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Ex Situ Electroreclamation of Heavy Metals Contaminated Sludge: Pilot Scale Study |
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| Authors: | Gérald J. Zagury Yves Dartiguenave Jean-Claude Setier |
| Affiliation: | 11Res., NSERC Industrial Chair in Site Bioremediation, Dept. of Chem. Engrg., école Polytechnique de Montréal, P.O. Box 6079, Station Centre-ville, Montreal, Québec, Canada H3C 3A7. 22Prof., Laboratoire de Chimie Inorganique, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 04, France. 33Sr. Engr., Elf Exploration Production, Direction Sécurité Environnement, Centre Scientifique et Technique Jean Feger, Avenue Larribau, 64018 Pau Cedex, France. |
| Abstract: | The ex situ remediation of heavy metals-contaminated industrial sludge (pH = 10.35, Zn = 3,500 mg∕kg) by electroreclamation (I = 2.5 A) was studied at pilot scale (42.5 kg of sludge). This research focused on acidification of sludge and electrochemically induced migration of metals, emphasizing their partitioning prior to electroreclamation. The sludge was preacidified to an initial pH of 4.5. After treatment, a very low anode reservoir pH (near 0) was reached, and the average sludge pH was 2. Addition of 1 M HNO3 to the cathode reservoir prevented basic conditions in the sludge. In accordance with selective sequential extraction results, a low migration of Zn and Cu was obtained. In the anode region, Zn and Cu concentrations decreased by 33 and 39%, respectively, and increased in the cathode region by 33 and 26%, respectively. These metals were concentrated in the cathode area but were not effectively transported onto the cathode. Mn appeared to be more mobile than other metals. After 10 days of current application, a layer mainly composed of Ca, Fe, and Mn appeared on the cathode surface. |
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