The Fenton’s Factor
In Situ Chemical Oxidation (ISCO) is a technology used to remediate subsurface soils and groundwater by direct injection of chemicals that break down the contaminating molecules into water, oxygen and carbon dioxide. Where chlorinated solvents are treated, one of the by products is also free (harmless) chlorine.
The most effective reagent known is the ”classical” Fenton’s reagent. This Fenton's reagent is an acidified mixture of hydrogen peroxide and ferrous iron whose exceptionally strong oxidizing ability was first identified by H.J.H. Fenton in 1894. It effectively oxidizes a wide range of compounds including BTEX, MTBE, TBA, petroleum hydrocarbons, chlorinated solvents, such as trichloroethylene (TCE) and perchloroethylene (PCE), as well as natural organic matter.
Fenton’s reagent can be used to treat both soil and groundwater. Factors to consider when assessing the feasibility of Fenton's reagent include the formation of off-gases (1 liter of 1% hydrogen peroxide produces approximately 3 liters of oxygen gas), the formation of heat, and the need to reduce pH (at least temporarily) to pH < 4. Fenton's reagent decomposes to oxygen and water. Contaminants can be completely oxidized to carbon dioxide and water.
Remediation of a plume of perchloroethylene (PCE) at Naval Submarine Base Kings Bay, Georgia, has been achieved by removal of PCE in the source area, an old landfill, by in-situ chemical oxidation with Fenton's reagent. Fenton's reagent was injected into the subsurface through an array of injection wells. This technology has reduced the time to remediate the site from over 30 years, based on traditional methods, to less than two years. This, in turn, has lowered lifetime remediation costs at the site from $30 million to approximately $5 million. Due to the expected success of this project, the Navy is now exploring the possibility of implementing this treatment method at other Navy sites.
Acknowledgments:
U.S. Department of the Interior, U.S. Geological Survey; Toxic Substances Hydrology Program; http://toxics.usgs.gov/definitions/fentons_reagent.html
http://toxics.usgs.gov/topics/rem_act/solvent_plume.html
U.S. Department of Navy
http://5yrplan.nfesc.navy.mil/technologies/cleanup.htm
PRIMA Environmental
http://www.primaenvironmental.com/emergingtech.cfm#Fentons%20reagent |
