8. Bioventing

This technique involves supplying the oxygen required for biodegradation (figure 8 ) and is often confused with venting, which is based on pollutant volatilization (§ 36). Bioventing offers very low costs (very little treatment of outlet gases and smaller pumping equipment than conventional venting). This technique has been in use for some twenty years and is still widely used for sites polluted by biodegradable hydrocarbons.

• Principle

  Bioventing is an in situ process that aerates the unsaturated zone so that soil micro-organisms can breathe more easily and degrade pollutants. This technique consists of renewing the air by vacuum or injection in the unsaturated zone and inducing air circulations centered on and in the direction of each...