Objective: Recent advances in the use of activated peroxygens (hydrogen peroxide and persulfate) for in situ chemical oxidation (ISCO) hold promise for the rapid remediation of dissolved, sorbed, and dense nonaqueous phase liquid (DNAPL) contaminants. Although peroxygen chemistry is highly complex, most ISCO peroxygen vendors use one set of process conditions, not based on fundamental chemistry, for all sites. The objectives of this project are to (1) apply rational process chemistry to improve the design and implementation of peroxygen ISCO at the demonstration level; (2) validate the effectiveness of peroxygen ISCO in the field by detailed assessment of contaminant loss, fate, and product formation; and (3) implement an ISCO optimization approach that involves multiple iterations between oxidant applications and performance monitoring. Technology Description: Peroxygen ISCO processes include catalyzed H2O2 propagations (CHP) (i.e., modified Fenton's reagent) and activated persulfate. In CHP, hydrogen peroxide decomposition is catalyzed by soluble iron or naturally occurring subsurface minerals and results in the generation of a suite of oxidants, reductants, and nucleophiles, providing a universal treatment mixture capable of degrading oxidized, sorbed, and DNAPL contaminants. The primary disadvantage is low hydrogen peroxide stability. However, recent results from the Strategic Environmental Research and Development Program (SERDP) project ER-1288 demonstrate that hydrogen peroxide can be stabilized through the addition of salts of some organic acids, such as phytate, allowing the oxidant source to move greater distances downgradient from injection wells. Activated persulfate involves the use of persulfate anion (S2O82-) and an activator, such as iron or hydroxide, to generate a mixture of reactive oxygen species. Activated persulfate has similar reactivity to CHP and can destroy a wide range of contaminants. Persulfate is more stable than hydrogen peroxide, with a half-life of 100 to 500 days. Disadvantages include its higher cost relative to hydrogen peroxide and the lack of stability of some of the activators. Expected Benefits: To be successful, peroxygen ISCO must incorporate process conditions that are specific to both the site and the contaminants. In this project, an experienced field team will apply state-of-the-art peroxygen ISCO process chemistry and phased optimization to a representative field site to demonstrate the full potential of peroxygen ISCO, validate its effectiveness, and give Department of Defense (DoD) remedial project managers knowledge of more effective process conditions for successful peroxygen ISCO implementation. Results of this project have the potential to provide rational design criteria for peroxygen ISCO, resulting in faster, more effective, and more economical cleanup of contaminated DoD sites. (Anticipated Project Completion - 2010) Principal Investigator: Dr. Richard Watts Washington State University Department of Civil and Environmental Engineering 101 Sloan Hall Pullman, WA 99164-2910 Telephone: (509) 335-3761 Fax: (509) 335-7632 E-mail: rjwatts@wsu.edu DoD Liaison: Dr. Nancy Ruiz Naval Facilities Engineering Service Center 1100 23rd Avenue, ESC411 Port Hueneme, CA 93043 Telephone: (805) 982-1155 Fax: (805) 982-4304 E-mail: nancy.ruiz@navy.mil |
