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Systems and processes for soil treatment

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TERRAFERM®-Soil Treatment Process

Biological soil remediation and recycling of biological and mineral waste materials

Process description: The biological treatment process TERRAFERM®-Biosystem ERDE enables soil-based microorganisms to degrade organic compounds that act as contaminating agents in the soil. Our experts had launched the TERRAFERM®-process in the 1980’s already, in order to remediate soils that were contaminated by mineral oil-derived hydrocarbons. The process has been in the meantime further developed and is now perfectly able to also treat other organic and mineral waste materials. The process has been dimensioned in a way to maintain an optimum balance of all process parameters, which are decisive for the activity of those microorganisms that are responsible for the degradation of contaminating agents. This soil treatment process may be used either as an individual treatment process or it may be combined with the soil washing process TERRALAVAR® and with thermal soil treatment processes. The TERRAFERM®-process is applied either in mobile or stationary plants.

Biologically degradable compounds: The following hazardous substances may be degraded by means of microbiological remediation processes:

  • Mineral oil-derived hydrocarbons
  • Aromatic hydrocarbons (benzene, toluene, phenol)
  • Polycyclic aromatic hydrocarbons (PAH)
Mineral oil-derived hydrocarbons and aromatic hydrocarbons such as benzene and toluene are basic components of mineral oil products and thus appear as contaminating agents on sites that are operated by mineral oil processing industries. As far as stored, transported and reloaded quantities are concerned, mineral oil-derived hydrocarbons represent, far and away, the most important group of elements. Phenols and PAH are mainly found in soils where coking plants and gas works had been operated or in soils where any type of carbon exploitation/processing had taken place. These two element groups, too, are frequently found in our environment since in the past almost any larger city did have a gas plant.

Preliminary analyses: A highly systematic and well-targeted control of the complex substance conversion processes is required and indispensable to secure the successful biological treatment of soils and other mineral waste materials. In a first step, the material is analysed in order to determine substance-specific and process-relevant parameters. The results obtained in the scope of these analyses and the limiting values for the reception of the waste, which are specified in the individual plants’ operation permits based on the Federal Immission Control Act (BImSchG), decide on the reception of the waste materials. The individual process parameters that are required for the biological degradation of contaminating agents will be identified on the basis of preliminary analyses on biological degradability of contaminating agents.

Process sequence: Once the material has been supplied to the plant, large-sized soil particles and waste materials are reduced in size and any interfering substances are removed. Organic substrates, which are specifically adapted to the waste structure (e.g. bark mulch, straw, bush cuttings), will be added to the material in order to improve degradation conditions. If required, additional nutrients will be added in order to provide for a balanced carbon-nitrogen-phosphorous proportion and for the rapid and complete degradation of organic contaminating agents. As for easily volatile substances and strong-smelling substances, the treatment will be executed in closed plants, which will be equipped with appropriate waste air treatment units. The exact and appropriate ambient conditions that are required for the microbial degradation of contaminating agents, such as material humidity, structure and nutrient substance supply, will be exactly adjusted by using adequate treatment techniques and –procedures (use of a mole-type mixing-kneading-crushing unit, of correct quantities of appropriate substrates, and optimum turning rhythm of the stacks).

All relevant process parameters (e.g. microbial activity, contaminating agent contents) will be regularly controlled during the microbiological treatment / remediation process. Once the target value of the remediation process has been achieved, the biological treatment / remediation process will have been concluded. The successful treatment process will be recorded through a representative sampling and analytical control that is executed by an external laboratory with ensuing surveyor release of individual lots. The assessment and recycling of decontaminated soils will be made on the grounds of pertinent requirements concerning material recycling of mineral residues/ wastes. Other products, generated in the course of the biological treatment process, will be appraised and used on the grounds of valid technical rules and regulations (e.g. RAL-quality label of the Federal Quality Association for Compost - Bundesgütegemeinschaft Kompost e.V.).

Re-use / recycling: The assessment and release for the recycling of decontaminated soils will be made on the grounds of pertinent requirements concerning material recycling of mineral residues/ wastes. Other products, generated in the course of the biological treatment process, will be appraised and used on the grounds of valid technical rules and regulations (e.g. RAL-quality label of the Federal Quality Association for Compost - Bundesgütegemeinschaft Kompost e.V.). The main objective of soil- and waste treatment is to obtain products, which comply with the requirements of a sustainable flow economy. The product’s quality is defined, on the one hand, by type, origin and characteristics of the input material and, on the other hand, by market requirements made to the soils and substrates that are to be re-used. The biological remediation process allows to re-establish the soil’s multi-functionality, thus creating numerous utilisation possibilities for decontaminated soils, such as in the field of landscaping (construction of noise barriers) or in the field of land reclamation measures. Up to the year 2008, we have been able to successfully biologically treat, remediate and then recycle a total of 8.8 million tons of contaminated soils and organic waste materials by means of the TERRAFERM®-process.



TERRAFERM® Soil Treatment Scheme

Prinzip TERRAFERM Bodenreinigung