Characteristics and stabilities of residues from the Wheal Jane constructed wetlands

Swash, P. M.; Monhemius, A.J.

doi:10.1016/j.scitotenv.2004.09.009

Cited by 11 publications

(3 citation statements)

References 2 publications

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“…The study conducted by Swash and Monhemius [121] focused on analyzing the solubility of residues formed during the effluent treatment of an acidic (pH 3 to 4) mine discharge enriched in iron (<100 mg/L), zinc (<80 mg/L), manganese (<20 mg/L), and arsenic (<2 mg/L) at the Wheal Jane constructed wetland facility in Cornwall, UK. Their results demonstrated that in the aerobic cells, the iron was precipitated as an amorphous (poorly crystalline goethite and ferrihydrite), orange-brown material, usually referred to as ochre, onto which arsenic (>0.1%) and trace amounts of base metals were adsorbed.…”

Section: Implementation Of Constructed Wetlands (Cw) For Mine Water Rmentioning

confidence: 99%

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Review of Constructed Wetlands for Acid Mine Drainage Treatment

Pat-Espadas

Loredo-Portales

Amábilis-Sosa

et al. 2018

Water

107

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The mining industry is the major producer of acid mine drainage (AMD). The problem of AMD concerns at active and abandoned mine sites. Acid mine drainage needs to be treated since it can contaminate surface water. Constructed wetlands (CW), a passive treatment technology, combines naturally-occurring biogeochemical, geochemical, and physical processes. This technology can be used for the long-term remediation of AMD. The challenge is to overcome some factors, for instance, chemical characteristics of AMD such a high acidity and toxic metals concentrations, to achieve efficient CW systems. Design criteria, conformational arrangements, and careful selection of each component must be considered to achieve the treatment. The main objective of this review is to summarize the current advances, applications, and the prevalent difficulties and opportunities to apply the CW technology for AMD treatment. According to the cited literature, sub-surface CW (SS-CW) systems are suggested for an efficient AMD treatment. The synergistic interactions between CW components determine heavy metal removal from water solution. The microorganism-plant interaction is considered the most important since it implies symbiosis mechanisms for heavy metal removal and tolerance. In addition, formation of litter and biofilm layers contributes to heavy metal removal by adsorption mechanisms. The addition of organic amendments to the substrate material and AMD bacterial consortium inoculation are some of the strategies to improve heavy metal removal. Adequate experimental design from laboratory to full scale systems need to be used to optimize equilibria between CW components selection and construction and operational costs. The principal limitations for CW treating AMD is the toxicity effect that heavy metals produce on CW plants and microorganisms. However, these aspects can be solved partially by choosing carefully constructed wetlands components suitable for the AMD characteristics. From the economic point of view, a variety of factors affects the cost of constructed wetlands, such as: detention time, treatment goals, media type, pretreatment type, number of cells, source, and availability of gravel media, and land requirements, among others.

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Section: Implementation Of Constructed Wetlands (Cw) For Mine Water Rmentioning

confidence: 99%

“…On the other hand, the anaerobic samples were composed mostly of carbonaceous material onto which inorganic elements were adsorbed or had precipitated. They were found to contain minimal amounts of toxic compounds and were considered to be less of a disposal problem [121].…”

Section: Implementation Of Constructed Wetlands (Cw) For Mine Water Rmentioning

confidence: 99%

Review of Constructed Wetlands for Acid Mine Drainage Treatment

Pat-Espadas

Loredo-Portales

Amábilis-Sosa

et al. 2018

Water

107

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“…Swash and Monhemius studied calcium arsenates and found that at temperatures of less than 373.15 K and pH 6, crystalline hydrates of CaHAsO 4 form, such as haidingerite (CaHAsO 4 ·H 2 O), which forms at 323.15 K, and pharmacolite (CaHAsO 4 ·2H 2 O), which forms at 293.15 K. At temperatures higher than 373.15 K, the solids have little water of hydration, consequently weilita forms (CaHAsO 4 ). TCLP tests conducted on these calcium arsenates show that they are soluble in water, with an arsenic lixiviation range of (900 to 4400) mg·L −1 , which is not a good indicator to immobilize arsenic.…”

Section: Introductionmentioning

confidence: 99%

Equilibria of Aqueous System Phases Containing Arsenic + Iron and Arsenic + Calcium at (323.15 and 343.15) K

et al. 2009

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The present study includes solubility measurements, density, and refractive indices of saturated solutions of the systems As 2 O 5 + Fe(OH) 3 + H 2 O and As 2 O 5 + CaCO 3 + H 2 O. The experimental study was carried out at (323.15 and 343.15) K and for different mass fractions of arsenic, iron, and calcium. With the experimental results obtained, phase diagrams at these two temperatures and their regions were determined. The most important precipitated salt for the first system was FeAsO 4 • 2H 2 O (scorodite) and for the second system CaHAsO 4 • H 2 O (haidingerite). The experimental data on solubility and physical properties as a function of the mass fraction of iron and calcium were correlated for both systems. These equations allowed determination of the invariant points (double saturation equilibrium) of both systems for the two temperatures studied in this work and verified by scanning electron microscopy by the second system. This work is a contribution to the mining industry, to fix arsenic to solid matrices from industrial liquid residues.

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