Post your RO/DI waste water ideas!

[Me No Nemo]

Mike (Mflamb) brought up an excellent point. With water shortages a constant concern, the waste water dispersed from your unit is a valuable resource that can be put to many uses.

We run our waste line through the wall and into a Rubbermaid tank in our yard. We use it to water plants and fill our pond. Any other ideas?

 

[jenlovesty]

I have heard of people using the waste in their washing machines. We keep the excess in a container outside for the flower beds.

 

[skinnyjoe1976]

run mine through the wall and it is intalled on mirco style sparyers for the plants

 

[mfp4073]

I let it go into the drain, into the septic and into the ground....its like the circle of life!

 

[plyle02]

I use it to fill my washer, and to feed my plants. Works well for both IMO....

 

[jsl6v8]

water my plants, and drive the pool guy nuts, why is there so much algae build up in the pool?! Well not anymore, one day my aunts go oh the pool guy said the algae problem could be from the RODI waste water, to which I respond "could have told you that."

 

[wardworld]

I drain my through a soaker hose for some shrubs, plus we sometimes fill up a garbage can for my wife's pond.

 

[Me No Nemo]

<a href=showthread.php?s=&postid=10026752#post10026752 target=_blank>Originally posted</a> by jsl6v8
water my plants, and drive the pool guy nuts, why is there so much algae build up in the pool?! Well not anymore, one day my aunts go oh the pool guy said the algae problem could be from the RODI waste water, to which I respond "could have told you that."

Wow, never heard of having problems with algae...I know lots of people who use theirs for pool topoff. If we didn't have a 3500 gallon pond to top off, we would probably be using it for the pool as well. Our pond doesn't have any algae either from the waste water use. You sure that's what's causing the algae? Wouldn't the chlorine take care of that?

 

[jsl6v8]

problem stopped as soon as we stopped adding waste water.

 

[ben&bobbi]

washing machine here too.

 

[Lutefisk]

Add a second RO membrane from the waste of the first membrane and make a big difference to your product to waste ratio. (And then drain to your garden, washer, etc.)


Here is a hypothetical to what your water savings would be.

With a 1:4 product to waste ratio:

With one RO membrane:
5 gallons of water input to produce 1 gal. product and 4 ga. waste. 5:1.

Second RO membrane:
4 gal. in and output at 1:4 ratio = .8 gal. product and 3.2 gal. waste

This would increase the product to waste ratio in our hypothetical situation from 1:5 to 1.8 to 5, an 80% efficiency increase.

But, what about the increased TDS coming into the second membrane?

My incoming TDS runs about 350-375 ppm with my RO output running 7-8 ppm.
(Incoming TDS - Product TDS)/Waste to product ratio = approx increase in incoming TDS to second membrane.

(375-7)/4=92 ppm TDS increase to each gallon of waste (At a little better than a 98% rejection ratio)

That would put the TDS coming into the second membrane at about 467 ppm. There are a lot of reefers that would love to have water that good.

With a 1:3 product to waste ratio:

<indent>Waste from first stage (375-7)/3= 122.7 ppm TDS increase to each gallon of waste (498 ppm TDS to the second RO â€"œ still pretty good!)

At a 98% rejection rate the second RO output would be around 10 ppm â€"œ still not bad.
Output from the second RO stage would be .75 gal. product to 2.25 gal. waste.

The overall system efficiency would increase from 1:4 to 1.75:4 a 75% efficiency increase.

For the nit pickers, it will result in a slightly higher product TDS due to the increased TDS entering the second RO membrane resulting in a slightly increased DI depletion per gallon but that is nearly negligible.</indent>

An additional bonus:
More than making up for that additional DI cost side, you nearly double the life of your filters and carbon since the everything going to the second membrane has already been filtered.

Of course the ultimate water saving systems are like the Kold Steril units with no waste water (but plenty of lye and acid to dispose of when recharging the resin).