Page 26 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Contents xxv

18.2 Gas Transfer Theory................................................................................................................................ 573
18.2.1 Equilibria .................................................................................................................................... 573
18.2.1.1 Henry’s Law................................................................................................................ 573
18.2.2 Kinetics....................................................................................................................................... 573
18.2.2.1 Diffusion ..................................................................................................................... 573
18.2.2.2 Adaptation of Fick’s Law to Two-Film Theory......................................................... 575
18.2.2.3 Surface Renewal Models ............................................................................................ 579
18.2.2.4 K L a as a Design Parameter......................................................................................... 580
18.2.2.5 Derivation of Working Equation ................................................................................ 580
18.2.3 Reactor Modeling....................................................................................................................... 583
18.2.3.1 Continuous-Flow Complete-Mix Reactor Modeling for Gas Transfer ...................... 583
18.2.3.2 Batch Reactor Aeration Modeling.............................................................................. 584
18.2.3.3 Column Reactor Modeling ......................................................................................... 585
18.2.3.4 Column Reactor Modeling: Packed Beds................................................................... 588
18.2.3.5 Effect of Gas on K L a and Uptake=Stripping Effects.................................................. 588
18.3 Design...................................................................................................................................................... 589
18.3.1 Aerator Design............................................................................................................................ 589
18.3.1.1 Algorithm for Aerator Sizing...................................................................................... 589
18.3.1.2 Oxygen Transferred per Unit of Energy Expenditure................................................ 591
18.3.2 Equipment................................................................................................................................... 591
18.3.2.1 Reactor Types ............................................................................................................. 592
18.3.2.2 Turbine Aerators ......................................................................................................... 592
18.3.2.3 Diffused Aeration........................................................................................................ 594
18.3.3 Operation .................................................................................................................................... 597
18.4 Case Studies............................................................................................................................................. 597
18.4.1 Fine-Bubble Diffusers ................................................................................................................ 597
18.4.2 Air Stripping............................................................................................................................... 597
18.4.2.1 Sydney Mine at Valrico, Florida ................................................................................ 597
18.4.2.2 Well 12A: City of Tacoma, Washington.................................................................... 597
18.4.2.3 Wurtsmith AFB: Oscoda, Miami................................................................................ 599
18.4.2.4 Hyde Park Superfund Site, New York ....................................................................... 599
Problems............................................................................................................................................................. 599
Acknowledgments .............................................................................................................................................. 601
Appendix 18.A: Onda Coefficients ................................................................................................................. 602
18.A.1 Onda Correlations....................................................................................................................... 602
18.A.2 Onda Equations .......................................................................................................................... 602
Glossary.............................................................................................................................................................. 603
References .......................................................................................................................................................... 604

Chapter 19 Disinfection ........................................................................................................................................................ 607

19.1 Fundamentals........................................................................................................................................... 607
19.1.1 Microorganisms and Diseases.................................................................................................... 607
19.1.2 Disinfectants ............................................................................................................................... 607
19.2 History ..................................................................................................................................................... 607
19.2.1 Chlorine ...................................................................................................................................... 607
19.2.1.1 Story of Chlorine ........................................................................................................ 607
19.2.1.2 Disinfection Byproducts Issue.................................................................................... 610
19.2.2 Ozone.......................................................................................................................................... 610
19.2.3 Chlorine Dioxide ........................................................................................................................ 611
19.2.4 Ultraviolet Radiation .................................................................................................................. 611
19.2.5 Other Disinfectants..................................................................................................................... 612
19.2.5.1 Iodine .......................................................................................................................... 612
19.2.5.2 Bromine....................................................................................................................... 612
19.2.5.3 Silver........................................................................................................................... 612