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Characterization of Free and Bound PBDEs in Sewage Sludge from Waste Water Treatment Plants (WWTPs) of Shanghai

In this study, sewage sludge samples were collected from 25 wastewater treatment plants (WWTPs) in Shanghai, and free and bound PBDEs were extracted in different ways. The concentrations of free and bound PBDEs were in the range of 111.69 to 13119.59 ng/g dry weight (dw) and 4.30 to 60.17 ng/g dw, respectively. BDE209 were the dominate congener and the concentrations of free and bound BDE209 ranged from 89.64 to 12424.84 ng/g dw and 0.85 to 44.00 ng/g dw, respectively. The concentrations of bound PBDEs were quite stable, indicating bound PBDEs werent high related with the input of total PBDEs. The fractions of bound PBDE congeners increased with the numbers of Br atoms, which suggested that PBDE congeners with low molecular weights were more prone to desorb from micro-pores of organic matters in sewage sludge. The fractions of bound PBDEs in total PBDEs were in the range of 0.16 to 22.73%, suggesting bound PBDEs played an important role in farmland soils after sludge application.