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Chemical - In-itu Chemical Oxidation
Verhoeve Environment & Water is market leader within in-situ chemical oxidation (ISCO) in the Netherlands and Belgium. We have some 10 years experience in chemical technologies for remediation of soils and water treatment. These techniques are particularly suitable for obtaining high decontamination yields in a relatively short period of time (several months up to 2 years) and generally in source areas. In areas where the biological approach of the plume zone fails or can not succeed because of the soil matrix, we frequent put chemical oxidation in as a last resort for the final settlement of the remediation. More and more, this technique is applied where others fail. Worldwide, Verhoeve Environment & Water has 10 chemical units and plants to remediate contaminations. All these facilities are equipped with PLC and are therefore remote controlled.For feasibility testing, we use our own laboratory to execute batch tests. We also execute pilot tests on location, frequently with a result guarantee. We weekly sample groundwater and air flows to control, and if necessary adjust, the chemical process.
We apply the following chemical techniques:
- Ozone+peroxide and / or permanganate
- Persulphate (oxidant solution)
- Fenton’s Reagent (liquid oxidant)
When are techniques most effective?
Substances to be addressed by chemical oxidation, can be divided as follows:
- Saturated hydrocarbons (chlorinated) alkanes (CH): mineral oils, trichloroethane, dichloroethane, carbon tetrachloride, ethers and alcohols: MTBE, ETBE, TBA, TAME
- Unsaturated hydrocarbons (chlorinated) alkenes (C = C): Per, Tri, Cis and VC;
- Cyanide (C ≡ N).
Monocyclic aromatics
- BTEX
- Styrene, phthalates
- (Chloro) phenols (e.g. PCP) and chlorobenzenes
- TNT, RDX and derivatives, nitro-anilines (explosives)
Polycyclic aromatic compounds: PAHs, PCBs and pesticides.
In some cases, these compounds are not fully chemically oxidized but, as it were, pre-treated (“predigestion”) in order to facilitate biological treatment. After all, soil has an intrinsic ability to biodegrade organic compounds.
Our main chemical oxidation technique is ozone in combination with hydrogen peroxide. Since we feel that the oxidant should be distributed as well as possible in (often) clayey or silty soils, a gas/liquid is particularly suitable.
The technique is based on creating tiny bubbles (ozone), to which hydrogen peroxide is added through special filters. In this process OH radicals occur, providing high oxidizing power. With this technique, it is not necessary to add primers or acids to the soil and therefore it can also be used in calcareous soils.
The technique is a highly flexible and continuous process that can be used in various ways, if needed in combination with complementary techniques. For example, switching to a biological treatment after the chemical phase is as easily administrated as injecting compressed air as pre-treatment or bacteria doses, all through the same system. Instead of hydrogen peroxide, a different type of oxidant may also be chosen.
Suitable for:
- Sandy or silty soils (from k: 0.1 m / d)
- Compatible with multi-phase extraction and biological treatment
- Chlorinated Solvents, cyanides, MTBE, MO / BTEX