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The sequential extraction procedure proposed by the European Standard, Measurements and Testing (SM&T) program, formerly the Community Bureau of Reference (BCR), was applied for partitioning of heavy metals (HMs) in river sediments collected along the course of Sungai Buloh and the Straits of Malacca in Selangor, Malaysia. Eight elements (V, Pb, Cd, Cr, Co, Ni, Cu and Zn) from seven stations (S1-S7) and at different depths were analyzed using the modified BCR Sequential Extraction Procedure (SEP) in combination with ICP-MS to obtain the metal distribution patterns in this region. The results showed that heavy metal contaminations at S2 and S3 was more severe than at other sampling sites, especially for Zn, Cu, Ni and Pb. Nevertheless, the element concentrations from top to bottom layers decreased predominantly. The samples from the Straits of Malacca (S4-S7) the highest contamination factors obtained were for Co, Zn and Pb while the lowest were found for V and Cr, similar to Sungai Buloh sediments. The sediments showed a low risk for V, Cr, Cu and Pb with RAC values of less than 10%, but medium risk for Co, Zn (except S3), Cd at S1 and S2 and Ni at S1, S3 and S5. Zn at S3 and Cd at S3-S7 showed high risk to our sediment samples. There is not any element of very high risk conditions in the selected samples., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Remediation of metals-contaminated soil typically uses solidification/stabilization and "dig and haul". Soil washing and physical separation have been applied to a much lesser extent to reduce soil volumes requiring aggressive treatment and to improve performance of follow-up treatments. In earlier work [J. Hazard. Mater. 66 (1999) 15], we used a simple, vertical-column hydroclassifier, to separate four soils contaminated with heavy metals, defining a "best case" performance for larger-scale (minerals processing) equipment. Such processes, using water-based slurries, generate substantial volumes of water with suspended solids. These typically contain disproportionately high concentrations of heavy metals. Here, we performed an initial screening of settling, coagulation, and centrifugation for reducing suspended solids, and thus suspended metals from soil slurries following processing. The four soils, previously hydroclassified, were sieved to <600 microm, slurried with a 4:1 weight ratio of water, and allowed to settle. Slurry samples were collected at settling times of 0, 0.0833, 1, 5, and 22-24h. Coagulant (alum) addition and centrifugation were investigated. The slurries were filtered, digested, and analyzed by atomic absorption for lead and chromium content. Two soil slurries clarified in <5 min. In all four cases, 90% of solids and metals settled within 5h. However, completion may require up to 24h, or other intervention, i.e. coagulants. The metal concentration in the residual suspended solids increased with settling time, implying an enrichment of metals in finer, suspended particles. Metals dissolved in the slurry water ranged from 3 to 5mg/l for chromium and lead. This screening study provides guidance for water treatment requirements and treatability studies for the integration of hydroclassification and solids removal.

The purpose of this work was to reduce soil volumes requiring aggressive treatment. A second purpose was to determine differences in separation due to distinct forms of the metal contamination and soil texture. The objectives were to apply hydroclassification and find mass and metal-contaminant distribution of four soils contaminated with heavy metals from firing ranges, a small arms incinerator, and an electroplating operation. The soils were slurried in water, sieved, and exposed to upward flowing water to separate the soil particles into four nominal size ranges. The popping furnace soil exhibited substantial lead among all particle size fractions. The firing range soils exhibited bimodal distributions. The electroplating soil exhibited a strong concentration of metals toward the <63 microm fraction. Attrition scrubbing moderately improved the enrichment of metals in several fractions. Extraction revealed the lead and chromium in the electroplating soil to be relatively immobile. These results suggest metal distributions are influenced by the different mechanisms of introduction into the soil. They also help to predict performance of processing options such as sieving hydroclassification and attrition scrubbing., (Copyright 1999 Elsevier Science B.V.)