Heap leaching of Cu contaminated soil with [S,S]-EDDS in a closed process loop

Heap leaching of Cu contaminated soil (412 +/- 11 mg kg(-1)) with 5 mmol kg(-1) ethylenediamine disuccinate [S,S]-EDDS as a chelator was tested in a laboratory-scale soil column study. The washing solution was recycled in a closed process loop after microbial (using a microbially active permeable bed, composed of substrate and absorbent) and oxidative chemical (using combined ozonation and UV irradiation) degradation of metal-[S,S]-EDDS complexes and retention of released Cu on a commercial absorbent Slovakite. Heap leaching using the permeable bed removed 25.5 +/- 3.6% of initial total Cu from the soil. Ozone/UV treatment of the [S,S]-EDDS washing solution removed much more, 47.5 +/- 7.4%, of Cu. Both methods yielded a clear and colorless final (waste) washing solution, with 7.0 +/- 10.0 and 2.6 +/- 0.7 mg L-1 Cu (permeable bed and ozone/UV method, respectively). The results of our study indicate that chemical treatment of chelator washing solution with ozone/UV in a closed process loop could lead to the development of a new, efficient and environmentally safe remediation method with controllable Cu emissions. (c) 2005 Elsevier B.V. All rights reserved.