RegenOx

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Contents

Technology

RegenOx, offered by Regenesis, is a chemical oxidant designed for reduction of contaminant mass. It is a two part product. Part A is the oxidizer, a mixture of sodium percarbonate [2Na2CO3- 3H2O2], sodium carbonate [Na2CO3], sodium silicate and silica gel. Part B is the catalyst, a mixture of sodium silicate solution, silica gel and ferrous sulfate.

RegenOx is typically injected into the subsurface and produces a number of oxidation reactions via different mechanisms including: surface mediated oxidation (the Part B creates a reaction surface), direct oxidation (the hydrogen peroxide in the sodium percarbonate directly attacks contamination), and free radical oxidation (perhydroxyl, hydroxyl, superoxide, and organic free radicals).

Part A is typically mixed with water to create an oxidizer solution, then mixed with Part B, before application to the subsurface. The ratio is normally 1:1 between Part A and Part B to start, but this ratio can be shifted towards Part A in subsequent injections as the Part B is persistent in the aquifer.

RegenOx typically packaged and delivered in 30 lb PVC buckets, but the Part A can be made available in 45 lb bags.

Multiple injections are generally required to treat a site to levels which reach criteria or to levels where bioremediation can become effective.

Applications

RegenOx is suitable for a wide range of contaminants including, but not limited to, BTEX, TPH, PAHs, as well as chlorinated ethenes and ethanes.

It works best on high concentrations of dissolved phase contamination, its effective range from ppm levels to the appearance of sheen.

It can be applied ex-situ or in-situ. In-situ applications include direct-injection for source area and permeable reactive barrier applications or straight application into excavations to clean up residual.

It can be applied into either vadose or saturated zones, but when dealing with vadose zone, the oxidation reaction takes place only in the aqueous phase created by the added water.

Limitations

Because of the specificity of its reaction, it has a relatively small radius of influence around its injection point. As a result, it is less effective on very low concentrations (sub-ppm levels) of contaminants as contact between product and contamination can be an issue.

Free product and sheen can also be a limitation due to high stoichiometric demand. While there are incidents where RegenOx has been shown to be effective on sheen, it is generally more cost-effective to utilize some form of mechanical removal.

Application into tight clays can be difficult due to challenges related to distribution. RegenOx will also suffer from a low radius of influence resulting from the low hydraulic conductivity associated with injection into these soil types which will drastically reduce its effectiveness.

High natural organic demand can also be a limiting factor as it will result in stoichiometric demand that can render the product economically infeasible or require product loadings that are physically impossible to inject given the available pore space.

Ayn chemical oxidation takes place in the aqueous phase or in the partition between aqueous and non-aqueous phases, so treating the vadose zone requires the addition of water.

Advantages

RegenOx is an alkaline oxidant and will create alkaline conditions in the aquifer. This precludes the necessity of a pH adjustment prior to injection. As well, because the Part B is persistent, it doesn't require multiple injections of acids/caustics to maintain a pH level that keeps the oxidant active.

Because the hydrogen peroxide is embedded into the RegenOx as a hydration molecule, it does not generate excessive heat or gas which results in less concerns with health and safety and no detrimental effects to underground utilities.

RegenOx can destroy a broad range of contaminants which makes it effective for the treatment of mixed plumes.

RegenOx can be easily applied using readily available equipment.

RegenOx has relatively high longevity in the subsurface for an oxidant (~ 25 days).

Designed to enhance subsequent bioremediation by breaking long-chain hydrocarbons into shorter, more soluble and degradable hydrocarbons. It also does not leave any residuals behind which may interfere with subsequent bioremediation.

Disadvantages

RegenOx can be more expensive than other oxidants on a per weight basis due to the high cost of the catalyzing agent compared to other activators.

Will increase the concentrations of sodium in the subsurface which can be an issue with aquifers that could potentially exceed criteria for sodium or have issues with Sodium Adsorption Ratios (SAR).

Shifts in oxidation/reduction potential (ORP) can result in a temporary mobilization of metals such as hexavalent chromium and arsenic.

Characterization Parameters

Parameters required to evaluate RegenOx applicability:

1. Contaminant concentrations

2. pH/ORP

3. Hydrogeological parameters (conductivity, gradient, velocity, porosity)

4. Total oxidant demand

5. Chemical oxidant demand

6. Major anions/cations


Parameters required to evaluate RegenOx efficacy:

1. Contaminant concentrations

2. pH/ORP

3. Major anions

General Costs

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Personal Experiences

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External Links

Manufacturer's Website [1]

RegenOx Case Studies [2]

Personal tools