Effectiveness of various dispersed alkaline substrates for the pre-treatment of ferriferous acid mine drainage. (October 2016)

• Record Type: Journal Article
• Authors: Rakotonimaro, Tsiverihasina V.; Neculita, Carmen Mihaela; Bussière, Bruno; Zagury, Gérald J.
• Is Part Of: Applied geochemistry. Volume 73(2016:Oct.)
• Page Start: 13
• Page End: 23
• Publication Date: 2016-10
• Subjects: Ferriferous acid mine drainage -- Iron pre-treatment -- Dispersed alkaline substrate -- Calcite -- Dolomite; ALD Anoxic limestone drains -- AMD Acid mine drainage -- DAS Dispersed alkaline substrate -- LOI Loss on ignition -- NFOL Natural Fe-oxidizing lagoon -- OLD Oxic limestone drains -- PBR Passive bioreactor -- WA-DAS Wood ash-dispersed alkaline substrate; Environmental geochemistry -- Periodicals; Water chemistry -- Periodicals; Geochemistry -- Social aspects -- Periodicals; Geochemistry -- Periodicals; 551.9
• DOI: 10.1016/j.apgeochem.2016.07.014
• Languages: English
• ISSNs: 0883-2927

Abstract

Abstract: Dispersed alkaline substrates (DAS) have been successfully used in passive treatment of highly contaminated acid mine drainage (AMD) to limit coating and clogging issues. However, further optimization of DAS systems is still needed, especially for their long-term efficiency during the treatment of ferriferous AMD. In the present study, three types of DAS comprised of natural alkaline materials (wood ash, calcite, dolomite), in different proportions (20%v/v, 50%v/v, 80%v/v), and a substrate with high surface area (wood chips) were tested in 9 batch reactors. The testing was carried out, in duplicate, for a period of 91 days, to evaluate the comparative performance of the mixtures for iron pre-treatment in ferriferous AMD (2500 mg/L Fe, at pH 4). Results showed increasing of pH (between 4.15 and 7.12), regardless of the proportion of alkaline materials in the DAS mixtures. Among the tested mixtures, wood ash type DAS were more effective for Fe removal (99.9%) than calcite or dolomite type DAS (up to 66%). All tested DAS had limited efficiency for sulfate removal and an additional treatment unit, such as a sulfate-reducing biochemical reactor, is needed. Moreover, due to the similar performances of the calcite and dolomite DAS, they could be potentially substituted and rather be used in a polishing treatment unit. Based on these findings, the most promising mixture was the 50% wood ash type DAS (WA50-DAS). Highlights: Wood ash dispersed alkaline substrate (DAS) was very efficient in iron pre-treatment. Very short-term better performance of calcite-DAS than of dolomite-DAS was found. Calcite- and dolomite-DAS gave comparable Fe removal and could be substituted. All tested DAS mixtures showed limited sulfate removal.