Triclosan, chlorinated triclosan derivatives, and hydroxylated polybrominated diphenyl ethers (OH-BDEs) in wastewater effluents†
Various halohydroxydiphenyl ethers, including triclosan, chlorinated triclosan derivatives (CTDs), and hydroxylated polybrominated diphenyl ethers (OH-BDEs), are present in aquatic systems. While it is well established that wastewater effluents are a source of triclosan and CTDs, the evidence for OH-BDEs being in wastewater is limited. In this work, pre- and post-disinfection effluent samples were taken from four activated sludge plants, two using chlorine and two using ultraviolet (UV) disinfection. Triclosan levels ranged from 36–465 ng L−1 and CTD levels were non-detect to 27 ng L−1. While CTDs were generally higher in the plants using chlorine, they were also present in the UV plants, likely due to chlorine residual in the drinking water. Of the five target OH-BDE congeners (selected because they produce dioxins upon photolysis), three were detected. When detected the levels were generally 1–10 ng L−1, but some samples had levels as high as 100 ng L−1. Three different analytical methods were used to quantify OH-BDEs, and the levels were comparable using the different methods. Results were inconclusive as to the effect of disinfection method on OH-BDE levels. This study confirms that wastewater is a source of selected OH-BDEs to surface waters, but the overall loading is likely small. Further experiments and analyses are required to determine if the OH-BDEs are formed during the wastewater treatment process.