The fate of triclocarban in activated sludge and its influence on biological wastewater treatment system

Triclocarban (TCC), a typical emerging contaminant, was abundantly released into environment and frequently detected in practical wastewater treatment plants. However it is also an important material when being added to personal skin care products as a antibacterial agent. In this work, the behavior of TCC in wastewater treatment process was investigated. Experiments showed that similar to 82% of influent TCC was removed by activated sludge adsorption and its adsorption isotherm was well fitted with Linear model and Freundich model. High levels of TCC had seriously impact on the settleability, dewaterability and extracellular polymetric substance (EPS) of activated sludge, even on effluent turbidity after a long-term exposure. Furthermore, the performance of biological wastewater treatment was damaged by TCC long-term exposure as well. The removal rates of total nitrogen and phosphorus decreased from 91.2 +/- 2.1% to 72.6 +/- 2.2% and from 94.7 +/- 3.1% to 78.4 +/- 2.3%, respectively, with TCC level increasing from 0 to 100 mu g/L. Mechanism analysis showed that TCC exposure significantly inhibited the relevant biological processes, such as ammonia oxidation, denitrification, phosphorus release and uptake, which were closely relevant to nitrogen and phosphorus removal.