When Is a Preliminary or Pre-Examination Before Thermal Treatment Worthwhile?

A preliminary or pre-treatment investigation before thermal treatment is always advisable when the composition of the contaminated material is not clearly known, when contaminants with special requirements for treatment technology are present, or when legal regulations require characterization of the waste. For complex contaminations, mixed pollutant loads, or unknown contaminated sites, it is indispensable in practice. The following sections answer the most important questions about preliminary investigations and explain when and why they are worthwhile.

Which contaminants make a preliminary investigation particularly important?

A preliminary investigation is particularly important for contaminants that are volatile, involve multiple pollutant loads, or can trigger special reactions during thermal treatment. These include in particular mercury (Hg), polychlorinated biphenyls (PCB), PFAS/PFOS, polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDF), as well as nitroaromatics and chlorinated hydrocarbon compounds.

These groups of substances behave differently in the rotary kiln: mercury evaporates at low temperatures and must be specifically separated. PFAS compounds require sufficiently high treatment temperatures and reliable exhaust gas aftertreatment. PCB and PCDD/PCDF can react to form problematic by-products if the process is not managed adequately.

Mixed contaminations of organic and inorganic pollutants, such as those frequently found at former gasworks, chemical sites, or military installations, also make a thorough preliminary investigation necessary. Only when the pollutant composition is known can the treatment temperature, residence time, and exhaust gas purification be optimally configured.

What is specifically analyzed in a preliminary or pre-treatment investigation?

In a preliminary investigation before thermal desorption, the chemical composition, pollutant content, physical material properties, and the behavior of the material under heat exposure are examined. The goal is a complete characterization of the waste as the basis for safe process planning.

Specifically, the analysis typically covers the following points:

Pollutant spectrum: concentrations of TPH, BTEX, PAH, phenols, cyanides, heavy metals, and halogenated compounds
Moisture content and particle size distribution, which affect throughput and energy balance
Loss on ignition and organic carbon content as a measure of the proportion of combustible substances
Chlorine and sulfur content, which are relevant for exhaust gas purification and corrosion protection
pH value and eluate behavior for assessing aftercare and the recyclability of the treated material

If special contaminants such as PFAS or PCDD/PCDF are suspected, additional specialized analyses are carried out. The results feed directly into plant control and the permit documentation.

When is a preliminary investigation required by law?

A preliminary investigation is legally required when waste is delivered for disposal or thermal treatment and waste characterization is required under the Landfill Ordinance (DepV) or the requirements of the competent authority. In addition, the Evidence Ordinance (NachwV) requires a basic characterization for hazardous waste.

In detail, the obligation to carry out a preliminary investigation arises from various legal bases:

The Waste Framework Directive and the Circular Economy Act (KrWG) require the characterization of hazardous waste before disposal.
The Evidence Ordinance requires a declaration analysis for waste subject to monitoring, documenting the type and concentration of pollutants.
The operator permit for the thermal treatment plant under the Federal Immission Control Act (BImSchG) specifies which types of waste and pollutant concentrations are permissible. Deviations must be checked before delivery.
For projects within the scope of contaminated site remediation, authorities regularly require a preliminary investigation as part of the remediation plan.

Even without a legal obligation, a preliminary investigation is recommended for liability reasons and to secure the disposal route.

How does a preliminary investigation before thermal desorption proceed?

A preliminary investigation before thermal desorption proceeds in several successive steps: on-site sampling, laboratory analysis, evaluation of results, and coordination with the plant operator regarding admissibility and process management.

The process in detail:

Sampling: Qualified personnel take representative samples according to recognized procedures (e.g., in accordance with DIN EN ISO 10381). For heterogeneous materials, composite samples are formed from multiple sampling points.
Laboratory analysis: An accredited laboratory examines the samples for the relevant pollutant spectrum as well as physicochemical parameters.
Evaluation of results: The analytical results are compared with the approval parameters of the treatment plant. In the event of limit value exceedances or unexpected contaminants, the disposal route is reassessed.
Coordination and approval: The plant operator checks whether the material can be accepted and treated, and if necessary specifies special process parameters.
Documentation: All results are documented for the disposal record and regulatory reporting.

This structured process ensures that the quality requirements are met and that the material can be treated safely and properly.

What does a preliminary investigation cost compared to the risks of not having one?

The costs of a preliminary investigation are generally low compared to the financial and legal risks that can arise without one. Laboratory analyses for a soil sample range from a few hundred to a few thousand euros depending on the pollutant spectrum. The consequential costs of a failed or inadmissible disposal can be many times higher.

Specific risks without a preliminary investigation:

Rejection: If a material is delivered that does not meet the plant’s approval parameters, it must be transported back at the client’s expense.
Plant damage: Unknown contaminants or material compositions can lead to corrosion, blockages, or emission limit value exceedances.
Regulatory violations and liability: Anyone who disposes of hazardous waste without proper characterization risks fines and civil liability.
Project delays: Subsequent analyses and regulatory coordination cost time and can significantly delay remediation projects.

An early soil analysis before thermal desorption is therefore not only a matter of due diligence, but also of economic efficiency.

For which types of waste and projects is a preliminary investigation particularly worthwhile?

A preliminary investigation is particularly worthwhile for projects with an unknown or complex contamination history, heterogeneous materials, or high pollutant concentrations. This applies above all to the remediation of brownfield sites, gasworks, chemical sites, and military properties.

Within the scope of material flow management, the following types of waste and project types are particularly relevant:

Soils and excavated material from contaminated sites with an unknown usage history
Construction rubble and demolition material from contaminated buildings, particularly where asbestos, PCB, or PAH are suspected
Sludges, ashes, and process residues from industrial processes with variable pollutant concentrations
Dredged material from contaminated bodies of water or ports
Large-scale projects with high material volumes, where early characterization secures logistics and cost planning

A preliminary investigation is also essential for projects in which the treated material is subsequently to be recycled. It demonstrates that the source material is suitable for the intended treatment and creates the basis for the recyclability of the end product.

How ARE Deutzen supports the preparation of thermal treatment

ARE Deutzen accompanies clients from the initial material assessment through to completed disposal. With over 30 years of experience in thermal soil treatment and more than 2.5 million tonnes of treated mineral materials, the company has the expertise to safely assess and process even complex contaminations.

Specifically, ARE Deutzen provides support with:

Assessment of analytical results and verification of the material’s acceptability
Determination of the appropriate disposal route based on the waste characteristics
Coordination of the preliminary investigation and documentation for the disposal record
Treatment of soils, construction rubble, and mineral waste containing pollutants such as TPH, PAH, PCB, PFAS, Hg, and chlorinated hydrocarbons in the rotary kiln at up to approximately 600 °C, depending on the material and pollutant load
Acceptance of process residues such as sludges, ashes, and dusts within the framework of material flow management

If you are planning a remediation project or need to dispose of contaminated materials, speak directly with the contact persons at ARE Deutzen. Early coordination saves time, secures the disposal route, and avoids costly surprises.