View Full Version : Increasing recovery

02/28/2015, 05:40 PM
Is there something i can do to reduce my waste water percentage. i see most ro's run at 1:4 what can i do to get a better recovery:waste ratio.

03/01/2015, 11:48 PM
You can run dual ro membranes.

03/02/2015, 07:18 AM
Will that work? Or will i just make double the permeate and double the waste?

03/02/2015, 08:06 AM
The simple answer is...yes.
You can adjust your flow restrictor to obtain "less water waste".

Depending on your water conditions, you will reduce the lifespan and effectiveness of your membrane, and increase your non water cost related expenses such as DI costs, and membrane replacement costs.

Again, depending on your water conditions, there are other techniques (and hardware) to ameliorate the effects of reducing the waste ratio on your membrane. These include, but are not limited to:

-if you have a water softener, use that to feed your RODI system. This will reduce the harmful scaling of your membrane and again, extend the life and performance.

-a manual membrane flush kit which allows you to flush hardness components from the membrane to extend the life of the membrane. http://spectrapure.com/RO-RODI/ADD-ONS/Flush-Valve-Kit-w-1-4in-fittings

Or, if you want a system from the factory that is designed for high recovery:

single stage DI:

or dual stage:

or our highest recovery system:

Again, the first question I have when asked what can I do to improve recovery, is to find out what your water conditions are as that set of factors will determine what can be done to improve (cost effectively) your waste ratio.


03/02/2015, 09:48 AM
This is really interesting, i maintain a osmo 23g RO system and it make 8g of permeate and 2.0 of waste per min. it has a adjustable waste control valve and some ro's have a recirc from waste back to the feed. Ill try to add a waste valve to reduce my waste water, i know it will kill my membrane quicker but i think its work the water savings. I also currently temper my feed water to 77F.

does spectrapure sell a valve that will be appropriate to control the waste flow? or is it just a normal JG valve?

What do you think about adding a second membrane in series to the first membrane?

03/23/2015, 10:06 AM
You can use a simple ball valve.
That said, adding a second membrane is typically done in series, and has been for years. That is nothing new.
However, one must install the appropriate flow restrictor or risk premature failure of the downstream membrane as the hardness components collect on the downstream second membrane.

Essentially, nothing is for free, ie; a second membrane requires proper waste ratios or risk premature membrane failure. You can experiment first with simply adjusting your existing flow restrictor to reduce your waste and see if you still have suitable life of your membrane, and performance.

That said, if your local water conditions allow you to run with less waste water and you obtain suitable production and rejection, than good on you.