Fate and transport of engineered nanomaterials in conventional and advanced water treatment processes

The overall goal of this research was to understand the fate of engineered nanomaterials (ENMs) in conventional and advanced separation processes. To accomplish this, three different ENMs having unique characteristics, were studied in order to correlate nanoparticle properties with their removal. Those ENMs that were studied included: cerium dioxide (CeO2), citrate coated nano-silver (nAg), and titanium dioxide (TiO2). Pristine ENMs, and ENMs that had been coated with natural organic matter, were removed in flocculation-clarification processes, with efficiencies ranging from 60 to 99%. High mass removals did not correlate with an absence of nanoparticles in the finished water. ENM mobility in media and membrane filtration positively correlated with nanoparticle size and surface charge. Conversely, ENM mobility in anthracite, was inversely proportional to nanoparticle size. Overall, the studied separation processes provide a substantial, but incomplete, barrier to ENMs in drinking water treatment.