Abstract: Parts of Britain have large accumulations of metalliferous tailings derived from mining in the lath, 19th and 20th centuries. These tailings were never subject to land reclamation schemes at the time of mining and are situated very close to water courses. They cause considerable environmental damage in terms of contamination of soils, dust blow and pollution of water courses and groundwater. In some parts of the country mine drainage is a major part of river pollution. In recent years, particularly in Wales, efforts have been made to “clean up” these sites. This has involved using techniques to isolate and contain the spoil, diversion of water courses, and the installation of water treatment facilities and drainage and the establishment of a vegetation cover. Research is also being initiated to investigate ways of decontaminating these metalliferous spoils as an alternative to using covering systems to reclaim them.

Abstract: 400 systems installed within 4 years During the last two decades, the United States mining industry has greatly increased the amount it spends on pollution control. The application of biotechnology to mine water can reduce the industry's water treatment costs (estimated at over a million dollars a day) and improve water quality in streams and rivers adversely affected by acidic mine water draining from abandoned mines. Biological treatment of mine waste water is typically conducted in a series of small excavated ponds that resemble, in a superficial way, a small marsh area. The ponds are engineered to first facilitate bacterial oxidation of iron; ideally, the water then flows through a composted organic substrate that supports a population of sulfate-reducing bacteria. The latter process raises the pH. During the past four years, over 400 wetland water treatment systems have been built on mined lands as a result of research by the U.S. Bureau of Mines. In general, mine operators find that the wetlands reduce chemical treatment costs enough to repay the cost of wetland construction in less than a year. Actual rates of iron removal at field sites have been used to develop empirical sizing criteria based on iron loading and pH. If the pH is 6 or above, the wetland area (in2) required is equivalent to the iron. load (grams/day) divided by 10. Theis requirement doubles at a pH of 4 to 5. At a pH below 4, the iron load (grams/day) should be divided by 2 to estimate the area required (in2).