RO washing procedure

[cjf12]

I bought a used nuts and bolts RO last year. Membrane was shot and passed sugar. Got a new MES 4040 for it and I am in the process of running it the third time this year.

I am thinking of washing it after this batch. I have savon super flow soap and citric acid both from CDL. No where on the label does it mention amounts. Interested in others technique to learn how to do this myself.
I have a ph tester but no calibration fluid to know it's working. I calibrated it last year but have not touched it since.. I also struggle with ph strips. How do you guys KNOW your on ph wise and won't ruin your membrane?
Is it necessary to worry if the soap is buffered? And is CDL soap buffered?

[SmellsLikeSyrupNH]

I have all of these same questions. The Lapierre soap also has no instructions :-(

[wnybassman]

I bought a used nuts and bolts RO last year. Membrane was shot and passed sugar. Got a new MES 4040 for it and I am in the process of running it the third time this year.

I am thinking of washing it after this batch. I have savon super flow soap and citric acid both from CDL. No where on the label does it mention amounts. Interested in others technique to learn how to do this myself.
I have a ph tester but no calibration fluid to know it's working. I calibrated it last year but have not touched it since.. I also struggle with ph strips. How do you guys KNOW your on ph wise and won't ruin your membrane?
Is it necessary to worry if the soap is buffered? And is CDL soap buffered?

I've been kinda feeling my way thru this myself. I have the same soap. I believe it is buffered. I use a 5 gallon pail of warm permeate. 1 1/2 tablespoons of powder makes Ph12 in the bucket, but by the time it dilutes with RO contents it knocks back to about Ph9 or little more. 2 tablespoons keeps it at 12. I wash with 100º water for a solid 30 minutes then rinse with your RO's recommended amount of permeate then make sure Ph is back to what your permeate is.

I found the Ph test strips to be easier to work with than I thought.

[Russell Lampron]

When I first got my RO in 2004 the manual that Lapierre gave me with it said to use 1/2 a container of soap to do a wash and that was it. It was written in Frenglish and the translation left a lot to the imagination. I learned from the good folks here and from trial and error that you gauge the amount of soap that you use by the ph of your wash solution. The amount of soap needed varies by wash tank capacity and the number and size of the membranes. I have a 4" membrane and use 2 oz. in 15 gallons of permeate to do a wash cycle adding more if needed if the membrane is really fouled.

An acid wash is whole different ball game and needs to be done when a soap wash won't bring your flow rates back. You do that by doing a soap wash and rinse first and then doing the acid wash. I don't remember the ph for the acid wash but think that it was around 2. When you've got the acid in the membrane you let it sit for 24 hours then rinse it out. After that you do another soap wash and rinse and then you're good to go. I find with my RO that a 50 gallon rinse will get the ph back to that of the permeate but I do at least 100 gallons just to make sure that all of the soap or acid is out of the membrane before I go on to the next step.

I do a soap wash after every time that I use my RO. I have 550 gallons of permeate storage and use what's left after I do a wash to rinse the machine.

[cjf12]

I do a soap wash after every time that I use my RO. I have 550 gallons of permeate storage and use what's left after I do a wash to rinse the machine.[/QUOTE]

How much are you processing at a time on average?

[Russell Lampron]

I do a soap wash after every time that I use my RO. I have 550 gallons of permeate storage and use what's left after I do a wash to rinse the machine.

How much are you processing at a time on average?[/QUOTE]

I process anywhere from 600 to 1200 gallons at a time depending on the sap flow. I do less than that too if the sap isn't running that good and I need to boil it to keep it from spoiling. I pump a lot of permeate down the drain on the big runs. I've got 725 taps.

[bowhunter]

You can use some common household things to check your pH meter. Vinegar has a pH 2 and soapy water is about 11-12. Your tap water should be 6.5 - 7.0. Dow recommends a pH of 12 and a maximum temperature of 95 F for cleaning the XLE membranes. The nanofiltration membranes such as the NF 270 and NF 90 need the pH to be 10.5- 11 max. These vary a little by manufacturer. I'm pretty sure the MES is not a nanofiltration membrane so you should be good to 12.

[fred]

what bowhuner said!! it says right on the containers ph of 12 for soap wash then every 4-6 wash you need to do an acid wash at ph of 2-3.

[maple flats]

I only do an acid wash if performance drops. In fact, I only do a soap wash unless I detect a problem about 2-3 times during the season. I always then do both after the season. The soap wash gets bacteria out, the acid wash gets minerals out. Most days I just do a warm (113-115F permeate wash after pushing cold permeate thru and into the heat tank for about 5-6 minutes. Then the permeate rinse, for at least 10 minutes but more often I let that recirculate for 15-20 minutes, then I do at least 5 minutes cold permeate rinse.
I did that method for 4 seasons, then sent my membrane in to Lapierre for their professional cleaning. The report came back that the membranes were actually a little over 100% (?, how can it be better than 100%). I have continued to do what worked the first 4 seasons. Thinking I may again send them in again after 2020 or 2021. That will then be 5 or 6 seasons.

[DrTimPerkins]

I only do an acid wash if performance drops. In fact, I only do a soap wash unless I detect a problem about 2-3 times during the season.

Soap washing removes microbial buildup on the membranes. There are two schools of thought on soap washing.

#1. Check your flow rates (corrected for temperatures). Don't wash after (or during) a concentration cycle unless your flow rates drop off by 20% or more. This approach is favored by organic producers, particularly with some certifiers, and particularly in Quebec.
#2. Wash after every concentration cycle. This is more common in the U.S.

Acid washing (typically citric acid) is typically only performed if flow rates are NOT restored by soap washing. As others have said, it is for mineral buildup. I know for sure that we've not done an acid wash on any RO we've had at UVM PMRC since at least 2004, so it isn't something that "needs" to be done by everybody (but we always have some around just in case). That said, there are some sites with far more minerals in the sap than others. One indicator of high minerals is RED RO wash water. If you see RED wash water, you might be looking at mineral build-up. The solution is to do a soap-wash and check the flow rates. If flow is not restored, do an acid wash. If you do have mineral plugging, it's best not to let it get too bad. We've heard of membranes being so badly plugged you can't get solution into them to dissolve the buildup.

Some formulations of soap and acid are buffered so they won't exceed the tolerances of membranes, some are not. Be sure to know which it is you have, and what membranes you have and what the manufacturer recommends for washing materials and procedures. Using what works for your neighbor might work....or might not, and might damage your membrane...or might not. Better to know what to do before you start.