Sewage sludge is a main sink of brominated flame retardants (BFRs) and is likely a carrier of further emission of the compounds into the environment. Detailed knowledge about the fate and behaviour of BFRs during sludge treatment, thus, is important in order to prevent further distribution of BFRs in the environment. In this study, batch experiments of BFRs in sludge under different conditions (anaerobic, aerobic, anaerobic-aerobic, and UV/Vis irradiation) were performed in order to simulate

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... ferent treatment processes of sludge. Four test compounds were selected: tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), decabromodiphenyl ether (BDE-209), and decabromodiphenyl ethane (deBDethane). In the anaerobic batch test, the dissipation rate decreased according to the following order: HBCD > TBBPA > BDE-209 >> deBDethane. It was found that anaerobic conditions are preferable for BFRs degradation by reductive debromination. In the aerobic batch test, the dissipation of BFRs was slower, and the order of dissipation was as the following: HBCD >> TBBPA > BDE-209 ~ deBDethane. Higher than anaerobic dissipation rates for BFRs were not measured under the sequential anaerobic-aerobic treatment. In the UV/Vis irradiation test, fast dissipation of BDE-209 and HBCD was observed, and the order of dissipation was as the following: BDE-209 ~ HBCD > TBBPA >> deBDethane. The irradiation test also showed that dissipation process was highly dependent on the penetration of light into the deeper layer of the sludge. Degradation products of test compounds were detected during the batch tests. Lower brominated congeners were identified as biodegradation products of BDE-209 under anaerobic and UV/Vis irradiation test. In total, not all BFRs have to be classified as persistent in sewage sludge. DeBDethane was the most persistent compound under all test conditions. It is remarkable since deBDethane was chosen for replacement of BDE-209 in the context of PBDD/PBDF regulation.