周楚缘,彭星星,贾晓珊.活性污泥降解四溴双酚A的特性、途径及毒性评估[J].环境科学学报,2019,39(9):2928-2937
活性污泥降解四溴双酚A的特性、途径及毒性评估
- Degradation of tetrabromobisphenol A by activated sludge: Characteristics, pathway and toxicity assessment
- 基金项目：国家自然科学基金（No.41703086，51878676）；广州市珠江科技新星项目（No.201806010100）
- 周楚缘
- 1. 中山大学环境科学与工程学院, 广州 510275;2. 广东省环境污染控制与修复技术重点实验室, 广州 510275
- 彭星星
- 1. 中山大学环境科学与工程学院, 广州 510275;2. 广东省环境污染控制与修复技术重点实验室, 广州 510275
- 贾晓珊
- 1. 中山大学环境科学与工程学院, 广州 510275;2. 广东省环境污染控制与修复技术重点实验室, 广州 510275
- 摘要：电子行业典型污染物溴代阻燃剂对环境的污染引起了广泛关注.本文以产量最大、应用最广的典型溴代阻燃剂四溴双酚A （Tetrabromobisphenol A，TBBPA）为研究对象，考察了活性污泥降解四溴双酚A的特性、影响因素、降解途径并进行毒性评估.结果显示：活性污泥能有效降解水体中的TBBPA；在初始接菌量OD600=0.77，TBBPA浓度为2.50 mg·L-1，温度为40℃，pH值为6.0时，经6 h反应后降解率可达58.46%，脱溴率达43.80%；在自然水体中活性污泥对TBBPA的降解受到抑制，尤其在腐殖质含量较高时；自然光能促进TBBPA降解，紫外光则抑制其降解活性；利用LC-Q-TOF-MS/MS检测到3种中间产物，推测TBBPA可能通过以下两种路径降解：①TBBPA发生甲基化和脱溴反应，产生甲基化的二溴双酚A，随后发生羟基化反应生成5-[1-（3-溴-4-甲氧基-苯基）-1-甲基-乙基]-2-甲氧基-苯酚；②TBBPA发生羟基化反应生成5-[1-（3-溴-4，5-二羟基-苯基）-1-甲基-乙基]-苯-1，2，3-三醇，随后发生脱溴、羟基化和甲基化反应，生成5-[1-（3-羟基-4，5-二甲氧基-苯基）-1-甲基-乙基]-2-甲氧基-苯-1，3-二醇；最后，利用发光细菌对该降解过程进行毒性评价，结果表明，活性污泥降解TBBPA的过程中其毒性未被完全去除，仍存在一定的环境风险.
- Abstract：The environmental pollution caused by brominated flame retardants, typical pollutants from electronic industry, has attracted much attention worldwide. The present study selected tetrabromobisphenol A (TBBPA), one of the typical brominated flame retardants which has the largest production and the most extensive applications, as the concerned chemical to investigate its degradation characteristics by activated sludge. The influencing factors, transformation pathway and toxicity assessment were investigated. The results show that activated sludge could effectively degrade TBBPA in water. Under the optimal condition (a bacterial inoculum of 0.77, an initial concentration of TBBPA of 2.50 mg·L-1, a temperature of 40 ℃, and initial pH value of 6.0), 58.46% of TBBPA could be removed in 6 h, with an incompletely debromination rate as high as 43.80%. The degradation would be inhibited in natural water, especially due to high concentration of humus. Natural light could enhance the degradation. However, ultraviolet light would decrease the degradation efficiency. Three intermediates were identified by using the LC-Q-TOF-MS/MS analysis, and two pathways of TBBPA biodegradation were proposed as follows: (I) Methylated dibromobisphenol A was generated by methylation and debromination, followed by the formation of 5-[1-(3-Bromo-4-methoxy-phenyl)-1-methyl-ethyl]-2-methoxy-phenol through hydroxylation; (Ⅱ) TBBPA was first attacked by HO· to form 5-[1-(3-Bromo-4,5-dihydroxy-phenyl)-1-methyl-ethyl]-benzene-1,2,3-triol, which was then transformed to 5-[1-(3-Hydroxy-4,5-dimethoxy-phenyl)-1-methyl-ethyl]-2-methoxy-benzene-1,3-diol by hydroxylation and methylation. The toxicity evaluated by luminous bacteria indicated that the toxicity risk was not completely erased through the biodegradation process, suggesting a potential threat to the environment safety.
