Techniques for the stabilization and assessment of treated copper- chromium- and arsenic-contaminated soil

• Remediation mainly based on excavation and burial of the contaminated soil is impractical with regard to the large numbers of sites identified as being in need of remediation. Therefore alternative methods are needed for brownfield remediation. This study was conducted to assess a chemical stabilisation procedure of CCA-contaminated soil using iron-containing blaster sand or oxygen scarfing granulate. The stabilisation technique was assessed with regard to the feasibility of mixing ameliorants at an industrial scale and the efficiency of the stabilisation under different redox conditions. The stability was investigated under natural conditions in 1-m3 lysimeters in a field experiment and the effect of redox conditions was assessed in a laboratory experiment (10 l). The treatments with high additions of ameliorant (8 and 17%) were more successful in both the laboratory and field experiments, even though there was enough iron on a stochiometric basis even at the lowest addition rates (0.1 and 1%). The particle size of the iron and the mixing influenced the stabilisation efficiency. The development of anaerobic conditions, simulated by water saturation, increases the fraction of AsIII and, consequently, arsenic mobility. The use of high concentrations of OSG under aerobic conditions increased the concentrations of Ni and Cu in the pore water. However, under anaerobic conditions, it decreased the arsenic leaching compared to the untreated soil and Ni and Cu leaching was not critical. The final destination of the treated soil should govern the amendment choice, e.g. an OSG concentration around 10% may be suitable if the soil is to be landfilled under anaerobic conditions. Alternatively, the soil mixed with 1% BS could be kept under aerobic conditions in a landfill cover or in situ at brownfield site. In addition, the treatment with BS appeared to produce better effects in the long term than with OSG.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Annan naturresursteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Other Environmental Engineering (hsv//eng)

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Avfallsteknik

Waste Science and Technology

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