Membrane smells after washing

[SugarHill]

First of all this was the first year we used a RO so it's been a learning process. Attempted to store my membranes (2-4 inch) until next year. The other day and when I took the membranes out of the housing one had a really sour smell to it. The last time we actually used the RO I did a soap wash and then a rinse. It sat for over a week before I had time to tear the membranes out. Before I did take them out I did another warm water soap wash followed by a flush of 500 gallons of permeate. The wash/rinse cycle finished late at night so first thing the next morning I took out them membranes and thats when I discovered that one of them had the smell and the other one didn't. Do I need to wash the membranes again?

[maple flats]

I'd say yes. Did you do a soap wash, then acid wash, let set several days, then a soap wash and finally a long rinse? That is what my RO calls for. Mine is still in the acid set. Mine says to set for 2-4 weeks after season in the acid.

[SugarHill]

I did the soap wash, but not the acid wash. My equipment supplier did not say anything about the acid wash, he said to do a warm water soap wash and then a good rinse to clean them up. Do you let your membranes sit in the soap akaline wash water for a few days as well?

[Sunday Rock Maple]

The sour smell is organic fouling. If you store them in a sodium bisulfate solution in an air-tight container that should stop that. Then next season you can wash and rinse and start.

[RO_Guy]

Storing your membranes in the sodium metabisulfite solution will also prevent any mold or mildew from growing in them in the off season.

[Jeff E]

Agree with these last 2 comments. Follow your manufacturers recommendations, store in solution, and your set for next year.

[Brent]

I did the soap wash, but not the acid wash. My equipment supplier did not say anything about the acid wash, he said to do a warm water soap wash and then a good rinse to clean them up. Do you let your membranes sit in the soap akaline wash water for a few days as well?

The soap (alkaline ) wash is only to remove organics. The acid wash (like using acid in your pans ) is to remove the mineral build up. If he didn't tell you to do that at the end of each season, over a few years you'll lose performance and he'll get to sell you new membranes.!!!!

If you send the membranes for professional cleaning, they cycle them through alternate alkaline and acid baths until they get the specs back to original, or very close to it. I don't have 20 years with ROs yet but it looks to me like one acid bath (soak as noted above ) per season, should do it for
sugarmakers.

Then of coarse, the SMBS for off season storage.