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Water Air Soil Pollut (2015) 226: 96 DOI 10.1007/s11270-015-2377-7
EDTA Chelating Process for Lead Removal: Evaluation of Approaches by Means of a Reactive Transport Model
Elisa Martorelli & Angela Antonucci & Antonella Luciano &
Elisabetta Rossi & Massimo Raboni & Giuseppe Mancini &
Paolo Viotti
Received: 18 November 2014 /Accepted: 27 February 2015 /Published online: 15 March 2015 # Springer International Publishing Switzerland 2015
Abstract A 1D reactive model is developed to simulate the EDTA chelating process in a lead (Pb)-contaminated saturated soil. The model is implemented using a multistep numerical approach in order to avoid numerical diffusion assuring at the same time the algorithm stability. The model takes into account first-order reactions where the lead species are splitted into three fractions: C1 (easily mobilized lead), C2 (lead associated with iron and manganese oxides), and C3 (lead bound to organic matter and in the residual fraction). Two different mobilization kinetics (Bslow^ and Bfast^) are considered for each fraction. The model was therefore calibrated and validated using laboratory experimental data. A sequential extraction procedure was conducted to evaluate the lead mobilization due to the EDTA flushing through the column and to take into account the different soil fraction
at which the metal is bound. Several remediation scenarios are used to show the suitability of the model to provide information and knowledge of the best EDTA feed and flux conditions for the lead extraction from soil. The model can therefore be considered as a tool to know in advance the performances of a remediation treatment and to optimize the extraction process minimizing the chelating agent costs and its effects on the soil.
Keywords Lead-contaminated soils . EDTA flushing . Modeling . Remediation
1 Introduction
The remediation of heavy metal-contaminated soils is nowadays a difficult problem to be solved mainly because generally, these pollutants show low mobility in many porous media. Lead (Pb) is one of the most common soil pollutants, and its accumulation in the soil, which can adversely affect soil quality and can be toxic to humans (Wuana and Okieimen 2011), may be caused by several anthropic activities such as lead mining, disposal of lead-based paints, lead battery reclamation, and use of leaded gasoline for motor vehicles. Several techniques have been developed to remove lead from...