Document Detail


Passive treatment of acid mine drainage with high metal concentrations using dispersed alkaline substrate.
MedLine Citation:
PMID:  18689735     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Passive treatment systems based on the dissolution of coarse calcite grains are widely used to remediate acid mine drainage (AMD). Unfortunately, they tolerate only low metal concentrations or acidity loads, because they are prone to passivation (loss of reactivity due to coating) and/or clogging (loss of permeability) by precipitates. To overcome these problems, a dispersed alkaline substrate (DAS) composed of a fine-grained alkaline reagent (calcite sand) mixed with a coarse inert matrix (wood chips) was developed. The small grains provide a large reactive surface and dissolve almost completely before the growing layer of precipitates passivates the substrate, whereas the dispersion of nuclei for precipitation on the inert surfaces retards clogging. Chemical and hydraulic performance of DAS was investigated in two laboratory columns fed at different flow rates with natural AMD of pH 2.3 to 3.5 and inflow net acidity 1350 to 2300 mg/L as CaCO(3). The DAS columns removed 900 to 1600 mg/L net acidity, 3 to 4.5 times more than conventional passive treatment systems. Regardless of the flow rate employed, Al, Fe(III), Cu, and Pb were virtually eliminated. Minor Zn, Ni, and Cd were removed at low flow rates. High acidity removal is possible because these metals accumulate intentionally in DAS, and their precipitation promotes further calcite dissolution. During 15 mo, DAS operated without clogging at 120 g acidity/m(2).d, four times the loading rate recommended for conventional passive systems; DAS may therefore be capable of treating AMD at sites where influent chemistry precludes the use of other passive systems.
Authors:
Tobias S Rötting; Robert C Thomas; Carlos Ayora; Jesús Carrera
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-08-08
Journal Detail:
Title:  Journal of environmental quality     Volume:  37     ISSN:  0047-2425     ISO Abbreviation:  J. Environ. Qual.     Publication Date:    2008 Sep-Oct
Date Detail:
Created Date:  2008-08-11     Completed Date:  2008-12-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0330666     Medline TA:  J Environ Qual     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1741-51     Citation Subset:  IM    
Affiliation:
Hydrogeochemical Engineering Res. and Outreach Group, Sir Joseph Swan Inst. for Energy Res., 3rd Floor, Devonshire Bldg., Devonshire Terrace, Newcastle Univ., Newcastle on Tyne, NE1 7RU, UK. Tobias.Roetting@newcastle.ac.uk
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MeSH Terms
Descriptor/Qualifier:
Environmental Monitoring
Hydrogen-Ion Concentration
Metals / chemistry*
Mining*
Time Factors
Water Pollutants, Chemical / chemistry*
Water Pollution, Chemical / prevention & control*
Chemical
Reg. No./Substance:
0/Metals; 0/Water Pollutants, Chemical

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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