Combined sieving and washing of multi-metal-contaminated soils using remediation equipment: A pilot-scale demonstration

• Published in: Journal of cleaner production Vol. 212; pp. 81 - 89
• Main Authors: Li, You, Liao, Xiaoyong, Li, Wunan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2019
• Subjects: Multi-metal contamination; Optimization; Physical separation; Remediation equipment; Soil washing; Physical separation; Remediation equipment; Soil washing; Multi-metal contamination; Optimization
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2018.11.294

This study mainly examines the effects of combined sieving and washing process by remediation equipment for heavy metal decontamination at a historically contaminated site. The laboratory results showed that the optimum parameters for the washing process were pH 2, 30 °C, and 10:1 liquid/soil ratio. The results from field remediation proved that the overall removal of arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn) could reach 37.1–51.1%, 44.3–78.1%, 21.2–64.3% and 29.2–59.4%, respectively, in various particle fractions. To prevent secondary pollution, coagulating sedimentation and adsorption processes were used to treat the wastewater, with removal rates of 99.4% As, 99.9% Cd, 93.5% Pb and 99.1% Zn. A composite material was adopted to solidify the fine clay that was enriched with a large amount of metals and form it into non-fired bricks. As seen from the mass balance, 23 kg of stone and 140 kg of gravel were separated, and 367 kg of fine clay with a 45% soil moisture content was treated by solidification and stabilization, achieving a volume reduction of approximately 36.5%. In conclusion, the presented method can be applied to heavy-metal-contaminated sites to greatly reduce the amount of pollutants in soils while at the same time minimizing the environmental risk. [Display omitted] •Combined sieving and washing successfully facilitated metals extraction and volume reduction.•A mobile and automated equipment for soil remediation was manufactured and successfully applied.•Technological parameters of soil washing for different soil particles were optimized.•The removal efficiency can be enhanced by increasing the washing cycles.•Secured disposal was conducted for wastewater and sludge generated from the washing process.