The application of the oxidizers and catalysts into the soil to achieve pollutant destruction has been studied by university researchers and others for a number of years. In past attempts the only way to assure that the oxidizers, catalysts and organic pollutants would come into direct contact was to create a slurry. Slurry type oxidation processes can be very effective. However, slurries are inherently problematic with respect to de-watering the material post treatment and can increase the waste stream in the event that the treatment is unsuccessful. In order to solve some of the negative aspects of chemical oxidation in the slurry phase, H&H Eco Systems Inc. developed a method of applying oxidizers and catalysts efficiently to soil while it is maintained in the solid state.
The key to success of H&H's technology is the direct contact between the treatment chemicals and pollutant chemicals. This technology utilizes a piece of equipment called the Microenfractionator®. The Microenfractionator® is capable of the level of homogenization required for Solid State Chemical Oxidation™ to be successful in large-scale projects. The mixing action of the Microenfractionator® entrains the contaminated soil particles with catalysts and oxidizers in colliding air streams, homogenizing the soil and amendments down to microscopic levels. This mixing action is termed microenfractionation®. During microenfractionation®, oxidizers and catalysts are injected directly into the microenfractionation chamber®. Catalyzed oxidative reactions tend to be very immediate in nature. Because of this, the placement and timing of the catalysts and oxidizers is critical. The Microenfractionator® is also capable treating large volumes of soil. Depending on soil type, the Microenfractionator® is capable of treating from 400 to 1000 cubic meters of soil per hour. This equipment can treat soil types ranging from sandy to very heavy clay.
The Microenfractionator® is only part of the H&H Eco Systems Inc. process. As good as the mixing capabilities are, if the chemistry of the soil matrix and organic contaminant are not identified and compensated for, the chemical reactions necessary to the process cannot occur. For one SSCO™ process, H&H Eco Systems Inc. utilizes a modified Fenton reaction. However, unlike the classic Fenton reaction, the H&H process does not require very low pH to complete the reaction. 50% hydrogen peroxide solution is utilized in conjunction with various metal, metal complexes, and proprietary activating compounds, depending on the organic pollutant in question. Other oxidizing compounds can also be utilized when hydrogen peroxide is not feasible for a specific set of circumstances. This process relies on the generation of hydroxyl radicals to destroy the organic pollutants. The hydroxyl radical is very effective in the destruction of most organic molecules. However, because it is very unstable and highly reactive, the contact between the hydroxyl radical and the organic pollutant must be almost instantaneous.
Other forms of SSCO™ are sometimes warranted based on the chemistry of the soil and/or contaminant. In some cases, the most cost effective protocol is to pre-treat the contaminated soil with a lower dosage SSCO™ method, followed by enhanced bioremediation. The initial treatment with the oxidizers and catalysts will tend to render the contaminant more bio-available.
Alternative compounds may also be utilized to create a sustained oxygen release for an enhanced aerobic bioremediation. Per-carbonate, Per-acetic acid, and various slow-release oxygen compounds may be effectively utilized for this purpose.
Permanganate is also used to oxidize the same organic
compounds. H&H Eco Systems has partnered with the Carus Corporation
to utilize the Microenfractionator in conjunction with the various
permanganate compounds produced by Carus, to treat contaminated soil.
The types of organic pollutants typically targeted for Solid State Chemical Oxidation™ include PAH compounds associated with coal tar wood preservatives such as creosote, recalcitrant petroleum hydrocarbons in the C-30 plus range and organic solvents such as TCE/PCE. Other contaminants may be treatable with this process and can be verified with feasibility study testing performed prior to treatment.