Chemical Oxidation

Introduction to Chemical Oxidation Principles

In chemical oxidation, specific chemicals are introduced into the ground to oxidise contaminants in a source (or plume) area. The process transforms contaminants into less hazardous or toxic compounds that are more stable and less mobile. For organic compounds, such as petroleum, chemical oxidation converts them into carbon dioxide and water. Under the correct conditions, oxidation can also be applied in above-ground water treatment systems.

Common Oxidising Agents in Chemical Oxidation

The most common oxidising agents include hydrogen peroxide (H2O2), potassium permanganate (KMnO4), ozone (O3), and sodium persulfate. Chemical oxidation can be conducted either in-situ or ex-situ, depending on site-specific requirements. In-situ involves injecting chemical oxidants into the contamination plume, while ex-situ involves mixing the oxidants into excavated soils and pumped groundwater.

Tailoring Chemical Oxidation to Site-Specific Needs for Effective Remediation

No two contaminated sites are the same, which is why our approach to chemical oxidation is always customised to the specific needs of the site in question. Whether the contamination involves petroleum hydrocarbons, chlorinated solvents, or complex mixtures of pollutants, we utilise a range of oxidising agents to achieve the best possible outcomes. The selection of the appropriate oxidant, whether it be hydrogen peroxide, potassium permanganate, ozone, or sodium persulfate; depends on the chemical nature of the contaminants, the environmental conditions, and the desired end goals of the remediation process.

Choosing the Right Oxidant for Contaminant-Specific Needs

For example, in cases where chlorinated hydrocarbons are the primary contaminants, potassium permanganate is often the preferred oxidant due to its longer lifespan and effectiveness in treating these specific compounds. Conversely, for more reactive and fast-acting needs, Fenton’s Reagent, which involves the use of hydrogen peroxide with an iron catalyst, can be employed to rapidly reduce contaminant concentrations, especially in acidic environments.

Permanganate (KMnO4) for Effective Chlorinated Hydrocarbon Remediation

Crystalline potassium permanganate (KMnO4) is mixed onsite with abstracted groundwater to reach an appropriate concentration or is delivered in liquid form. The average lifespan of potassium permanganate in the plume is 0 to 3 months. While it has lower reactivity compared to Fenton’s Reagent, it offers a longer-lasting treatment effect. This oxidant is particularly well-suited for the remediation of chlorinated hydrocarbons, ensuring thorough contaminant breakdown over time.

Applicable Contaminants for Chemical Oxidation

Chemical oxidation is best suited to contaminants that can be oxidised and is generally unsuitable for free products or extremely high concentrations. Suitable contaminants for RegenOx™ include, but are not limited to:

Petroleum hydrocarbons
Chlorinated solvents
Polycyclic aromatic hydrocarbons (PAHs)
Phenols

Innovative Techniques for Effective Chemical Oxidation Application

The success of a chemical oxidation project depends not only on the choice of oxidant but also on the application method. At VertaseFLI, we utilise both in-situ and ex-situ techniques to address site-specific conditions and the unique challenges posed by each contamination scenario.

In-Situ Chemical Oxidation for Targeted Remediation

In-situ chemical oxidation involves the injection of oxidants directly into the contaminated soil or groundwater, providing a highly targeted approach. This method is particularly effective for reaching contaminants in difficult-to-access areas, making it ideal for sites where excavation is not feasible or where minimal environmental disruption is required. VertaseFLI’s expertise in direct push and abstraction-injection recirculation systems ensures that oxidants are delivered efficiently, enabling thorough treatment of the contamination plume and achieving optimal results.

Ex-Situ Chemical Oxidation in Controlled Environments

For sites where excavation is feasible, ex-situ chemical oxidation offers a robust remediation solution. This approach involves excavating contaminated soils and treating them outside the ground, often in specialised treatment facilities. By mixing the contaminated material with the chosen oxidant under controlled conditions, we can achieve a high level of remediation, even for contaminants that are resistant to biodegradation, ensuring safe and effective results.

Fenton’s Reagent (Hydrogen Peroxide + Iron Catalyst) for Rapid Oxidation

Fenton’s Reagent, a combination of hydrogen peroxide with an iron catalyst, is typically injected at concentrations ranging from 5% to 50% peroxide. With an average lifespan of less than two days in the contamination plume, this highly reactive oxidant delivers fast-acting results. Fenton’s Reagent is especially effective in acidic environments, where its reactivity is enhanced, although pH adjustment of the plume may be necessary to optimise conditions for effective remediation.

Chemical Oxidation Plant Description and Equipment

Chemical oxidation can be conducted through either in-situ or ex-situ methods. Ex-situ methods follow excavation, soil processing, and mixing, whereas in-situ chemical oxidation systems typically utilise two main approaches: direct push (single application) and abstraction-injection recirculation systems (permanent wells).

In-Situ Process Equipment for Chemical Oxidation

For effective in-situ chemical oxidation, VertaseFLI’s setup includes:

Chemical oxidant storage tanks
Secure storage facility for chemicals
Mixing tank
Injection pump
Abstraction pump
Multi-phase extraction systems
Direct push drill rig (direct push method)
Pipework (recirculation)
Control systems (recirculation)
Abstraction-injection wells (recirculation)
Groundwater storage tanks (recirculation)
Dosing pump (recirculation)

The direct push method offers simplicity and cost-effectiveness, particularly when only a single oxidant injection is required. However, in cases where multiple injections are necessary, recirculation systems may provide a more comprehensive solution.

Ensuring Comprehensive Environmental Protection in Chemical Oxidation

While chemical oxidation is a powerful remediation tool, it presents certain environmental challenges. Factors such as soil permeability and the presence of clay can significantly affect the distribution and effectiveness of oxidants. At VertaseFLI, we conduct detailed site assessments to identify potential issues and develop strategies to mitigate any adverse effects. This process includes evaluating the impact on aquifer properties and carefully managing oxidation reactions that may alter the geophysical characteristics of the soil.

Stringent Safety Protocols for Handling Hazardous Oxidants

Our team is highly skilled in managing the potential risks associated with chemical oxidants, including the safe handling of substances like hydrogen peroxide. We implement rigorous safety protocols and maintain comprehensive insurance coverage to ensure the protection of our team and the environment throughout the entire remediation process.

Successful Example of Ex-Situ Chemical Oxidation

VertaseFLI successfully conducted an ex-situ chemical oxidation of medium-chain hydrocarbons that were not suitable for bio-remediation using hydrogen peroxide. Contaminated material was processed with a specialised excavator as hydrogen peroxide was injected into the mixing chamber. Approximately 1,500 cubic meters of contaminated soil were effectively remediated, achieving concentrations below the site-specific target levels (SSTLs).

Suitable Contaminants for Chemical Oxidation

Chemical oxidation is generally unsuitable for low-permeability soils such as clay due to limited injection capability. Additionally, depending on the chemical oxidants used, reactions between the oxidant and clay can adversely affect the geophysical properties of the clay. Other potential environmental impacts include the oxidation of formation ions, such as metals, which may have negative effects on aquifer properties. These factors should be carefully considered in the site assessment process.

Contaminants Suited to Chemical Oxidation

Chemical oxidation is effective only for contaminants that can be oxidised and is typically unsuitable for free products or highly elevated concentrations. Suitable contaminants for this process include, but are not limited to:

Petroleum hydrocarbons
Diesel range hydrocarbons (DRO)
Polycyclic aromatic hydrocarbons (PAHs)
Phenols
Chlorinated solvents

Advantages and Limitations of Chemical Oxidation

Advantages of Chemical Oxidation

Proven Track Record: Chemical oxidation has been effectively used across various contaminated sites.
In-Situ Application: Only a small area is required for unit setup, making it ideal for sites with limited space.
Rapid Reduction in Contaminant Concentrations: Delivers fast-acting results, significantly lowering contaminant levels.
Wide Range of Contaminants Remediated: Effective for multiple contaminants, including petroleum hydrocarbons, PAHs, and chlorinated solvents.

Limitations of Chemical Oxidation

Multiple Applications May Be Necessary: Some sites may require several treatments for full remediation.
High Volume of Chemical Oxidant: Certain applications may require large quantities of oxidants, impacting costs.
Low Clay Content Preferred: Chemical oxidation is generally more effective in soils with lower clay content.
Potentially Hazardous Chemicals: The process involves chemicals like hydrogen peroxide, which require careful handling.
Impact on Aquifer Properties: Chemical oxidation may alter aquifer characteristics, requiring thorough site assessment.
Contamination Rebound: Treated areas may experience contaminant rebound if the contamination plume is not fully delineated.

A Proven Track Record of Success in Chemical Oxidation

VertaseFLI’s extensive experience in chemical oxidation is demonstrated by our successful remediation of a wide range of contaminants across various sites. From petroleum hydrocarbons to chlorinated solvents, our track record highlights our ability to deliver effective, sustainable solutions that meet site-specific target levels (SSTLs). By combining technical expertise with a strong commitment to environmental stewardship, VertaseFLI continues to set the standard for chemical oxidation in the remediation industry.

Commitment to Advancing Chemical Oxidation Technology

Looking to the future, VertaseFLI remains dedicated to advancing our chemical oxidation capabilities, ensuring we stay at the forefront of remediation technology. Our goal is to provide clients with the highest level of service, transforming contaminated sites into safe, viable spaces that contribute to a healthier planet.

Very polite and professional throughout, from all staff. Vertase managed the dynamic shifts in our project timeline with ease.

Paul Keates

Engineering Manager, UK, Capstone

Get in touch

If you'd like to find out more about who we are, what we do or how we can work together, get in touch today. We'd love to hear from you.

Talk to us