Polybrominated diphenyl ethers in sewage sludge from Shanghai, China: possible ecological risk applied to agricultural land

Abstract

Ideally, agricultural use is a treatment for the sewage sludge generated from municipal wastewater. However, this treatment probably causes ecological risks due to the occurrence of organic contaminants in sludge, which has attracted rising concerns recently. To assess the possible ecological risk, in this study, sewage sludge samples were collected from 28 wastewater treatment plants (WWTPs) in Shanghai, China for exploring the level and profile of polybrominated diphenyl ethers (PBDEs). The mean concentration of Σ18PBDE (sum of all target analytes except for BDE-209) was at the low end of global range. However, we found the highest reported BDE-209 levels (34,900 ng g(-1) dw) in sewage sludge/biosoilds to date. The annual mass loadings of penta-BDE, octa-BDE, and deca-BDE were 3.6, 0.6, and 763 kg through sludge, respectively. Following sludge application in agricultural land, the concentrations of penta-BDE, octa-BDE, and deca-BDE in soil were 0.19, 0.03, and 39.5 ng g(-1), respectively. Preliminary results indicate that the ecological risk of soil in organisms exposed to PBDEs was relatively low. Nevertheless, further studies are needed to explore the fate of PBDEs in sewage sludge due to no restriction on the usage and production of PBDEs products in China currently.