Toxicity of Titanium Dioxide Nanoparticles on Growth Kinetics of Activated Biomass

This study focused on effect of titanium dioxide (TiO2) nanoparticles (NPs) on growth kinetic parameters of aerobic sludge bacteria and its associated toxicity to the activated biomass of a typical sewage treatment plant. Initially no difference in lag periods or exponential growth periods was found due to presence of nanoparticles. Also, a considerable amount of decrement in the absorbance values of the bacterial growth phase due to the toxicity of the NPs with the highest toxicity obtained during the stationery phase after 72 hours with a reduction of almost 52% in presence of 2 mg/L and 72% in presence of 20 mg/L of TiO2 NPs. Further, the amount of culturable bacteria also was reduced to almost 50% due to the effect of 2 mg/L and 20% due to the presence of 20 mg/L of TiO2 NPs, indicating effect of NP on culturability of bacteria. More kinetic studies using TiO2 concentrations till 20 mg/L are required to understand its toxicity to activated biomass.