How Is Thermal Treatment Integrated Into a Remediation and Disposal Concept?

Thermal treatment is integrated into a remediation and disposal concept by embedding it as the central process for contaminant destruction within a multi-stage procedure: from site analysis and mechanical pre-treatment through the actual desorption process to the recycling or landfilling of the treated material. The process is particularly suitable for sites with complex organic contaminations where biological or physico-chemical methods reach their limits. The following sections shed light on the most important questions surrounding the application, process flow, and legal framework of thermal soil treatment.

Which contaminants can be removed by thermal desorption?

Thermal desorption is suitable for removing a wide range of organic contaminants from contaminated soils and mineral waste. Treatable substances include in particular mineral oil hydrocarbons (TPH), BTEX compounds, phenols, polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), dioxins and furans (PCDD/PCDF), PFAS/PFOS, cyanides, nitroaromatics, and numerous other chlorinated hydrocarbon compounds. Mercury (Hg) can also be driven out of the solid material using this process.

The decisive advantage over other methods is that, at sufficiently high temperatures, the contaminants are either completely destroyed or converted into a gaseous state. In the gaseous state, they can subsequently be safely captured and treated in a multi-stage exhaust gas purification system. This makes thermal desorption particularly suitable for sites with multiple contaminations, where different classes of pollutants occur simultaneously, such as at former gasworks, chemical sites, or military properties.

Careful input analysis is essential: not every contaminant responds identically to heat, and the composition of the waste determines the required treatment temperature as well as the requirements for the downstream exhaust air purification system.

How does the process of thermal soil treatment in a rotary kiln work?

Thermal soil treatment in a rotary kiln takes place in several coordinated steps: first, the feed material is mechanically pre-treated, then heated in the rotating kiln at temperatures of up to approximately 600 °C depending on the material and contaminant load, before the resulting exhaust gas passes through a multi-stage purification line and the treated material is cooled and assessed.

Mechanical pre-treatment and feeding

Before being introduced into the kiln, the feed material is screened, crushed, and brought to a suitable particle size. Interfering materials such as metals or coarse components are sorted out. This step ensures uniform heat transfer in the kiln and protects the system from damage.

Thermal treatment and exhaust gas purification

In the rotary kiln, the material slowly rotates through the heating zone. Treatment takes place under oxygen exclusion, i.e. in desorption mode, so that organic contaminants evaporate without combustion. The resulting pollutant gas is then fed to a thermal afterburner, where temperatures exceeding 1,000 °C permanently destroy the contaminants. Dust removal, flue gas scrubbing, and activated carbon filters ensure that the emission limits of the 17th BImSchV are reliably met.

When is thermal treatment the appropriate method for a remediation project?

Thermal treatment is the appropriate method when organic contaminants are present in high concentrations, biological methods are ineffective due to the toxicity of the contamination, or complete destruction of the contaminants is legally or technically required. It offers clear advantages over alternative methods, particularly for multiple contaminations and time-critical projects.

Specifically, thermal desorption is recommended in the following situations:

Heavily contaminated soils with TPH, PAH, PCB, or PFAS that exceed the limits for direct landfilling
Sites with mixed contaminations from multiple pollutant classes
Projects where the treated soil is subsequently to be recycled
Remediation projects under time pressure that require a fast, reliable solution
Cases where biological or physico-chemical methods are ineffective due to contaminant toxicity

The process is not suitable for purely inorganically contaminated soils, such as those containing heavy metals like lead or arsenic, as these are not destroyed by heat but at best redistributed. Other disposal routes must be chosen in such cases.

How is thermal treatment integrated into a comprehensive material flow management system?

Thermal treatment is not an isolated process but a building block within a structured material flow management system. It is deployed when the characterization of the waste indicates that thermal destruction of the contaminants is necessary or economically viable. Upstream and downstream processes such as interim storage, mechanical-physical pre-treatment, and the recycling of the treated material are equally part of the overall concept.

A complete material flow management system typically comprises the following stages:

Analysis and characterization: Determination of the contaminant composition and waste classification
Acceptance and interim storage: Secured storage until treatment
Mechanical-physical pre-treatment: Screening, crushing, separation of interfering materials
Thermal treatment: Desorption in the rotary kiln with subsequent exhaust gas purification
Recycling or disposal of the output material: Reuse as a construction material or landfilling depending on the eluate class

This integrated approach makes it possible to manage even complex waste streams from large-scale projects in an orderly manner. The material flow management provided by ARE Deutzen not only handles the thermal treatment but also coordinates the entire disposal pathway from acceptance to documentation.

What legal requirements apply to thermal soil treatment in Germany?

Thermal soil treatment in Germany is subject to a strict regulatory framework. Facilities of this type require a permit under the Federal Immission Control Act (BImSchG), and operations are governed in particular by the 17th BImSchV, which sets emission limit values for incineration and co-incineration plants. Additional requirements arise from the Circular Economy Act (KrWG) as well as waste law documentation obligations.

Relevant legal bases at a glance:

BImSchG: Permit requirement for thermal treatment facilities
17th BImSchV: Emission limit values for pollutants in exhaust gas, including dioxins, heavy metals, and particulates
KrWG: Requirements for the proper and harmless recovery and disposal of waste
Verification Ordinance: Documentation obligations for hazardous waste from generation to disposal
Certification as a specialist waste management company (EfB): Proof of expertise, reliability, and technical equipment pursuant to Section 52 KrWG

Operators of thermal treatment facilities must carry out and document regular emissions measurements and demonstrate continuous compliance with the limit values. For clients, this means: choosing a certified specialist waste management company is not only a matter of quality but also of their own liability protection.

What happens to the soil after thermal treatment?

After thermal treatment, the soil is generally free of organic contaminants and can, depending on the analytical results, either be recycled as a construction material or deposited at a suitable landfill. The decision depends on the eluate values and the solid content of the treated material.

The treated material is sampled and analytically assessed after cooling. If the contaminant levels are below the relevant assignment values, the soil can be used as a mineral recycled material in construction projects, for example in road construction or earthworks. This conserves natural resources and significantly reduces the need for landfilling.

If recycling is not possible, orderly landfilling takes place at a licensed landfill of the appropriate class. This route is also part of a complete disposal concept and is documented through seamless record-keeping. More on the post-treatment and assessment of the output material is explained on the page on soil treatment and resource conservation.

How ARE Deutzen GmbH integrates thermal soil treatment into your remediation concept

ARE Deutzen GmbH, as a specialized waste management company with over 30 years of experience, offers a fully integrated solution for the treatment of contaminated mineral waste. The facility in Deutzen, western Saxony, is designed for the thermal desorption of complex contaminations and covers the entire process from acceptance to documentation.

Specifically, ARE Deutzen offers the following services as part of a remediation or disposal concept:

Acceptance and analytical characterization of soils, construction rubble, sludges, ashes, and other mineral waste
Secured interim storage until treatment
Mechanical-physical pre-treatment to prepare the feed material
Thermal desorption in the rotary kiln at temperatures of up to approximately 600 °C depending on the material and contaminant load, with multi-stage exhaust gas purification
Recycling or orderly disposal of the treated material
Seamless documentation and record-keeping in accordance with legal requirements

For civil engineering companies and industrial clients wishing to remediate or revitalize a contaminated site, ARE Deutzen is a reliable partner with the technical expertise and regulatory approvals that demanding projects require. Get in touch and discuss your project directly with the contact persons at ARE Deutzen.