Review of Passive Systems for Acid Mine Drainage Treatment

Abstract

acid neutralization and oxidation and precipitation of the resulting metal flocs. Before selecting an appropriate treatment technology, the AMD conditions and chemistry must be characterized. Flow, acidity and alkalinity, metal, and dissolved oxygen concentrations are critical parameters. This paper reviews the current state of passive system technology development, provides results for various system types, and provides guidance for sizing and effective operation.Keywords Anoxic limestone drains · Bioreactors · Limestone leach beds · Low-pH Fe oxidation channels · Open limestone channels · Wetlands Acid Mine DrainageOxidation of pyritic materials during and after mining produces sulfuric acid and metal ions. These products react with host rock and surface and groundwater to create a range of water chemistries from pH 2 to 8 and elevated ion concentrations. Such waters have traditionally been called acid mine drainage (AMD) and alkaline mine drainage. I n this paper, we use AMD when the water is acidic and state clearly in the text when the water being referred to is not acidic. When AMD enters surface water bodies, biotic impairment often occurs through direct toxicity, habitat alteration by metal precipitates, nutrient cycle alterations, or other mechanisms, and the water often becomes unsuitable for domestic, agricultural, and industrial uses. The process of pyrite oxidation and its effects on water resources have been known for centuries (Nordstrom 2011;Seal and Shanks 2008) and AMD is a worldwide concern (Younger and Wolkersdorfer 2004). Damaging effects of AMD have been described by researchers in Asia (David 2003; Wei Abstract When appropriately designed and maintained, passive systems can provide long-term, efficient, and effective treatment for many acid mine drainage (AMD) sources. Passive AMD treatment relies on natural processes to neutralize acidity and to oxidize or reduce and precipitate metal contaminants. Passive treatment is most suitable for small to moderate AMD discharges of appropriate chemistry, but periodic inspection and maintenance plus eventual renovation are generally required. Passive treatment technologies can be separated into biological and geochemical types. Biological passive treatment technologies generally rely on bacterial activity, and may use organic matter to stimulate microbial sulfate reduction and to adsorb contaminants; constructed wetlands, vertical flow wetlands, and bioreactors are all examples. Geochemical systems place alkalinity-generating materials such as limestone in contact with AMD (direct treatment) or with fresh water upgradient of the AMD. Most passive treatment systems employ multiple methods, often in series, to promote 1 3Mine Water Environ (2017) 36:133-153

Overview of Active and Passive Systems for Treating Acid Mine Drainage

“…In too low slope drains heavy metal precipitates(armoring or the coating of the limestone ) will occur around limestone and within its void spaces and decreases the neutralizing capacity [7]. For efficient performance, channel gradient should be more than 20%.OLC, when used with other passive treatment methods, can make the most of the treatment and remove the heavy and toxic metals [28]. Armoring of the limestone by Fe(CO) 3 and Fe(OH) 3 produced by neutralization decreases the generation of alkalinity, so huge amount of limestone are needed for the long success of the method.…”

Dynamic Experimental Study on Treatment of Acid Mine Drainage by Bacteria Supported in Natural Minerals

“…Some associated minerals in coal mines will undergo oxidation reactions after contact with water and oxygen, and dissolve SO 4 2− and a variety of metal ions to form acid mine drainage (AMD). AMD is characterized by extremely low pH value and elevated in SO 4 2− , Fe 2+ , Mn 2+ and other polluting ions [3]. The untreated AMD directly flows into surface water and groundwater, which will adversely impact water resources [4].…”

“…AMD is characterized by extremely low pH value and elevated in SO 4 2− , Fe 2+ , Mn 2+ and other polluting ions [3]. The untreated AMD directly flows into surface water and groundwater, which will adversely impact water resources [4]. AMD has become a global environmental threat, seriously affecting the water resources and soil ecosystem around the coal-mining areas [5].…”

Biomass Ashes for Acid Mine Drainage Remediation

“…Active and passive systems using physicochemical, chemical or biological treatment are presently employed for AMD remediation [11][12][13][14][15]. Various materials such as limestone, lime, clay, activated carbon, zeolite, iron (III) hydroxide, cellulose, rice husks, coal fly ash, waste green seeds and peat-humic agent are used for AMD remediation [9,[16][17][18][19][20][21][22][23][24].…”