Nitrification inhibition by silver nanoparticles.

Nitrification inhibition by silver nanoparticles (nanosilver) was evaluated by extant respirometry using enriched nitrifying bacteria isolated from wastewater treatment plants. Silver nanoparticles were more toxic than silver ions or silver chloride colloids, all of which did not disrupt cell membrane integrity at 1 mg/L Ag. The toxicity of silver nanoparticles was reduced in the presence of various anions, especially sulfide. The results suggest that silver nanoparticles have the same behaviour of surface complexation as silver ions, and inhibition by nanosilver in wastewater treatment may be removed by reaction of silver nanoparticles with soluble sulfide species.