Double Pass Reverse Osmosis Systems
Double Pass Reverse Osmosis Systems are when the permeate water goes into a second RO unit to produce more pure water. Hence, a two or double stage RO is when the concentrate or reject stream is fed into a second RO system to recover water, respectively. So we design reverse osmosis system to purify water by rejecting around 99% of total dissolved solids from the feed water. Meanwhile, Single Pass RO Systems produce product water (permeate) and reject water (concentrate) at the same time.
How does a Double Pass RO System Work?
First of all, Double Pass Reverse Osmosis Systems are including of two RO systems (1st Pass and 2nd Pass). Wherein the 1st pass has a larger flow rate capacity than the 2nd pass. In between them, there can be middle storage tank. So either permeate or the concentrate water of the 1st pass RO is stored and fed into the 2nd pass RO for further filtration. Meanwhile, system need Pre-treatment to be provided for both the 1st pass and the 2nd pass RO systems if the application will be water recovery. Afterward, ss the quality of the concentrate water on the 1st pass should be bordering on the saturation point. On the other hand, an application might only require a 1st pass pre-treatment. If it’s being used as permeate to feed the 2nd pass accordingly.
Double Pass Reverse Osmosis Systems Flow Chart
Why do i use Double Pass Reverse Osmosis System?
Sometimes desired water TDS (total dissolved solids) level on the final permeate needs to be very less consequently. And maybe you cannot reach this value with one pass reverse osmosis system at last. It can be a combination of two brackish water RO systems or a sea water RO followed by a brackish water RO system accordingly. Some plants are starting to reuse water. Due to community pressure to minimize the use of either city supplied water. Or drawing water from raw sources, which dries up the aquifer of their area consequently. Since, these plants use double pass reverse osmosis systems to increase water efficiency of their systems. Single Pass RO systems can only recover up to 80% of the feed water by design accordingly. So, using a double pass reverse osmosis membrane technology can increase water recovery above 90%.
