RO Waste Water - Run through a second membrane?

[btkrausen]

Trying to figure out an easy way to get more clean water quicker, without buying a higher rated RO membrane and restrictors, and I'm wondering if anybody has run their waste water from the first membrane into a second RO membrane. Figured it would give me more clean water without creating double the waste.

Thoughts?

 

[kuyatwo]

Brs sells kits to do what your asking adding second ro membrane. I think it depends on the psi also but they have info and video


Sent from my iPhone using Tapatalk

 

[Troylee]

Ro booster pump will give ya more.. I have a 35gpd Kent's hi-s unit and I bought a 65gpd membrane when it was time to change... There all interchangeable to the best of knowledge... What exactly are you trying accomplish??

 

[btkrausen]

First and foremost, I'm just trying to make RODI faster. But I was thinking about using the output to help conserve some water. If its better to do it with just a secondary membrane, I'm ok with that, since I'll waste the same amount of water...just faster...when I will be making 40gal at a time.

 

[Troylee]

Hmmm well don't quote me but I believe.... Your waste water from the first membrane is highly dirty and running it through a second membrane would kill it pretty quick IMHO... I could be wrong just my beliefs... I'm actually building some alkaline water machines at my new job and we have a recirc loop on the waste.. What I'm seeing is the membrane failing prematurely due to this... Granted there much larger than what we use there like 8" cylinders 2 ft long and good for 10,000 gallons... I would just by a 120gpd membrane when it's time it should make 40 gal in a few hours... Your looking into buying a membrane either way why not just get a faster one??

 

[mfdrookie516]

I asked about something similar to this on another forum with no luck... figure this is a good place to see. I was looking on BRS yesterday and saw this which claims to reduce waste by up to 80%. I can't find any reviews, and it looks like the only stipulation is that you have to have a pressurized storage container. If it really works, it might do what you're wanting.

 

[AZDesertRat]

Dual membrane systems will make water faster, provided you have a minimum of 65 psi available at the tap or a booster pump. They are never to be considered a water saving device as the membranes must still be flushed and since you are sending concentrated waste from the first membrane to the second it is even more important to keep the waste ratio at 3:1 or 4:1.


Permeate pumps do work as advertised and will cut waste significantly but as noted, you must have a pressure tank since this is what provides the backpressure to drive the pump since it is non electric. Other than that I suggest a capillary tube flow restrictor so you can fine tune your waste ratio according to your unique conditions and not depend on a "one size fits all" flow restrictor that is rarely correct and usually sends more water down the drain than necessary cutting the pressure available to the membrane and reducing efficiency and rejection rate. With the capillary tube you measure your exact production and waste then trim it according to your own results not some guess as the fixed ones are.

 

[-Logzor]

I bought the Bulk Reef Supply 150 gpd water saving upgrade kit, along with the booster pump. It snapped right onto my existing 75 gpd kit. Another poster mentioned a pressurized storage tank, I've never heard of that and I'm pretty sure it's not necessary for this application.

I can pump water twice as fast as before, definitely money well spent! Highly recommend the combination. Been running the same membrane since 2009, the additional membrane was added about a year ago. Still going strong.

Need to have at least 65 psi though, in my case I needed the booster pump.

 

[Blufgan]

Wt I know this is an old thread but I personally run three membranes and use a booster pump to achieve the high pressure needed to obtain the 65-70 psi required to run two membranes. When it comes to dirty water going into the second membrane a membrane flush kit is very important you should have one anyway. A flush kit Runs water at high pressure throughout your ro system and flushes scale and sediment out of your system a flush kit will prolong your membrane life.

 

[AZDesertRat]

Flush kits are really a waste of money in most cases and most people don't know how to properly use them to be of any possible benefit. First off, what is it you are trying to flush, when are you flushing, how often and for how long? In reality the flush kit does not neither the volume nor the pressure for any scouring action which requires more than a little 1/4" flow and bypassing the flow restrictor can provide.