How reverse osmosis system works

(Manoj Singh) #1

Reverse Osmosis works by using a high pressure pump to increase the pressure on the salt side of the RO and force the water across the semi-permeable RO membrane, leaving almost all (around 95% to 99%) of dissolved salts behind in the reject stream. The amount of pressure required depends on the salt concentration of the feed water. The more concentrated the feed water, the more pressure is required to overcome the osmotic pressure.

The desalinated water that is demineralized or deionized, is called permeate (or product) water. The water stream that carries the concentrated contaminants that did not pass through the RO membrane is called the reject (or concentrate) stream.
As the feed water enters the RO membrane under pressure (enough pressure to overcome osmotic pressure) the water molecules pass through the semi-permeable membrane and the salts and other contaminants are not allowed to pass and are discharged through the reject stream (also known as the concentrate or brine stream), which goes to drain or can be fed back into the feed water supply in some circumstances to be recycled through the RO system to save water. The water that makes it through the RO membrane is called permeate or product water and usually has around 95% to 99% of the dissolved salts removed from it.

It is important to understand that an RO system employs cross filtration rather than standard filtration where the contaminants are collected within the filter media. With cross filtration, the solution passes through the filter, or crosses the filter, with two outlets: the filtered water goes one way and the contaminated water goes another way. To avoid build up of contaminants, cross flow filtration allows water to sweep away contaminant build up and also allow enough turbulence to keep the membrane surface clean


(Sajjad Ahmad) #2

How filtration capacity of a RO plant is determined?
if we feed 100 liter of portable water how much liters of RO filtered water is obtained and how much is rejected?


(Manoj Singh) #4

For example if the recovery rate is 75% then this means that for every 100 gallons of feed water that enter the RO system ,u r recovering 75 gallon as usable permeate water and 25 gallon are going to drain as concentrate.Industrial RO system typically run anywhere from 50 to 85% recovery depending the feed water characteristics and other design consideration.


(Sajjad Ahmad) #5

is uv treatment is necessery after ro


(Manoj Singh) #6

UV rays kill bacteria and protozoa but their dead bodies remain in the water. RO filters bacteria, viruses, protozoa, nematodes,spores etc along with toxic ions like arsenic.
UV treatment is essential for maximum effectiveness and protection against bacteria. Its sole purpose is to kill harmful biological contaminants.


(Md.Asif Hussain) #7

1.How the UV set-up is installed along the line, is there any requirement to validate the UV set-up and it’s effectiveness?

  1. Is there any study required after fixing a new set-up replacing the old one?