During the US-Vietnam War, millions of liters of herbicides were dropped over Vietnam: The Rainbow agents. Agent Orange was proven to cause severe health issues, including birth defects, neurological problems and cancers. More than four decades after the Vietnam War ended (in 1975), the stability and bioaccumulation of dioxins – originating from agent orange – still affect the inhabitants.

The Center for Technology Environmental Treatment/Chemical Force (CTET/CF), the GAET Corporation and HAEMERS Technologies SA agreed to establish a joint operation to proceed testing activities proving the effectiveness of thermal desorption treatment on dioxin-contaminated soils at Biên Hòa Airbase.

The key objective of the trial treatment is to demonstrate the effectiveness of the Smart Burners treatment technology and design in order to meet the site-specific dioxins and furans target levels.

The target temperature of 335°C is reached after 40 days of heat treatment. A destruction rate efficiency of dioxins of 99% is achieved. Particularity of the project lies in the method of treatment of the vapors via a thermal oxidizer, demonstrating compliant emissions and avoiding the generation of any solid or liquid waste. The project demonstrates that ESTD with a Thermal Oxidizer is a very effective technology for treating dioxin-contaminated soils in the most sustainable way

Therefore, Haemers Technologies has designed a thermal treatment pilot plant composed of two main units:

The thermal pile of 237m³ composed of 3 types of materials: 187m³ of contaminated soils, 25m³ od contaminated sludges and 25m³ of soil washing cake.

The vapor treatment unit where dioxins are destroyed composed of a Thermal Oxidizer, avoiding the production of any liquid and solid waste.

• 250°C at the cold points
• Soil targets: TPH (C10-C40) < 300 mg/kg of dry soil
• Groundwater targets: TPH (C10-C40) < 300 µg/l

1) Temperature in the pile

335°C has been reached in the thermal pile after 40 heating days.

Mean Temperature evolution during treatment:

2) Soil pressure and Ambient Air monitoring

Vacuum was maintained in the thermal pile throughout the treatment (pressure < 0 mbar). These results demonstrate that no fugitive emissions occurred. Results of ambient air monitoring (conducted by the CTET) also confirm these findings (< 0,6 pg-TEQ/m³).

3) Emission control

The temperature in the Thermal Oxidizer maintained over 1.100°C during all treatment resulting in compliant emission at the stack (< 0,1 ng-TEQ/Nm³). Air emissions were fully compliant with VN, EU and US standards.

Although the project was mobilized and started early 2020, it was interrupted due to the COVID pandemic.

At the end of December 2021, Haemers returned on site and resumed its activities to fulfill its commitment on the demonstration project. On February 2nd 2022, the pile was restarted. Treatment stopped on March 14th, 2022, after 40 days of treatment. HT left the site on April 2022.

Haemers Technologies’ pilot thermal desorption treatment of very heavily dioxin-contaminated soils has demonstrated that:

• Ex-situ thermal desorption can effectively recycle highly dioxin-contaminated soils to residential levels for subsequent beneficial use.
• Haemers Technologies’ design has proven to be effective in destroying dioxin and producing zero waste.
• Haemers Technologies’ operations have proven to be fully compliant with air emission and did not affect ambient air quality.

The pilot project demonstrated that Ex-Situ Thermal Desorption with diesel burners is a very effective technology for treating dioxin-contaminated soils in the most sustainable way.