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.

Abstract: Some Polish coal mines are reviewed with respect to the disposal of saline wastewater into rivers and its environmental impact. The drainage water from mines has a daily contribution of, in the order of magnitude, 6,500 tons chlorides (Cl-) and 0.5 tons sulphates (SO42-) to the rivers Wisla and Odra. The river Wisla contributes to about 55 % of the water resources in Poland. This report is based on a part of a commission for the Ministry of Environmental Protection, National Resources and Forestry ofPoland by COWI-VBB VIAK joint venture.Different treatment and disposal schemes are described and compared from a technical-economical point of view, out of which methods for desalination with zero discharge as well as deep well injection are the most promising ones.The desalination methods include reverse osmosis (RO) plant, thermal powered desalination and crystallization plant as well as facilities for dewatering and drying of sodium chloride (NaCl) to be sold in Poland and/or on the export market, The valuable main products are potable water, boiler feed water and sodium chloride. A special problem in this connection may be the radioactivity in the wastewater from some of the mines. Special treatment methods for radioactivity removal in the selected treatment and disposal scheme for the mine wastewater are discussed with respect to the effects of radioactivity on the saleability of the recovered salt. In addition methods for recovery of the by-products magnesium hydroxide, iodine and bromine are considered from the point of view of economy and environmental protection.Finally, the desalination project in Katowice for the coal mines Debiensko and Budryk is now in the end of the construction phase. Some modifications of the original design ace shown.

Abstract: Seven kilometres of the River Pelenna in South Wales were impacted for approximately 30 years by discharges from abandoned coal mines. Elevated iron and low pH caused significant ochreous staining and had detrimental effects on the river ecology. The River Pelenna Mine water project constructed a series of passive wetland treatment systems to treat these discharges. Monitoring of the performance and environmental benefits of these has been undertaken as part of an Environment Agency R&D project. This project has assessed the changes in water quality as well as monitoring populations of invertebrates, fish and birds between 1993 and 2001. Performance data from the wetlands show that on average the three systems are removing between 82 and 95% of the iron loading from the mine waters. In the rivers downstream, the dissolved iron concentration has dropped to below the Environmental Quality Standard (EQS) of 1 mg/L for the majority of the time. Increases in pH downstream of the discharges have also been demonstrated. Trout (Salmo trutta) recovered quickly following mine water treatment, returning the next year to areas that previously had no fish. Intermittent problems with overflows from the treatment systems temporarily depleted the numbers, but the latest data indicate a thriving population. The overflow problems and also background episodes of acidity have affected the recovery of the riverine invertebrates. However, there have been gradual improvements in the catchment, and in the summer of 2001 most sites held faunas which approached those found in unpolluted controls. Recovery of the invertebrate fauna is reflected in marked increases in the breeding success of riverine birds between 1996 and 2001. This study has shown that constructed wetlands can be an effective, low cost and sustainable solution to ecological damage caused by abandoned mine drainage.