Effect of Activated Sludge Bioselector Designs on Estrogen-Degradation Kinetics

PI：H.David StenselProposal number：CBET-106744机构：华盛顿大学题目：活性污泥生物选择器设计对雌激素降解动力学的影响雌激素是已知的内分泌干扰物(EDC)，可在低至0.35 ng/L的浓度下影响水生生物。雌激素通过正常的人类用水进入污水处理厂。这些雌激素按其EDC效力的顺序是17α-乙炔基雌二醇(EE_2，一种合成雌激素)、17‘-雌二醇(E_2)、雌酮(E_1)和雌三醇(E_3)。生物降解是污水处理厂去除雌激素的主要机制，EE2的降解速度比E1和E2慢得多。研究小组之前的工作发现，异养细菌在雌激素生物降解中发挥着重要作用，即使在广泛的有机底物上生长也是如此。三个生物反应器的实验室试验表明，EE2、E1和E2的降解动力学在厌氧/好氧序贯处理、缺氧/好氧序贯处理和好氧处理的反应器中有所不同，厌氧/好氧序贯处理选择聚磷微生物，缺氧/好氧序贯处理选择兼性生物。厌氧和缺氧选择器的设计对于当今常用的生物营养去除(BNR)系统也很重要。这项研究的关键问题是：(1)在处理实际城市污水和处理合成城市污水时，不同微生物种群(厌氧好氧缺氧)的相对降解动力学是否相似，(2)在选择器设计中微生物种群将如何比较，以及(3)能否在纯培养条件下确定EE2降解菌进行研究。类似于上述三种配置的处理城市一级污水的平行小试规模反应器将与机械模拟和先进的分子和微生物技术相结合，以研究相关ng/L浓度下雌激素的生物降解动力学。具体的研究目标包括：(1)评估选择器/BNR工艺设计对雌激素去除性能的影响；(2)比较不同反应器配置下EE2、E1和E2的降解动力学；(3)通过末端限制性片段长度多态性(T-RFLP)表征不同选择器设计的微生物种群；(4)确定雌激素降解率较高的生物反应器中雌激素降解生物量的比例是否更高；以及(5)评估从研究生物反应器获得的微生物菌株(包括厌氧和缺氧选择器)的雌激素降解能力。研究结果将被纳入以国际水协会ASM1和ASM2d模型为基础的雌激素/活性污泥综合模型。我们应用工业GPS-X软件完成了雌激素/ASM1模型的建立。ASM2d模型也将进行类似的工作，其中包括强化生物除磷。这些模型包括自由和共轭形式的E1、E2和EE2，去共轭和生物降解动力学，E2降解可能产生的E1，以及雌酚的液固分配。该项目的智能优势在于其变革性的方法，它集成了基于基本共底物机制的微污染物在生物过程中的命运建模，生物选择器设计效应，以及基于分子方法的微生物组成。第二个潜在的深远好处是开发能够在类似于污水处理厂的条件下降解EE2的纯培养物，用于未来的动力学和遗传学研究，以及开发用于监测污水处理厂设施中选择的降解EE2的异养菌的qPCR引物集。该项目的更广泛的影响是通过提供一个基础来优化污水处理厂的生物处理设计，以最大限度地减少对环境的雌激素释放，从而造福社会。直接的教育效益包括研究生的培养和本科生研究人员的参与。代表不足的群体的更多参与将通过华盛顿大学现有的项目和继续与华盛顿大学工程学院多样性办公室建立合作伙伴关系来实现。

PI: H. David StenselProposal Number: CBET-106744Institution: University of WashingtonTitle: Effect of Activated Sludge Bioselector Designs on Estrogen-Degradation KineticsEstrogens are known endocrine disruptor compounds (EDC) that can affect aquatic life at concentrations as low as 0.35 ng/L. A main source of aquatic estrogen contamination is wastewater treatment plant (WWTPs) effluents. Estrogens enter the WWTP through normal human water use. In order of their EDC potency these estrogens are 17á-ethynyl estradiol (EE2, a synthetic estrogen), 17â- estradiol (E2), estrone (E1) and estriol (E3). Biological degradation is a primary estrogen removal mechanism at WWTPs and EE2 is degraded much slower than E1 and E2. Prior work by the research team found that heterotrophic bacteria play a major role in estrogen biodegradation even when grown on a wide range of organic substrates. Laboratory experiments with three bioreactors fed synthetic feed showed that EE2, E1 and E2 degradation kinetics varied among reactors configured for anaerobic/aerobic sequenced treatment, which selects for phosphorus accumulation organism; anoxic/aerobic sequenced treatment, which selects for facultative organisms; and aerobic treatment. The anaerobic and anoxic selector designs are also important for biological nutrient removal (BNR) systems, commonly used today. Critical questions for this research are: (1) will similar relative degradation kinetics for the different microbial populations (anaerobicaerobicanoxic) occur when treating actual municipal wastewater versus synthetic, (2) how will microbial populations compare within the selector designs, and (3) can EE2-degrading bacteria be identified for study in pure culture. Parallel bench scale reactors similar to those described above for the three configurations treating municipal primary effluent will be integrated with mechanistic modeling and advanced molecular and microbial techniques to address biodegradation kinetics of estrogens at relevant ng/L concentrations. Specific research goals include: (1) Evaluate the effect of selector/BNR process designs on estrogen removal performance; (2) compare the EE2, E1, and E2 degradation kinetics in the different reactor configurations; (3) characterize the microbial populations for the different selector designs through terminal restriction fragment length polymorphism (T-RFLP), (4) determine if the fraction of estrogen-degrading biomass is higher for the bioreactors with higher specific estrogen degradation rates, and (5) evaluate estrogen degradation ability of microbial isolates obtained from the study bioreactors (including anaerobic and anoxic selectors). The results will be incorporated into a comprehensive estrogen/activated sludge model based on the International Water Association ASM1 and ASM2d models. The estrogen/ASM1 model has been completed by us by applying the industry GPS-X software. Similar work will be done with the ASM2d model, which includes enhanced biological phosphorus removal. The models include free and conjugated forms of E1, E2 and EE2, deconjugation and biodegradation kinetics, possible production of E1 from E2 degradation, and liquid-solids partitioning of estrogens.The intellectual merit of the project is its transformational approach, which integrates modeling the fate of a micropollutant in a biological process with a fundamental co-substrate mechanism, bioselector design effects, and microbial composition based on molecular methods. A second potential far reaching benefit will be the development of pure cultures capable of EE2 degradation under condition similar to WWTP for future kinetic and genetic studies, and development of qPCR primer sets for monitoring select EE2-degrading heterotrophs in WWTP facilities.The broader impacts of the project are benefits to society by providing a basis to optimize WWTP biotreatment design to minimize estrogen release to the environment. Direct educational benefits include the training of graduate students, and participation of undergraduate researchers. Increased participation by underrepresented groups will be realized through established University of Washington programs and continued partnership with the UW, College of Engineering Office of Diversity.