ElectroChemical Remediation Technologies for Metals Remediation in Soil, Sediment and Ground Water, Presentation of Case Histories

Abstract

Abstract. ElectroChemical Remediation Technologies (ECRTs) utilize an AC/DC current passed between an electrode pair (one anode and one cathode) in soil, sediment, or ground water to either mineralize organic contaminants through the ElectroChemicalGeoOxidation (ECGO) process, or complex, mobilize, and remove metal contaminants through the Induced Complexation (IC) process, either in-situ or ex-situ. Field remediation data suggest that ECRTs-IC cause electrochemical reactions in soil, sediment, and ground water that generate metallic ion complexes from the target contaminant metals. These complexes, along with naturally occurring dissolved metals, migrate to the electrodes down the electrokinetic gradient and are either concentrated at the electrode (e.g., cesium, strontium) or deposited onto the electrodes (e.g., mercury, cadmium, lead). The metal contaminants concentrated at the electrodes can be pumped and treated, and the metals that deposit on the electrodes can be either disposed of or recycled. ECRTs-IC operates at electrical power levels below those of conventional electrokinetic methods. A unique feature of ECRTs-IC, in marked contrast to electrokinetics, is that metals generally migrate to both the anode and cathode. European field projects include remediation of (1) mercury in brackish water silty sediments, where 76 kg (168 lbs) of mostly mercury were deposited at both electrodes in 26 days of total remediation time; (2) parts per billion ground water contamination of a variety of metals beneath a steel mill waste lagoon, where metal concentration decreases up to 93% were achieved in 30 days of total remediation time; and (3) mercury in sewage sludge contaminated with dental amalgams, which showed an average decrease from 35 mg/kg to 0.185 mg/kg in seven days. A recently completed U.S. laboratory test for the U.S. Department of Energy under fresh water conditions corroborated the European field remediation results. Existing field and laboratory results indicate that ECRTs-IC is a rapid and effective remediation process. Additional