Chemical Oxidation & Reduction Services
Chemical oxidants and reductants react quickly and effectively with many organic contaminants, including petroleum hydrocarbons and chlorinated solvents. The challenge is getting the reagents to contact the contaminant, often over an extended time frame. Practitioners refer to chemical oxidation and reduction in the subsurface as a `contact sport.` Applied correctly, the process can reduce contaminant levels and flux efficiently. It is important to note that chemical oxidation and reduction occur primarily in the aqueous phase. Because there is equilibrium between the non-aqueous and aqueous phases, by lowering the aqueous phase concentrations directly adjacent to the non-aqueous phase liquid (NAPL), you will enable more rapid NAPL dissolution.
Thus, chemical oxidation/reduction can work quite well at sites where NAPL is present. Of course, we are now dealing with a dissolution limited system, which will take time to remediate. That is OK, as long as we add additional reagents at appropriate times.
Please note that it may make economic sense to remove as much NAPL as practicable (e.g., by applying surfactants), before adding oxidants or reductants to the matrix.
As mentioned, the chemical remedial process is a contact sport. If the contaminant is in a tight unit, such as clay, contact may not be easy to achieve. Still, chemical oxidation/reduction may be useful, as the contaminant flux from the low permeability unit to a receptor is probably insignificant. The vast majority of contaminant transport occurs via the higher conductivity strata. Due to concentration gradients, the contaminants will diffuse out of the clay into the cleaner, higher permeability units. This is sometimes called back diffusion. As long as we appropriately add reagents over time in the strata where transport takes place, we can achieve our remedial objectives.
There are a variety of chemical oxidants and reductants available, with relative advantages and disadvantages. As choosing the correct reagent(s) and injection strategy can be daunting, it is important to consult knowledgeable practitioners. At challenging sites, it probably makes sense to do a treatability study. Although a successful bench-top study will not guarantee a successful field implementation, if the remedy does not work in the laboratory, there is no chance of it working in the field. Treatability studies demonstrate proof-of-concept and help to optimize the remedy.
Geo-Cleanse International provides in-situ chemical oxidation and reduction solutions specific to site geochemistry, contaminants of concern and client goals and objectives. Geo-Cleanse has completed well over 200 projects throughout the United States and Europe. Founded in 1995, Geo-Cleanse has a reputation for innovation, integrity and success.
Geo-Cleanse services follow:
- Remediation design
- Treatability studies – bench-scale testing of potential solutions
- Pilot-scale studies
- Full-scale remedy implementation
- Reagent injection
- Real-time monitoring for process optimization