Joint effect of triclosan and copper nanoparticles on wastewater biological nutrient removal

Triclosan (TCS) is widely used in household and personal care products, and its release into wastewater might have impact on wastewater biological treatment for its antibacterial property. Besides, emerging pollutant such as copper nanoparticles (CuNPs) will also release from nanoparticle-containing products, showing a joint effect with TCS on biological nutrient removal. The TCS of 1 and 10mg/L inhibited the nitrosification and nitrification stage, and the first step of denitrification was suppressed as well, causing a decline in final TN removal efficiency. Additionally, the phosphorus uptake was inhibited seriously, leading to a remarkable decrease in phosphorus removal efficiency. When they were co-existed, the TCS concentration decreased due to the absorption by CuNPs, and the released Cu2+ from CuNPs increased. Further investigation revealed that when 5mg/L CuNPs and 1mg/L TCS were immediately added to the activated sludge, the final joint toxicity was similar to the individual effect of 1mg/L TCS, while 10mg/L CuNPs contributed to the final stronger toxicity. When TCS was sufficiently reacted with CuNPs in wastewater, their final toxicity to activated sludge was enhanced because the extent of toxicity relief caused by decrease in TCS concentration was less than the degree of deteriorating effect due to the promotion of Cu2+ release from CuNPs.