Influence of Soil Parameters on the Efficiency of the Attrition Process to Remove Metals, PCP, Dioxins and Furans from Contaminated Soils

Abstract

The objective of this study was to evaluate the influence of the soil parameters (particle size, initial contamination level, etc.) on the performances of an attrition process to remove As, Cr, Cu, pentachlorophenol (PCP) and dioxins and furans (PCDD/F). Five different contaminated soils were wet-sieved to isolate five soil fractions (< 0.250, 0.250-1, 1-4, 4-12 and > mm). Five attrition steps of 20 min each, carried out in the presence of a biodegradable surfactant ([BW] = 2%, w.w-1) at room temperature with a pulp density fixed at 40% (w.w-1), were applied to the coarse soil fractions (> 0.250 mm) of different soils. The results showed good performances of the attrition process to simultaneously remove PCP and PCDD/F from contaminated soil fractions initially containing between 1.1 and 13 mg of PCP.kg-1 (dry basis) and between 1,795 and 5,720 ng TEQ of PCDD/F.kg-1. It appeared that the amounts of contaminants removed were significantly correlated (p-value < 0.05, R 2 = 0.96) with the initial amounts of PCP and PCDD/F, regardless of the particle size of the soils studied. The nature of the soil (granulometric distribution, pH, total organic carbon (TOC) (organic matter) and diverse industrial origin) slightly and negatively influenced the efficiency of organic contaminants removals using attrition. However, the attrition treatment allowed an efficient removal of both PCP and PCDD/F from the coarse fraction of contaminated soil; despite the nature of the soil.

Removal of chlorinated pesticide contamination by soil washing with sole water

“…The mixture was stirred for 120 min at 90 min −1 obtaining a dense paste with no appreciable pH variation. It is noticeable, that solid-to-liquid ratio was within the range recommended in the literature on attrition scrubbing while rotation speed was lower [17]. These mild conditions were adopted to avoid production of further silt, emulsion and heating due to friction.…”