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Recommendations for RO system Pumps


BeasileyBub

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I've been looking at a permeate pump because I partially wanted to reduce the utilities footprint for my RO unit. Does anyone have any experience with these? From what I gather water is forced in one direction rather than driving the fore line pressure with an electrical pump. They are hypothetically supposed to improve the performance by 80% compared to a functional system, with no assists. My concern is that it wont' actually improve by such a large margin and that I'm better off purchasing an electrically driven pump. 

I need to spec out the specific permeate pump I would need for my system but here is a general idea of what I have been looking at.  
http://www.amazon.com/Permeate-Pump-Reverse-Osmosis-Systems/dp/B0038ZYG3G

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I'm not quite sure what you are talking about when referencing gravity and pressure. I'm not trying to overcome head pressure. The RO unit is installed and rather than adding additional components to the RO filtration system itself I want to use a permeate pump to reduce the waste water generated.

My question was whether or not people had issues with efficiency. Sometimes design ratings aren't always accurate, in my mind, and an 80% efficiency is reasonable but I just wanted to see if people were happy with their performance. 

I could decrease the amount of water wasted by adding electricity into the mix but would rather avoid using an electric pump to cycle water back into my line or hot water line. 

 

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I was confused with what you were asking. Thanks for clearing it up. Now I understand what you are trying to do.

 

Saving water is definitely a good idea. I know RODI units waste a lot, unless caught and re-purposed. I've never heard of people using a permeate pump for their RODI unit, but it sounds like a good idea. I am going to tag along and see what people say.

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  • 3 weeks later...

Permeate pumps are used to maintain consistent pressure across the system when the product water is being stored in a pressurized water storage tank. Like the little 3-5 gal "drinking water tanks"often sold with RO units.

 

Example. The white tank shown here

http://www.bulkreefsupply.com/brs-5-stage-drinking-water-ro-system-75gpd.html

 

As the pressurized water tank gets full it puts pressure on the product water coming out of the RO membrane this causes the membrane to lose efficiency and more waste water to be generated. The permeate pump uses the pressure of the waste water to keep the pressure on the product water consistent so as the water tank fills the efficiency stays the same.

If the water tank is empty then the permeate pump doesn't necessarily add value since there is no back pressure on the membrane.

Electric pumps increase pressure for systems that have low water pressure coming into the system or to increase the speed of water production of the membrane. If you are looking to reduce your waste water you would be better off adding another RO membrane being fed off the waste water of your first membrane.

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I have a pressurized storage container. From my understanding you are essentially converting lost energy by harnessing waste water pressure, forcing it through a one way valve, and using it to generate consistent pressure across the RO membrane. So yes the refresh rate is reduce but also the amount of waste water with the pump only functioning in one direction. I see no reason why you would want to maintain pressure across the RO membrane when it's in standby, so yes there is no added benefit from a standing permeate pump. My city water pressure is high enough I don't need a booster pump, per say. It's a matter of refresh rate versus waste water. So you still get waste water but it's a favorable enough ratio that you reduce your waste water without adding electricity into the equation. Or another membrane. I'm waiting to see how much my water bill reduces by before I decide to put on another ro membrane. It makes sense to add one but I want to see how efficient each component is first. Thanks for your input. 

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yes if you are using a pressurized storage container then the permeate pump will help reduce waste water. Typically the benefits are seen when the pressure in the storage tank reaches 2/3rds of the inlet pressure. This is where a typical auto shut off would slow water production and then turn off. The permeate pump will allow the water production to continue at the normal rate ( not slow thus not creating additional waste) and continue to fill the storage container until it reaches the same pressure as the inlet.

 

This is a good article about the permeate pump.

 

http://www.purewaterproducts.com/aquatec-permeate-pump

 

What I gather from this article is, if like me you usually turn on your RO unit to produce more water at a given time than what is typically stored in the pressure storage container (I usually turn it on to do about 10 gals at a time my container stores 3-5g) then the benefit won't be realized until I start filling the storage container again and the container reaches ~40psi (my inlet is about 60psi).

 

My process:

I open the valve on my product water (it's after the pressure tank) on my RO to fill a 10 gal top off container. The first 4 gals come out in a rush because it's stored in the pressure tank, when the pressure tank is empty the RO produces at its normal rate for the remaining 6 gals and it takes like 30 mins for my top off container to fill. Then I turn off the valve on the product water, the RO unit continues to produce, storing water in the pressure tank. For me I would not see a benefit to the permeate pump during this process until after I close the valve on the product water and the pressure tank starts filling and reaches 2/3rds pressure. The permeate pump would allow the RO to not slow at 2/3rds pressure and continue to store until the pressure equals the inlet. This would allow my pressure container to essentially store more than the ~4gals it normally does.

 

But if you typically only use less than what the pressure container stores. Say 2 gals at a time, then you are constantly in that zone of approx 2/3rds pressure that a permeate pump would be a benefit.

 

I hope that helps.

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  • 2 weeks later...

84eccb583729e40a2aabfb28f5c42684.jpg

 

8c3c5646564b582ef571c5af3fd9a4de.jpg

 

This is the coral I was making mention of. If you have an idea as to what it is that would be appreciated. As of now I don't have identification for it.

 

Ignore my obvious hair algae issue I have a sea hare hopefully sorting out the situation.

 

 

Sent from my iPhone using Tapatalk

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