Formatted Title
An Innovative Remediation Approach for In Situ Neutralization of Halogens and Sulfur during Thermal Desorption
Background/Objectives
In the context of in situ thermal desorption, contaminated soil containing pollutants like TPH, PAH, mercury, chlorinated solvents, and others undergoes heating to induce vaporization of these contaminants. The resulting vapors are then drawn through perforated steel tubes, referred to as vapor tubes, which are surrounded by gravel serving as a drainage medium to prevent clogging. These recovered vapors can be either treated in a vapor treatment unit or reintroduced into the flame, particularly for hydrocarbon pollution when using burners.
Approach/Activities
In many instances, the contaminated soil contains various process-disturbing elements, such as phosphorus, sulfur, or halogenated compounds like chlorine. The heat applied during the process vaporizes many chemical compounds, including those that could contribute to equipment corrosion when carried through the porous medium to the extraction wells. The issue arises when these agents become highly corrosive, potentially undermining the effectiveness of the remediation technology. Left untreated, they can also lead to non-compliant air emissions.
Thermoreact® is an innovative product designed to replace traditional gravel around vapor tubes. This product facilitates in situ neutralization of vapors before they exit the soil pack, reducing treatment requirements and yielding significant cost savings. Its composition can be customized according to the nature and concentration of pollutants in the soil, ensuring optimal neutralization reactions while maintaining the required permeability for effective vapor extraction. The resulting neutralization byproducts consist of inert minerals that can be safely retained in the soil, offering a genuinely zero-waste treatment solution for a wide range of contaminants.
Results/Lessons Learned
This paper presents performance results from in situ thermal desorption treatment utilizing Thermoreact® as a sulfur neutralization filter media around vapor tubes. This study demonstrates the following key findings:
- The technology effectively neutralizes sulfur-containing vapors.
- The effectiveness in sulfur neutralization remains consistent even in the presence of other pollutants.
- The visual appearance of the soil remains unchanged after treatment, allowing for the retention of inert neutralization products in the soil without affecting the site's visual aspect.
- The composition can be tailored to specific site parameters, including moisture levels, sulfur, hydrocarbon, halogen concentrations, and other soil chemical characteristics.