Page 24 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Contents xxiii

Chapter 17 Membrane Processes .......................................................................................................................................... 539
17.1 Description............................................................................................................................................... 539
17.1.1 Membranes In-a-Nutshell........................................................................................................... 539
17.1.1.1 Analysis: Flow Balance Principle............................................................................... 539
17.1.1.2 Definitions................................................................................................................... 539
17.1.1.3 Acronyms for Membrane Materials and Membranes................................................. 539
17.1.1.4 Process Description..................................................................................................... 539
17.1.1.5 Membrane Technology............................................................................................... 540
17.1.1.6 Racks........................................................................................................................... 541
17.1.1.7 Treatment Train .......................................................................................................... 541
17.1.1.8 Operation..................................................................................................................... 541
17.1.2 Global Capacity.......................................................................................................................... 542
17.1.3 Membrane Types........................................................................................................................ 542
17.1.4 Membrane Materials................................................................................................................... 543
17.1.5 Membrane Structure ................................................................................................................... 543
17.1.5.1 Microporous Membranes............................................................................................ 543
17.1.5.2 Asymmetric Membranes............................................................................................. 543
17.1.6 Manufacturing ............................................................................................................................ 544
17.1.6.1 Flat Sheets................................................................................................................... 544
17.1.6.2 Tubes........................................................................................................................... 544
17.1.7 Packaging ................................................................................................................................... 545
17.1.7.1 Plate-and-Frame Modules........................................................................................... 545
17.1.7.2 Spiral-Wound Membrane Modules ............................................................................ 545
17.1.7.3 Hollow-Fiber Modules................................................................................................ 545
17.1.7.4 Flow within Membrane Element ................................................................................ 547
17.1.7.5 Ratings ........................................................................................................................ 547
17.1.7.6 Variations in Manufacturer’s Products ....................................................................... 548
17.1.8 Applications................................................................................................................................ 548
17.1.8.1 Particle Removals ....................................................................................................... 549
17.1.8.2 Removal of Organics .................................................................................................. 549
17.1.8.3 Removal of Cations and Anions................................................................................. 549
17.1.9 Pros and Cons............................................................................................................................. 549
17.1.9.1 Advantages.................................................................................................................. 549
17.1.9.2 Disadvantages ............................................................................................................. 549
17.2 History ..................................................................................................................................................... 549
17.2.1 Membranes in Science................................................................................................................ 549
17.2.1.1 Beginnings .................................................................................................................. 550
17.2.1.2 The Development Period ............................................................................................ 550
17.2.1.3 Modern Period ............................................................................................................ 550
17.2.2 Membranes in Water Treatment Practice................................................................................... 550
17.3 Theory...................................................................................................................................................... 550
17.3.1 Performance Variables................................................................................................................ 550
17.3.2 Solute=Particle Rejection............................................................................................................ 550
17.3.3 Models Describing Water and Solute Flux through Membranes .............................................. 551
17.3.4 Basic Notions for a Cross-Flow Membrane Element ................................................................ 551
17.3.4.1 Flow Balance .............................................................................................................. 551
17.3.4.2 Mass Balance and Pressures....................................................................................... 552
17.3.4.3 Water Flux Density..................................................................................................... 552
17.3.4.4 Solute Mass Flux ........................................................................................................ 552
17.3.4.5 Transmembrane Pressure ............................................................................................ 552
17.3.5 Poiseuille Law ............................................................................................................................ 552
17.3.6 Osmosis ...................................................................................................................................... 554
17.3.6.1 Osmotic Pressure ........................................................................................................ 554
17.3.6.2 Reverse Osmosis......................................................................................................... 554
17.3.6.3 Effect of Membrane Pressure on Water Flux Density ............................................... 555