RCEES OpenIR  > 环境水质学国家重点实验室
典型污水处理系统中有机磷阻燃剂 的暴露归趋与去除机制
Alternative TitleExposure fate and removal mechanism of Organophosphate flame retardants in a typical wastewater treatment system
青达罕
Subtype硕士
Thesis Advisor许宜平
2019-06
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name工程硕士
Degree Discipline环境工程
Keyword有机磷阻燃剂 ,被动式采样 时间加权浓度, 多介质 逸度模型, A2/o系统 organophosphate Flame Retardants, Passive Sampling, Time Weighted Average Concentration, mulTimedia Fugacity Model, A2/o System
Abstract

        随着溴代阻燃剂在全球范围内逐渐禁用,有机磷 阻燃剂 organophosphate flame retardants, OPFRs)因其良好的阻燃性 能 正在成为重要的替代型阻燃剂 。 物理添加为主的 有机磷阻燃剂可以通过各种途径从材料中释放到环境介质中, 其中污水被认为是 环境水体中 有机磷阻燃剂的重要来源,因此 研究其在污水处理系统中的暴露分布特征、行为归趋以及去除过程与机制至关重要, 可以 为工艺参数优化提供科学依据。目前水体中 OPFRs的 监测主要采用 瞬时 主动式采样方法 ,虽然方法成熟但在 操作便捷性、环境友好性等方面存在 一定 欠缺, 并且瞬时采样对有机污染物在环境中长期暴露浓度 反映不足 (例如污水进水浓度的波动现象等 。被动式采样测定的是有机污染物在水体中的溶解态浓度,同时通过 采样器的相对较长时间的暴露,可以获得目标污染 物 在水体中的时间加权 平均 浓度 time weighted average concentration, TWAC 。 故基于连续流动暴露方式的被动式采样技术可以作为一种有效的替代方法。

        本研究选择11种 典型 有机磷阻燃剂作为目标污染物质, 包括氯取代、烷基取代、芳基取代的不同结构特征, 使用 三油酸甘油酯 -醋酸纤维素半透复合膜triolein-embedded cellulose acetate membranes, TECAM 以及 聚苯乙烯 -N-吡咯烷酮共聚物 -醋酸纤维素半透复合膜 HLB-embedded cellulose acetate membranes, HECAM 作为被动式采样器,原位 采样并分析 了 不同结构(极性)的 OPFRs在典型 A2/O污水处理系统工艺流程中 的暴露分布特征 并 计算了去除效率 。 同时应用 参数优化的污水处理厂逸度模型 Sewage Treatment Plant, STP 对部分有机磷阻燃剂 (氯代 /烷基 /芳基) 进行归趋模拟 ,以期更好的阐明有机磷阻燃剂在污水处理系统中的迁移转化规律。 取得以下主要研究成果:
        (1) 污水厂进水等水质条件恶劣的水体对被动式采样可造成较大的影响,生物淤积等不利因素会造成采样器对有机磷阻燃剂吸附 量 的降低,尤其是对于氯代OPFRs等极性较强的物质影响最为明显,在一级处理工艺 段的 膜中富集浓度远低于二沉池出水 处膜中富集 浓度。在污水处理系统中,氯代 OPFRs在生物处理单元无明显去除;烷基 OPFRs中, 磷酸三 2-丁氧乙 基 酯 tris(2-butoxyethyl) phosphate, TBOEP 可在缺氧处理与好氧处理中被显著去除(去除率 58.9%、64.6%),而 磷酸三丁酯( tris(butyl) phosphate, TNBP 与 磷酸三( 2-乙基己基 酯tris(2-ethylhexyl) phosphate, TEHP 可在二沉池被部分去除(去除率 41.7%、13.8%),在生物处理阶段去除规律并不明显;大部分芳基 OPFRs在厌氧处理及缺氧处理阶段可被有效去除(去除率 16.7%-74.5%),而在好氧处理阶段 无明显去除 。在不同季度的污水处理厂出水中,夏季出水中 OPFRs总浓度最高,达到 798.9 ng/L,同时在各季度出水中 磷酸三 2-氯乙基 酯( tris(2-chloroethyl) phosphate, TCEP 均占据了大多数的比例。
       (2) 污水厂逸度模型能够较好的模拟 OPFRs在污水处理系统中的行为与归趋,并且与实测结果较为一致,对于 OPFRs的归趋研究以及排放监测具有一定的指导意义。 模拟结果 显示 对于 磷酸三 2-氯乙基 酯 tris(2-chloroethyl) phosphate, TCEP 、 磷酸三 2-丁氧 乙基 酯 tris(2-butoxyethyl) phosphate, TBOEP 、 磷酸三苯酯( tris(phenyl) phosphate, TPHP 等 3种 OPFRs而言,污水处理系统中 挥发去除作用均极为有限,表明挥发不是 OPFRs从污水处理系统去除的主要途径。进入系统中的大部分 TBOEP可被生物降解(去除率为 TPHP则可被生物降解(去除率为 40.3%)与吸附去除(去除率为 29.6%),而 TCEP因其亲水性以及对生物降解的抗性,无法从系统中有效去除。同时,进水流量、污泥生物质含量以及污泥浓度、污泥量等因素会影响逸度模型中 OFPRs的去除率,在污水处理厂实际运行中应当考虑上述参数并根据实际情况作适当调整,以更 有效的 去除OPFRs类 有机污染物。

Other Abstract

        As brominated flame retardants are gradually banned worldwide, organophosphate flame retardants (OPFRs) are becoming important alternative flame retardants. OPFRs can be released from products into environmental media through various routes and wastewater is considered as a major source of OPFRs in environmental waters. Therefore, it is critical to investigate the exposure, fate and removal mechanism of OPFRs in wastewater treatment system, to provide scientific support for process parameter optimization. OPFRs in water have been mostly monitored with grab and active samplings, a developed method but with complex operation and cost of solvents, which also cannot actually reflect the long-term exposure concentration of pollutants especially for fluctuation scenarios. Passive sampler can provide time-weighted average (TWA) concentrations under integrated exposure which can be used as an effective alternative.
        In this study, we used triolein-embedded cellulose acetate membranes (TECAM) and HLB-embedded cellulose acetate membranes (HECAM) as passive samplers to monitor the exposure and distribution characteristics of 11 typical OPFRs with varied structures and polarities in processes of an A2/O wastewater treatment system. Removal efficiency of OPFRs was also evaluated based on time-weighted average concentrations in wastewater obtained from passive sampling results. In addition, a fugacity-based sewage treatment plant (STP) model was optimized with in situ data to simulate fate of three typical chlorinated-/alkyl-/aryl-OPFRs, in order to better understand the transportation and transformation mechanism of OPFRs in the wastewater treatment system. The main findings are shown below.
        (1) Poor water quality had a great adverse effect on passive sampling. Unfavorable factors such as biofouling caused samplers to reduce the accumulation of OPFRs, especially for chlorinated OPFRs. The accumulated concentration in samplers retrieved from primary treatment facilities was much lower than that from the settling tank. In wastewater treatment system, chlorinated OPFRs cannot be removed from bio-treatment units effectively; for alkyl OPFRs, tris(2-butoxyethyl) phosphate (TBOEP) was significantly removed from the anoxic and aerobic treatment unit (removal efficiency were 58.9%, 64.6%, respectively), while tris(butyl) phosphate (TNBP) and tris(2-ethylhexyl) phosphate (TEHP) can be partially removed from the settling tank (removal efficiency were 41.7%, 13.8%, respectively); most of aryl OPFRs can be effectively removed from the anaerobic and anoxic treatment unit (removal efficiency range 16.7%-74.5%), while the removal efficiency was negative in the aerobic treatment unit. The total concentration of OPFRs in effluent was the highest in summer (798.9 ng/L), and tris(2-chloroethyl) phosphate (TCEP) accounted for the majority of the effluent in each quarter.
        (2) Simulation results from optimized STP model were well consistent with measured results (TWA concentrations) from passive sampling of OPFRs. The simulation results shown that for the three kinds of OPFRs, i.e. tris(chloroethyl) phosphate, tris(2-butoxyethyl) phosphate and tris(phenyl) phosphate (TPHP), volatilization was not the main process to remove OPFRs in wastewater. Most of the TBOEP entering the system could be biodegraded (with removal efficiency of 62%), while TPHP could be removed by both biodegradation (with removal efficiency of 40%) and adsorption (with removal efficiency of 30%). However, TCEP could be hardly removed from the system due to its strong hydrophilicity and resistance to biodegradation. Furthermore, the most sensitive parameters affecting the removal efficiency of OPFRs from the wastewater treatment system were screened as the influent flow, biomass fraction in sludge, as well as sludge concentration. The technology parameter related to the processes above should be considered in the actual operation of the wastewater treatment system.
 

Pages89
Language中文
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/42274
Collection环境水质学国家重点实验室
Recommended Citation
GB/T 7714
青达罕. 典型污水处理系统中有机磷阻燃剂 的暴露归趋与去除机制[D]. 北京. 中国科学院生态环境研究中心,2019.
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