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Simultaneous Electrochemical Leaching and Electrodeposition of Heavy Metals in a Single-Cell Process for Wastewater Sludge Treatment.

Beauchesne, Isabel; Drogui, Patrick; Seyhi, Brahima; Mercier, Guy; Blais, Jean-François (2014). Simultaneous Electrochemical Leaching and Electrodeposition of Heavy Metals in a Single-Cell Process for Wastewater Sludge Treatment. Journal of Environmental Engineering , vol. 140 , nº 8. Article number 04014030. DOI: 10.1061/(ASCE)EE.1943-7870.0000856.

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Résumé

The performance of a two-stage process that combines electrochemical leaching and electrodeposition of copper (Cu) for the decontamination of sewage sludge was studied in a single cell. The sewage sludge was treated in a 12-L cylindrical electrolytic cell containing a titanium (Ti)/RuO2 anode and a Ti cathode. Current densities varying from 3.0 to 12 A/dm(2) were tested with the addition of a supporting electrolyte [154-283 kg H2SO4 (5 M)/t of dry sludge (tds)] by imposing a pH of approximately 2.0. The electrochemical treatment induces the anodic oxidation of organometallic complexes and metal oxides so that Cu can be released in solution and later deposited on the cathode. The best performance for Cu removal was obtained when the electrolytic cell was operated for 240 min at a current density of 12 A/dm(2) in the presence of 180 kg H2SO4/tds. Under these conditions, 92.5% of the Cu was leached, and 99% of the Cu was successively recovered on the cathode electrode. However, in terms of cost-effectiveness, Cu can be optimally removed from sludge when the electrolytic cell is operated for 90 min at a current density of 9 A/dm(2) in the presence of 283 kg H2SO4/tds. At the same time, the electrochemical process preserved its fertilizing properties by maintaining the concentration of inorganic nutrients (P, K, Ca, Na, and Mg) in dewatered sludge.

Type de document:
Mots-clés libres: clean technology; copper; electrodeposition; metal leaching; wastewater sludge
Centre: Centre Eau Terre Environnement
Date de dépôt: 13 déc. 2016 20:49
Dernière modification: 13 déc. 2016 20:49
URI: http://espace.inrs.ca/id/eprint/3538

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