title: Washing of metal contaminated soil with EDTA and process water recycling.
abstract: We demonstrate here, in a laboratory scale experiment, the feasibility of using the base/acid pair Ca(OH)(2)/H(2)SO(4) to impose a pH gradient for EDTA recycling and, coupled with an electrochemical advanced oxidation process using a graphite anode, of recycling process water as part of a novel remediation technology for multi-metal contaminated soils. In the first batch, 60 mmol EDTA kg(-1) of soil removed 72, 27, and 71% of Pb, Zn, and Cd, respectively, from soil contaminated with 5329±685, 3401±193, and 35±6 mg kg(-1) of Pb, Zn, and Cd, respectively. In the subsequent four batches, we demonstrated that up to 88% of EDTA was recycled from each batch, with the potential to extract up to 98, 94, and 109% of Pb, Zn, and Cd, respectively, that the fresh EDTA extracted. Accumulation of salts in the process water through multiple remediation batches/recycles was prevented by CaSO(4) precipitation. Recycled process water toxicity testing indicated no significant effect on plant seed germination but some inhibition of root elongation.
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Pociecha
authors.forename: Domen
authors.initials: D
authors.lastname: Lestan
mesh_terms: D002126:Calcium Hydroxide / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D018525:Germination; D006863:Hydrogen-Ion Concentration; D019684:Magnoliopsida / Q000254:growth & development; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D018517:Plant Roots / Q000254:growth & development; D059027:Recycling; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D019216:Metals, Heavy; D012989:Soil Pollutants; D013464:Sulfuric Acids; D014867:Water; D004492:Edetic Acid; C033158:sulfuric acid; D002126:Calcium Hydroxide