Characterization of nanoparticulate emissions from the incineration of wastes containing manufactured nanomaterials
Résumé
In a perspective of sustainable innovation, the development of nanotechnologies requires a deep insight in the nanosafety during the whole life cycle of products containing nanomaterials, from production, to recycling and final destruction. Up to now there is no peculiar approved procedure for the waste management of nanoobjects at their end of life, mainly because the current regulation does not consider the typical nano-specificity of such emerging products. The French project called NANOFlueGas has been dedicated to nanosafety aspects during the final destruction of nanomanufactured products by specialized thermal treatment. The main objectives of this project are: (1) to better understand possible mechanisms of nanoparticle release in the raw gas during the combustion of different kinds of wastes containing manufactured nanomaterials and (2) to evaluate the efficiency of the current pollution control processes and procedures implemented to clean the flue gas on waste incineration facilities. Results obtained for objective 1 are presented here. The selection and sampling of three types of hazardous wastes was performed on the basis of a preliminary identification of waste deposits potentially containing nano-contents. These wastes have different physical forms: a carbon residue (finely divided solid), an organo-silicon residue (viscoelastic solid), and a residue of water-based paints (liquid). The presence of nano-fillers in these residues has been shown and described qualitatively as well as quantitatively via an original multidisciplinary, analytical approach. An experimental setup for incineration (primary chamber) has been selected, developed and fully instrumented for the measurement of gas and particulate phases. Such an experimental setup allows to reproduce at best at the laboratory scale, the conditions and Best Practices implemented industrially. The reproducible results showed a presence of nanoparticles in the primary incineration chamber during normal operation (excluding start-up and shutdown) in varying amounts, depending upon the tested waste type. The particle size distributions, during the incineration phase, are dominated by the size component <100 nm. The paint and polymer wastes generate abundant aerosol which consists mainly of nano-silica, while the powdery waste, much less contributory itself, mainly emits carbon nanoparticles.