Effectiveness of Mg–Al-layered double hydroxide for heavy metal removal from mine wastewater and sludge volume reduction

M. Tamzid Rahman, T. Kameda, S. Kumagai, T. Yoshioka

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Health hazards from heavy metal pollution in water systems are a global environmental problem. Of similar concern is sludge that results from wastewater treatment due to unsatisfactory sludge management technology. Therefore, the effectiveness of using Mg–Al-layered double hydroxide in the removal of heavy metals from mine wastewater was tested and compared with that of calcium hydroxide [Ca(OH)2], which is a common treatment method for heavy metal removal. Initially, the mine wastewater contained cations of the heavy metals iron (Fe), zinc (Zn), copper (Cu), and lead (Pb). The Mg–Al-layered double hydroxides were able to remove 371, 7.2, 121, and 0.4 mg/L of these pollutants, respectively, using the co-precipitation method. The removal of these metals is most effective using 0.5 g Mg–Al-layered double hydroxide (Mg/Al molar ratio 4) and 20 min of shaking. Zn was removed by the formation of Zn(NO3)(OH)·H2O and Zn5(NO3)2(OH)8 when LDH, Mg/Al molar ratios of 4 and 2, respectively, were used. Similarly, Fe, Cu, and Pb were removed by the formation of Fe–Al-layered double hydroxide, Cu2(OH)3·NO3 and Pb4(OH)4(NO3)4, respectively. While Ca(OH)2 is also capable of reducing the heavy metal concentrations below the Japanese recommended values, this analysis shows that using 0.5 g Mg–Al-layered double hydroxide is a better treatment condition for mine wastewater, because it generates lower sludge volumes than 0.1 g of Ca(OH)2. The measured sludge volume was 1.5 mL for Mg–Al-layered double hydroxide and 2.5 mL for Ca(OH)2, a nearly twofold further reduction.

Original languageEnglish
Pages (from-to)263-272
Number of pages10
JournalInternational Journal of Environmental Science and Technology
Volume15
Issue number2
DOIs
Publication statusPublished - 2018 Feb 1

Keywords

  • Copper
  • Iron
  • Lead
  • Sludge
  • Zinc

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Agricultural and Biological Sciences(all)

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