Recycling of water after Ion Exchanger Backwash

[gladkenn]

We are trying to reduce our plants consumption of water. I am planning to recover the water discharge from a Cation exchanger when its regenerating. Is this ok? Any contamination it might bring?

 

[GarySCWSVI]

About the only water you would want to recover would be the latter portion of the Slow Rinse cycle and the last half of the Fast Rinse cycle. The rest of the water will contain any of the cations that the resin exchanged and the excess of either Sodium, Potassium, HCl or H2SO4 depending upon the regenerant used.

Gary Schreiber, CWS VI
The Purolite Co.

 

[bimr]

Would be helpful if you would provide information on your application.

GarySCWSVI has present the options for saving water with the DI equipment. Have you thought about RO in front of the DI?

 

[DeltaCascade]

What do you do with the RO reject stream?

At risk of sounding obvoius, audit the demin plant (or softener, whatever it is) to understand it better first (eg: quality of each waste stream as regeneration progresses .. online conductivity data would provide insight). Make sure the demin plant is 'tuned up' (using the right amount of water and regenerants (NaCl or H2SO4?) in the first place, etc). Gary has certainly identified good opportunity ... commonly practiced where water is highly valued, so it is proven good opportunity at that!
Sounds worth pursuing. Good luck.

 

[cub3bead]

Do you have rinse recycle capabilities? It is one of the best ways to minimize both water consumption and wastewater generation.

 

[gladkenn]

I am planning to reuse the water recovery of backwash/fianl rinse as potable water. Meaning I will bring it back to the raw water storage tank for use the same as our raw water.
Does this make any sense in terms of the safety of water, ie. drinking it?
Thank you.

gladkenn

 

[cub3bead]

Are you sure that you want to accept the liability for this scheme? Remember Murphy's Law!

If you want to recover the water and do not have rinse recycle, send it to a cooling tower or some other water consumer on the site.

 

[GarySCWSVI]

I would not recommend using that for potable water. I would only recommend recovering it and reusing it for non-potable use. Part of the fast rinse cycle can contain high levels of sodium or potassium chloride for a softener and high chloride or sulphate levels from a demineralizer. Also, part of the backwash water will contain dirt and broken resin beads that will not be good for potable use.

Gary Schreiber, CWS VI
The Purolite Co.