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Contaminant mobility and carbon sequestration downstream of the Ajka (Hungary) red mud spill : the effects of gypsum dosing

Renforth, P.; Mayes, W. M.; Jarvis, A. P.; Burke, I. T.; Manning, D. A.C.; Gruiz, K.


P. Renforth

A. P. Jarvis

I. T. Burke

D. A.C. Manning

K. Gruiz


A number of emergency pollution management measures were enacted after the accidental release of caustic bauxite processing residue that occurred in Ajka, western Hungary in October, 2010. These centred on acid and gypsum dosing to reduce pH and minimise mobility of oxyanion contaminants mobile at high pH. This study assessed the effectiveness of gypsum dosing on contaminant mobility and carbon sequestration through assessment of red mud and gypsum-affected fluvial sediments via elemental analysis and stable isotope analysis. There was a modest uptake of contaminants (notably As, Cr, and Mn) on secondary carbonate-dominated deposits in reaches subjected to gypsum dosing. C and O stable isotope ratios of carbonate precipitates formed as a result of gypsum dosing were used to quantify the importance of the neutralisation process in sequestering atmospheric carbon dioxide. This process was particularly pronounced at sites most affected by gypsum addition, where up to 36% of carbonate-C appears to be derived from atmospheric in-gassing of CO2. The site is discussed as a large scale analogue for potential remedial approaches and carbon sequestration technologies that could be applied to red mud slurries and other hyperalkaline wastes. The results of this work have substantial implications for the aluminium production industry in which 3–4% of the direct CO2emissions may be offset by carbonate precipitation. Furthermore, carbonation by gypsum addition may be important for contaminant remediation, also providing a physical stabilisation strategy for the numerous historic stockpiles of red mud.


Renforth, P., Mayes, W. M., Jarvis, A. P., Burke, I. T., Manning, D. A., & Gruiz, K. (2012). Contaminant mobility and carbon sequestration downstream of the Ajka (Hungary) red mud spill : the effects of gypsum dosing. The Science of the total environment, 421-422, 253-259.

Journal Article Type Article
Acceptance Date Jan 20, 2012
Online Publication Date Feb 18, 2012
Publication Date Apr 1, 2012
Journal Science of the Total Environment
Print ISSN 0048-9697
Electronic ISSN 1879-1026
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 421-422
Pages 253-259
Keywords Bauxite processing residue; Red mud; Carbon dioxide removal; Stable isotope; Hyperalkaline wastes; Carbonate precipitation
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