Thus, in 2012 a historical waste inventory began identifying the number of potentially polluted sites in Wallonia at between 3400 and 17000 according to whether there was a high or low-level of pollution, whereas 994 sites were counted where the level of pollution was established and 1322 were sites that had already been cleaned(7). It has now become clear that this is not just an environmental necessity but also a promising market from a commercial point of view. By way of example, it includes sites such as oil depots and major users of fuels (TEC and SNCB depots…), service stations, domestic tanks and non-excavatable urban sites. The company SANIFOX has been active for several years in the area of bioremediation-biostimulation (stimulation of endogenous and/or exogenous microorganisms) for the degradation of pollutants in soils and underground water. SANIFOX acts for leading clients in the chemical and petrochemical industry and among other activities targets the treatment of non-chlorinated pollutants, that is to say “the hydrocarbons you might find for example in the ground below a former petrol station”. NANOMICRO has therefore primarily focussed on these types of pollutants.

The beginnings of a success story

The NANOMICRO project is the result of an encounter between the Wallonia Centre for Industrial Biology (CWBI) directed at that time by Pr. Philippe Thonart and the company SANIFOX, which was co-founded by Benoît Lavigne who also happens to be the current manager. “The researchers at CWBI had succeeded in isolating and developing a strain of microorganisms that degrade aromatic hydrocarbons which was exactly what SANIFOX was researching in order to increase the kinetics of biodegradation, otherwise known as the speed of degradation of hydrocarbonated pollutants in soils which it treated for its clients. Moreover, in the wake of completely original and encouraging results in another area of biotechnology (the production of biohydrogen)(8) it was observed that the growth of the bacterial strain in question was stimulated when in the presence of nanoparticles which were synthesized in the Department of Chemical Engineering – Nanomaterials, Catalysis and Electrochemistry, explains Stéphanie Lambert-Jamoulle. This gave rise to the NANOMICRO project. In time, we would like to develop a microorganism/nanoparticle formula which could be used by the company SANIFOX in the context of soils treatments and polluted groundwater tables for its different clients. ” The particularity of the project lies in the strain of microorganisms on one hand and the procedure for the use of the nanoparticles on the other. In fact, the strain in question, Rhodococcus erythropolis, is the property of ARTECHNO and CWBI. In this case, the nanoparticles, with  sizes of 2-3 nm, present the specificity of being encapsulated in an inert silica matrix  which prevents them from sintering  and also being dispersed in a random fashion and uncontrolled in their natural state. The use of this specificity does not correspond to the method developed by other researchers which involves the use of metallic nanoparticles directly injected into the soil. In fact, there is an environmental risk with regard to the use of traditional nanoparticles (non-encapsulated) in bioremediation processes. It is linked to their high surface/volume ratio making them highly reactive which could lead to problems of toxicity. Stéphanie Lambert-Jamoulle explains: “A nanoparticle is a particle whose size is around 10⁻⁹ metres. It is extremely small and of course it is reactive because the smaller particles are, the more reactive they are due to the fact that the surface/volume ratio is very high. The danger with nanoparticles is that if they are liberated in an uncontrolled fashion, they risk polluting soils and runoff waters. ” In order to compensate for this, the nanoparticles have been “blocked” within another medium, inert silicone in this case. “ This is a micrometric powder, comparable in size to sand which can be found in the average garden. This silica powder is sufficiently porous to act as a reservoir for nanoparticles. We carried out different tests in the aqueous phase: when silica powder containing nanoparticles was added to water, almost none of these nanoparticles were re-released into the water after several weeks. ” Consequently, this was a great success!

(7) Source: Walloon Environment Portal. http://etat.environnement.wallonie.be/
(8) http://www.microh2.ulg.ac.be/, http://orbi.ulg.ac.be/handle/2268/143706

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