Stability of heavy metals in soil washing residue with and without biochar addition under accelerated ageing

Zhengtao Shen, Deyi Hou, Bin Zhao, Wendi Xu, Yong Sik Ok, Nanthi S. Bolan, Daniel S. Alessi

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Soil washing residue (SWR), which typically concentrates the washed toxic metals and is comprised of high contents of clay particles, may pose risks to the surrounding environment. This study aims to simulate accelerated ageing to assess the stability of selected metals (Cd2 + (132 mg/kg), Cu2 + (248 mg/kg) and Pb2 + (3470 mg/kg)) in a SWR (89.68% of clay) with and without biochar treatment. The soil was incubated under constant moisture and wet-dry cycles (accelerated ageing), respectively, and the mobility and fractions of heavy metals in the soils with and without biochar treatment were examined. Under the constant moisture condition, biochar addition at 5% w/w reduced the leached Cd2 + (by 1.81%) and Cu2 + (by 8.70%) from SWR at day 1 and the leached Cu2 + (by 51.08%) and Pb2 + (by 25.36%) from SWR at day 14; however, the leached metals in the TCLP solution from the biochar-amended soils still exceed the regulatory limits (1 mg/L for Cd2 +, 5 mg/L for Pb2 +, no regulatory limits for Cu2 +). Conversely, accelerated ageing (14 days) significantly increased the fractions of exchangeable Cd2 + (from 3.63–3.94% to 6.21–6.29%) and Pb2 + (from 0.025–0.027% to 0.034–0.041%) as well as the TCLP leachabilities of Cd2 + (from 2.91–3.28% to 3.46–3.73%), Cu2 + (from 0.08–0.10% to 0.03–0.06%) and Pb2 + (from 0.25–0.35% to 0.52–0.57%) in the soils, as compared with those incubated under constant moisture, regardless of biochar addition. This study reveals challenges associated with stabilising SWR due to the presence of residual fine-grained particles.

Original languageEnglish
Pages (from-to)185-193
Number of pages9
JournalScience of the Total Environment
Volume619-620
DOIs
Publication statusPublished - 2018 Apr 1

Fingerprint

Heavy Metals
Washing
Heavy metals
Aging of materials
heavy metal
Soils
soil
Moisture
Metals
moisture
Clay
biochar
clay
Poisons
metal

Keywords

  • Accelerated ageing
  • Biochar
  • Black carbon
  • Leaching
  • Soil remediation
  • Soil washing

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

Cite this

Stability of heavy metals in soil washing residue with and without biochar addition under accelerated ageing. / Shen, Zhengtao; Hou, Deyi; Zhao, Bin; Xu, Wendi; Ok, Yong Sik; Bolan, Nanthi S.; Alessi, Daniel S.

In: Science of the Total Environment, Vol. 619-620, 01.04.2018, p. 185-193.

Research output: Contribution to journalArticle

Shen, Zhengtao ; Hou, Deyi ; Zhao, Bin ; Xu, Wendi ; Ok, Yong Sik ; Bolan, Nanthi S. ; Alessi, Daniel S. / Stability of heavy metals in soil washing residue with and without biochar addition under accelerated ageing. In: Science of the Total Environment. 2018 ; Vol. 619-620. pp. 185-193.
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abstract = "Soil washing residue (SWR), which typically concentrates the washed toxic metals and is comprised of high contents of clay particles, may pose risks to the surrounding environment. This study aims to simulate accelerated ageing to assess the stability of selected metals (Cd2 + (132 mg/kg), Cu2 + (248 mg/kg) and Pb2 + (3470 mg/kg)) in a SWR (89.68{\%} of clay) with and without biochar treatment. The soil was incubated under constant moisture and wet-dry cycles (accelerated ageing), respectively, and the mobility and fractions of heavy metals in the soils with and without biochar treatment were examined. Under the constant moisture condition, biochar addition at 5{\%} w/w reduced the leached Cd2 + (by 1.81{\%}) and Cu2 + (by 8.70{\%}) from SWR at day 1 and the leached Cu2 + (by 51.08{\%}) and Pb2 + (by 25.36{\%}) from SWR at day 14; however, the leached metals in the TCLP solution from the biochar-amended soils still exceed the regulatory limits (1 mg/L for Cd2 +, 5 mg/L for Pb2 +, no regulatory limits for Cu2 +). Conversely, accelerated ageing (14 days) significantly increased the fractions of exchangeable Cd2 + (from 3.63–3.94{\%} to 6.21–6.29{\%}) and Pb2 + (from 0.025–0.027{\%} to 0.034–0.041{\%}) as well as the TCLP leachabilities of Cd2 + (from 2.91–3.28{\%} to 3.46–3.73{\%}), Cu2 + (from 0.08–0.10{\%} to 0.03–0.06{\%}) and Pb2 + (from 0.25–0.35{\%} to 0.52–0.57{\%}) in the soils, as compared with those incubated under constant moisture, regardless of biochar addition. This study reveals challenges associated with stabilising SWR due to the presence of residual fine-grained particles.",
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AU - Xu, Wendi

AU - Ok, Yong Sik

AU - Bolan, Nanthi S.

AU - Alessi, Daniel S.

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AB - Soil washing residue (SWR), which typically concentrates the washed toxic metals and is comprised of high contents of clay particles, may pose risks to the surrounding environment. This study aims to simulate accelerated ageing to assess the stability of selected metals (Cd2 + (132 mg/kg), Cu2 + (248 mg/kg) and Pb2 + (3470 mg/kg)) in a SWR (89.68% of clay) with and without biochar treatment. The soil was incubated under constant moisture and wet-dry cycles (accelerated ageing), respectively, and the mobility and fractions of heavy metals in the soils with and without biochar treatment were examined. Under the constant moisture condition, biochar addition at 5% w/w reduced the leached Cd2 + (by 1.81%) and Cu2 + (by 8.70%) from SWR at day 1 and the leached Cu2 + (by 51.08%) and Pb2 + (by 25.36%) from SWR at day 14; however, the leached metals in the TCLP solution from the biochar-amended soils still exceed the regulatory limits (1 mg/L for Cd2 +, 5 mg/L for Pb2 +, no regulatory limits for Cu2 +). Conversely, accelerated ageing (14 days) significantly increased the fractions of exchangeable Cd2 + (from 3.63–3.94% to 6.21–6.29%) and Pb2 + (from 0.025–0.027% to 0.034–0.041%) as well as the TCLP leachabilities of Cd2 + (from 2.91–3.28% to 3.46–3.73%), Cu2 + (from 0.08–0.10% to 0.03–0.06%) and Pb2 + (from 0.25–0.35% to 0.52–0.57%) in the soils, as compared with those incubated under constant moisture, regardless of biochar addition. This study reveals challenges associated with stabilising SWR due to the presence of residual fine-grained particles.

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