Electrochemical Remediation

ERDC TN-DOER-T2

December 2000

In operation, the dredged sediment is screened to remove large debris and then transferred to a

blending mixer. Some dewatering of the sediment may be required prior to processing. Proprietary

silicate binders and fine aggregate waste material are added to the mixer and the water content is

adjusted until the mixture is thoroughly blended. Once blended, the product is transferred directly to

mixer vehicles for immediate transport to the place of use. The product requires immediate use and

cannot be stored for any extended period of time. No off-gas requiring treatment is generated during

the process.

Electrochemical Remediation. ElectroChemical Remediation Technologies (ECRT) are

marketed by Weiss Associates, Emeryville, CA, under license to the European technology

developer. There are two principal ECRT technologies: (1) ElectroChemical GeoOxidation

(ECGO), which mineralizes organics to their inorganic components (e.g., carbon dioxide and

water), and (2) Induced Complexation (IC), which enhances the mobilization of metals to be plated

on electrodes. These technologies can be used as ex situ or as in situ processes. The technologies are

based on imposing a direct electrical current through the contaminated material with a superimposed

alternating energy current using buried electrodes. The superimposed electrical field creates an

induced polarization effect in the sediment that, in turn, induces redox reactions that decompose

organic contaminants through ECGO and provide enhanced mobilization of metals through IC.

Removal efficiency is contaminant specific, and the treatment process treats clays and silts much

faster than coarse-grained sand and gravel. The process does not produce a final marketable

product, but rather affects a reduction in contaminant concentrations thus allowing (1) the sediment

to be left in place, (2) the sediment to be disposed of as nonhazardous, or (3) the sediment to be

reused as a soil-like product after further processing.

For application of the technology, the sediment is treated in situ or in a confined area. Electrodes are

installed either through borings in the material or as sheet piles on approximately 10-m centers.

Local electrical power is passed through proprietary d-c/a-c converters, and then the current is

applied to the sediment through electrodes implanted in the sediment. Optimum remediation is

generally achieved in less than 6 months.

Sediment Washing - BioGenesis. Advanced Sediment Washing Technology is marketed

jointly by WESTON and BioGenesis, West Chester, PA. This technology is a multistaged sediment

washing and organic oxidation process for decontaminating dredged sediments and producing a

marketable fine-grained soil-like product for reuse after the addition of bulking materials. During

the process, organic material is stripped from the solid particles and chemically oxidized. Removal

efficiency is contaminant specific.

In operation, the dredged sediment is screened, and then high-pressure water and chemical cleaners

are used to strip the outer layers of organic material from the sediment particles. Floatable organic

material is removed using air sparging. Organic and inorganic materials are stripped from the

sediment particles using high-pressure water and chemicals in a collision chamber. Organic

material is oxidized by means of chemical oxidizer addition and processing in a cavitation unit. The

treated sediment slurry is dewatered using a centrifuge and hydrocyclone. Bulking materials are

added and mixed to produce a manufactured soil. Wastewater from the process is recycled into the

process and/or treated and discharged.