Can i use an old RO?

[plecocicho]

Hello,
i have an old ro (was used for 2 years), that hasnt been used for little more than two years. I started it again today and the productivity and ratio were normal. The only difference is, that the permaet has a conductivity of 40 microsiemens (tap has 380 microsiemens) and GH and KH of 1,5. You think i could use this ro, or is the mebrane to damaged so the carbonates will creep over the use and can i use such permaet from the old ro? I plan to couple two membranes, so the waste water from the first would go into the incoming water for the second membrane, thus achieving higher production and decreasing waste ermaet ratio.

[DiscusLoverJeff]

I would change the membrane and filters and you will be good to go. The membrane if it sat dry for years is more than likely no good.

[nc0gnet0]

I plan to couple two membranes, so the waste water from the first would go into the incoming water for the second membrane, thus achieving higher production and decreasing waste permeat ratio.

You can do this, but you might be a bit disappointed in he results. One thing to consider, is the back pressure to the first membrane will be increased when you do this, and as a result will shorten it's life span. Better off getting a booster pump IME, or getting two additional membranes and a booster pump, feeding the waste water outs from two membranes into a third.

-Rick

[plecocicho]

So if i couple the two mebranes, the first one will suffer more, but not the second one? Can you elaborate more where should i put booster pump if i use one and where when i use two membranes?

[nc0gnet0]

So if i couple the two mebranes, the first one will suffer more, but not the second one? Can you elaborate more where should i put booster pump if i use one and where when i use two membranes?

Yes the first membrane will experience an increase in back pressure, this will "force" more water through the membrane causing is to "scale" faster. Commercial membranes do exactly this to get better product water to waste water ratio's, but they typically have automated flush timers to help with membrane life. The second membrane will also have significantly less pressure than the first, reducing it's output. I am not saying what you propose will not work, but there will be trade-offs and you will not get 2x the output water expected.

Booster pump should go inline prior to the pre-filters.

[plecocicho]

So it the first ro has a manual flushing valve, it can prolong membrane life?

[nc0gnet0]

In theory, yes. Bear in mind on the commercial units with increased backpressure they are flushed roughly every hour for 30 seconds.

[Buckeye Hydro]

Hello,
i have an old ro (was used for 2 years), that hasnt been used for little more than two years. I started it again today and the productivity and ratio were normal. The only difference is, that the permaet has a conductivity of 40 microsiemens (tap has 380 microsiemens) and GH and KH of 1,5. You think i could use this ro, or is the mebrane to damaged so the carbonates will creep over the use and can i use such permaet from the old ro?

All the existing filters should be tossed. The unit should be sanitized, and then new filters, including the membrane, loaded.

Russ

[plecocicho]

Well i finally got an ro with a flushing valve and the results scare me a little. On its own, ro with a valve (190l/day) gives me 10l of osmose water and 20 l of waste water (nominal 240l/day, 50 l more than it says). Coupled together with the second membrane i get 14 l of permaet and only 12 l of waste water! Permaet of the first osmosis has a conductivity of 20 microS, permaet of the second one 20 microS, waste of the first one 510 and combined waste (when coupled ) of 710 microS; tap water has a conductivity of 380 microS. So, when coupled i have a ratio, where i get more permaet than waste water. I used the coupled system twice (once 2h+, second one 1h+), both times i flushed the first osmosis for a couple of minutes.

[nc0gnet0]

bear in mind you have effetively increased the back pressure to the first ro membrane which in turn will force more water through that membrane. yes, you will have a net increase in product water, albeit at the expense of shorter membrane life. Be sure to flush the membrane often to help offset this.

To test this out, uncouple the second membrane althogether, and time how long it takes for the first membrane to output 2l of water (fill a soda bottle).

Then repeat the test, attaching the second membrane, but only timing the output of the first (with the second attached).

-Rick

( I am assuming that when you say you coupled the second membrane you are feeding it with the waste water out of the first).

[Buckeye Hydro]

Well i finally got an ro with a flushing valve and the results scare me a little. On its own, ro with a valve (190l/day) gives me 10l of osmose water and 20 l of waste water (nominal 240l/day, 50 l more than it says). Coupled together with the second membrane i get 14 l of permaet and only 12 l of waste water! Permaet of the first osmosis has a conductivity of 20 microS, permaet of the second one 20 microS, waste of the first one 510 and combined waste (when coupled ) of 710 microS; tap water has a conductivity of 380 microS. So, when coupled i have a ratio, where i get more permaet than waste water. I used the coupled system twice (once 2h+, second one 1h+), both times i flushed the first osmosis for a couple of minutes.

Yeow. Sorry but I'm having a hard time following your thoughts here. Again, if you'd like to give us a call when you are in front of your system we'd be happy to resolve all your questions.

Russ
513-312-2343

[plecocicho]

For a better understandment of what i am talking about.
Here is picture of the osmosis coupling, that i have, only with two differencies: i only coupled one extra osmosis, not three and secondly, my first osmosis has a flushing valve. The idea behind it is, that you invert the the waste water into the the second osmosis. By this way you get a higher yield (in my case even higher than waste water), but you shorten your membranes life. Thats why i use the flushing valve on the first osmosis.

Rick, if i use only one membrane i get to 2l in 12 minutes. I did test the outlet of both permaets and a waste water when both osmosis were connected. i counted how long would it take to fill 20 ml cup. First permaete and a waste water needed 14 counts (app. seconds), the second permaete took around 34-36 counts. Yes i flush after each use. How long shoud i flush it after each use and would a little opening of the flush vlave prolong membrane life (i didnt see any change in a flow of all effluents (permaete and waste ) when i fully opened the flush valve. ).
I hope i made my case clearer.

And Russ i am from Europe, Slovenia to be precise, so its a little expansive to call you. Appreciate the helping hand though.

[Buckeye Hydro]

You'll want to check the specks on the little taste and odor (GAC) inline filter and make sure you don't exceed the max flow rate. I'd change it out at about half the stated chlorine capacity.

[nc0gnet0]

I see 4 ro membrane housings? but only 1 sediment and 1 carbon block, is that correct?

If that is the case you need to upgrade your sediment/carbon block filtration, as Russ has stated.

[plecocicho]

No, i have only one extra membrane, not three like in the picture. Yes i only have one sediment and carbon filter, the water flows like this: tap valve-sediment filter-carbon filter-first osmosis-waste into the second osmosis. As a pressure, you mean if the filters cant take the full water pressure? Why would i need filters on rhe second osmosis, isnt waste water devoid of chlorine, small particles? Thanks