In-Situ Chemical Oxidation (ISCO)
Chemical oxidation is a process that involves the injection of reactive chemical oxidants into groundwater and/or soil for the primary purpose of rapid contaminant destruction. Also known as In-Situ Chemical Oxidation (ISCO), this process is most often deployed at sites with high contaminant concentrations in the source area and in the downgradient plume(s). Chemical oxidation of high concentration areas is often part of a multi-step remediation approach that paves the way for more biologically mediated, less costly approaches such as accelerated bioremediation or monitored natural attenuation.
In-Situ Chemical Oxidation is a Contaminant Mass Reduction Technology
In-situ chemical oxidation has been used successfully to remove significant contaminant mass from soils and groundwater at thousands of sites. Most researchers and practitioners believe that the technology has the ability to rapidly reduce large masses of contamination; however, the promise of chemical oxidation to rapidly and completely degrade target contaminants in-situ has in many cases been overstated. Site owners or responsible parties have historically been disappointed as chemical oxidation has failed to meet their expectations of reaching low (ppb) contaminant concentrations within a short period of time. The requirement for direct oxidant-contaminant interaction, matrix interactions effects, contaminant desorption, plume distribution, and a range of other factors are now seen as inhibiting the simplistic view of complete and rapid treatment in-situ chemical destruction.
The technologies are technically sound and process works for destroying contaminant mass in a relatively short period of time, however, the mindset of using the technology as a single “magic bullet” solution often leads to frustration as contaminant rebound of dissolved contaminant concentrations is typical at most sites. Most practioners now realize that in order to reach low contaminant concentrations there is a requirement for a treatment regimen or multiple chemical oxidation injections followed by enhanced or accelerated bioremediation.
In-Situ Chemical Oxidation Coupled with Accelerated Bioremediation
In- situ accelerated bioremediation through the use of injectable controlled-release substrates (such as Oxygen Release Compound (ORC®) or Hydrogen Release Compound (HRC®)) has long been recognized as an extremely cost- effective technology for achieving low contaminant concentrations when applied to dissolved phase contaminant plumes. Areas of high contaminant concentrations such as source zones within and above the aquifer have remained a challenge to these and other technologies due to the high contaminant demand. What has emerged is the integrated approach of coupling chemical oxidation technology to reduce the contaminant mass in high concentration areas with a simultaneous or subsequent application of a controlled-release bioremediation substrate to treat the remaining low-level contaminant concentrations biologically over a longer period of time.
Indigenous Microbes Survive Chemical Oxidation
It was thought by many that microbes indigenous to the subsurface would simply be completely destroyed by the application of aggressive and harsh chemical oxidants. Today, this notion is now widely disregarded as an increasing amount of research and field experience has indicated the contrary. Today there is little doubt that indigenous microbial flora present prior to a chemical oxidation application will indeed rapidly re-colonize the treated area and will flourish in the presence of the right conditions.
Products
RegenOx™ – is a product designed specifically for the in-situ and/or ex-situ chemical oxidation of a broad range of contaminants including both chlorinated solvents and petroleum hydrocarbons. RegenOx delivers rapid and effective contaminant mass reduction using a solid alkaline oxidant that is activated to a very high performance level through the action of a unique catalytic complex. Once in the subsurface, the combined product produces an effective oxidation reaction comparable to that of Fenton’s Reagent without a violent exothermic reaction. Strategies employing multiple RegenOx injections coupled with follow-on accelerated bioremediation can be used to cost-effectively treat highly contaminated sites to regulatory closure. RegenOx has been rigorously tested in both the laboratory and the field on petroleum hydrocarbons (TPH, BTEX, MTBE, etc), polyaromatic hydrocarbons (naphthalene, phenanthrene, etc) and chlorinated hydrocarbons (PCE, TCE, TCA, etc).