Clay liner materials for land disposal of hazardous non-metal wastes

I. M C Lo, H. M. Liljestrand, Jeehyeong Khim, Y. Shimizu

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Simple land disposal systems for hazardous and mixed wastes contain heavy metal cationic species through precipitation and ion exchange mechanisms but typically fail by releasing soluble organic and inorganic anionic species. To enhance the removal of anions from leachate, clays are modified with coatings of iron or aluminium cations to bridge between the anionic surface and the anionic pollutants. A competitive surface ligand exchange model indicates that surface coatings of 10 meq cation/gm montmorillonite under typical leachate conditions increase the inorganic anion sorption capacity by at least a factor of 6 and increase the intrinsic surface exchange constants by more than a factor of 100. Similarly, metal hydroxide coatings on montmorillonite increase the organic anion sorption capacity by a factor of 9 and increase the intrinsic surface exchange constants by a factor of 20. For historical concentrations of non-metal anions in US hazardous and mixed waste leachate, sorption onto natural clay liner materials is dominated by arsenate sorption. With cation coatings, anion exchange provides an effective removal for arsenate, selenate, phenols, cresols, and phthalates. Engineering applications are presented for the use of modified clays as in situ barriers to leachate transport of anionic pollutants as well as for above ground treatment of recovered leachate.

Original languageEnglish
Pages (from-to)71-77
Number of pages7
JournalWater Science and Technology
Volume33
Issue number8
DOIs
Publication statusPublished - 1996 Jul 4
Externally publishedYes

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Keywords

  • Anion sorption
  • Hazardous waste management
  • Modified clay liner

ASJC Scopus subject areas

  • Water Science and Technology

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