An Evaluation of Substrate Types in Constructed Wetlands Acid Drainage Treatment Systems

Brodie, Gregory A.; Hammer, Donald A.; Tomljanovich, D.A.

doi:10.21000/jasmr88010389

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…In anaerobic wetlands, the sorption of metals occurs on the organic substrates through exchangeable or complexation reactions. Initially, 50-80 % of metal removal from the AMD inside the anaerobic wetland system takes place due to sorption, which decreases over time due to the substrate saturation [17,57]. The retention of metals as of oxide, hydroxide, carbonate and sulfide precipitates also occurs in anaerobic wetlands.…”

Section: Constructed Wetlandsmentioning

confidence: 99%

Remediation of Acid Mine Drainage-Impacted Water

2015

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The formation of acid mine drainage (AMD), a highly acidic and metal-rich solution, is the biggest environmental concern associated with coal and mineral mining. Once produced, AMD can severely impact the surrounding ecosystem due to its acidity, metal toxicity, sedimentation and other deleterious properties. Hence, implementations of effective post-mining management practices are necessary to control AMD pollution. Due to the existence of a number of federal and state regulations, it is necessary for private and government agencies to come up with various AMD treatment and/or control technologies. This review describes some of the widely used AMD remediation technologies in terms of their general working principles, advantages and shortcomings. AMD treatment technologies can be divided into two major categories, namely prevention and remediation. Prevention techniques mainly focus on inhibiting AMD formation reactions by controlling the source. Remediation techniques focus on the treatment of already produced AMD before their discharge into water bodies. Remediation technologies can be further divided into two broad categories: active and passive. Due to high cost and intensive labor requirements for maintenance of active treatment technologies, passive treatments are widely used all over the world. Besides the conventional passive treatment technologies such as constructed wetlands, anaerobic sulfate-reducing bioreactors, anoxic limestone drains, open limestone channels, limestone leach beds and slag leach beds, this paper also describes emerging passive treatment technologies such as phytoremediation. More intensive research is needed to develop an efficient and cost-effective AMD treatment technology, which can sustain persistent and long-term AMD load.

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Section: Constructed Wetlandsmentioning

confidence: 99%

Remediation of Acid Mine Drainage-Impacted Water

2015

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“…TVA has initiated research addressing basic design questions. including optimum substrates and vegetation, hydraulic and contaminant loading rates, treatment system capacity and longevity, storm event and ground water monitoring, and limestone bed design (Brodie et al 1988…”

Section: Discussionmentioning

confidence: 99%

Constructed Wetlands for Acid Drainage Control in the Tennessee Valley

Brodie¹,

Hammer²,

Tomljanovich³

1988

ASMR

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Constructed wetlands are often a preferred alternative to conventional methods of treating acid drainage at mine sites, coal preparation facilities, and coal-fired power plants. The Tennessee Valley Authority (TVA) has designed and constructed wetlands in Alabama and Tennessee to treat acid discharges from these sources. Between June 1985 and August 1987, seven wetlands were constructed to treat acid drainage at an inactive coal preparation plant and adjacent mined area and four wetlands were constructed at TVA coal-fired power plants. Although sitespecific characteristics often restricted use of standardized methods, generic design, construction. and operation guidelines have been developed. Treatment efficiencies have ranged from 82%-99% removal for total iron and 9%-98% removal for total manganese. Preliminary design guidelines for required treatment area were: ph <

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“…Sorption onto organic materials (such as peat and sawdust) can initially remove 50 to 80% of the metals in AMD (Brodie et al, 1988), but the exchange capacity declines with time. Over the long term, metal hydroxide precipitation is the predominant form of metal retention in a wetland.…”

Section: Passive Treatment Of Amdmentioning

confidence: 99%

A Brief Overview of Control and Treatment Technologies for Acid Mine Drainge

Skousen

2002

JASMR

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Abstract. Acid mine drainage (AMD) occurs when metal sulfides are exposed to oxidizing conditions. Leaching of reaction products into surface waters pollute over 20,000 km of streams in the USA alone. Mining companies must predict the potential of creating AMD by using overburden analyses. Where a potential exists, special handling of overburden materials and quick coverage of acid-producing materials in the backfill should be practiced. The addition of acid-neutralizing materials can reduce or eliminate AMD problems. Placing acid-producing materials under dry barriers can isolate these materials from air and water. Other AMD control technologies being researched include injection of alkaline materials (ashes and limestone) into abandoned underground mines and into buried acid material in mine backfills, remining of abandoned areas, and installation of alkaline recharge trenches. Chemicals used for treating AMD are Ca(OH) 2 , CaO, NaOH, Na 2 CO 3 , and NH 3 , with each having advantages under certain conditions. Under low-flow situations, all of the chemicals except Ca(OH) 2 are cost effective, while at high flow Ca(OH) 2 and CaO are clearly the most cost effective. Floc, the metal hydroxide material collected after treatment, is disposed of in abandoned deep mines, refuse piles, or left in collection ponds. Wetlands remove metals from AMD through formation of oxyhydroxides and sulfides, exchange and organic complexation reactions, and direct plant uptake. Aerobic wetlands are used when water contains enough alkalinity to promote metal precipitation and anaerobic wetlands are used when alkalinity must be generated by microbial sulfate reduction and limestone dissolution. Anoxic limestone drains are buried trenches of limestone that intercept AMD underground to generate alkalinity. Under anoxia, limestone should not be coated with Fe +3 hydroxides in the drain, decreasing the likelihood of clogging. Successive alkalinity-producing systems pre-treat oxygenated AMD with organic matter to remove oxygen and Fe +3 , and then the water is introduced into limestone underneath the organic matter. Open limestone channels use limestone in aerobic environments to treat AMD. Coating of limestone occurs and the reduced limestone dissolution is designed into the treatment system. Alkaline leach beds, containing either limestone or slag, are used to add alkalinity to acid water. At present, most passive systems offer short-term treatment, and are more practical for installation on abandoned sites or watershed restoration projects where effluent limits do not apply and where some removal of acid and metals will benefit a stream.Additional

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An Evaluation of Substrate Types in Constructed Wetlands Acid Drainage Treatment Systems

Cited by 6 publications

References 2 publications

Remediation of Acid Mine Drainage-Impacted Water

Remediation of Acid Mine Drainage-Impacted Water

Constructed Wetlands for Acid Drainage Control in the Tennessee Valley

A Brief Overview of Control and Treatment Technologies for Acid Mine Drainge

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