An idea to eliminate waste water from RO/DI. Will it work?

[cryptics]

I have been thinking how much waste water I create making RO/DI and frightened to get my next water bill. I am going on the premise that waste water is actually not bad water just not RO/DI. From most that I read it is actually better filtered than tap. With that I have come up a plan I may try to at least somewhat implement. Feel free to blow it to pieces if I am completely off the mark. Just brainstorming won't take it personal

Here is what you would need

2 large containers (I am thinking about 35g Rubbermaid garbage cans)
RO/DI unit
RO/DI booster pump

optional
ATO

It is actually pretty simple fill the first container with tap water. Have the booster pump pull out of this container into the RO/DI. The RO/DI water goes into the second container and the waste goes back into the first. Then top off the first container as needed with tap. You can set the ATO to auto fill the first container and also shut off the pump if the second container is full.

This is a really simple concept but I think it will work and work without any waste since the waste water is cleaner than tap you never get a buildup in the first container of anything you don't want.

Let me know what I haven't thought of.

 

[qy7400]

Problem I see is whatever was in the waste water being recycled is now doubled in concentration the next go around, I'd guess it will work but burn up the RO membrane faster than normal.

Why not use the waste water for household use? Water the plants, laundry or mop bucket.

 

[cryptics]

Actually the waste water has less stuff in it than tap. The water has already gone through the carbon filters once.

 

[mbg75]

Actually the waste water has less stuff in it than tap. The water has already gone through the carbon filters once.

Not completely correct, yes some stuff was taken out, but u also removed approx 25% of pure water (RO out), so the rejected water has more concentrated solids than after the sediment filters, but before the membrane.
Try testing Tds on your waste water and you'll see.

 

[albano]

Not completely correct, yes some stuff was taken out, but u also removed approx 25% of pure water (RO out), so the rejected water has more concentrated solids than after the sediment filters, but before the membrane.
Try testing Tds on your waste water and you'll see.

+1... the waste water has already been filtered...how much more RO water do you expect to 'squeeze' out of it? IMO...Instead of wasting water, you'll be wasting electricity and possibly the filters.


.

 

[cryptics]

err my premise was that the waste water was actually "cleaner" than tap. If that is not true this won't work. I will test everything tonight and report. I'll test my tap water, RODI water (should be 0) and the waste water. I expect you are right though. Thanks for the input.

 

[bizzarro]

If you have a sediment and carbon block, your TDS is lowered before going into the RO. How can it be higher coming out?

I've tested this and it is lowered by a good amount where I took a taste test. It was too minerally for me instead i just use it for water changes on my 90G F/W.

 

[irvp13]

+1 waste water can go into another bucket and use to rinse your equipment after a maintenace or household stuff.

Problem I see is whatever was in the waste water being recycled is now doubled in concentration the next go around, I'd guess it will work but burn up the RO membrane faster than normal.

Why not use the waste water for household use? Water the plants, laundry or mop bucket.

 

[mbg75]

Not sure how much water costs where u are, but to run a booster pump, and replacing membranes and DI, might cost u more than wasted water. Unless your doing it to be more environmentally responsible.

Sent from my ADR6300 using Tapatalk

 

[albano]

If you have a sediment and carbon block, your TDS is lowered before going into the RO. How can it be higher coming out?

Referring to waste water...I would think, because it's more concentrated


.

 

[knockout]

+1
you can also add a second membrane and produce more water than with a single membrane and reduce waste

Why not use the waste water for household use? Water the plants, laundry or mop bucket.

 

[cryptics]

Not sure how much water costs where u are, but to run a booster pump, and replacing membranes and DI, might cost u more than wasted water. Unless your doing it to be more environmentally responsible.

Sent from my ADR6300 using Tapatalk

It does seem like a waste to me but my main reasoning is time. I was planning on getting the pump anyway because I have 150gpd unit but only get about 3gph because my pressure is around 42psi. I usually can only run the RODI at night of an hour or two so I feel like I am always making water for topoff (3-4g per week) and 10-15g for a weekly water change. With using the two cans and the RODI pump I was going to get anyway I could have it run while at work as long as i had an ATO stop the pump when the RODI bucket is full.

 

[knockout]

It does seem like a waste to me but my main reasoning is time. I was planning on getting the pump anyway because I have 150gpd unit but only get about 3gph because my pressure is around 42psi. I usually can only run the RODI at night of an hour or two so I feel like I am always making water for topoff (3-4g per week) and 10-15g for a weekly water change. With using the two cans and the RODI pump I was going to get anyway I could have it run while at work as long as i had an ATO stop the pump when the RODI bucket is full.

my boost pump shuts off automatically when the pressure builds inside the ro/di filter.
Are you planing in using an ATO and simply drip water over the top of the bucket and expect the ATO to stop the pump when full? I can see the ATO failing one day and you having LOTS of water running in your floor.
IMO the safest bet is to use a float valve to stop the flow of water into the container when full, this creates the pressure in the ro and shuts off the booster pump and is much cheaper than an ATO

 

[cryptics]

my boost pump shuts off automatically when the pressure builds inside the ro/di filter.
Are you planing in using an ATO and simply drip water over the top of the bucket and expect the ATO to stop the pump when full? I can see the ATO failing one day and you having LOTS of water running in your floor.
IMO the safest bet is to use a float valve to stop the flow of water into the container when full, this creates the pressure in the ro and shuts off the booster pump and is much cheaper than an ATO

That sounds like a much better idea. Thank you!

 

[cryptics]

Ok tests run

Tap 104ppm
RODI 0ppm
Waste water 94ppm

Of course this is a very limited subset so can't be taken as law. Tap was taken after running for 5minutes to clear any standing water in the pipes. The waste water was taken after running for 30 minutes.

 

[cryptics]

Would be great if others that making RODI could do a quick test on Tap vs. waste

 

[ed4]

Seems like a waste (no pun intended) just from the frighteningly diminishing returns.

 

[masterswimmer]

Would be great if others that making RODI could do a quick test on Tap vs. waste

Tap water = 105
Waste water = 175
Permeate water = 0

Russ

 

[Buckeye Field Supply]

Remember that the prefilters (sediment filter, carbon block) don't remove TDS.

The TDS in the waste water will be about 20% higher than the TDS in the tap water.

Russ