Sorption-Desorption Tests on the Performance of Non-Hazardous Industrial Wastes in Decreasing Leachability of Trace Metals on Contaminated Lands

Abstract

Soil stabilization by addition of industrial solid wastes in order to increase trace metals retention and (a minor secondary effect) to dilute their concentrations is an environmentally friendly and attractive soil remediation process that attenuates trace metals impact. In this study, non-hazardous industrial by-products (sugar foam, gypsum, zeolitic materials and fly ashes) were tested using laboratory scale experiments to assess their performance on the remediation of acidic soil that has been affected by a pyritic source of contamination at Aljaraque, Spain. In this soil, the concentration of metals in the Aqua Regia and soil-water extracts confirmed the extent of the soil contamination since all seven trace metals (Cu, Cd, As, Pb, Zn, Co and Sb) analyzed from the Aqua Regia extracts and nine trace metals (Cu, As, Cd, Zn, Pb, Co, Sb, Ni and Cr) analyzed in soil-water extract were found above the intervention limits specified in the Junta de Andalucia (Spain) and Germany National Standard (DIN) respectively for both Agriculture and Industrial activities. Metal sorption and desorption capacity of the industrial wastes were estimated in a soil water extract medium. Fly ashes and zeolitic material were found to be the best candidate materials for soil remediation due to their ability to increase soil pH, exhibiting greater solid-liquid distribution coefficient (Kd), lower sorption reversibility (Kd, des) and lower desorption yields to almost all trace metals analyzed. Key words: - amendment materials, contaminated soil, trace metals, soil remediation, leachability