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In-situ Chemical Oxidation

Churngold has considerable experience of chemical oxidants used in the remediation of groundwater...

A number of chemical oxidants are available for use in remediation of groundwater. These include Potassium/Sodium Permanganate, Modified Hydrogen Peroxide and Sodium Persulfate. The selection of the best oxidant is dependent on site-specific information. For instance Permanganate, although having the advantage of not requiring activation unlike most other oxidants, can only effectively oxidise a small range of contaminants (the most notable being chlorinated solvents) . However Modified Fentons Reagent and Sodium Persulfate (once activated) have very similar oxidative strengths and reaction mechanisms, which enables them to target a wide range of organic contaminants. Churngold can offer an "in-house" facility to assess different oxidants and then optimise them on a site by site basis.

As oxidation is a non-selective process understanding how oxidants are expended is critical. Soil Oxidant Demand (SOD) is often used to measure oxidant consumption on non-targeted substances within a designated treatment zone. It should be noted that SOD could account for more than 90% of the oxidant consumption relative to the targeted pollutants. Chemical Oxidation processes also occur mostly in the dissolved phase and therefore detailed modelling is required to ensure its applicability. Sites where NAPLs are present (particularly LNAPL) may not be treatable using oxidation methods.

Mode of Delivery

The delivery of oxidants is also critical as the oxidant must come into contact for the oxidant to work. Fixed wells to set-up re-circulation pathways and direct push-point wells have been used successfully in the past. However for the appropriate site Churngold has developed in-situ soil mixing technology to deliver high-strength chemical oxidants, overcoming some of the hydrogeological shortfalls of traditional injection based techniques. The greater robustness offered by the in-situ soil mixing can provide greater possibility of treatment after only one round of injection.

Where previously low permeability soils and soils containing NAPL may have precluded consideration of chemical oxidation Churngold now have the ability to surmount these obstacles.