Fate of polybrominated diphenyl ethers during wastewater treatment process producing reclaimed water

Polybrominated diphenyl ethers (PBDEs), flame retardants, have been applied to consumer goods, such as furniture, electrical devices, textiles, and appliances for decades. Due to their physico-chemical properties, PBDEs are semi-volatile and easily leach off the consumer good during aging, stress, or normal wear and tear of the good. Once airborne, they pose an environmental health threat because they can adsorb onto dust particles, soil, or other particulates that can be inhaled, ingested, or come into contact with the dermal layer. Additionally, PBDEs have a molecular structure similar to other persistent organic pollutants, such as polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins and furans. They are a health threat due to their endocrine-disrupting nature by affecting thyroid functioning, fertility, and child development. The purpose of the study is to measure selected PBDEs in a wastewater treatment plant (WWTP) that produces reclaimed water, such that a mass balance can be completed, and to compare this mass balance with theoretically expected concentrations. The mass balance includes the collection of samples from wastewater, sewage sludge, and air at points within the WWTP. The PBDEs examined are BDE-28, 47, 99, 100, 153, 154, and 183. The second part of the study will compare effluent concentrations to reclaimed water concentrations in order to examine the potential exposure (if any) of using reclaimed water. Influent concentration of mean (sum7)PBDE was found to be 49,117 pg/L and effluent concentration was 4,603 pg/L, illustrating a 91% removal rate of PBDEs during the wastewater treatment plant. Sludge samples contained the highest total concentrations of PBDEs with mean (sum7)PBDE ranging from 14.0 to 41.3 ug/kg dry weight. Air samples were highest at the post-aeration (248 pg/m3 mean (sum7)PBDE) step due to the use of highly oxygenated air assisting in the release and volatilization of the PBDEs. Sludge was found to carry the largest mass loading at 14.2 lb/day (sum7)PBDE. Of the total mass loading of PBDEs from the WWTP, sludge is responsible for 86.7%, followed by reclaimed water and effluent (11.7% and 1.6%, respectively). The mass loading from air was negligible with less than 0.01% contribution to the total mass loading. Whereas reclaimed water overall had higher PBDE congener mean concentrations than the effluent, the independent samples t-test found no statistically significant differences between the two groups. The results of this study can be used to improve the wastewater treatment process to reduce the impact of PBDEs being released into the environment by WWTPs, and to educate the public on utilizing reclaimed water in a safe and healthy manner