STARx (Ex Situ) Reactor and ‘Hottpad’ Soil Pile Systems

STARx Treatment Systems for Contaminated Soils and Liquid Organic Wastes

Similar to in situ STAR, STARx is based on smoldering combustion where the contaminants/waste materials are the source of fuel. The process is self-sustaining following a short duration, low energy input ‘ignition event’, such that the energy of the reacting contaminants is used to pre-heat and initiate combustion of contaminants in the adjacent area, propagating a combustion front through the vessel, provided a sufficint flux of air is supplied.

ex situ star
Image 1: Pilot scale STARx fabricated vessel system.

System Description

The STARx process is carried out in fabricated vessels or in engineering soil piles depending on throughput requirements, available footprint, and treatment time requirements. These systems are ideal for stockpiles of contaminated soils, sites where surficial soils are contaminated, or for waste oils and sludges.

With waste oils and sludges, the STARx process includes the admixing of a porous matrix (e.g., coarse sand) to facilitate the self-sustained smoldering process. This is a necessary step to transform waste materials that will not burn on their own, to a mixture that will smolder in a self-sustaining (i.e., low energy) process. The STARx system is capable of destroying greater than 99.9% of contaminant/waste mass.

ex situ star
Image 2a: Porous matrix used to enable smoldering following oily waste treatment. Porous matrix can be re-used in subsequent batches.
ex situ star
Image 2b: Oily waste mixed with a coarse sand; the presence of a porous matrix permits smoldering and enables the process to proceed in a self-sustaining manner.
ex situ star
Image 3: Placement of petroleum hydrocarbon-impacted soils on a small scale (prototype) STARx soil pile system


ex situ star
Image 4: Contaminated soils before and after treatment in a STARx system. Post-treatment concentrations = non detect (<10 mg/kg), indicating complete destruction/removal of contaminants.


  • STARx systems are capable of treating excavated soils and organic wastes such as waste oils and lagoon sludge safely, cost effectively, and rapidly.
  • The system is ideally suited for applications related to the oil and gas and chemical manufacturing industries and for sites that produce a continuous/semi-continuous stream of liquid organic wastes.

More Information

Download the PDF version

Back to top