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Combined fouling of pressure-driven membranes treating feed waters of complex composition.

机译：压力驱动膜的综合污染处理复杂成分的给水。

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摘要

Pressure-driven membrane filtration processes can serve as a reliable barrier for microorganisms, organics, precursors of disinfection by-products (DBPs), colloids, and other contaminants. However, membrane fouling impedes a wider application of membrane filtration technology. Because typical feed waters have complex composition and the pretreatment often can not guarantee a complete removal of foulants, different fouling mechanisms act simultaneously resulting in combined fouling. Although each of the individual fouling mechanisms has been extensively studied, there have been only very few studies examining the effect of combined fouling on membrane performance. The focus of this work is on identifying contributions of individual fouling mechanisms in the overall fouling process and on evaluating the synergistic effects stemming from interactions between individual mechanisms.;In Chapter 2, concentration of rejected salt at the membrane surface when colloidal particles were deposited on the membrane is determined experimentally based on measured salt permeability constant. This approach allowed for a clear identification of individual contributions of concentration polarization and colloidal fouling to the permeate flux decline.;In Chapter 3, a method based on a simple linear regression fitting is proposed and used to determine the type, the chronological sequence, and the relative importance of individual fouling mechanisms in the experiments on the dead-end membrane filtration of colloidal suspensions. For all membranes, flux decline was consistent with one or more pore blocking mechanisms during the earlier stages and with the cake filtration mechanism during the later stages of filtration.;In Chapter 4, a model is proposed for predicting the permeability of porous media consisting of fibers and spherical particles. The model combines Kozeny-Carman equation and Ethier's theoretical model to predict the permeability of the mixed media based on the permeability of the porous bed of particles alone and on the volume fraction of the fibers. The model prediction was found to be in accordance with the experimental observations for the fiber mass fractions of less than 50%.;Chapters 5 and 6 examine the effect of combined colloidal fouling and gypsum scaling on the performance of RO membranes. In Chapter 5, the effect of silica colloids on gypsum scaling is studied in a batch system. The results showed that silica colloids retarded the induction of gypsum crystallization and decreased the nucleation rate. It was also found that gypsum crystallization rate increased in the presence of silica colloids. Chapter 6 presents the first study on the combined colloidal fouling and gypsum scaling in RO membrane systems. A significant synergistic effect between gypsum scaling and colloidal fouling was observed.
机译：压力驱动的膜过滤过程可作为微生物，有机物，消毒副产物（DBP）的前体，胶体和其他污染物的可靠屏障。然而，膜污染阻碍了膜过滤技术的广泛应用。因为典型的给水具有复杂的成分，并且预处理通常不能保证完全清除污垢，所以不同的污垢机理会同时起作用，从而导致组合污垢。尽管已经对每种单独的结垢机制进行了广泛的研究，但只有很少的研究来研究组合结垢对膜性能的影响。这项工作的重点是确定单个结垢机制在整个结垢过程中的作用，并评估由于单个机制之间的相互作用而产生的协同效应。在第二章中，当胶体颗粒沉积在膜表面时，盐分在膜表面的浓度该膜是根据测得的盐渗透常数通过实验确定的。这种方法可以清楚地识别出浓度极化和胶体结垢对渗透通量下降的单独贡献。在第三章中，提出了一种基于简单线性回归拟合的方法，用于确定类型，时间顺序和单个结垢机制在胶体悬浮液死膜过滤实验中的相对重要性。对于所有膜，通量下降与早期过滤过程中的一种或多种孔阻塞机制以及后期过滤过程中的滤饼过滤机制是一致的。在第四章​​中，提出了一个模型来预测多孔介质的渗透性，该模型包括纤维和球形颗粒。该模型将Kozeny-Carman方程和Ethier的理论模型结合起来，根据单独的颗粒多孔床的渗透率和纤维的体积分数预测混合介质的渗透率。发现该模型预测与纤维质量分数小于50％的实验观察结果一致。第5章和第6章研究了胶体结垢和石膏结垢相结合对反渗透膜性能的影响。在第5章中，以批处理系统研究了二氧化硅胶体对石膏结垢的影响。结果表明，二氧化硅胶体延缓了石膏结晶的诱导，降低了成核速率。还发现在二氧化硅胶体的存在下石膏的结晶速率增加。第六章介绍了反渗透膜系统中胶体结垢和石膏结垢的综合研究。观察到石膏结垢和胶体结垢之间的显着协同作用。

著录项

  • 作者

    Wang, Fulin.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 214 p.
  • 总页数 214
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境污染及其防治;
  • 关键词

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