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From 2011.igem.org

Environment and risks prevention issues are a major stake in our society. The Rhône-Alpes region has understood that very early, especially through the importance of its chemical and nuclear activities. Industrial wastewater treatment permits their reuse in industrial use and improve their quality, enabling compliance with discharge standards. Various processes are currently implemented to clear the wastewater from its contaminants (e.g. biological, membrane liquid-solid separation, physical, chemical and thermal processes). One of them is bioremediation. It embraces processes that use microorganism metabolism to remove pollutants from a contaminated environment. This rather new approach, the less expensive to put in place, is especially interesting in the treatment of poorly contaminated effluents.

However, these microorganisms must respect a few criteria:
- harmlessness towards the environment and human nature,
- easiness of cultivation,
- tolerance to treated pollutant(s),
- ability to be separated from the treated effluent.

It is in compliance with this latter requirement that lies our project. In fact, the immobilization of bacteria on a solid support makes it possible to retrieve more easily the residue in treated wastewater. The activity of modern nuclear power plants with pressurized water reactors generates radioactive effluents that contain among other things radioactive cobalt. The tubing of the cooling circuit is made of a steel alloy rich in stable cobalt (59Co). Undergoing neutron bombardment coming from the reactor, this stable cobalt changes into its radioactive isotope, cobalt 60 (60Co). The capture of this metal is interesting on a sanitary point of view, because it represents a danger under both its radioactive and stable forms (carcinogenic). It also represents an advantage on an environmental point of view, in order to avoid contamination of waters, soil and groundwater. Even with a short half life, cobalt 60 emits high intensity gamma rays, and decays to nickel, which is stable but polluting.

Controlled immobilization of radioactive cobalt is both an important sanitary and environmental issue, which we intend to solve with an innovative and economical response.