Document Actions
On-site Recycling of Complex Waste Contaminated Soils
Most remediation techniques have only a specific, and sometimes limited, effect in complex contamination conditions. The Retek Process, however, is the first remediation approach that treats multiple contaminants, in all types of soil, in a single fast treatment. After just four days, soils previously contaminated with leaching metals, short chain hydrocarbons, PAH, BTEX and Cyanides, are ready for re-deposit or reuse elsewhere on site.
|
The Retek Process employs a mixture of chemical and physical processes, including redox, alkaline chlorination and chemical oxidation, as well as “solidification" and "stabilisation" techniques, refined in the field over the past 20 years. Stabilisation and solidification sound similar, but describe different effects that occur in the process as binding agents and reagents work to immobilise hazardous materials. In the UK, Stabilisation/Solidification is a well known treatment for the geo-technical improvement of soils and dredge materials, but this has led to many people misunderstanding the nature of this technology when it is used as a soil remediation technique. What is often overlooked is the complex chemistry of contaminated soils, and the chemical interactions that can be engineered using s/s technologies. |
|
Stabilisation refers to the chemical changes to the hazardous constituents in a soil, including converting the contaminants into a less soluble, less mobile and less toxic forms. A good example is the approach to heavy metals. These may be precipitated from contaminated soils through the conversion of soluble heavy metal salts to insoluble salts, and these salts can then in turn be irreversibly bound in permanent low water-permeable matrices.
These chemical reactions offer essentially permanent solutions to the fixation of heavy metals such as lead, cadmium, arsenic, zinc, chromium, copper and others. The technology reduces the leachability of metals allowing treated material to pass the Toxicity Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP) and the Multiple Extraction Procedure (MEP).
Due to the great variation of waste constituents and media, any individual remediation project will usually require a mixture of reagents and processing conditions. Typically, such site-specific treatments are based on mixes derived from a database of formulae compiled from the treatment of contaminated wastes in thousands of prior projects.