Reverse Osmosis questions. (1 Viewer)

[RickD]

Question, I have an RO for drinking water that also uses a boost pump before the membrane, I have a 3.5gal holding tank. I want to add a DI canister and upgrade to a dual membrane drop the TDS and lower the amount of wastewater. I’m currently running 100 gpd.

In my mind I’m thinking run the membranes in parallel, and tee connector just before the water tank and install a check valve and a ball valve before the DI. See the image.

Wanted to know if anyone has this setup or what the plumbing would look like?

 

[kris4647]

[mention]Buckeye Hydro [/mention]


Sent from my iPhone using Tapatalk

 

[PorpoiseHork]

I have mine setup in water saver configuration similar to your schematic.

The waste water line from the first RO membrane feeds the secondary RO inlet. The product lines from both go into a t-fitting to join them together to one main line. This main line then branches off to a second set of valves. One line feeds to a alkalinity/mineral filter for drinking water. The second line feeds to the DI stages for aquarium water. With this I can filter drinking water or tank water as needed.

The waste lines is where it gets complicated. I have it setup so I can purge each RO membrane individually via inlet valves and t-fittings. This way I can isolate either the primary or secondary RO for purging after processing water.

When running at 72 psi this setup can easily produce about 350 gallons of drinking water at 10 TDS post mineral filter. The TDS after RO is only 1-2 TDS with 170-190 source, but the mineral filter raises it up slightly. or 320 gallons of 0-TDS water per day.


Shoot me a msg and I'll go over it in more detail with you if you want.

 

[RickD]

I have mine setup in water saver configuration similar to your schematic.

The waste water line from the first RO membrane feeds the secondary RO inlet. The product lines from both go into a t-fitting to join them together to one main line. This main line then branches off to a second set of valves. One line feeds to a alkalinity/mineral filter for drinking water. The second line feeds to the DI stages for aquarium water. With this I can filter drinking water or tank water as needed.

The waste lines is where it gets complicated. I have it setup so I can purge each RO membrane individually via inlet valves and t-fittings. This way I can isolate either the primary or secondary RO for purging after processing water.

When running at 72 psi this setup can easily produce about 350 gallons of drinking water at 10 TDS post mineral filter. The TDS after RO is only 1-2 TDS with 170-190 source, but the mineral filter raises it up slightly. or 320 gallons of 0-TDS water per day.


Shoot me a msg and I'll go over it in more detail with you if you want.

Thanks. I'll shoot you a PM.

 

[steveb]

@Buckeye Hydro

 

[Buckeye Hydro]

Hi Rick - did we talk on the phone today? I believe we did.

Russ

 

[RickD]

I'd

Hi Rick - did we talk on the phone today? I believe we did.

Russ

I posted here first then a few directed the response to you. Yes Russ, we spoke earlier. !

In summary to share the answers. A dual RO Membrane in series may not be advantageous to me because hardness would be a factor. Unless I was using a water softener, it would drastically shorten my membrane life. The schematic was similar to the documentation on your website. Other things to consider to check with the city water report on what type of disinfectant they use to add additional carbon as needed. Hopefully I covered it?

Thanks!

 

[decimal]

i sort of have the same setup as @PorpoiseHork. 3 stage pre filtration (1 micron spun, .5 micron carbon block X2), From there on it gets tricky. after the 3 stage, the line runs into an auto shut off valve and onward to the RO membrane. the post RO water then runs to a 3 way T with directional valve. Here i can send the post RO water either to the drinking water segment that consists of an additional pass through a mineral cartridge and then to a 5g storage tank. On its final way to the spout, it goes through an inline carbon filter. I can also flip the switch and send it to the dual stage DI filters for reef water skipping the mineral cartridge etc.

easy..

 

[steveb]

we be hitech red necks lol...

 

[PorpoiseHork]

we be hitech red necks lol...

Yep..





Almost time to replace the sediment filter too.

I tried, once mind you, to show my wife how to filter water for drinking if for any reason I wasn't at home to do so. I got as far as turning on the booster pump (second step) when her eyes glazed over and she swears she heard me speaking in binary or something similar at that point...

Since then I always make sure that there's at least a 5 gallon jug with filtered drinking water ready to go...

 

[decimal]

my family accuses me of "mansplaining" all the time.. its not my fault they don't understand that almost everything in our world is designed by engineering and verified through math and science sheesh..

nice set ups. its always interesting to see different approaches.

 

[PorpoiseHork]

my family accuses me of "mansplaining" all the time.. its not my fault they don't understand that almost everything in our world is designed by engineering and verified through math and science sheesh..

nice set ups. its always interesting to see different approaches.

Just tell them that you'd be more than happy to manspread on the couch to mansplain all this from your manlist while manterrupting them if they object or your manderstanding or bropriating them, and possibly manslam anyone who accuses you of being too mansorbed over all this...

On a different note, if you want to see a completely different approach at RO filtration. you need to see @Unlimited Color Corals RO setup.. hehe.

 

[Unlimited Color Corals]

Yeah, we have a targeted approach to the water purification process. EXCEPT for the high CO2 in the source water. The old vertex RODI systems ran the membranes in parallel to increase production and kept things at a 1:1 ratio or better with the booster pump. I learned through trial and error of figuring out what would work to get what I wanted to start with. I wanted the purest water I could possibly afford to produce in large quantities.

Houston’s water quality changes with the seasons as well so we change our approach earlier in the year to adjust for the higher concentration of phosphates in the source water then change out those cartridges later in the year adding more carbon during our “rainy” season. We find that during the rainy season the chloramines go through the roof as they dump chloramines into the water supply to account for the influx of water they are getting from the rainwater.

I am no professional like some of the major producers of RODI systems and I may do things a little different than they suggest but it is only after many years of trial and error and adjusting to the source water during each season to find out what works for us. I also do not use a traditional TDS meter I go to the micro sievert level.

 

[decimal]

In summary to share the answers. A dual RO Membrane in series may not be advantageous to me because hardness would be a factor. Unless I was using a water softener, it would drastically shorten my membrane life. The schematic was similar to the documentation on your website. Other things to consider to check with the city water report on what type of disinfectant they use to add additional carbon as needed. Hopefully I covered it?

Thanks!

looking at your schematic, i would venture to say you might have some issues in that the output pressure of membrane #2 will equal the output pressure from membrane #1. logic would dictate that a pressure valve will prevent #2 from backwashing into #1. the check valve can only be open or closed however so whatever membrane has more pressure will be the primary (and only) membrane in use. maybe someone can confirm?

I am no professional like some of the major producers of RODI systems and I may do things a little different than they suggest but it is only after many years of trial and error and adjusting to the source water during each season to find out what works for us. I also do not use a traditional TDS meter I go to the micro sievert level.

i must admit, it never considered changes in city water based on season but makes perfect sense. it took me years to get this thing set up and running the way it is now too. The auto shut off valve really threw me for a loop. It feeds the RO and pushes the clean water out too it was a little tricky to know whats coming out and now there is a possibility of cross contamination etc. the pressure check valves where the key and once the entire unit was evenly pressured, it works like a charm.

 

[RickD]

looking at your schematic, i would venture to say you might have some issues in that the output pressure of membrane #2 will equal the output pressure from membrane #1. logic would dictate that a pressure valve will prevent #2 from backwashing into #1. the check valve can only be open or closed however so whatever membrane has more pressure will be the primary (and only) membrane in use. maybe someone can confirm?

Yes, logically it would make sense. The only way to get equal pressure is to run them in parallel, but you aren't using the reject water to the second membrane. I think you would need to have a boost pump to make the second membrane more efficient or design it with permeate pumps and a higher rated boost pump after the pre-filters.

I haven't put in the second membrane yet, I want to test this solution first then try with a permeate pump (below). I did some modifications because the DI output was draining my refrigerator supply (water tank) . I either have to get a larger tank or put a ball valve (BV) in place when I'm creating DI water. (see diagram below)




My only issue right now is water pressure to the refrigerator is low. I might install a permeate pump to help increase the pressure or get a larger booster. I think the system I had was for 75gpd and the booster pump probably didn't push more than 60 psi (need another pressure gauge), I think Brett's pump has a higher output rating that he dialed in.

I might test this out with the Permeate and looking for one if someone has one. I may have spoken with @Buckeye Hydro about this, but it was suggested that permeate pump might be a better solution to the pressure problem and waste water. This is all a science experiment just to get better performance and less waste water. My TDS is at 220 (tap), 9 (after membrane) and 0 (after DI)