Bioremediation consists of using biological processes to accelerate the decontamination of a site. Amongst the possible biorestoration techniques, biostimulation accelerates the development of bacteria naturally present in the environment and capable of breaking down hydrocarbons. This acceleration can occur by optimising the environmental conditions necessary for bacteria, in particular the presence of nutritional elements and the availability of oxygen. This is a finishing technique, which can be used in situ, whilst respecting the ecosystem, or on sediments transported offsite. Various members of the industry have greatly invested in this field, by participating in international research programmes on bioremediation techniques and developing products designed to accelerate the biodegradation of oil.
Ploughing to encourage biodegradation
Offsite biorestoration is a technique whereby operational techniques for industrial treatment of contaminated soil are applied to some of the waste from the site. It is currently used for soiled sediments collected on beaches, in general through landfarming, i.e. spreading and tilling small quantities of soiled sediments on agricultural land, in the presence of natural biorestoration accelerating agents.
Research has shown that cultivated plants in these conditions do not contain a single trace of hydrocarbons during the breakdown process in the soil.
In situ biorestoration experiment
In situ biorestoration was used on a large scale in the accident involving the oil tanker the Exxon Valdez in Alaska (1989), in a bid to provoke major acceleration of the elimination of biodegradable hydrocarbons through the provision of nitrogen and phosphorous.
Wharf of the Exxon Valdez (Alaska, USA)