NANOSEP: Removal of Nanoparticles using optimized conventional processes

摘要

Nanoparticles can be of 3 types: one-dimensional (nanotubes), two-dimensional (flat shape) or three-dimensional (sphere) and at least one of these 3 dimensions must measure less than 100 nm. Recently we have seen an explosion of the human production of nanoparticles due to increased commercialization and new technologies. If the harmful effects on human health of airborne nanoparticles is well documented [1], [2], the effects on human health of waterborne nanoparticles however, are only related in a few in vivo studies. For these reasons it is necessary to assess the efficiency of conventional water treatment steps to stop nanoparticles spreading into the environment. Based on the yearly tonnage produced in France nanoparticles of silicon dioxide (SiO_2) and titanium dioxide (TiO_2) were selected for this study. Both laboratory scale and pilot scale experiments were performed in Le Pecq, France, with tap water and raw Seine River water spiked with these nanoparticles. Two main clarification processes were tested at pilot scale to assess the nanoparticles removal performances: lamellar settling and dissolved air flotation. Results show that SiO_2 nanoparticles are nearly completely removed using lamellar settling process. Concerning the dissolved air flotation technology, results show that the presence of natural organic matters and suspended solids enhanced the global performance of the process for turbidity removal.