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Sustained bauxite residue rehabilitation with gypsum and organic matter 16 years after initial treatment

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posted on 2018-01-15, 14:32 authored by Andrew W. Bray, Douglas I. Stewart, RONAN COURTNEYRONAN COURTNEY, Simon P. Rout, Paul N. Humphreys, William M. Mayes, Ian T. Burke
Bauxite residue is a high volume byproduct of alumina manufacture which is commonly disposed of in purpose-built bauxite residue disposal areas (BRDAs). Natural waters interacting with bauxite residue are characteristically highly alkaline, and have elevated concentrations of Na, Al, and other trace metals. Rehabilitation of BRDAs is therefore often costly and resource/infrastructure intensive. Data is presented from three neighboring plots of bauxite residue that was deposited 20 years ago. One plot was amended 16 years ago with process sand, organic matter, gypsum, and seeded (fully treated), another plot was amended 16 years ago with process sand, organic matter, and seeded (partially treated), and a third plot was left untreated. These surface treatments lower alkalinity and salinity, and thus produce a substrate more suitable for biological colonisation from seeding. The reduction of pH leads to much lower Al, V, and As mobility in the actively treated residue and the beneficial effects of treatment extend passively 20–30 cm below the depth of the original amendment. These positive rehabilitation effects are maintained after 2 decades due to the presence of an active and resilient biological community. This treatment may provide a lower cost solution to BRDA end of use closure plans and orphaned BRDA rehabilitation.

Funding

Developmentand design of a new dry cleaning process for HCFC 225, an alternaive to CFC 113, with a low emission

European Commission

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History

Publication

Environmental Science and Technology: 52, pp. 152-161

Publisher

American Chemical Society

Note

peer-reviewed

Other Funding information

NERC, Patil University

Language

English

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