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Coulton, R., Bullen, C., & Hallett, C. (2003). The design and optimisation of active mine water treatment plants. Land Contam. Reclam., 11(2), 273–280.
Abstract: This paper provides a 'state of the art' overview of active mine water treatment. The paper discusses the process and reagent selection options commonly available to the designer of an active mine water treatment plant. Comparisons are made between each of these options, based on technical and financial criteria. The various different treatment technologies available are reviewed and comparisons made between conventional precipitation (using hydroxides, sulphides and carbonates), high density sludge processes and super-saturation precipitation. The selection of reagents (quick lime, slaked lime, sodium hydroxide, sodium carbonate, magnesium hydroxide, and proprietary chemicals) is considered and a comparison made on the basis of reagent cost, ease of use, final effluent quality and sludge settling criteria. The choice of oxidising agent (air, pure oxygen, peroxide, etc.) for conversion of ferrous to ferric iron is also considered. Whole life costs comparisons (capital, operational and decommissioning) are made between conventional hydroxide precipitation and the high density sludge process, based on the actual treatment requirements for four different mine waters.
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Wiseman, I. M., Edwards, P. J., & Rutt, G. P. (2003). Recovery of an aquatic ecosystem following treatment of abandoned mine drainage with constructed wetlands. Land Contam. Reclam., 11(2), 221–230.
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.
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Banks, S. B. (2003). The Coal Authority Minewater Treatment Programme: An update on the performance of operational schemes. Land Contam. Reclam., 11(2), 161–164.
Abstract: The performance of mine water treatment schemes, operated under the Coal Authority's national Minewater Treatment Programme, is summarised. Most schemes for which data are available perform successfully and remove over 90% iron. Mean area-adjusted iron removal rates for reedbed components of treatment schemes, range from 1.5 to 5.5 g Fe/m2, with percentage iron removal rates ranging from 68% to 99%. In the majority of cases, calculated area-adjusted removal rates are limited by influent iron loadings, and the empirical sizing criterion for aerobic wetlands, based on American removal rates of 10 g Fe/m2day, remains a valuable tool in the initial stages of treatment system design and estimation of land area requirements. Where a number of schemes have required modification after becoming operational, due consideration must always be given to the potential for dramatic increases in influent iron loadings, and to how the balance between performance efficiency and aesthetic appearance can best be achieved. Continual review and feedback on the performance of treatment systems, and the problems encountered during design implementation, will enhance the efficiency and effectiveness of the Minewater Treatment Programme within the UK.
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Rukin, N. (2003). Whittle mine water treatment system: In-river attenuation of manganese. Land Contam. Reclam., 11(2), 137–144.
Abstract: Much work has been undertaken on the design of treatment systems to remove iron from ochreous mine water discharges. Unlike iron, manganese removal is far more difficult and generally requires active chemical dosing rather than passive treatment. The need for manganese removal can therefore significantly change the economics, management attention and sustainability of a site. Understanding natural attenuation of manganese in river systems is therefore key to deciding whether (active) manganese treatment is needed to protect downstream receptors. Nuttall (2002, this volume) describes the effectiveness of the passive treatment system at Whittle in reducing both iron and manganese concentrations in ochreous mine waters. This paper discusses the results of in-river monitoring and provides evidence for manganese removal downstream of the discharge point. In addition to dilution, attenuation appears to be in the order of 20 to 50%, depending on relative rates of mine water discharge and river flows. Such attenuation means that active treatment may not be needed for the long-term operation of the Whittle scheme. Operation of the scheme commenced in July 2002, with monitoring to further examine evidence for manganese attenuation and any impact on the ecology of the recipient watercourses.
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Laine, D. M., & Jarvis, A. P. (2003). Engineering design aspects of passive in situ remediation of mining effluents. Land Contam. Reclam., 11(2), 113–126.
Abstract: Passive treatment of contaminated effluents can offer a 'low cost' management opportunity to remediate drainages to the standards required by enforcement agencies. However, the initial cost of construction of passive treatment systems is significant and often in excess of that for active treatment systems. It is therefore important that the engineering design of the passive systems produces an effective and efficient scheme to enable the construction and maintenance costs to be minimised as far as possible. Possible parameters for the design of passive systems are suggested to seek to obtain uniformity in size and layout of treatment elements where this may be possible. Passive treatment systems include aeration systems, sedimentation ponds, aerobic and anaerobic wetlands, anoxic limestone drains and reducing alkalinity producing systems. Most active treatment systems also include passive elements in the treatment stream. The basic design considerations that should be considered to ensure the construction of efficient systems are discussed.
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