Assessing long-term stability of cadmium and lead in a soil washing residue amended with MgO-based binders using quantitative accelerated ageing

Zhengtao Shen; Deyi Hou; Wendi Xu; Jingzhuo Zhang; Fei Jin; Bin Zhao; Shizhen Pan; Tianyue Peng; Daniel S Alessi

doi:10.1016/j.scitotenv.2018.06.321

Assessing long-term stability of cadmium and lead in a soil washing residue amended with MgO-based binders using quantitative accelerated ageing

Sci Total Environ. 2018 Dec 1:643:1571-1578. doi: 10.1016/j.scitotenv.2018.06.321. Epub 2018 Jul 4.

Authors

Zhengtao Shen¹, Deyi Hou², Wendi Xu³, Jingzhuo Zhang³, Fei Jin⁴, Bin Zhao³, Shizhen Pan⁵, Tianyue Peng³, Daniel S Alessi⁶

Affiliations

¹ School of Environment, Tsinghua University, Beijing 100084, China; Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada.
² School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: houdeyi@tsinghua.edu.cn.
³ School of Environment, Tsinghua University, Beijing 100084, China.
⁴ School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK.
⁵ School of Environment, Tsinghua University, Beijing 100084, China; School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China.
⁶ Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada.

PMID: 30189573
DOI: 10.1016/j.scitotenv.2018.06.321

Abstract

A soil washing residue (SWR) (containing 90% clay, cadmium (Cd²⁺) of 132 mg/kg, lead (Pb²⁺) of 3410 mg/kg) was stabilized with MgO (M) and MgO + bioapatite (MB) respectively at a dosage of 5% in w/w. The stability of the metals in original and amended SWRs was assessed after immediate treatment and using a laboratory accelerated ageing method simulating 26, 52, 78 and 104 years in field conditions. The dissolved Cd²⁺ and Pb²⁺ from the SWR in Toxicity Characteristic Leaching Procedure (TCLP) leachates significantly reduced (by 96.84-99.06%) by both amendments after immediate treatment. The stabilization remained effective within simulated 26 years as the TCLP leached Cd²⁺ and Pb²⁺ kept below regulatory levels. This immobilization was mainly due to the increased non-bioavailable Cd²⁺ and Pb²⁺ from sequential extraction tests in SWR by the amendments. At simulated 52 years, the TCLP leached Cd²⁺ from M and MB exceeded regulatory level by 106% and 1% respectively. Large amounts of Cd²⁺ and Pb²⁺ were leached out by 36.74-48.18% regardless of the treatments at simulated 104 years. Although bioapatite can significantly aid the stabilization of metals by MgO, the stabilization effectiveness for both treatments diminished at simulated 52 years and from 52 to 104 years.

Keywords: Accelerated ageing; Cd and Pb stabilization; Heavy metal; MgO; Soil washing residue.