Chelant-enhanced washing of CCA-contaminated soil: Coupled with selective dissolution or soil stabilization.

摘要: Abstract Remediation of CCA-contaminated soil (Cr, Cu, and As) by biodegradable chelant-enhanced washing (EDDS, S,S -ethylene-diamine-disuccinic-acid) needs further enhancement. This study investigated the effectiveness coupling with pre-treatment selective dissolution post-treatment amendments, respectively. Three groups reagents (reductants, alkaline solvents, organic ligands) were adopted in to dissolve oxide minerals before EDDS extraction. In post-treatment, amendments (coal fly ash (CFA), acid mine drainage sludge (AMDS), green waste compost (GWC)), their mixtures) used for a 2-month stabilization after 2-h washing. Multi-endpoint evaluation was performed assessing chemical state, leachability, mobility, bioaccessibility, plant-availability residual metal(loid)s as well cytotoxicity, enzyme activities, available nutrients treated soils. Pre-treatment dithionite-citrate-bicarbonate significantly enhanced extraction efficiency, but also increased leachability As Cr bioaccessibility While sodium hydroxide removed majority without increasing its it cytotoxicity inhibited phosphatase activity. Post-treatment AMDS CFA effectively controlled mobility However, destabilized Cu only marginally immobilized GWC due strong Cu-EDDS complexation. The phytoavailability primarily reduced washing, while those could be attenuated CFA. indicates that subsequent amendment plays complementary roles mitigating effects improving environmental quality.