Occurrence and concentrations of polybrominated diphenyl ethers in sewage sludge from three wastewater treatment plants in Kuwait

Polybrominated diphenyl ether (PBDE) concentrations were measured in sewage sludge samples collected from three wastewater treatment plants in Kuwait over a six month period. PBDEs were detected in all samples analyzed and there were significant differences between the three wastewater treatment plants. The mean (and range) of ∑PBDEs concentrations measured are as follows: Jahra 52.5 ng g−1 (5.7–169.5 ng g−1); Reqqa, 144 ng g−1 (32–296 ng g−1); Umm Haylaman, 377 ng g−1 (23–1599 ng g−1). The differences in concentrations of the sum of penta congeners were consistently different at the three treatment plants with values increasing in the order: Jahra < Umm Haylaman < Reqqa. BDE 209 was the dominant congener in all samples, contributing between 70% and 99% of the ∑PBDEs, with lesser quantities of BDE 99 (6%), BDE 47 (3.3%), BDE 100 (1%) with BDEs 28, 153, 154, and 183 accounting for only 2% of the ∑PBDEs measured in most samples. A seasonal trend in concentrations was observed, presumably related to temperature effects, with lower concentrations between September and November, followed by a spike in the December samples and then a gradual decrease in the January and February samples.