Jean-Marc Aldric,* Jaqueline Destain and Philippe Thonnart

Faculté Universitaire des Sciences Agronomiques de Gembloux

Unit of Bioindustries

Centre Wallon de Biologie Industrielle - Belgium

E-mail : Bioindus@fsagx.ac.be

The malodorous and toxic effluent gases coming from various industrial activities are often polluted by several contaminants. Some activities generate toxic compounds called BTEX (Benzene, Toluene, Ethyl-benzene, Xylene).

Biological techniques such as biofiltration or bioscrubber are used. The latter can be effective for the treatment of polar organic compounds treatment but is limited for the treatment of substances slightly soluble in aqueous medium.

This research attempts to develop a biphasic reactor "water/silicon oil." Silicon-oil is used to allow a better biological abatement of the aromatics organic compounds by improving their solubility within the biphasic reactor. Initially, a bacterial strain (Rhodococcus erythropolis T 902.1 ) was selected on the basis of its capacity to degrade isopropyl benzene (IPB), a compound selected as a model. In a second approach, an experimental process was developed with to study the mass transfer and the biological abatement of the IPB within the reactor.

The results obtained show that the use of silicon oil makes it possible to absorb large quantities of IPB within the medium of biological abatement. Indeed, the total coefficient of mass transfer of IPB is proportional to gas flow and concentration of the effluent.

The rate of biodegradation does not seem to be related independently to the concentration of the effluent and the gas flow. On the other hand, the rate of biodegradation is directly related to the flow of IPB entering the reactor. Thus, in the configuration tested, the reactor is able to degrade 3 mg/min.l of reactional media. It is also shown that the transfer is not limiting beyond this limiting value.

In conclusion, the reactor presents interesting opportunities in the biological treatment of gas effluents polluted by aromatic compounds in strong concentration. The process suggested might be applied in field of concentration and flow where thermal oxidation is too expensive.