recirculating RO/DI

ejrabekoff

New member
I have an RO/DI unit, and was wondering if I could recirculate the waste water back through the filter. Any help would be greatly appreciated.
 
Also, test the TDS of the waste water, it will be higher than your tap because you removed some of the H2O and left the things that cause higher TDS.

If you keep recirculating the waste water the TDS will get higher and higher.
 
I have been checking into this as well. I am guessing that your wanting to reduce wasted water?

My goal has always been a TDS of 0 pmm. My tap is about 41ppm. Is 6ppm TDS your pure water?

I have a two stage RO system that runs the waste water of one RO membrane into another. This gets me a slightly better ratio of pure water to waste water by effectively doubling the output.

Another option for increasing the efficiency of your RO is a permeate pump. These come in very handy when you are using a storage tank that is pressurized. The permeate pump uses the pressure created by the waste water to "push" additional water into your storage tank. This allows higher efficiencies from your membrane and decreases your waste water production. Not many negatives except the pump makes a little noise sometimes. You would also want to use DI resins after the RO as the TDS is likely not perfect zero when using a permeate pump.

Another option is the zero waste RO systems that pump the brine (waste water) back into your hot water piping in your house plumbing. These systems are the most efficient but...the waste water goes back into the water you will use to wash dishes, clothes and shower with. :hmm1:

I have not use a zero waste unit. I have also not heard of anyone using one so very little feedback on the zero waste units. The permeate pump seems to work though.
 
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