A calcite permeable reactive barrier for the remediation of Fluoride from spent potliner (SPL) contaminated groundwater

B.D. Turner, Philip John Binning, S.W. Sloan

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The use of calcite (CaCO3) as a substrate for a permeable reactive barrier (PRB) for removing fluoride from contaminated groundwater is proposed and is illustrated by application to groundwater contaminated by spent potliner leachate (SPL), a waste derived from the aluminium smelting process. The paper focuses on two issues in the implementation of calcite permeable reactive barriers for remediating fluoride contaminated water: the impact of the groundwater chemical matrix and CO2 addition on fluoride removal. Column tests comparing pure NaF solutions, synthetic SPL solutions, and actual SPL leachate indicate that the complex chemical matrix of the SPL leachate can impact fluoride removal significantly. For SPL contaminant mixtures, fluoride removal is initially less than expected from idealized, pure, solutions. However, with time, the effect of other contaminants on fluoride removal diminishes. Column tests also show that pH control is important for optimizing fluoride removal with the mass removed increasing with decreasing pH. Barrier pH can be regulated by CO2 addition with the point of injection being critical for optimising the remediation performance. Experimental and model results show that approximately 99% of 2300 mg/L fluoride can be removed when CO2 is injected directly into the barrier. This can be compared to approximately 30-50% removal when the influent solution is equilibrated with atmospheric CO2 before contact with calcite.
Original languageEnglish
JournalJournal of Contaminant Hydrology
Volume95
Issue number3-4
Pages (from-to)110-120
ISSN0169-7722
DOIs
Publication statusPublished - 2008

Keywords

  • spent potliner
  • SPL
  • PRB
  • permeable reactive barrier
  • calcite
  • remediation

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