A+ Environmental Solutions, LLC

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 contaminant concentrations in the source area. 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

A+ Environmental Solutions, LLC (AES), has successfully used in-situ chemical oxidation (ISCO) in hundreds of injections. This proven technology removes significant contaminant mass from soils and groundwater. Most researchers and practitioners believe that ISCO technology has the ability to rapidly reduce large areas of contamination, however, the promise of rapidly and completely degrading targeted contaminants in place has been overstated in many cases. Site owners or responsible parties have historically been disappointed when a single ISCO injection has failed to meet anticipated low (ppb) contaminant concentrations. Direct oxidant-contaminant contact, matrix interaction effects, contaminant desorption, plume distribution, and a range of other factors complicate the expectation of ISCO to completely and rapidly destroy all contaminants.

To maximize ISCO benefits, AES uses a complex mix of injectants. We add surfactants, adjust pH, and control heat to achieve the best results. ISCO technologies are technically sound and the process works to destroy contaminants in a relatively short period of time, however, AES has not seen that the use of a single injectant is a  “magic bullet” solution. A single injectant can lead to frustration, as contaminant rebound is typical at most sites. Through experience, AES achieves low contaminant concentrations via a treatment regimen or multiple chemical oxidation injections followed by accelerated bioremediation.

In-Situ Chemical Oxidation Coupled with Accelerated Bioremediation

In-situ accelerated bioremediation through the use of injectable compounds (i.e., Oxygen Release Compound (ORC®), Hydrogen Release Compound (HRC®), vegetable oil, organic material, cheese whey) has long been recognized as an extremely cost-effective technology. When applied to dissolved phase contaminant plumes, low contaminant concentrations result. 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. Depth of contaminant, overlying structures, and cost of other methods are evaluated in order to determine the best and most cost-effective solution. AES has developed an integrated approach of coupling ISCO technology with simultaneous or subsequent application of a bioremediation substrate to treat remaining low-level contaminant concentrations and contaminant rebound.

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.