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DESIGN-ORIENTED REVERSE OSMOSIS MODEL John F. Metzger, Graduate Student Donald Angelbeck, Associate Professor Civil Engineering Department University of Toledo Toledo, Ohio 43606 Over the past decade, effluent discharge standards have become increasingly more stringent. In some industrial categories, even zero discharge has been proposed as best available technology. As such, zero discharge can consist of either a true reduction of hydraulically discharged water to zero through total recirculation systems or a discharge with suspended and dissolved contaminants (contaminant mass) reduced to levels equal to those in intake waters. In the case of total recirculation, dissolved solids must be continuously removed to control high dissolved solids levels that are caused by evaporative hydraulic losses within the system; otherwise, scaling or corrosive conditions will result. There are several methods of demineralization available: ion exchange, electrodialysis, evaporation and solvent extraction. Reverse osmosis may provide a significant advantage over the others in that the process can remove a wide range of chemical species including many dissolved organics that may have escaped removal by classical, upstream processes. Design of reliable, low cost, reverse osmosis systems present many difficult engineering problems. Some of these problems include: (1) fragile membrane support design to sustain differential pressures of 300 to 1500 psi, (2) separation of the high pressure feed and brine streams from low pressure product water, (3) development of high density packaging to minimize pressure vessel cost, (4) minimizing concentration polarization and fouling effects in feed channels, (5) overcoming parasitic pressure drops in feed, brine and product streams, and (6) development of low cost replacement membranes. Much of the research and development related to reverse osmosis in the past five to ten years has been done in the interest of desalting water supplies. These efforts have resulted in some innovative reverse osmosis system designs which have reduced many problems associated with widespread application of the process. The predominant problems related to wastewater treatment are, most probably, related to membrane stability and membrane fouling through concentration polarization and/or physical plugging. As in any field of rapidly increasing technological improvement, it may be safe to assume that reverse osmosis system improvements will be made, and as discharge standards require increasingly exotic treatment solutions, the practical design engineer will need accurate and unencumbered methods or models to represent the reverse osmosis system. Much information detailing theoretical aspects of reverse osmosis systems can be found in the literature. Lakshminarayanaiah [1], Friedlander and Rickles [2] and Rickles [3] have studied the process in some detail. However, little information is given offering design techniques and equations that are both reliable and easily applied. For example, a model devised by Tweddle et al. [4], involves eight equations for eight dimensionless quantities. Weber [5] offers a somewhat simpler approach, but this model requires an iterative solution of the primary design equations. The remainder of this chapter proposes a direct model that can potentially be used to design and operate reverse osmosis systems as well as to define operational field data. In its present form, this model successfully describes reverse osmosis systems. With future refinements, it should be an even more effective and simple tool for the theoretically complicated process of reverse osmosis. 785
Object Description
Purdue Identification Number | ETRIWC198280 |
Title | Design-oriented reverse osmosis model |
Author |
Metzger, John F. Angelbeck, Donald I. |
Date of Original | 1982 |
Conference Title | Proceedings of the 37th Industrial Waste Conference |
Extent of Original | p. 785-794 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-07-14 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 785 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | DESIGN-ORIENTED REVERSE OSMOSIS MODEL John F. Metzger, Graduate Student Donald Angelbeck, Associate Professor Civil Engineering Department University of Toledo Toledo, Ohio 43606 Over the past decade, effluent discharge standards have become increasingly more stringent. In some industrial categories, even zero discharge has been proposed as best available technology. As such, zero discharge can consist of either a true reduction of hydraulically discharged water to zero through total recirculation systems or a discharge with suspended and dissolved contaminants (contaminant mass) reduced to levels equal to those in intake waters. In the case of total recirculation, dissolved solids must be continuously removed to control high dissolved solids levels that are caused by evaporative hydraulic losses within the system; otherwise, scaling or corrosive conditions will result. There are several methods of demineralization available: ion exchange, electrodialysis, evaporation and solvent extraction. Reverse osmosis may provide a significant advantage over the others in that the process can remove a wide range of chemical species including many dissolved organics that may have escaped removal by classical, upstream processes. Design of reliable, low cost, reverse osmosis systems present many difficult engineering problems. Some of these problems include: (1) fragile membrane support design to sustain differential pressures of 300 to 1500 psi, (2) separation of the high pressure feed and brine streams from low pressure product water, (3) development of high density packaging to minimize pressure vessel cost, (4) minimizing concentration polarization and fouling effects in feed channels, (5) overcoming parasitic pressure drops in feed, brine and product streams, and (6) development of low cost replacement membranes. Much of the research and development related to reverse osmosis in the past five to ten years has been done in the interest of desalting water supplies. These efforts have resulted in some innovative reverse osmosis system designs which have reduced many problems associated with widespread application of the process. The predominant problems related to wastewater treatment are, most probably, related to membrane stability and membrane fouling through concentration polarization and/or physical plugging. As in any field of rapidly increasing technological improvement, it may be safe to assume that reverse osmosis system improvements will be made, and as discharge standards require increasingly exotic treatment solutions, the practical design engineer will need accurate and unencumbered methods or models to represent the reverse osmosis system. Much information detailing theoretical aspects of reverse osmosis systems can be found in the literature. Lakshminarayanaiah [1], Friedlander and Rickles [2] and Rickles [3] have studied the process in some detail. However, little information is given offering design techniques and equations that are both reliable and easily applied. For example, a model devised by Tweddle et al. [4], involves eight equations for eight dimensionless quantities. Weber [5] offers a somewhat simpler approach, but this model requires an iterative solution of the primary design equations. The remainder of this chapter proposes a direct model that can potentially be used to design and operate reverse osmosis systems as well as to define operational field data. In its present form, this model successfully describes reverse osmosis systems. With future refinements, it should be an even more effective and simple tool for the theoretically complicated process of reverse osmosis. 785 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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