Contaminated site remediation

A method based on the ability of microorganisms to use organic contaminants and break them down to harmless products. This method can be used for the treatment of groundwater, wastewater, soil and sludge. It is mainly used for the removal of petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) or BTEX. The actual remediation technology consists in inducing optimum conditions for biological degradation of the contaminant. The technology can be applied both in-situ and ex-situ.

Advantages

• Contaminants are not transferred to a different environmental media, therefore, no additional waste is generated.
• Applicable to a wide range of organic substances.
• Lower costs than chemical/physical methods.
• Simple, proven technology.

This method is among the most widely used remediation techniques for groundwater decontamination. The method consists of pumping contaminated groundwater to the ground surface where it is subsequently treated using different technologies depending on the characteristics of contaminants. The treatment technologies are based on gravity (e.g. sedimentation), on physical and chemical processes (e.g. adsorption on activated carbon, various types of separators/filters, chemical oxidation), biological (e.g. bioreactors). After treatment, the water is either pumped back underground or discharged to surface water. The Pump and Treat method is effective for most common groundwater contaminants, but tends to be one of the more expensive remediation methods.

Advantages

• Fast reduction of contaminant concentrations, particularly at elevated input levels
• Flexibility in use of various clean-up processes with the ability to integrate multiple remediation techniques based on pollutant type 

A method that excels in high efficiency at relatively low cost. It is primarily applied ex-situ, though on-site application is also possible in principle.

It is used for soils containing organic contaminants that cannot be effectively removed by traditional biodegradation methods – such as polycyclic aromatic hydrocarbons (PAHs), typical for former gasworks sites, wood impregnation plants, and some chemical plants, polychlorinated biphenyls (PCBs) previously used in asphalt mix production technologies, and other persistent organic pollutants (POPs).

Advantages

• Effective even for soils contaminated with hard-to-degrade substances.
• Relatively inexpensive and operationally simple method.
• Possibility of using organic waste materials as a substrate.
• Can be applied off-site or on-site.

A mobile technological system primarily used for in-situ remediation of groundwater and soils in the saturated zone, contaminated with various organic substances and hard-to-degrade compounds, such as organochlorine pesticides, polychlorinated biphenyls, and others.

Advantages

• Ozone is a powerful oxidizing agent that can be applied to a wide range of organic contaminants.
• The technological equipment can be installed in easily transportable containers and operated in a fully automated mode.
• No waste is generated that requires further processing.

A technological system consisting of storage tanks for oxidizing agents and activators, pumps, infiltration wells, monitoring wells, and measuring equipment. Oxidation leads to the destruction of the contaminant or its transformation into harmless or less toxic compounds.

Sodium persulfate (Na₂S₂O₈) is known for its effectiveness in remediating sites contaminated with persistent organic pollutants, where conventional oxidizing agents fail or are not suitable for operational reasons.

Advantages

• Better stability and migration parameters compared to hydroxyl radicals.
• A strong oxidizing agent without many of the application and operational limitations of common oxidizing agents (discoloration of groundwater with potassium permanganate, higher safety requirements with hydrogen peroxide and Fenton's reagent, etc.).
• Low reactivity with organic soil components (lower consumption compared to permanganate).

The ISCO technology is applicable for the remediation of contaminated groundwater and soils in the saturated zone. The in situ chemical oxidation (ISCO) remediation method is generally based on the principle of an oxidation-reduction reaction, where the oxidizing agent is reduced, and the pollutant is oxidized.

Advantages

• Oxidation leads to the destruction of the contaminant or its transformation into harmless or less toxic compounds.
• Fast reaction rate.
• Virtually 100% efficiency if optimal contact between the reagent and pollutant is achieved.

A technology applicable for in situ remediation of groundwater and soils in the saturated zone contaminated with Cr(VI). It is especially suitable for the remediation of areas affected by so-called contamination plumes.

Cr(VI) has significantly negative effects on humans and the environment, particularly due to its high solubility, mobility, oxidative potential, and general toxicity. Additionally, it is a confirmed carcinogen.

Advantages:

• A cost-effective remediation method.
• The technology is simple to install and operate.
• Suitable for large contaminated areas.

Reduction using nZVI (nano zero-valent iron) is suitable for removing a wide range of organic contaminants, such as chlorinated hydrocarbons, PCBs, nitro derivatives, and even some heavy metals (e.g., Cr(VI)).

The technology is typically applied in situ, by infiltrating an nZVI suspension into equipped wells (this can be done repeatedly) or by direct injection into single-use unequipped probes.

Advantages

• Good migration capabilities compared to macro/micro iron particles.
• No formation of toxic by-products, as Fe is a natural component of the environment.
• Suitable for source zones of contamination (presence of phases, high contaminant concentrations).
• Fast kinetics of the decontamination process.
• Easy application.
• Relatively low investment costs for building the remediation system.

An effective and relatively inexpensive method for decontaminating materials containing hard-to-remove halogenated organic compounds, such as lindane (HCH - hexachlorocyclohexane), DDT (dichlorodiphenyltrichloroethane), and other persistent organic pollutants (POPs).

The combined technology of biological reductive dechlorination and chemical reduction using ZVI is suitable for remediating soils and groundwater contaminated with halogenated organic substances, including persistent organic pollutants (e.g., HCH and DDT). It can be applied both in-situ and ex-situ.

Advantages

• High efficiency, even for decontaminating materials containing hard-to-degrade halogenated organic compounds (including POPs).
• Relatively low investment and operational costs.
• Suitable for use even in cases of high contaminant concentrations.

This involves controlled heating of solid contaminated materials in an inert atmosphere using microwave radiation to a temperature at which the pollutants contained in the solid matrix evaporate. The released gas phase (containing not only pollutant vapors but also evaporated water) is directed to a condenser, where it liquifies.

Advantages

• High efficiency in removing contaminants with a relatively short heating time.
• Simple system for process monitoring and control.
• Safe operation.
• Lower energy consumption compared to electric heating.
• Possibility of a containerized technology solution.