Physical and chemical treatment processes for polluted soils

A wide range of human activities (industrial, mining, agricultural, military, urban, transport, etc.) are responsible for polluting sites, soils and groundwater. In France, thousands of hectares of polluted sites have been inventoried [1] (see Basol website). Today, awareness of this pollution, changes in industrial practices and the disappearance of certain activities have curbed the spread of pollutants in soils, and most of the cases dealt with are legacies of the past. Many sites are affected by multiple types of pollution (organic and/or mineral), superimposed or separated geographically. The nature and distribution of pollutants depend on the chemicals involved in a given process or in successive processes at different points on the site. These polluted sites can then present risks of pollutant transfer to sensitive targets, such as water resources, ecosystems and human health. Over time, they can also disperse into the environment, increasing the size of polluted surfaces.

The decision whether or not to decontaminate is based on a number of criteria, including health risk, site location, intended future use, cost and timeframe. These same criteria guide the choice of techniques to be used.

Some of these techniques are designed to immobilize pollution, others to extract or destroy it. They are generally classified into three families: physical, chemical and biological treatments (table 1 ).