The integrated equipment train that performs thermal desorption: feed system, primary desorber, secondary oxidizer, off-gas quench, particulate control, and acid-gas scrubbing. Mobile TDUs are skid- or trailer-mounted and sized by throughput (tonnes per hour) and treatment temperature.
A thermal desorption unit is the physical kit that delivers a thermal remediation outcome. The primary desorber, either direct-fired rotary, indirect-fired rotary, or screw-conveyor design, volatilizes contaminants off the soil matrix. A secondary chamber, usually a thermal oxidizer operating above 1,000 degrees Celsius with at least two seconds of residence time, destroys the volatilized organics before the gas stream is cooled and cleaned.
Mobile TDUs are the deployment model that distinguishes a modern remediation contractor from a fixed-facility incinerator. They arrive on-site by truck, set up on a prepared pad, treat the soil where it sits, and demobilize when the work is finished. Throughput ranges from roughly 5 tonnes per hour for compact units to over 40 tonnes per hour for the largest skid-mounted systems. Nelson's fleet (RS-20, RS-40, RS-45, RS-945) spans this range and treats hydrocarbons, dioxins, PCBs, and PFAS to permanent destruction.
TDU specification matters: primary temperature, secondary residence time, oxygen control, off-gas treatment train, and continuous emissions monitoring together determine whether the unit qualifies as Best Available Technology under European and Canadian standards.
Also known as: TDU, thermal desorption system, TDS.
Dioxins and Furans (PCDD/PCDF): treatment approach
A family of 210 chlorinated tricyclic aromatic congeners — including 2,3,7,8-TCDD — formed as unintended byproducts of combustion, chlorine chemistry, and legacy herbicide manufacture; persistent, bioaccumulative, and destroyed only by high-temperature thermal treatment.
An ex-situ soil treatment process that heats contaminated soil to volatilize and separate organic contaminants from the soil matrix, after which the liberated vapors are captured and treated, usually in a high-temperature oxidizer.
A thermal desorption configuration where the heat source contacts the soil directly inside the rotary unit, delivering high heat-transfer efficiency and supporting higher treatment temperatures.
A thermal desorption configuration where heat is conducted through the wall of the treatment vessel without combustion gases contacting the soil, producing a concentrated, lower-volume vapor stream suitable for condensation and recovery.
Treatment that heats contaminated soil and groundwater in place, typically with electrical resistance, thermal conduction, or steam injection, to volatilize and recover contaminants without excavation. Used where excavation is impractical or where the contaminant zone sits beneath active infrastructure.