehensive evaluation of the performance of each treatment type for a wide variety of conditions. We evaluated 83 systems: five types in eight states. Each system was monitored for influent and effluent flow, pH, net acidity, and metal concentrations. Performance was normalized among types by calculating acid load reductions and removals, and by converting construction cost, projected service life, and metric tonnes of acid load treated into cost per tonne of acid treated. Of the 83 systems, 82 reduced acid load. Average acid load reductions were 9.9 t/yr for open limestone channels (OLC), 10.1 t/yr for vertical flow wetlands (VFW), 11.9 t/yr for anaerobic wetlands (AnW), 16.6 t/yr for limestone leach beds (LSB), and 22.2 t/yr for anoxic limestone drains (ALD). Average costs for acid removal varied from $83/t/yr for ALDs to $527 for AnWs. Average acid removals were 25 g/m2/day for AnWs, 62 g/m2/day for VFWs, 22 g/day/t for OLCs, 28 g/day/t for LSBs, and 56 g/day/t for ALDs. It appears that the majority of passive systems are effective but there was wide variation within each system type, so improved reliability and efficiency are needed. This report is an initial step in determining passive treatment system performance; additional work is needed to refine system designs and monitoring.
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Naugle, W. K. (2003). Remediation of the Eagle Mine superfund site: a biological success story. Tailings and Mine Waste '03, , 481–485.
Abstract: Remediation of the Eagle Mine Superfund Site began in 1988. Remedial action included: bulk-heading adits, flooding mine workings; constructing diversion ditches around waste rock; consolidating mine wastes in an on-site tailings pile; capping the tailings pile with a multi-layer, engineered cap; and revegetating disturbed areas with native plants. Flooding the mine workings resulted in unacceptable seepage into the Eagle River in late 1989. A water treatment plant was constructed to collect mine seepage and groundwater at the main tailings pile. In October 2001, construction of the remedy was declared “complete” and the site is now in the operation, maintenance and monitoring phase. A strong downward trend in zinc and cadmium concentrations in the Eagle River has occurred and, trout and macroinvertebrate populations have increased. Biological data are being used to establish water quality standards for the Eagle River.
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Younger, P. L. (2003). Passive in situ remediation of acidic mine waste leachates: progress and prospects. Land Reclamation: Extending the Boundaries, , 253–264.
Abstract: The reclamation of former mining sites is a major challenge in many parts of the world. In relation to the restoration of spoil heaps (mine waste rock piles) and similar bodies of opencast backfill, key challenges include (i) the establishment of stable slopes and minimization of other geotechnical hazards (ii) developing and maintaining a healthy vegetative cover (iii) managing the hydrological behaviour of the restored ground. Significant advances have been made over the past four decades in relation to all four of these objectives. One of the most recalcitrant problems is the ongoing generation and release of acidic leachates, which typically emerge at the toes of (otherwise restored) spoil heaps in the form of springs and seepage areas. Such features are testament to the presence of a “perched” groundwater circulation system within the spoil, and their acidity reflects the continued penetration of oxygen to zones within the heaps which contain reactive pyrite (and other iron sulphide minerals). Two obvious strategies for dealing with this problem are disruption of the perched groundwater system and/or exclusion of oxygen entry. These strategies are now being pursued with considerable success where spoil is being reclaimed for the first time, by the installation of two types of physical barrier (dry covers and water covers). However, where a spoil heap has already been revegetated some decades ago, the destruction of an established sward or woodland in order to retro-fit a dry cover or water cover is rarely an attractive option for dealing with the “secondary dereliction” represented by ongoing toe seepages of acidic leachates. More attractive by far are passive treatment techniques, in which the polluted water is forced to flow through reactive media which serve to neutralize its acidity and remove toxic metals from solution. A brief historical review of the development of such systems reveals a general progression from using limestone as the key neutralizing agent, through a combined use of limestone and compost, to systems in which almost all of the neutralization is achieved by means of bacterial sulphate reduction in the saturated compost media of subsurface-flow bioreactors. In almost all cases, these passive treatment systems include an aerobic, surface flow wetland as the final “polishing” step in the treatment process. Such wetlands combine treatment functions (efficient removal of metals from the now-neutralized waters down to low residual concentrations, and re-oxygenating the water prior to discharge to receiving watercourses) with amenity value (attractive areas for recreational walking, bird-watching etc) and ecological value.
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McLeod, K. W., & Ciravolo, T. G. (2003). Sensitivity of water tupelo (Nyssa aquatica) and bald cypress (Taxodium distichum) seedlings to manganese enrichment under water-saturated conditions. Environmental Toxicology and Chemistry, 22(12), 2948–2951.
Abstract: In anaerobic soils of wetlands, Mn is highly available to plants because of the decreasing redox potential and pH of flooded soil. When growing adjacent to each another in wetland forests, water tupelo (Nyssa aquatica L.) had 10 times greater leaf manganese concentration than bald cypress (Taxodium distichum [L.] Richard). This interspecific difference was examined over a range of manganese-enriched soil conditions in a greenhouse experiment. Water tupelo and bald cypress seedlings were grown in fertilized potting soil enriched with 0, 40, 80, 160, 240, 320, and 400 mg Mn/L of soil and kept at saturated to slightly flooded conditions. Leaf Mn concentration was greater in water tupelo than bald cypress for all but the highest Mn addition treatment. Growth of water tupelo seedlings was adversely affected in treatments greater than 160 mg Mn/L. Total biomass of water tupelo in the highest Mn treatment was less than 50% of the control. At low levels of added Mn, bald cypress was able to restrict uptake of Mn at the roots with resulting low leaf Mn concentrations. Once that root restriction was exceeded, Mn concentration in bald cypress leaves increased greatly with treatment; that is, the highest treatment was 40 times greater than control (4,603 vs 100 < mu >g/g, respectively), but biomass of bald cypress was unaffected by manganese additions. Bald cypress, a tree that does not naturally accumulate manganese, does so under manganese-enriched conditions and without biomass reduction in contrast to water tupelo, which is severely affected by higher soil Mn concentrations. Thus, bald cypress would be less affected by increased manganese availability in swamps receiving acidic inputs such as acid mine drainage, acid rain, or oxidization of pyritic soils.
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