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Jones, D. R. (1995). Passive treatment of mine water. Sudbury '95 – Mining and the Environment, Conference Proceedings, Vols 1-3, , 755–763.
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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. (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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Davison, W. (1988). Neutralizing Strategies For Acid Waters – Sodium And Calcium Products Generate Different Acid Neutralizing Capacities. Water Res, 22(5), 577–583.
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Turek, M., & Gonet, M. (1997). Nanofiltration in the utilization of coal-mine brines. Desalination, 108(1-3), 171–177.
Abstract: The utilization of saline coal mine waters is considered to be the most adequate method of solving ecological problems caused by this kind of water in Poland. In the case of most concentrated waters, the so-called coalmine brines, the method of concentrating by evaporation in a twelve-stage expansion installation or vapour compression is applied, after which sodium chloride is manufactured. A considerable restriction in the utilization of coal mine brines is the high energy consumption in these methods of evaporation. An obstacle in the application of low energy evaporation processes, e.g. multi-stage flash, is the high concentration of calcium and sulfate ions in the coal mine brines. The present paper deals with the application of nanofiltration in the pretreatment of the brine. The application of nanofiltration membranes with an adequate pore size, including charged membranes, makes it possible to decrease the concentration of divalent ions in the permeate practically without any changes in the concentration of sodium chloride. Then the permeate may be concentrated in a multi-stage evaporation process, e.g. MSF, without any risk of the crystallization of gypsum. A combination of NF and MSF ought to set down the unit costs of the concentration of coal mine brines below those of mere evaporation.
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