Open AccessEvaluation of Electrochemical Treatment for Removal of Arsenic and Manganese from Field Soil
Author(s) -
Taiwo O. Akinleye,
Idil Deniz Akin,
Amanda K. Hohner,
Indranil Chowdhury,
R.E. Watts,
Xianming Shi,
Brendan Dutmer,
J. Muêller,
Will Moody
Publication year - 2021
Language(s) - English
Resource type - Reports
DOI - 10.36501/0197-9191/21-019
Subject(s) - soil water , arsenic , manganese , electrochemistry , sorption , chemistry , environmental chemistry , soil ph , environmental science , electrolyte , materials science , metallurgy , soil science , electrode , adsorption , organic chemistry
Soils containing inorganic compounds are frequently encountered by transportation agencies during construction within the right-of-way, and they pose a threat to human health and the environment. As a result, construction activities may experience project delays and increased costs associated with management of inorganic compounds containing soils required to meet environmental regulations. Recalcitrance of metal-contaminated soils toward conventional treatment technologies is exacerbated in clay or organic content-rich fine-grained soils with low permeability and high sorption capacity because of increased treatment complexity, cost, and duration. The objective of this study was to develop an accelerated in situ electrochemical treatment approach to extract inorganic compounds from fine-grained soils, with the treatment time comparable to excavation and off-site disposal. Three reactor experiments were conducted on samples collected from two borehole locations from a field site in Illinois that contained arsenic (As)(~7.4 mg/kg) and manganese (Mn)(~700 mg/kg). A combination of hydrogen peroxide (H2O2) and/or citrate buffer solution was used to treat the soils. A low-intensity electrical field was applied to soil samples using a bench-scale reactor that resembles field-scale in situ electrochemical systems. For the treatment using 10% H2O2 and citrate buffer solution, average removal of 23% and 8% were achieved for Mn and As, respectively. With 4% H2O2 and citrate buffer, 39% and 24% removal were achieved for Mn and As; while using only citrate buffer as the electrolyte, 49% and 9% removal were achieved for Mn and As, respectively. All chemical regimes adopted in this study reduced the inorganic compound concentrations to below the maximum allowable concentration for Illinois as specified by the Illinois Environmental Protection Agency. The results from this work indicate that electrochemical systems that leverage low concentrations of hydrogen peroxide and citrate buffer can be effective for remediating soils containing manganese and arsenic.