Bench Scale and Treatability Testing
The performance of a Bench Scale Treatability Test is probably the most fiscally prudent task that can be performed to evaluate the technical feasibility of using Chemical Oxidation, Chemical Reduction, or Enhanced Anaerobic Bioremediation for in-situ remediation. A properly performed Bench Scale Test can determine not only whether the technology will be effective in the destruction of VOCs in the field, but also whether it will be cost effective. It will also determine whether any adverse side effects may occur. Finally, a properly performed Bench Test will aid in the engineering design of a successful injection project.
Among the many important questions that a well designed Bench Scale Test can answer include the following:
- Can the chemical reagent effectively destroy the primary contaminants of concern? For hard to treat contaminants, such as 1,4-dioxane, chlorobenzenes, and pesticides, this may be the most important question to answer before spending money on field injections.
- What is the optimal dose of chemical reagent to use in the field? Each site has variable soil and water quality characteristics such as high bicarbonate, high sulfate, or high TDS, which might inhibit certain chemical processes. It is important to determine the level of any interferences that may occur so as to not under-dose nor overdose the site.
- What will be expected life (duration) of the chemical reagents in the field? The longer the chemical reagents survive in the subsurface the longer time they will have to make contact with and destroy the contaminants of concern.
- Is the Soil Oxidant Demand in the moderate range? If the SOD or TOD is elevated, much of the oxidant may be consumed by the naturally occurring organics in the soil and the oxidant will not efficiently destroy contaminants.
- Will an any adverse side effects occur? Tests can determine whether undesirable daughter products such as 1,2-DCE or vinyl chloride will be generated during bio-degradation of chlorinated compounds. Other tests can determine whether hexavalent chromium generation may occur during oxidation testing.
- How buffered are the soils? Sites with highly buffered soils will require larger quantities of acid or base to change the pH. This is important for determining the proper amount of base to add to induce high pH activation of sodium persulfate as well as for neutralizing Bioremediation reagents that might lower the pH of the groundwater.
- Can LNAPL or DNAPL be effectively removed? Often times, Bench Tests can confirm that measurable amounts of NAPL can be removed using chemical oxidation