3. Special processing materials

The main physico-chemical processes involved in pollutant retention are adsorption, ion exchange, precipitation, complexation and redox.

Retention agents are selected on a case-by-case basis according to the nature of the organic and/or inorganic pollutants present.

Reactive materials can act on pollutants by :

• chemical or biological degradation ;

• modification of their chemical form ;

• adsorption.

The following specific materials can be used to retain pollutants, but this is by no means an exhaustive list.