GOALI: In situ generation of two phase flows to eliminate membrane concentration polarization and fouling

PI名称：Darrell VeleolProposal编号：1705278膜技术，特别是反渗透(RO)技术，目前处于从海水、微咸水和废水等较低质量水源净化水的前沿。该项目的目的是通过在膜表面产生氧气来阻止膜上生物膜的生长，从而最大限度地减少膜污染。生物污染对海水淡化膜性能的负面影响最大。这项基础研究有可能通过显著降低膜的能量消耗和延长膜的使用寿命来改变膜的性能。学习的基本原则有望导致可扩展和商业可行的解决方案，并可以改善市政和工业水处理，以帮助满足国家对饮用水日益增长的需求。大量的努力集中在通过预处理、最小化浓差极化(CP)和减轻污垢来提高反渗透效率。目前的方法还不能很好地克服这一问题，特别是对于浓差极化问题；然而，利用原位产生的微气泡来扰动CP边界层的研究尚未见报道。假设在膜表面催化产生微气泡将产生局部微混合，这将显著减少浓差极化和颗粒-细菌-有机污染。为了验证整个假设和达到目标，必须回答三个重要的基本问题，并形成这项研究的智力价值：1)在给定特定催化剂类型、催化剂负载率、过氧化氢(H_2O_2)投加量和局部压力(即必须超过亨利定律溶解度)的情况下，微气泡的形成速度和微气泡尺寸分布是什么？2)对于给定的微气泡产生率和尺寸分布，由于浓差极化的不同微混合机制和膜污染物质的升空机理，微气泡的出水量增加了多少？3)对于给定的微泡产生率，在避免膜损伤的生产水平上，使用所产生的氧化剂(活性氧种)对形成生物膜的微生物的消毒能力是多少？这种方法是在膜组件(膜表面或间隔物)中加入催化剂，然后在膜操作期间，向膜表面注入将在膜表面产生微泡的过氧化氢或其他反应物的脉冲。这项工作的一个主要优点是随着时间的推移，通过膜的水通量增加。这项提议的更广泛影响集中在培养博士生(包括我们的NSF目标合作伙伴陶氏化学公司的实习)和本科生，以及技术商业化(与合作伙伴陶氏化学公司)。产生微气泡和产生局部微混合可以在商业规模上实现。博士和本科生教育以及实习和创业培训将成为学生体验的一部分。

PI Name: Darrell VelegolProposal Number: 1705278Membrane technologies, especially reverse osmosis (RO), are now at the forefront of water purification from lower-quality water sources such as seawater, brackish water, and wastewater. The objective of this project is to minimize membrane fouling by producing oxygen at the membrane surface to impede the growth of biofilms on the membrane. Biofouling has the largest negative impact on desalination membrane performance. This fundamental research has the potential to transform membrane performance by significantly decreasing the energy use of membranes and increasing their usable lifetime. The fundamental principles learned are anticipated to lead to solutions that are scalable and commercially viable and can improve municipal and industrial water treatment to help meet the growing national demand for potable water.Numerous efforts have focused on improving RO efficiency by pretreatment, minimizing concentration polarization (CP), and mitigating fouling. Current methods have not overcome the problem in a feasible manner, especially for concentration polarization; however, no study has been reported on the application of microbubbles generated in situ to disturb the CP boundary layer. The hypothesis is that catalytically generating microbubbles at a membrane surface will produce localized micromixing, which will significantly reduce both concentration polarization and particle-bacteria-organic fouling. To test the overall hypothesis and meet the objective, three important fundamental questions must be answered, and form the intellectual merit of this research: 1) What is the rate of microbubble formation, and the microbubble size distribution, given a particular catalyst type, catalyst loading fraction, hydrogen peroxide (H2O2) dosing profile, and local pressure (i.e., must exceed Henry's law solubility)? 2) For a given microbubble production rate and size distribution, what is the increase in water effluent due to the different mechanisms of micromixing for concentration polarization, and liftoff for membrane fouling species? and 3) For a given microbubble production rate, what is the disinfection capacity for biofilm-forming microorganisms using the produced oxidant (reactive oxygen species), at production levels that avoid membrane damage? The approach is to incorporate catalysts in the membrane module (either membrane surface or spacers), and then during the operation of the membrane, to inject pulses of H2O2 or other reactants that will produce microbubbles at the membrane surface. A primary figure of merit for this work is an increased water flux through the membrane over time. The broader impacts of this proposal focus on educating Ph.D. students (including internships with Dow Chemical, our NSF GOALI partner) and undergrads, as well as technological commercialization (with partner Dow Chemical). Producing microbubbles and generating localized micromixing could be achieved at commercial scale. Ph.D. and undergrad education as well as internships and entrepreneurship training will form part of the student experience.