Can plugged 400gpd membranes be saved

[mi-maple]

I built a small to this year that worked fantastic. I only used 3 400gpd membranes due to budget. I did not have the proper ro soap and acid wash but did permeate flushes often and a few peroxide cleanings. I'm done for the year now but at the end I couldn't get near as much permeate even after flushing. it would get better but still very slow. My question is if I get the right soap and acid to clean them, could they be brought back to life to use next year? thanks

[wobbletop]

From reading another thread, the soap wash clears out the sugars, and the acid wash clears out the minerals. So I would think it would be able to be brought back. You'll need the chemicals at some point anyway, so might as well buy them and try.

[Russell Lampron]

If you get the RO soap and acid you can do an acid wash and multiple soap washes and get the flow rates back. Depending on how plugged up they are you may not be able to get them back to 100% but it's worth a try. I do it to mine following the instructions on the acid and soap containers with good results.

[Greg MacWilliam]

warm water 110 degrees will help, let circulate for a couple of hours.

[mi-maple]

Thanks for tips. Would I be better off recirculating to get my sugar up? I ran the 3 in series and was getting 7-7.5% in 1 pass. maybe that's fouling them quicker.

[bowhunter]

The membrane will foul even if the flow rates and the recovery are at the desired levels, however you probably do need to recirculate to get the flows up to satisfy the manufacturers recommendations. If you send me a private message with a little more information I can maybe give you some advice about required flows and recirculation rates. I need to know the brand and model number of the membranes, the size of the pump, brand and model number and how much sap per hour you are trying to process.

It looks like you've gotten good recommendations on cleaning the membrane. I would highly recommend you start with a warm water flush out using water that is no hotter than 110 degrees F. You will get a lot of clear slimy sugar out of the system this way. You may have to do this several times. After you are no longer getting out any slimy stuff using warm water washes you can start doing soap washes. Follow the directions on the soap. As a general rule keep the pH at 12 or less and the soap wash should not exceed 110 degrees F to prevent damage to the membrane. Make sure you don't use city water as the chlorine in the water can damage the membrane. Well water or rain water are both fine. You may have to do 2-3 soap washes. After you get all the organic material out with the soap you can do a citric acid wash to remove any mineral deposits. The membrane needs to be stored in a preservative solution of 1% sodium metabisulfite and water after it is clean. You can test the membrane on clean water and see how much permeate you get at 100 psi on well water. The permeation rate for water is very sensitive to the water temperature so don't be alarmed if the rates as less than the rated flows on colder water. A typical membrane will pass 3% less permeate per degree F below 77 degrees F, so if your water temperature is 70 F it will only do about 80% of it's rated capacity.