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

Bray, Andrew W.; Stewart, Douglas I.; Courtney, Ronan; Rout, Simon P.; Humphreys, Paul N.; Mayes, William M.; Burke, Ian T.

Abstract

Bauxite residue is a high volume by-product 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 neighbouring plots of bauxite residue that was deposited twenty 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.

Citation

Bray, A. W., Stewart, D. I., Courtney, R., Rout, S. P., Humphreys, P. N., Mayes, W. M., & Burke, I. T. (2018). Sustained bauxite residue rehabilitation with gypsum and organic matter 16 years after initial treatment. Environmental Science and Technology, 52(1), 152-161. https://doi.org/10.1021/acs.est.7b03568

• Journal Article Type: Article
• Acceptance Date: Nov 28, 2017
• Online Publication Date: Nov 28, 2017
• Publication Date: Jan 2, 2018
• Deposit Date: Nov 30, 2017
• Publicly Available Date: Nov 29, 2018
• Journal: Environmental Science & Technology
• Print ISSN: 0013-936X
• Electronic ISSN: 1520-5851
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 52
• Issue: 1
• Pages: 152-161
• DOI: https://doi.org/10.1021/acs.est.7b03568
• Keywords: General chemistry; Environmental chemistry
• Public URL: https://hull-repository.worktribe.com/output/479683
• Publisher URL: http://pubs.acs.org/doi/10.1021/acs.est.7b03568