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Wolkersdorfer, C., & Younger, P. L. (2002). Passive mine water treatment as an alternative to active systems. Grundwasser, 7(2), 67–77.
Abstract: For the treatment of contaminated mine waters reliable treatment methods with low investment and operational costs are essential. Therefore, passive treatment systems recently have been installed in Great Britain and in Germany (e.g. anoxic limestone drains, constructed wetlands, reactive barriers, roughing filters) and during the last eight years such systems successfully treated mine waters, using up to 6 ha of space. In some cases with highly contaminated mine water, a combination of active and passive systems should be applied, as in any case the water quality has to reach the limits. Because not all the processes of passive treatment systems are understood in detail, current research projects (e.g. EU-project PIRAMID) were established to clarify open questions.
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Jarvis, A. P., & Younger, P. L. (2001). Passive treatment of ferruginous mine waters using high surface area media. Water Res., 35(15), 3643–3648.
Abstract: Rapid oxidation and accretion of iron onto high surface area media has been investigated as a potential passive treatment option for ferruginous, net-alkaline minewaters. Two pilot-scale reactors were installed at a site in County Durham, UK. Each 2.0m high cylinder contained different high surface area plastic trickling filter media. Ferruginous minewater was fed downwards over the media at various flow-rates with the objective of establishing the efficiency of iron removal at different loading rates. Residence time of water within the reactors was between 70 and 360s depending on the flow-rate (1 and 12l/min, respectively). Average influent total iron concentration for the duration of these experiments was 1.43mg/l (range 1.08-1.84mg/l; n=16), whilst effluent iron concentrations averaged 0.41mg/l (range 0.20-1.04mg/l; n=15) for Reactor A and 0.38mg/l (range 0.11-0.93mg/l; n=16) for Reactor B. There is a strong correlation between influent iron load and iron removal rate. Even at the highest loading rates (approximately 31.6g/day) 43% and 49% of the total iron load was removed in Reactors A and B, respectively. At low manganese loading rates (approximately 0.50-0.90g/day) over 50% of the manganese was removed in Reactor B. Iron removal rate (g/m3/d) increases linearly with loading rate (g/day) up to 14g/d and the slope of the line indicates that a mean of 85% of the iron is removed. In conclusion, it appears that the oxidation and accretion of ochre on high surface area media may be a promising alternative passive technology to constructed wetlands at certain sites.
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Younger, P. L. (2000). The adoption and adaptation of passive treatment technologies for mine waters in the United Kingdom. Mine Water Env., 19(2), 84–97.
Abstract: During the 1990s, passive treatment technology was introduced to the United Kingdom (UK). Early hesitancy on the part of regulators and practitioners was rapidly overcome, at least for net-alkaline mine waters, so that passive treatment is now the technology of choice for the long-term remediation of such discharges, wherever land availability is not unduly limiting. Six types of passive systems are now being used in the UK for mine water treatment: ¨ aerobic, surface flow wetlands (reed-beds); ¨ anaerobic, compost wetlands with significant surface flow; ¨ mixed compost / limestone systems, with predominantly subsurface flow (so-called Reducing and Alkalinity Producing Systems (RAPS)); ¨ subsurface reactive barriers to treat acidic, metalliferous ground waters; ¨ closed-system limestone dissolution systems for zinc removal from alkaline waters; ¨ roughing filters for treating ferruginous mine waters where land availability is limited. Each of these technologies is appropriate for a different kind of mine water, or for specific hydraulic circumstances. The degree to which each type of system can be considered “proven technology” corresponds to the order in which they are listed above. Many of these passive systems have become foci for detailed scientific research, as part of a $1.5M European Commission project running from 2000 to 2003.
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Younger, P. L., Neal, C., House, W. A., Leeks, G. J. L., & Marker, A. H. (1997). The longevity of minewater pollution; a basis for decision-making U.K. fluxes to the North Sea; Land Ocean Interaction Study (LOIS); river basins research, the first two years. The Science of the Total Environment, 194-195, 457–466.
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