†State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, 210023 Nanjing, China.
‡Fujian Provincial Academy of Environmental Science, No. 10, Huan Bei San Cun, Fuzhou 350013, China.
Environ Sci Technol. 2015 Apr 7;49(7):4283-92. doi: 10.1021/es5059007. Epub 2015 Mar 23.
The fate of the most commonly used brominated flame retardant, tetrabromobisphenol A (TBBPA), in wastewater treatment plants is obscure. Using a (14)C-tracer, we studied TBBPA transformation in nitrifying activated sludge (NAS). During the 31-day incubation, TBBPA transformation (half-life 10.3 days) was accompanied by mineralization (17% of initial TBBPA). Twelve metabolites, including those with single benzene ring, O-methyl TBBPA ether, and nitro compounds, were identified. When allylthiourea was added to the sludge to completely inhibit nitrification, TBBPA transformation was significantly reduced (half-life 28.9 days), formation of the polar and single-ring metabolites stopped, but O-methylation was not significantly affected. Abiotic experiments confirmed the generation of mono- and dinitro-brominated forms of bisphenol A in NAS by the abiotic nitration of TBBPA by nitrite, a product of ammonia-oxidizing microorganisms (AOMs). Three biotic (type II ipso-substitution, oxidative skeletal cleavage, and O-methylation) and one abiotic (nitro-debromination) pathways were proposed for TBBPA transformation in NAS. Apart from O-methylation, AOMs were involved in three other pathways. Our results are the first to provide information about the complex metabolism of TBBPA in NAS, and they are consistent with a determining role for nitrifiers in TBBPA degradation by initiating its cleavage into single-ring metabolites that are substrates for the growth of heterotrophic bacteria.
最常用的溴系阻燃剂四溴双酚 A（TBBPA）在废水处理厂中的命运尚不清楚。本研究采用 14C 示踪剂，研究了硝化活性污泥（NAS）中 TBBPA 的转化。在 31 天的孵育过程中，TBBPA 的转化（半衰期为 10.3 天）伴随着矿化（占初始 TBBPA 的 17%）。共鉴定出 12 种代谢物，包括单苯环、O-甲基 TBBPA 醚和硝基化合物。当向污泥中添加烯丙基硫脲以完全抑制硝化时，TBBPA 的转化明显减少（半衰期为 28.9 天），极性和单环代谢物的形成停止，但 O-甲基化没有受到显著影响。非生物实验证实了 NAS 中 TBBPA 通过亚硝酸盐（氨氧化微生物（AOM）的产物）的非生物硝化生成单溴化和二溴化形式的双酚 A。提出了三种生物（II 型间位取代、氧化骨架裂解和 O-甲基化）和一种非生物（硝基脱溴）途径来解释 NAS 中 TBBPA 的转化。除了 O-甲基化，AOM 还参与了其他三种途径。本研究结果首次提供了关于 NAS 中 TBBPA 复杂代谢的信息，并且与硝化作用在 TBBPA 降解中起着启动作用的观点一致，因为硝化作用将 TBBPA 裂解成单环代谢物，这些代谢物是异养细菌生长的底物。
