WRF: Experimental observation and modeling of coagulant mediated contaminant removal: flocculation, floc blankets, and sedimentation

WRF：混凝剂介导的污染物去除的实验观察和建模：絮凝、絮凝层和沉淀

• 批准号: 1704472
• 负责人: Edwin Cowen
• 金额: $ 33万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1704472&HistoricalAwards=false
• 关键词: WRF; Experimental; observation; modeling; coagulant

PI Name: Monroe L. Weber-ShirkProposal Number: 1704472Flocculation is a core process used to convert water from rivers, streams, and reservoirs into safe drinking water. In the flocculation process, particles and some dissolved contaminants stick together and form large aggregates that can be removed by sedimentation. Although flocculation is the workhorse of surface water treatment, it is not well understood, and thus it has not been possible to optimize the design of the nation's drinking water treatment infrastructure. The PIs plan a detailed investigation of particle aggregation mechanisms that operate under decreasing mixing conditions (tapered flocculation) as a technique to enhance performance as measured by particle removal in drinking water treatment. Preliminary studies indicate that the proposed tapered flocculation design has the potential to decrease contaminant loading to filters by a factor of 10, which would significantly reduce operation and maintenance costs for drinking water treatment.Models produced by the PIs indicate that flocculation performance as measured by settled water turbidity is the most significant limiting factor for current treatment process sequences. In flocculation the increasing separation distance between flocculating particles, as the flocculation process proceeds, limits high rate flocculation/sedimentation from producing water with particle concentrations less than a few mg/L. The primary goal of this investigation is to increase the number of particles flocculating by lowering the relative velocity of particles at the moment of collision through a stepwise decrease in mixing intensity. A decrease in velocity gradient enables aggregates that had previously reached maximum size to have successful collisions with smaller particles. Thus, each time the fluid deformation rate is decreased, the distance between growing particles is decreased, and non-settleable particles have an additional opportunity to be transformed into settleable particles. Experiments will be carried out on pilot treatment plants with differing flow rates and imaging capacities. These experimental units have the combined capacity to vary velocity gradients and image flocs to determine size distribution in both influent and effluent. This experimental design has the capability to investigate tapered flocculation in hydraulic and floc blanket flocculators with varying residence time, velocity gradients, and energy dissipation rates to determine optimal flocculation design. The research performed under this project will be integrated into Cornell?s AguaClara program, which was initiated over a decade ago for developing low-cost water treatment technologies so that communities can self-finance and sustainably operate municipal water treatment plants. The tapered flocculation technology has the potential to significantly lower the cost of high quality water treatment and enable the development of lower cost treatment plants to protect the health of the approximately two billion people who do not yet have access to safe drinking water.

项目名称：Monroe L. Weber-ShirkProposal Number: 17044772絮凝是将河流、溪流和水库中的水转化为安全饮用水的核心过程。在絮凝过程中，颗粒和一些溶解的污染物粘在一起，形成大的聚集体，可以通过沉淀去除。虽然絮凝是地表水处理的主力，但人们对它的了解并不充分，因此不可能优化国家饮用水处理基础设施的设计。pi计划详细研究在减少混合条件下运行的颗粒聚集机制（锥形絮凝），作为一种技术，通过测量饮用水处理中的颗粒去除来提高性能。初步研究表明，提出的锥形絮凝设计有可能将过滤器的污染物负荷减少10倍，这将显著降低饮用水处理的运行和维护成本。由pi建立的模型表明，以沉淀水浊度衡量的絮凝性能是当前处理工艺序列中最重要的限制因素。在絮凝过程中，随着絮凝过程的进行，絮凝颗粒之间的分离距离越来越大，这限制了高速率絮凝/沉降产生颗粒浓度小于几mg/L的水。本研究的主要目的是通过逐步降低混合强度来降低颗粒在碰撞时刻的相对速度，从而增加絮凝颗粒的数量。速度梯度的减小使先前达到最大尺寸的聚集体能够与较小的粒子成功碰撞。因此，每次流体变形速率减小，生长颗粒之间的距离减小，并且非沉降颗粒有额外的机会转化为可沉降颗粒。实验将在不同流速和成像能力的中试处理厂进行。这些实验装置具有改变流速梯度和成像絮凝体的综合能力，以确定进水和出水中的粒径分布。该实验设计能够研究水力絮凝器和絮凝毯絮凝器在不同停留时间、速度梯度和能量耗散率下的锥形絮凝，以确定最佳絮凝设计。在这个项目下进行的研究将被整合到康奈尔大学？该项目于十多年前启动，旨在开发低成本的水处理技术，使社区能够自筹资金并可持续地运营市政水处理厂。锥形絮凝技术有可能大大降低高质量水处理的成本，并能够开发成本较低的处理厂，以保护尚未获得安全饮用水的大约20亿人的健康。