Combining Low-Energy Electrical Resistance Heating with Biotic and Abiotic Reactions for Treatment of Chlorinated Solvent DNAPL Source Areas
Abstract
The applicability of in situ groundwater remedies such as in situ bioremediation (ISB) or zero valent iron (ZVI) reduction in chlorinated solvent source zones (i.e., containing dense nonaqueous phase liquids [DNAPLs]) is often limited by the relatively long treatment timeframes required to meet remedial objectives at sites. Conceptually, the goal of this project was to evaluate moderate heating (i.e., 35-50 C) to accelerate the dissolution and desorption of residual trichloroethylene (TCE) contamination as well as accelerating the in situ degradation kinetics, and to minimize volatilization and therefore the need for soil gas extraction and treatment, as is typically required for high-temperature thermal applications. This field demonstration combined electrical resistance heating (ERH) with ZVI and ISB for TCE treatment in two separate test cells. The demonstration objectives included quantifying 1) the effect of low-energy heating on the extent and rate of contaminant degradation, 2) the impacts on the mass removal rate, 3) the relative contributions of biotic and abiotic contaminant degradation mechanisms at different temperatures, and 4) the costs and benefits of applying low-energy heating with in situ treatments. ERH technology is used to treat soil and groundwater contamination, and can be especially effective in treating TCE and other volatile organic compound (VOC) contaminant sources in the DNAPL phase. ERH increases subsurface temperatures to the boiling point of water at which point, steam is created in situ and contaminants are directly volatilized, extracted and treated in above-ground treatment systems. ISB is a demonstrated technology that relies on amendment injections to grow bacteria capable of dechlorinating chloroethenes. ZVI technologies rely on emplacement of ZVI in situ to facilitate abiotic reductive elimination reactions of chlorinated solvents, which does not generate hazardous degradation products.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2015
- Accession Number
- ADA619396
Entities
People
- Michael Truex
- Tamzen Macbeth
- Tom Powell
Organizations
- Pacific Northwest National Laboratory