Precipitation of heavy metals from wastewater using simulated flue gas: Sequent additions of fly ash, lime and carbon dioxide

Quanyuan Chen, Zhou Luo, Colin Hills, Gang Xue, Mark Tyrer

Research output: Contribution to journalArticle

222 Citations (Scopus)

Abstract

Lime is a preferred precipitant for the removal of heavy metals from industrial wastewater due to its relatively low cost. To reduce heavy metal concentration to an acceptable level for discharge, in this work, fly ash was added as a seed material to enhance lime precipitation and the suspension was exposed to CO2 gas. The fly ash-lime-carbonation treatment increased the particle size of the precipitate and significantly improved sedimentation of sludge and the efficiency of heavy metal removal. The residual concentrations of chromium, copper, lead and zinc in effluents can be reduced to (mg L-1) 0.08, 0.14, 0.03 and 0.45, respectively. Examination of the precipitates by XRD and thermal analysis techniques showed that calcium-heavy metal double hydroxides and carbonates were present. The precipitate agglomerated and hardened naturally, facilitating disposal without the need for additional solidification/stabilization measures prior to landfill. It is suggested that fly ash, lime and CO2, captured directly from flue gas, may have potential as a method for wastewater treatment. This method could allow the ex-situ sequestration of CO2, particularly where flue-gas derived CO2 is available near wastewater treatment facilities.

Original languageEnglish
Pages (from-to)2605-2614
Number of pages10
JournalWater Research
Volume43
Issue number10
Early online date17 Mar 2009
DOIs
Publication statusPublished - Jun 2009
Externally publishedYes

Keywords

  • Carbon dioxide
  • Carbonation
  • Double hydroxide
  • Flue gas
  • Hydroxyl carbonate
  • Precipitation

ASJC Scopus subject areas

  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Ecological Modelling

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