Toxicity of Nanoparticles: Cerium and Hafnium Oxides

Nanoparticles (NPs) are defined as particles that range in size from 1 to 100 nm. NPs play an important role in the Chemical-Mechanical Polishing (CMP) processes used by the semiconductor industry. CMP slurries are currently being treated at waste-water treatment (WWT) plants although the effects of NPs on WWT sludges and the environment have not been sufficiently studied. NPs could potentially affect the environment by changing toxin/nutrient levels, ecosystems and microstructures. The main goal of this project was to determine the toxicity of cerium oxide NPs on acetoclastic methanogens and aerobic bacteria found in sludges from wastewater treatment plants. This study also includes further CeO2 toxicity tests on aquatic bacteria.