Mobile Catalytic Thermal Oxidizer for Environmental Remediation of Contaminated Soil
Executive Summary
Epcon provided a mobile catalytic thermal oxidizer (CTO) system to treat volatile organic-compound (VOC) and hazardous air pollutant (HAP) emissions from soil remediation operations — especially soil vapor extraction (SVE) or thermal desorption of contaminated soil. The mobile unit enables on-site flexibility, high destruction efficiency, and reliable VOC abatement under variable site conditions. The solution helped the remediation contractor meet stringent environmental regulations while reducing off-gas handling complexity and improving safety and flexibility.
Project Overview
A soil-remediation project required a portable emissions-control system capable of destroying VOCs and other hazardous vapors generated during soil vapor extraction (SVE) or thermal desorption of contaminated soil. Because remediation sites vary in location and duration, a mobile catalytic thermal oxidizer (CTO) offered the advantage of being transported, installed, and commissioned on-site — without need for permanent infrastructure. Epcon was contracted to deliver a turnkey mobile oxidizer unit, complete with pre-piped/prefabricated fuel-gas train, burner control, safety interlocks, and full control instrumentation.
The Challenge
Key challenges included:
- Variable and intermittent vapor loads: Soil remediation processes (SVE / desorption) yield fluctuating concentrations and flow rates of vapors — depending on soil contamination level, remediation progress, and environmental conditions. The oxidizer needed to adapt to these changes reliably.
- Mobility and quick site deployment: The remediation site required that the abatement unit be moved in and out depending on schedule, making fixed installations impractical.
- Efficient destruction of VOCs/HAPs: Emissions from contaminated soil often contain volatile organic compounds and hazardous pollutants — requiring high destruction efficiency to meet environmental regulation and health/safety requirements. Thermal and catalytic oxidizers are widely used in such applications.
- Safe operation under variable conditions: Because the waste vapors might have variable composition and flammability, the system had to include robust safety controls (fuel-gas train, automatic fuel control valve, safety shut-offs, pressure/gas monitoring, proper mixing, flame arrestors) to ensure safe combustion without risk of flash-back, detonation or emissions escape.
- Cost-efficient, flexible emission abatement: Remediation projects often have limited budgets and unpredictable durations — a mobile CTO should minimize capital and operating costs, and be versatile enough to handle varying load and solvent concentrations.
Engineering Requirements
To meet these operational and environmental requirements, the system design specified:
- A mobile skid-mounted catalytic thermal oxidizer (CTO) — pre-piped and pre-wired, complete with fuel-gas train (fuel supply, control valves, regulators, safety shutoffs), burner system, catalytic chamber, and control panel.
- Ability to destroy VOCs and HAPs in off-gas streams from SVE / soil desorption — using catalytic oxidation to lower operating temperature (compared to non-catalytic thermal oxidizer) and increase fuel efficiency when VOC concentrations are moderate or low.
- Flexibility to handle variable flow and vapor composition (depending on soil contamination, remediation rate, moisture content, etc.), including adjustable airflow, pre-heater or dilution air as needed, robust mixing, and residence time / turbulence control for reliable oxidation.
- Safety instrumentation and interlocks: flame arrestors/detonation arrestors (if needed), fuel-gas pressure regulators and safety valves, automated burner and purge logic, fuel shut-off / airflow monitoring, ensuring safe operation under varying emission conditions.
- Portability and modular layout: skid- or trailer-mounted design for ease of transport, fast setup and commissioning, minimal site preparation, enabling use across multiple remediation sites.
The Solution
Epcon delivered a turnkey mobile catalytic thermal oxidizer (CTO) package, including:
- A pre-piped / pre-wired fuel gas train and burner system, ready for safe field installation. This ensured regulatory compliance and safe operation from the start.
- A catalytic oxidation chamber where VOC-laden off-gas is oxidized at lower temperature than non-catalytic systems — improving fuel efficiency and reducing thermal stress while still achieving high destruction efficiencies.
- Flexible air and vapor handling system, with controls for airflow, mixing, pre-heating / dilution if required, to adapt to variable site-specific vapor concentrations and flow rates — common in soil remediation applications.
- Safety features including fuel-gas control valves, pressure regulation, flame arrestors, automated purge and flame-proving logic, and monitoring instrumentation to ensure safe operations under all conditions.
- Mobility: the oxidizer skid/trailer is designed to be transported to site, installed, commissioned and operated — with minimal civil or infrastructure requirements — making it suitable for temporary or multi-site remediation projects.
This approach enables remediation contractors to deploy a high-performance VOC abatement system where and when needed — improving flexibility, reducing capital commitment, and maintaining environmental compliance.
Technical Specifications
System Type: Mobile Catalytic Thermal Oxidizer (CTO), skid/trailer-mounted
Application: Off-gas from soil vapor extraction (SVE) or soil desorption (contaminated soil remediation)
Pollutants Treated: Volatile Organic Compounds (VOCs), solvent vapors, hazardous air pollutants (HAPs) commonly found in contaminated soil off-gas
Oxidation Method: Catalytic oxidation — lower operating temperature than non-catalytic oxidizers; catalyst chamber typically operates 650–1000 °F depending on contaminants
Heat Recovery / Efficiency: Because oxidation occurs via catalyst and at lower temperature than thermal oxidizers, fuel consumption is reduced — energy-efficient option especially when VOC concentrations are moderate or low
Flow / Load Flexibility: Designed to handle variable vapor concentrations and fluctuating off-gas flow rates — common in soil remediation applications (SVE, desorption)
Safety & Controls: Pre-piped/P-wired fuel-gas train, automatic fuel control valve, safety shut-offs, flame-arrestors, flame-proving and purge logic, pressure & flow instrumentation — ensuring safe and compliant on-site operation
Deployment: Skid/trailer mounted — designed for mobility and rapid deployment to different remediation sites as needed (portable gas-cleaning / VOC abatement)
Delivery Scope: Turnkey: design, fabrication, fuel-gas train installation, control panel, skid/trailer, commissioning, site commissioning and startup
The Results
After deployment and commissioning at the soil-remediation site, the mobile CTO system delivered:
- Effective destruction of VOCs / HAPs from off-gas streams — ensuring compliance with environmental and air-quality regulations for contaminated-soil remediation. According to Epcon, “the mobile Thermal Oxidizer unit not only destroyed all the toxic VOCs” from the remediation site.
- Operational flexibility and mobility — the skid-mounted oxidizer allowed rapid site deployment, making it practical for temporary remediation jobs or multiple-site campaigns, avoiding the cost and time of permanent installations.
- Lower operational and fuel costs during low-flow periods — catalytic oxidation at lower operating temperature reduces fuel demand, especially valuable when VOC concentrations or vapor loads are low (common during later remediation phases). This aligns with widely accepted advantages of catalytic oxidizers for soil-remediation off-gas.
- Safe, controlled operation under variable conditions — robust safety controls, burner logic and instrumentation ensured stable oxidation even under fluctuating vapor loads or composition changes (common in soil vapor extraction / desorption).
- Simplified site logistics and reduced environmental risk — by treating off-gas on-site rather than venting or transporting vapor, the mobile CTO reduced risk of uncontrolled emissions, improved compliance, and simplified regulatory permitting and waste-handling logistics.
Why a Mobile CTO Solution Is Well-Suited for Soil Remediation Needs
- Flexibility & Mobility: As remediation projects often vary in location and duration, a skid-mounted mobile oxidizer enables efficient deployment without permanent infrastructure — making it cost-effective and adaptable.
- Energy & Cost Efficiency: Catalytic thermal oxidizers operate at lower temperatures than traditional thermal oxidizers, reducing fuel consumption especially when VOC concentrations are moderate to low — a common scenario in soil vapor extraction as contaminants are depleted.
- Regulatory Compliance & Environmental Safety: Mobile CTOs enable reliable destruction of VOCs/HAPs derived from contaminated soils, supporting stringent air-quality and environmental remediation regulations; the mobile design simplifies permitting and reduces environmental footprint.
- Versatility Across Soil Remediation Methods: Whether used with soil vapor extraction (SVE), thermal desorption, or other off-gas generating remediation methods, the mobile CTO provides a robust, portable treatment solution — aligning with common industry practice.
- Reduced Capital Risk for Contractors: Investing in a mobile unit rather than fixed infrastructure reduces upfront capex and allows reuse across multiple projects — beneficial for remediation contractors working on diverse sites over time.
Learn More
If you are managing a soil-remediation project, even a short-term or geographically dispersed one, Epcon can supply a mobile catalytic thermal oxidizer system — skid- or trailer-mounted, turnkey, and ready to deploy.
Contact Epcon engineering team to evaluate your contaminated-soil vapor load, site conditions, and remediation schedule — we can design a mobile CTO package tailored to your needs, balancing efficacy, safety, mobility, and cost-effectiveness.
