Solidification / stabilisation of waste
What is solidification /stabilisation of waste?
The principle of solidification /stabilisation is based on mixing wastes with the appropriate bonding and filling agents in order to modify their physical properties in a desirable way.
The objective of this process is to change waste properties. Such waste fulfils the requirements for the disposal in a landfill site.
Solidification/ stabilisation of wastes follows the engineering and technological processes (ETP) developed by an independent professional institution (e.g. accredited laboratory).
Solidification/ stabilisation process is applicable in the following cases:
- waste does not meet the leachability classification requirements for the disposal in a landfill site,
- waste is liquid or releases liquid phase by sedimentation,
- chemical composition of the waste (e.g. TK, NEL...) has possible negative effects on the quality of leachate,
- waste is dusty or reeking and may exceed defined emission limits,
- disposal of unmodified waste may result in an adverse reaction with the waste disposed in the active layer of a landfill body.
Which bonding and filling agents are used for solidification/ stabilisation?
They are materials with the capability to bind modified waste into solid matrix. Contaminants are thus fixed and cannot enter the environment.
The bonding and filling agents are:
- fly ash,
- hydraulic lime,
- hydrated lime.
Hydraulic lime is also used for the treatment of organically contaminated waste (oil, PCB). The chemical reaction leads to encapsulation of organic contaminants in the system of fine powdery dispersion with a large specific surface. Such modified waste has a long-time stability proven in laboratory and operation conditions.
As a bonding agent we use a wide range of lime-based wastes. Some waste types are also filling agents, e.g. energy ash, slag, inert soil, cellulose waste etc.
How is solidification/ stabilisation carried out in a solidification zone?
- If the supplied waste complies with quality certificates, it is weighed and registered.
- The waste is unloaded in an isolated zone and the bonding and filling agents are added, alternatively mixing water, in the ratios given by ETP.
- If the waste is dusty, then „sleeve“, as it is called, is used to reduce emissions during unloading.
- The material is thoroughly mixed by a hydraulic arm to achieve required homogeneity.
- Subsequently, the reaction mixture is disposed of in a defined landfill, and the modified waste undergoes the process of solidification.
How is the final product of solidification/ stabilisation treated?
The final products of solidification/ stabilisation process (modified wastes including bonding and filling agents) are classified according to quality (according to the regulation no. 381/2001 coll., Waste catalogue) into the following categories:
- 19 03 04* Hazardous waste, partially stabilised
- 19 03 05 Stabilised waste not defined by no. 19 03 04
- 19 03 06* Solidified hazardous waste
- 19 03 07 Solidified waste not defined by no. 19 03 06
The category of solidified/ stabilised material (other x hazardous) is always defined by the categories of modified waste.
Reclassification of the modified waste from „N“ category to „O“ category is possible exclusively through an expert assessment of all the hazardous qualities. The issue of the Certificate of exclusion of hazardous properties by a competent person is required.
If the solidified/ stabilised wastes are disposed of in landfills, Waste Act defines the obligation to pay a fee for the total amount of solidified/ stabilised waste disposal.
List of wastes accepted in solidification zone
Marius Pedersen has a standardized list of wastes common for all solidification zones. Further information on the list of accepted wastes is available in the production centres.