Experimental Evaluation and Modeling of Hydraulic Flocculation Systems Under Conditions of Turbulent Flow

1437961 .紊流条件下水力絮凝系统的实验评估和建模本项目的总体目标是使弹性水处理技术在南半球应用最经济，在工业化国家应用性能最高。水力絮凝不需要电力，没有活动部件，是地表水和砷污染地下水弹性高效处理的关键组成部分。本研究将建立并测试紊流水力絮凝的力学模型，并将该模型作为优化水力絮凝器设计的基础。在这个项目下进行的研究将被整合到康奈尔大学AguaClara项目中。这种整合确保了高水平的本科生参与研究，并将研究成果迅速转化为可扩展的设计算法，然后将研究成果转化为其他国家为需要安全饮用水的社区建造AguaClara设施的实施合作伙伴。具有国际背景的实践研究和设计经验创造了改变生活的工程教育。从这项研究中得到的基本理解将提高强大的重力动力水处理厂的性能，并将降低成本。大范围的相关长度尺度（nm到m）以及在用于水处理的顺序过程中发生的湍流和层流状态导致了经验设计方法不能正确地缩放适用于小型社区（1,000至50,000人）的流量。在本研究中，将采用理论分析与实验评价相结合的方法，确定影响絮凝颗粒生长和破碎的主要参数和机制，以及它们的沉降速度分布。大多数先前的絮凝工作都是利用机械搅拌反应器，其特性不佳且能量耗散率高度不均一。该项目将使用特性良好的湍流管流絮凝器和紊流蛇形折流反应器（以计算流体动力学（CFD）为特征）。通过层流条件下的絮凝研究，已经建立了该模型的核心组件，并揭示了絮凝对絮凝体体积分数、絮凝剂的胶体表面覆盖率（既取决于进水浊度、絮凝剂的类型和剂量）和反应器条件（能量耗散率、水力停留时间）的复合依赖。还建造了专门的仪器，可以对絮状颗粒沉降速度进行非破坏性分析，在实验反应器中对大范围时间和空间尺度的固体浓度进行视频监控，并实现实验自动化，从而可以探索更大范围的参数空间。

1437961LionExperimental Evaluation and Modeling of Hydraulic Flocculation Systems under Conditions of Turbulent FlowThe overall goal of this project is to make resilient water treatment technologies that are the most economical for application in the global south and the highest performing for application in industrialized countries. Hydraulic flocculation requires no electricity, has no moving parts, and is a key component of resilient high performing treatment of surface water and of arsenic contaminated groundwater. The proposed research will create and test a mechanistically based model for turbulent flow hydraulic flocculation and to use that model as a basis for optimizing hydraulic flocculator design. The research performed under this project will be integrated into the AguaClara program at Cornell University. This integration ensures a high level of undergraduate involvement in the research and rapid transfer of the research results into scalable design algorithms and then to implementation partners in other countries who build AguaClara facilities for communities in need of safe drinking water. The hands-on research and design experience with an international context creates an engineering education that changes lives. The fundamental understanding resulting from this research will improve the performance of robust gravity powered, water treatment plants and will reduce costs.The large range of relevant length scales (nm to m) and the turbulent and laminar flow regimes that occur in sequential processes used for water treatment have resulted in an empirical approach to design that does not correctly scale to the flows applicable to small communities (1,000 to 50,000 individuals). In the proposed research, theoretical analysis coupled with experimental evaluation will be used to identify the dominant parameters and mechanisms affecting the growth and breakup of flocculent particles, and their distribution of sedimentation velocities. Most previous work on flocculation has utilized mechanically-stirred reactors with poorly characterized and highly heterogeneous energy dissipation rates. This project will use well-characterized turbulent tube flow flocculators and turbulent serpentine baffled flow reactors (characterized by computational fluid dynamics (CFD)). Core components of the proposed model have already been created through studies of flocculation under laminar flow and reveal a composite dependence of flocculation on floc volume fraction, colloid surface coverage by coagulant (both dependent on influent turbidity and coagulant type and dose), and reactor conditions (energy dissipation rate, hydraulic residence time). Specialized instrumentation has also been constructed that permits non-destructive analysis of flocculent particle settling velocities, video monitoring of solids concentration over a wide range of time and spatial scales within experimental reactors, and automation of experiments which allows exploration of a greater range of parameter space than would otherwise be possible.