Best way to use RO Reject water?

[GoBuckeyes]

We removed two Laserwash 4000's and reloaded the wash with Petit I-360's. When we had the 4000's we were using 100% of our reject water because of the way the HP pump tanks were plumbed. Currently our reject water is being mixed back in with the feed to our hot water boiler. Hot water is only being used for low pressure functions and as a result our reject tank is typically full with water going down the drain. Thats a lot of water to just throw away.

The Petit holding tanks have an extra bulkhead fitting where I could easily re-route my reject plumbing using some PEX and some float valves. I'm positive this would keep my reject tank empty and prevent any water from going down the drain. Reject water is softened but contains a lot of TDS. Is this the best way to utilize the reject water? If not, where would you plumb it into? Our rinse water is currently cold, hard water....would introducing some softened water with high TDS have any negative impact?

Thanks

 

[soapy]

I have been using the reject RO water for 25 years in the high pressure rinse cycle of my automatics. In reality you are probably putting a better grade of water in with your HP rinse water if you use the RO reject water this way.

 

[Buckeye Hydro]

Also - make sure your RO is dialed in regarding the pump pressure, recovery (permeate flow) concentrate flow, and recycle flow (if any). We often find when we do maintenance on RO systems that the owner has no idea how these variables should be set. That's the first place my mind goes if you're trying to limit the amount of concentrate production.

Russ

 

[soonermajic]

Also - make sure your RO is dialed in regarding the pump pressure, recovery (permeate flow) concentrate flow, and recycle flow (if any). We often find when we do maintenance on RO systems that the owner has no idea how these variables should be set. That's the first place my mind goes if you're trying to limit the amount of concentrate production.

Russ

Good advice, but didn't answer his question.

What's his best use of reject water, specifically for his Petit?

 

[Blanco]

I use a storage tank. Let RO reject fill storage tank. Pump that water back into water supply for HP pumps (SS/Auto) with a flojet and check valves. Using RO reject water is not going to hurt anything for rinsing.

 

[Greg Pack]

My RO reject water is not bad in TDS( around 300ppm IIRC). I dump my RO reject water into a tank that is as tall as my RO storage tank. From there I gravity feed it into the booster chemical pump which is ground mounted and used on my Istobal for all chemical production. Nothing is more reliable than gravity. My other auto is a water wizard and it uses the hydrominder tank setup and would require a booster pump to pressurize the water so I didn't bother with that. If the use of autos gets lopsided and the Istobal is not washing much for whatever reason some of the reject might overflow to the drain, but it's a very simple system requiring no pumps. I also plumbed in a sprinkler valve to keep the reject tank topped off but it developed a plumbing leak a few Months ago and I shut if off. The unit hasn't run out of water yet.

If you shop for a tank get a tall, skinny tank as opposed to a short fat one. Gravity gives you roughly .5 psi per foot of elevation, so a column of water 6' has roughly 3 psi coming out of the bottom of the tank. I briefly owned one wash where an operator built a metal stand and placed his reject tank over the RO storage tank, that is another option that would allow you to gravity feed into storage tanks with valves that don't require pressure like BOB valves.

 

[sparkey]

Also - make sure your RO is dialed in regarding the pump pressure, recovery (permeate flow) concentrate flow, and recycle flow (if any). We often find when we do maintenance on RO systems that the owner has no idea how these variables should be set. That's the first place my mind goes if you're trying to limit the amount of concentrate production.

Russ

The amount of concentrate you are producing isn't that big of a deal if you are reusing it anyways

 

[GoBuckeyes]

My RO production settings are fine and we already have a 300 gallon tank feeding a centrifugal pump that will max out at 60psi. The system worked excellent with our previous autos as the reject was blended with the water feeding the boiler. My old autos used more hot water than the Petits which kept the Reject tank empty. It sounds like replumbing the reject into the HP Holding tank is the way to go. The reject is in a separate equipment room so it will require about 50' of pex and two cheap float valves. Another thing added to the project list.