A Systematic Investigation on Fouling of NF and RO Membranes by Complex Suspensions Containing Colloids and Dissolved Organic Macromolecules

纳米过滤（NF）和反渗透（RO）膜在胶体和有机大分子复合悬浮液中的污染研究由于世界范围内的水资源短缺，使得利用非传统水源生产饮用水成为一种有吸引力的饮用水供应方式，然而，目前NF和RO在这方面的应用在经济上是低效的，主要归因于膜材料的污染。改进需要阐明膜污染机理和膜性能的预测模型。虽然已经对膜污染进行了大量的研究，但几乎所有的机理研究都集中在单一的污染物类型上。这些研究的结果不适用于水和废水应用，因为这些系统中的结垢总是由胶体材料和溶解的有机大分子引起的，它们之间的相互作用可以显着改变彼此的行为。因此，我们认为，系统地研究NF和RO系统中含有胶体和溶解有机大分子的复杂悬浮液的行为，对于进一步开发这些水和废水应用技术是必不可少的。通过含有胶体和溶解的有机大分子的复杂悬浮液对NF和RO膜污染的大分子相互作用。研究计划基于三个假设：1）浓差极化层中胶体和大分子之间的相互作用阻碍了彼此的反向输运：2）溶解有机大分子的存在改变了胶体的表面性质，导致胶体相互作用的改变，从而改变了污垢层的性质; 3）颗粒输运和污垢层的形成受浓差极化和颗粒粘附两个耦合的物理化学过程控制。本项目将采用系统的理论和实验方法来量化重要的污染物-污染物和污染物-膜相互作用对膜污染的三个关键方面的影响：1）污染物的反向传输; 2）污染物在膜表面的沉积;和3）污染层的形态和水力阻力。这些相互作用将在纳米尺度上用原子力显微镜在各种溶液条件下测量。新的理论将被开发，以确定反扩散系数和沉积速率的基础上测得的相互作用势的相互作用污垢，并定量地将这些相互作用到污垢的传输模型和膜通量model.The拟议的研究旨在改善当前的技术可持续供水，这对全球水资源问题具有深远的影响。它具有很强的教育性。两名研究生和一些本科生将通过该项目获得研究培训。学生将在国家科学会议上发表演讲。膜过滤实验系统将被纳入研究生课程的实验室课程。为了达到更大的人口，这项研究将被介绍给高中生，大一本科生，并通过夏季科学学院计划，大一新生的方向班，和一系列关于纳米技术和可持续发展的公开研讨会当地社区。

ABSTRACTA Systematic Investigation on Fouling of NF and RO Membranes by Complex Suspensions Containing Colloids and Dissolved Organic MacromoleculesThe world-wide water shortage has made drinking water production from non-traditional sourcesusing nanofiltration (NF) and reverse osmosis (RO) an attractive option of potable water supplies.However, current applications of NF and RO for this purpose are economically inefficient, largely attributed to the fouling of membrane materials. Improvement requires elucidation of fouling mechanisms and predictive models for membrane performance. Although considerable research has been done on membrane fouling, almost all mechanistic studies have focused on a single foulant type. Results from these studies are not applicable to water and wastewater applications because fouling in these systems is always caused by both colloidal materials and dissolved organic macromolecules, the interactions between which can significantly alter the behavior of each other. Therefore, a systematic investigation on the behavior of complex suspensions containing colloids and dissolved organic macromolecules in NF and RO systems is imperative to further development of these technologies for water and wastewater applications.The overall project objective is to determine and quantitatively describe the effects of colloid-macromolecule interactions on fouling of NF and RO membranes by complex suspensions containing colloids and dissolved organic macromolecules. The research plan is based on three hypotheses: 1) The interactions between colloids and macromolecules hinder the back transport of each other in the concentration polarization layer; 2) The presence of dissolved organic macromolecules changes the surface properties of the colloids, leading to changes in colloidal interactions and consequently fouling layer properties; 3) The particle transport and fouling layer formation are governed by two coupled physical chemical processes: concentration polarization and particle adhesion. This project will take systematic theoretical and experimental approaches to quantify the effects of important foulant-foulant and foulant-membrane interactions on three key aspects of membrane fouling: 1) foulant back transport; 2) foulant deposition on the membrane surface; and 3) morphology and hydraulic resistance of the fouling layer. These interactions will be measured at nanoscale with atomic force microscopy under various solution conditions. New theories will be developed to determine the back diffusion coefficient and deposition rate of interacting foulants based on the measured interaction potentials, and to quantitatively incorporate these interactions into a foulant transport model and a membrane flux model.The proposed research aims at improving current technologies for sustainable water supply, which has profound broader impacts on global water resource issues. It has a strong educational component. Two graduate students and a number of undergraduate students will obtain research training through the project. Student presentations will be made at national scientific meetings. The membrane filtration experimental system will be incorporated into the laboratory sessions of a graduate level course. To reach a larger population, the research will be introduced to high school students, freshman undergraduate students, and the local community through the Summer Science Academy Program, the freshman orientation class, and a public seminar series on Nanotechnology and Sustainability.