The process begins with excavating the contaminated soil or material for treatment in a Thermal Desorber Unit (TDU). With NELSON, the unit is assembled on site and the remediation and reclamation process is completed on site.
To prepare the soil for treatment, large rocks or debris are removed or crushed, allowing the smaller particulates to heat more easily and evenly separate contaminants from the material. If the moisture of material is too high, additional mechanical handling may be required to improve the treatment process. The material is fed into the TDU on mechanical weigh belt and is then heated to between 350 and 450C to volatilize the organic contaminants effectively removing the contaminants from the material into the process gas stream, with a retention time of 12 to 15 minutes.
The vaporized contaminants are sent through a baghouse to remove dust and then sent to the secondary oxidizer. The process gas stream output from the baghouse is routed through the ID fan into a modular thermal oxidizer/stack unit, which reduces the hydrocarbon content of the gas stream with a destruction removal efficiency (DRE) capable of up to 99.99% depending on contaminant concentrations. At this stage, the clean soil material exits the primary chamber of the TDU is re-hydrated to between 8 and 10 % moisture and then cooled.