Published 08/25/2026
IN SITU REMEDIATION · CHEMICAL OXIDATION · ISCO
ISCO: in situ chemical oxidation for soil and groundwater remediation
In situ chemical oxidation makes it possible to act directly on contamination in the subsurface, but its effectiveness does not depend solely on the oxidising capacity of the reagent. The design must consider the contaminant, the hydrogeological setting, oxidant demand and, especially, the ability to deliver the reagent to the target zone.
In situ chemical oxidation (ISCO, In Situ Chemical Oxidation) is one of the remediation technologies used to reduce the mass of contaminants present in soil and groundwater by applying oxidising agents directly into the subsurface.
Unlike strategies based exclusively on extraction and on site treatment, ISCO acts on contamination directly at the site and can be particularly useful in source zones, hard-to-access contamination, or sites where excavation or intensive extraction are not viable.
The oxidising capacity of a reagent is important, but on its own it does not guarantee treatment effectiveness. The oxidant must reach the contamination, remain available for the required period and react preferentially with the target contaminant.
However, applying ISCO is not simply a matter of selecting an oxidant and dosing it. Treatment effectiveness depends on the interaction between the contaminant, the oxidant and the hydrogeological setting, as well as on the ability to distribute the reagent throughout the target zone.
For this reason, preliminary site characterisation and oxidant selection are fundamental aspects in the design of any ISCO treatment.
Contaminants Type and concentration of the contaminants.
Contaminant distribution Distribution of contamination in soil and groundwater.
Site characteristics Lithology, permeability and heterogeneity of the ground.
Organic matter Presence of natural organic matter and other oxidisable compounds.
Oxidant demand Natural oxidant demand of the ground (SOD/NOD).
Geochemical conditions pH, alkalinity, iron and other elements present.
Oxidant distribution Accessibility and ability to distribute the oxidant.
Reaction time and objectives Reaction time and contaminant reduction objectives.
Main oxidants used in ISCO
At Envirotecnics, we work with different families of oxidants, allowing the treatment strategy to be adapted to the specific characteristics of each site.
Oxidant selection is a fundamental part of the design
There is no single oxidant that is universally optimal for every site. Each technology has different advantages, limitations and application conditions.
| Oxidant | Main applications | Advantages | Key aspects to control |
|---|---|---|---|
| Sodium permanganate | Especially chlorinated solvents | Persistence and relative stability | Oxidant demand, MnO2 and distribution |
| Sodium percarbonate | Hydrocarbons and organic compounds | Solid source of H2O2 and application flexibility | Activation, natural demand and distribution |
| Sodium persulfate | Hydrocarbons, BTEX, PAHs and chlorinated compounds | High oxidative capacity and versatility | Activation system and non-productive consumption |
| H2O2 / Fenton-like | Hydrocarbons, BTEX, PAHs and phenols | High reactivity and rapid action | pH, iron, decomposition and reaction control |
From laboratory testing to treatment design
Before defining an injection campaign, treatability studies and laboratory tests should be used to assess aspects such as oxidant demand, reaction kinetics, the required concentration, by-product generation and compatibility with the site’s geochemical conditions.
The design must then transfer these results to field conditions, taking into account hydrogeological heterogeneity, injection radius of influence, reagent distribution and the evolution of contaminant concentrations.
The ultimate objective is not simply to achieve a chemical reaction in the laboratory, but to ensure that the oxidant reaches the contamination, remains available for the necessary period and reacts preferentially with the target contaminant.
ISCO solutions adapted to each site
At Envirotecnics, we provide a range of oxidising solutions for ISCO projects, combining reagent supply with the technical expertise required to select the most appropriate alternative according to the contaminant and the specific conditions of each site.
In in situ remediation, selecting the oxidant is only the first step. The real challenge is designing how to deliver it to the contamination and make it work effectively in the subsurface.
Are you evaluating an ISCO strategy?
We can help you assess the most appropriate oxidant and application strategy according to the contaminant and site conditions.
