Remediation of heavy metal contaminated solid wastes using agglomeration techniques

A process has been developed for the remediation of heavy metal contaminate d, fine textured; solid wastes so that the treated material will meet EPA's TCLP and Total Extractable Metal Limits. The process involves the formatio n of strong aggregates using dry agglomeration methods. Remediation is achi eved either by incorporating metal fixation agents into the agglomerates, o r by leaching of heavy metal and other soluble salts by percolation through a packed bed of agglomerated soil. The handling problems encountered durin g solid liquid separations in conventional soil washing are overcome by agg lomerating the fine textured solids. The newly developed process was applied to the remediation of a fine textur ed soil sample from a Dupont site contaminated with lead and a sediment fro m the Coeur d'Alene river, contaminated with Pb, Cd, and Zn. Because of low hydraulic flow-rates leaching of metals from unagglomerated solids was slo w. The removal of metals from agglomerated feed occurred on the time scale of hours compared to days for the original materials, Batch column extracti on studies showed that HCl, EDTA and citric acid were effective extractants for the removal of lead from the agglomerated material. The results of this study demonstrate that NRC's remediation process is sui table for the remediation of contaminated soil or soil like materials and h as potential for commercialization. Crown Copyright (C) 2001 Published by E lsevier Science Ltd. All rights reserved.