More Info...

Publication

STRATEGIES FOR TREATMENT OF VOC-IMPACTED GROUNDWATER COMBINING ZERO VALENT IRON AND REDUCTIVE DECHLORINATION

Donald F. Kidd, P.E. Innovative Engineering Solutions, Inc., Sam Fogel, Ph.D., Margaret Findlay, Ph.D., Bioremediation Consulting, Inc.,
Clint R. Bickmore, John O. Freim, OnMaterials, LLC, Frank Manale, TEA

Two bench scale treatment studies were completed to test the efficacy of high specific surface area zero valent iron against site groundwater contaminated with chlorinated solvents. Further, the tests evaluated potential toxicity of the reactive iron on native and introduced biological cultures to assess whether these two technologies can be combined. For both bench tests, low concentrations of iron were used in the reactors. In iron concentrations were specifically selected which could be replicated under field conditions, thus simplifying scale-up. 

For Site 1 (Northern California), carbon tetrachloride (CT) and chloroform (CF) are found locally at concentrations exceeding inhibitory levels for effective biological treatment. Elevated concentrations of sulfate and chloride are also found in this groundwater. 

Site 2 is characterized by aerobic conditions and low concentrations of tetrachloroethene (PCE) and trichloroethene (TCE). At this site, little evidence of natural biological degradation of the halogenated solvents has been observed. 

For the Site 1 test, rapid destruction of both CT and CF was observed using the low concentrations of ZVI. Rapid destruction of PCE and TCE was also observed for Site 2. In both cases, dechlorination followed single and multi-electron reduction sequences depending on the source iron. Inhibition of the biological processes in the presence of iron was observed in some cases. 

A degradation model, approximating the destruction as a first-order decay, was developed and matched to the laboratory data for both tests. This model was then used to predict performance of field-scale applications of the combined technologies under varying conditions. The economic considerations of the combined treatment will be presented.

The full version of this publication is available upon request, subject to IESI usage guidelines. 
Send requests to publications@iesionline.com.