title: Comparison between electrocoagulation and chemical precipitation for metals removal from acidic soil leachate.
abstract: This paper provides a quantitative comparison between electrocoagulation and chemical precipitation based on heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) removal from acidic soil leachate (ASL) at the laboratory pilot scale. Chemical precipitation was evaluated using either calcium hydroxide or sodium hydroxide, whereas electrocoagulation was evaluated via an electrolytic cell using mild steel electrodes. Chemical precipitation was as effective as electrocoagulation in removing metals from ASL having low contamination levels (30 mg Pbl(-1) and 18 mg Znl(-1)). For ASL enriched with different metals (each concentration of metals was initially adjusted to 100 mg l(-1)), the residual Cr, Cu, Pb and Zn concentrations at the end of the experiments were below the acceptable level recommended for discharge in sewage urban works (more than 99.8% of metal was removed) using either electrocoagulation or chemical precipitation. Cd was more effectively removed by electrochemical treatment, whereas Ni was easily removed by chemical treatment. The cost for energy, chemicals and disposal of metallic residue of electrocoagulation process ranged from USD 8.83 to 13.95 tds(-1), which was up to five times lower than that recorded using chemical precipitation. Highly effective electrocoagulation was observed as the ASL was specifically enriched with high concentration of Pb (250-2000 mg Pbl(-1)). More than 99.5% of Pb was removed regardless of the initial Pb concentration imposed in ASL and, in all cases, the residual Pb concentrations (0.0-1.44 mg l(-1)) were below the limiting value (2.0 mg l(-1)) for effluent discharge in sewage works.
authors.affiliation: Station expérimentale des procédés pilotes en environnement, Ecole de technologie supérieure, 1100 rue Notre-Dame Ouest, Montréal, Quebec, Canada H3C 1K3.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Meunier
authors.forename: Patrick
authors.initials: P
authors.lastname: Drogui
authors.forename: Camille
authors.initials: C
authors.lastname: Montané
authors.forename: Robert
authors.initials: R
authors.lastname: Hausler
authors.forename: Guy
authors.initials: G
authors.lastname: Mercier
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Blais
mesh_terms: D004563:Electrochemistry / Q000191:economics / Q000379:methods; D004564:Electrocoagulation / Q000379:methods*; D004572:Electrolysis; D004784:Environmental Monitoring / Q000191:economics / Q000379:methods*; D052918:Environmental Restoration and Remediation / Q000191:economics / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000737:chemistry; D008956:Models, Chemical; D012037:Refuse Disposal / Q000191:economics / Q000379:methods*; D012987:Soil; D012989:Soil Pollutants; D013997:Time Factors
chemical_list: D008670:Metals; D012987:Soil; D012989:Soil Pollutants