Deca-BDE and alternative halogenated flame retardants in a wastewater treatment plant in Harbin (2009-2016): Occurrence, temporal trends, seasonal variation, and fate.

This study is the first attempt to comprehensively investigate deca-BDE and alternative flame retardants in a wastewater treatment plant in such a long term in China (2009-2016). Influent, effluent and sludge samples were collected. The mean concentration of deca-BDE, Σ19NBFRs and ΣDPs in influent were 311.5, 76.0 and 1.4ng/L, respectively, which were at the low end of the global range. The levels of deca-BDE, Σ19NBFRs and ΣDPs in effluent were range from 9.5-68.6, 4.1-38.5 and BLD-1.6ng/L, respectively. In sludge samples, the mean concentrations were 406.7, 510.5 and 6.9ng/g dw for deca-BDE, Σ19NBFRs and ΣDPs. The concentration of temporal trends in this study may reflected the release of those compounds. Compared to the beginning year of this study, the usage of deca-BDE was decreased but the usage of total NBFRs and DPs presented sustained increase over the sampling period. There were no significant variation of deca-BDE, NBFRs and DPs in the wastewater treatment plant in Harbin was observed in the four seasons except for NBFRs in influents, which the Σ19NBFRs mean concentration in influents in the summer was statistically significantly higher than that in winter indicating that NBFRs was easier impacted by temperature compared to deca-BDE and DPs. In addition, sorption and accumulation to sludge was the major removal mechanism for those compounds, accounting for 73.3% to 89.0%.