Collaborative Research: Prechlorination, aging, and backwashing effects on spatiotemporal ultrafiltration fouling:  Optimizing productivity by combining experiments and theory

全世界约有40亿人每年至少有一个月严重缺水，超过5亿人全年缺水。 废水回收越来越多地被美国和世界各地的水务公司利用，以增加其饮用水供应。在许多废水回收厂中，中空纤维（HF）超滤（UF）膜系统与消毒预处理步骤（例如，氯化）以去除二级处理的废水中的悬浮固体，包括细菌、病毒和其它病原体。然而，过滤效率和水产量在操作期间降低，因为膜HF的孔被去除的悬浮固体堵塞。因此，废水回收系统的HF UF膜组件在其操作期间需要频繁清洗（每天多次）。该项目的总体目标是开发和验证新一代的数学和计算模型，这些模型可以指导HF UF膜系统的操作和优化，目的是最大限度地提高其产水量，同时降低废水回收过程中的能耗。为了推进这一目标，主要研究人员（PI）建议进行综合实验和建模研究计划，以建立和验证膜操作的数学/计算模型，考虑到膜组件的几何形状，纤维填充密度和氯预处理对HF UF膜系统的过滤效率和产水的影响。这项研究的成功完成将有益于社会，通过新的基础知识和建模工具的发展，可以指导废水回收厂的UF HF膜系统的操作，以提高和最大限度地提高水的生产，同时减少运行这些系统所需的能源。通过学生教育和培训，包括对佛罗里达州立大学、伍斯特理工学院和德克萨斯A M大学的三名研究生的指导，将为社会带来额外的好处。中空纤维（HF）超滤（UF）膜组件/系统越来越多地用于废水回收厂，以从二级处理的废水中去除悬浮固体、细菌、病毒和其他病原体。然而，经过验证的数学和计算模型，可以准确地模拟操作和性能的UF HF膜组件/系统的发展仍然难以捉摸。该项目的目标是从机制上了解HF UF膜组件/系统在多个时间和空间尺度上性能的时空变化。为了推进这一目标，主要研究者（PI）建议利用流体流动方程的解析解，从单根纤维开始，移动到以不同模式排列的“几根”纤维，以重现商业HF UF膜组件的几何形状和水力特性。此外，PI建议开发和验证一个计算模型，该模型可用于模拟HF UF膜组件的性能，目的是确定最佳操作参数，包括氯预处理浓度、正向过滤过程中的通量/压力制度以及清洁过程中的膜压力和运行时间。这项研究的成功完成有可能通过产生新的基础知识和经验证的数学/计算模型来指导废水回收厂中HF UF膜组件/系统的设计、操作和优化，从而产生变革性的影响。为了实现该项目的教育和培训目标，PI建议开发一个在线课程，以提高公众对水过滤和水再利用的认识，与Lifeology合作，Lifeology是一个汇集科学家，传播者和作家的平台，旨在设计和制作教育材料，以吸引更广泛的受众。此外，PI计划利用各自机构现有的推广计划，设计和实施K-12教师培训计划，重点是制定与水质和水处理相关的课程计划。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Worldwide, approximately 4 billion people experience severe water shortages at least one month per year and over 500 million people experience shortages throughout the year. Wastewater reclamation is increasingly being utilized by water utilities in the United States and worldwide to increase their supply of drinking water. In many wastewater-reclamation plants, a hollow fiber (HF) ultrafiltration (UF) membrane system is combined with a disinfection pretreatment step (e.g., chlorination) to remove suspended solids in secondary treated wastewater including bacteria, viruses, and other pathogens. However, the filtration efficiency and water production decrease during operation as the pores of the membrane HFs become clogged by the removed suspended solids. Thus, the HF UF membrane modules of wastewater reclamation systems needed frequent cleaning (multiple times per day) during their operation. The overarching goal of this project is to develop and validate a new generation of mathematical and computational models that could guide the operation and optimization of an HF UF membrane system with the aim of maximizing its water production while reducing its energy consumption during wastewater reclamation. To advance this goal, the Principal Investigators (PIs) propose to carry out an integrated experimental and modeling research program to build and validate mathematical/computational models of membrane operation that take into account the effects of membrane module geometry, fiber packing density, and chlorine pretreatment on the filtration efficiency and water production of an HF UF membrane system. The successful completion of this research will benefit society though the development of new fundamental knowledge and modeling tools that could guide the operation of UF HF membrane systems in wastewater reclamation plants to improve and maximize water production while reducing the energy required to operate such systems. Additional benefits to society will be achieved through student education and training including the mentoring of three graduate students at Florida State University, Worcester Polytechnic Institute, and Texas A&M University.Hollow fiber (HF) ultrafiltration (UF) membrane modules/systems are increasingly being used in wastewater reclamation plants to remove suspended solids, bacteria, viruses, and other pathogens from secondary treated wastewater. However, the development of validated mathematical and computational models that could accurately simulate the operation and performance of an UF HF membrane module/system has remained elusive. The goal of this project is to derive a mechanistic understanding of spatiotemporal variations in the performance of HF UF membrane module/system over multiple time and spatial scales. To advance this goal, the Principal Investigators (PIs) propose to leverage analytical solutions of fluid flow equations starting with a single fiber, moving to a “few” fibers arranged in different patterns to reproduce the geometry and hydraulic properties of a commercial HF UF membrane module. In addition, the PIs propose to develop and validate a computational model that could be used to simulate the performance of an HF UF membrane module with the goal of identifying optimal operational parameters including chlorine pretreatment concentration, the flux/pressure regimes during forward filtration, and the membrane backwash pressure and run time during cleaning. The successful completion of this research has the potential for transformative impact through the generation of new fundamental knowledge and validated mathematical/computational models to guide the design, operation, and optimization of HF UF membrane modules/systems in wastewater reclamation plants. To implement the educational and training goals of this project, the PIs propose to develop an online course to increase public literacy in water filtration and water reuse in collaboration with Lifeology—a platform that brings together scientists, communicators, and writers to design and produce educational materials to engage broader audiences. In addition, the PIs plan to leverage existing outreach programs at their respective institutions to design and implement K-12 teacher training programs with a focus on the development of lesson plans related to water quality and treatment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.