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Decontamination process

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Environmental remediation in 7 steps

RSI Environmental uses a unique high-thermal desorption process to treat contaminated soil.

1

Weighing

First of all, we register the shipment. A project number is assigned to each shipment in order to track it through the process. The weights are recorded directly into a database along with all other relevant information. The shipment is checked to ensure that the material matches the information received from the client. Once done, the shipment is accepted and unloaded into the warehouse.

2

Pre-treatment Storage

The contaminated soil and residual hazardous waste are stored in a highly secure warehouse until the treatment. The materials are separated so their origin can be easily tracked.

3

Conditioning

To facilitate the thermal treatment, the contaminated soil and residual hazardous waste are strained to separate debris larger than 5 cm. These larger debris are crushed for optimal thermal desorption. After this, the material is blended to ensure the stability of operating parameters. It should be noted that there is no dilution done during the soil conditioning process.

4

Thermal Treatment

The contaminated soil and residual hazardous waste are transported to the rotary kiln (primary combustion chamber) by a belt conveyor (equipped with a scale) and feeder screws to allow more precise control of the feed rate. For optimal thermal desorption, the rotary kiln temperature is kept above 650°C. After more than 20 minutes, all the organic material are desorbed and evaporated. The gas containing the organic contaminants swirls to the secondary combustion chamber, which continuously operates at more than 1000°C. At this temperature, the hazardous organic compounds (contaminants) are destroyed by thermal oxidation. The oxidized gas passes through a cooling chamber where, in less than three seconds, the temperature is reduced to less than 200°C by injecting atomized water. It is important that the cooling process happens very quickly to avoid reformation of the combustion by-products (dioxins, furans, PAHs). Afterward, hydrated lime and activated carbon are injected into the previously cooled gas. Hydrated lime neutralizes the acidity in the gas, and activated charcoal adds extra safety to the process by absorbing any organic compounds that may be left. Lastly, the gas is purified in the filtration system to remove any fine particles, then released through the stack. It should be noted that the six exhaust gas stacks are continuously monitored to ensure compliance with applicable laws and regulations.

5

Cooling

To avoid particles emissions, the decontaminated waste is cooled and moistened in a completely sealed environment. From the outlet of the primary combustion chamber, the decontaminated material is directed to a fluidized bed conveyor to be air-cooled. At the end of the conveyor, particles larger than two centimeters are separated so they can be directly extracted. Particles less than two centimeters are fed into a mixer to be rehydrated. The air used to cool the decontaminated soil goes through a filtration system of cyclones and dust collectors before being released into the atmosphere. The fine particles collected by the filtration system are also sent to the mixer for rehydration.

6

Post-Treatment Storage

The cooled and rehydrated decontaminated material is temporarily stored in a reserved area. The material processed each day is separated into a specific bay. The material remains in storage until the certified laboratory analysis results come back to confirm that the material is free of any organic contamination. When the results are published, a certificate of destruction is issued, stating that the material is free of any organic contamination.

7

Final disposal

Usage of soil after treatment depends on the terms of the Soil Protection and Contaminated Sites Rehabilitation Policy (MDDEP 1998) and is determined based on the concentrations of residual metals. Soil containing metal concentrations under the range A of the policy can be reused without restriction. Soil containing metals concentration between the ranges of A and C can be reused as daily cover layer in a landfill. Finally, soil containing concentrations above the C range must be buried in an authorized landfill for contaminated soil.

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Our process, High Temperature Thermal Desorption (HTTD), is recognized as being the most effective treatment against soil contamination

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