.
 Applied Membranes | Purchase Online |  Q & A | Technical Articles | Design Information | Search

Why Reverse Osmosis?

By: Gil K. Dhawan Ph.D., P.E., Applied Membranes, Inc.


To Remove Dissolved Solids

  • Calcium (Hardness)

  • Sodium

  • Sulfates

  • Others

Dissolved Solids

  • Evaporate Water

  • Residue Left

 REVERSE OSMOSIS VS. CONVENTIONAL FILTER      

 

RO

FILTER

Cross-Flow   

Yes

No

Dead-end

No

Yes

One liquid stream comes out

No

Yes

Dissolved solids      

Yes

No

Flushing action

Yes

No

Useful life

Long

Short

Pore Size

0.0001 micron

0.1 Micron (smallest)

* Although not a good use of RO for this purpose

What does RO do?

  • Permeate (Product)

  • Concentrate (Reject)

  • Impurities Are Concentrated

Osmotic Pressure

  • Created by ionic content of dissolved solids

  • Organics do not contribute significantly to the Osmotic Pressure

  • Rule of thumb:

                             Osmotic Pressure  =    TDS in PPM

                                   (PSI)                                100

 


                   OSMOTIC PRESSURE VS. CONCENTRATION

                                        Assume Feed TDS = 1000 PPM

      Reject Concentration =

100

Feed Concentration

(100-R)

 

Feed Flow
(GPM)

Permeate Flow (GPM)

Reject Flow (GPM)

Recovery (%)

Reject Conc. (PPM)

Osmotic Press. (PSI)

10

1

9

10

1,110

11.1

10

2

8

20

1,250

12.5

10

3

7

30

1,430

14.3

10

4

6

40

1,670

16.7

10

5

5

50

2,000

20

10

6

4

60

2,500

25

10

7

3

70

3,333

33.3

10

8

2

80

5,000

50

 

 
Back Home Up Next

 What is RO Why RO RO & Water Chemistry Suspended Solids Membrane Fouling Bio. Growth on Mem. Fouling Solutions Correcting Fouling Membrane Disinfec. Mistakes to Avoid Pretreatment Seawater Desalination Activated Carbon Filtration Factors Affecting Perf. Achieving Brine Efficiency Using Pyrolox Media Residential Systems Oxygen

Applied Membranes Product Selection Links:
[Reverse Osmosis Membranes] [Reverse Osmosis Systems][Home RO Systems][Seawater Desalination Reverse Osmosis Systems] [Media Filters, Carbon Filters, Water Softeners, Etc.] [RO Filters & Housings] [RO Membrane Housings/Pressure Vessels] [Residential RO Components] [Commercial RO Components] [RO Pumps] [Membrane Chemicals] [Ultravioloet (UV) Systems] [Ozone][Water Quality Testers  (SDI)]

 

All Content on this site is  intended for informational purposes for experienced water treatment professionals only.  Applied Membranes, Inc. does not assume any liability for any damages caused by the misapplication or misinterpretation of any of the information contained on this website.
Applied Membranes, Inc. 2007