Effect of Copper Oxide (CuO) Nanoparticles on the Denitrifying Consortia Isolated from an Anaerobic Digester of a Sewage Treatment Plant

Raj Boopathy



Nanoparticles(NPs) are useful molecules with large surface area to volume ratios that confer unique properties and a wide variety of potential uses in medicine and biotechnology. The use of NPs has increased significantly in recent years resulting in accumulation in biological systems. While larger molecules made of the same constituents may be understood to have minimal effects on biological organisms, nanoparticles have been shown to have disruptive and even antimicrobial effects. Nanoparticle accumulation is a potential problem for many environmental systems. Sewage treatment plant functioning relies heavily on bacteria to remove excess carbon and nitrogen from the sewage before discharged to the environment. Increasing concentrations of nanoparticles in these plants can decrease its effectiveness if nanoparticles reach toxic levels for ammonia oxidizing or denitrifying bacteria. The purpose of this study was to determine the effect of copper oxide (CuO) nanoparticles on denitrification in wastewater treatment plant. A bacterial consortia developed from an anaerobic digester of a sewage treatment plant was exposed to various concentrations of CuO nanoparticles. Bacterial growth and COD removal were not affected at low concentration of NPs such as 5, 10, and 25 mg/L. At higher doses of NPs exposure including 100 and 250 mg/L, bacterial growth was severely inhibited along with denitrification process, and carbon removal. The consortiawas stressed at higher doses above 25 mg/L of NP leading to excess production of extracellular polymeric substances (EPS).

Keywords: Nanoparticle; CuO; denitrification; ammonia oxidation; EPS