Integrating EDDS-enhanced washing with low-cost stabilization of metal-contaminated soil from an e-waste recycling site

Jingzi Beiyuan, Daniel C.W. Tsang, Yong Sik Ok, Weihua Zhang, Xin Yang, Kitae Baek, Xiang Dong Li

Research output: Contribution to journalArticlepeer-review

69 Citations (Scopus)


While chelant-enhanced soil washing has been widely studied for metal extraction from contaminated soils, there are concerns about destabilization and leaching of residual metals after remediation. This study integrated 2-h soil washing enhanced by biodegradable ethylenediaminedisuccinic acid (EDDS) and 2-month stabilization using agricultural waste product (soybean stover biochar pyrolyzed at 300 and 700 °C), industrial by-product (coal fly ash (CFA)), and their mixture. After integration with 2-month stabilization, the leachability and mobility of residual metals (Cu, Zn, and Pb) in the field-contaminated soil were significantly reduced, especially for Cu, in comparison with 2-h EDDS washing alone. This suggested that the metals destabilized by EDDS-washing could be immobilized by subsequent stabilization with biochar and CFA. Moreover, when the remediation performance was evaluated for phytoavailability and bioaccessibility, prior EDDS washing helped to achieve a greater reduction in the bioavailable fraction of metals than sole stabilization treatment. This was probably because the weakly-bound metals were first removed by EDDS washing before stabilization. Both individual and combined applications of biochar and CFA showed comparable effectiveness regardless of the difference in material properties, possibly due to the high level of amendments (150 ton ha−1). Based on the mobility and bioaccessibility results, the estimated human health risk (primarily resulting from Pb) could be mitigated to an acceptable level in water consumption pathway or reduced by half in soil ingestion pathway. These results suggest that an integration of EDDS washing with soil stabilization can alleviate post-remediation impacts of residual metals in the treated soil.

Original languageEnglish
Pages (from-to)426-432
Number of pages7
Publication statusPublished - 2016 Sept 1
Externally publishedYes

Bibliographical note

Funding Information:
The authors appreciate the financial support from the Hong Kong Research Grants Council ( PolyU 15222115 and PolyU 520911E ) and the National Research Foundation of Korea ( NRF-2015R1A2A2A11001432 ) for this study. Biochar production and characterization was performed at the Environmental Research Institute, Kangwon National University in Korea.

Publisher Copyright:
© 2016 Elsevier Ltd


  • Charcoal
  • Chelating agents
  • Heavy metals
  • Integrated remediation
  • Soil amendment

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Pollution
  • General Chemistry
  • Health, Toxicology and Mutagenesis
  • Environmental Engineering
  • Environmental Chemistry


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