RO calculations 1

[mechMH]

Hi everyone,
i'm designing Reverse osmosis project, and i'm seeking some rule of thumb for the design calculation. as number of stages, vessels, flux and feed pressure.

 

[bimr]

A little help please. Freshwater, brackish water or sea water? Industrial or potable?

 

[mechMH]

isn't it according to the ppm?
let's say for brackish water or sea water, Potable.

 

[dbill74]

You need to know quality of water you are treating, what's the purpose of the treated water, how much is needed daily/weekly, etc.
Because these vary site-to-site, project-to-project, not sure how you can rule-of-thumb an RO system.

 

[mechMH]

i read once that for a 1500 ppm brackish water the operating pressure range from 150:400 psi.
so that's why i'm asking for rule of thumb.

 

[bimr]

i read once that for a 1500 ppm brackish water the operating pressure range from 150:400 psi.
so that's why i'm asking for rule of thumb.

Typical "rules of thumb":

Typical recovery rate is 75% then this means that for every 100 gallons of feed water that
enter the RO system, you are recovering 75 gallons as usable permeate water and 25 gallons are going
to drain as concentrate.

Typical flux rate is 16 Gfd. This means that 16 gallons of water is passed through each square foot of each RO membrane per day for brackish well water.

2 stage array is most common: In a reverse osmosis system an array describes the physical arrangement of the pressure vessels in a 2 stage system. Pressure vessels contain RO membranes (usually from 1 to 6 RO membranes are in a pressure vessel). Each stage can have a certain amount of pressure vessels with RO membranes. The reject of each stage then becomes the feed stream for the next successive stage. The 2 stage RO system displayed on the previous page is a 2:1 array which means that the concentrate (reject) of the first 2 RO vessels is fed to the next 1 vessel.

A RO system with properly functioning RO membranes will reject 90+% of most feed water contaminants.

RO systems are typically operated at pressures up to 17 bar (250 psig) for fresh or brackish water.

Typical vessels are 6-Inch to 8-Inch diameter.

RO Link