EDSR – Leaders in Remediation Technology and Innovation
EDSR has unparalleled experience in applying proven remediation technologies across a range of complex projects. This experience includes successful application of the following technologies. In many cases, EDSR pioneered the application of these technologies for large-scale UK projects.
Use the links in the box on the left to view information on our specific technologies.
Thermal Desorption
Thermal desorption involves heating of contaminated soils in order to remove organic contaminants into gases. These gases are then subjected to high temperatures to break them down into basic chemical components, which are cooled and scrubbed. The result is a gas which is safe to release into the atmosphere.. The sterilised soil from the process is re-hydrated, chemically tested and returned to the ground.
Thermal desorption is particularly effective for large, complex sites where contaminants are not easily treated such as agrochemicals, gasworks waste, complex industrial chemicals and a wide range of other organic compounds.
Permeable Reactive Barriers (PRB)
PRBs are a proven technology for managing contaminated groundwater. They are barriers which run from the surface down to the nearest impermeable underground layer to trap groundwater. This water is either filtered through the barrier at a set rate, or is filtered through “gates” in the wall. The “gates” clean any contaminants out of the groundwater before it is discharged back into the ground. PBRs do not treat the source of contamination; however, they reduce the groundwater contamination before it migrates.
Bio - Remediation
Bio-remediation uses either naturally occurring or supplemented bacteria to degrade contaminants such as hydrocarbons, and some pesticides within soils and groundwater. This may be undertaken without excavation, or the contaminated material can be moved to a dedicated treatment system. EDSR utilises a number of established bio-remediation treatment technologies including ‘biopiles’, which are excavated mounds of contaminated soils where water and nutrients are added to augment the naturally occurring bacteria. The bacteria use the contaminant as a food source which is consumed over a predictable period. Other bio-remediation techniques include the use of wind rows where the soils are routinely turned and aerated.
Chemical Oxidation
Chemical Oxidation is a process which destroys organic contaminants either dissolved in groundwater, attached to aquifer material, or present in their free phase e.g. hydrocarbons. Oxidants most frequently used in the process include:
• Hydrogen peroxide (H2O2)
• Potassium permanganate (KMnO4)
• Persulphate (Na2O8S2)
• Ozone (O3)
• Peroxone (a combination of ozone and hydrogen peroxide)
• Fenton’s Reagent (hydrogen peroxide mixed with a metal to act as a catalyst)
Soil Flushing and Solvent Extraction
These techniques use abstraction and injection technologies to remove contaminants mainly associated with groundwater. Stripping agents can be employed which increases the mobility of the contamination such as steam, solvents and surfactants. The techniques are dependant on site geology and hydrogeology together with the relevant characteristics of the contaminant concerned.
Monitored Natural Attenuation
This system relies on a detailed knowledge of the contaminant as well as the site geology, hydrogeology and chemistry. The information is used to develop models which project the gradual reduction in contamination over time. This reduction occurs because of the natural breakdown of the contaminants in the presence of bacteria, together with some dilution and dispersal. The effectiveness of the process is monitored by regular sampling. This technique is site and contaminate specific.
Soil Washing
Soil washing is a physical process involving mechanical and chemical segregation of contaminated soil particles from uncontaminated soil and is ideally suited to the treatment of granular soils.
The soil is separated into several product streams, one of which is the fine fraction of the soil to which the contaminants normally adhere.
This can be a cost effective process depending of the level and type of contamination and the geotechnical properties of the soil.
Crushing and Screening
Suitable for processing as dug materials and demolition waste this process works on the principle that the fine fraction of the soil contains the most concentrated contamination. The process reduces the volume of material that needs remediation and the larger fraction of materials may be suitable for re use on site.
Soil Stabilisation
Stabilisation is the chemical fixation of contaminants in soils, normally with the introduction of additives to the soil, such that contaminants are converted into their least soluble or mobile form. This reduces the leachability and bioavailability of the contaminants.
This technique can also be applied to soils to improve their geotechnical properties and can be a cost effective alternative to removal of unsuitable material and import of suitable fill.
Containment / Impermeable Barrier Walls
Containment is often used when no economically viable solution is available to remove the source of the contamination. Containment through the use of impermeable barriers can provide a long term solution for preventing release of leachate to groundwater.
Capping systems and gas membranes can be utilised to protect human health by removing vertical pathways for contamination.
