Did you measure how many gallons came out each tubing per minute?Quote:
Originally Posted by sbedilion
Also check how the membranes are plumbed up, series or parallel?
Just a thought.
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Did you measure how many gallons came out each tubing per minute?Quote:
Originally Posted by sbedilion
Also check how the membranes are plumbed up, series or parallel?
Just a thought.
I would run the needle valve open so you maximize the flow across the membranes. This should improve the cleaning action. If you raise the pressure then a lot of the water will come through the membrane as permeate.
how much permeate to do the post-wash rinse?
It takes me about 30 minutes to rinse after a soap wash. I like to have 50 gallons on hand but if I remember correctly it is about 35 gallons.
Help me understand how membranes work. Wouldn’t I want to do the soap wash and rinse with the valve restricted so that it pushes soapy water through the membranes? If I do it with the valve open then won’t the stuff I’m trying to clean out stay in the flaps of the membrane?
Your thinking is correct however with membranes the best way to wash/flush them is to create turbulence across the membrane this loosens everything and allows it to flow out. The holes in the membrane are only large enough to allow water molecules to pass through. Sugar molecules are too large and cannot pass through but sometimes will get stuck under pressure. By leaving the needle valve open the flow will loosen everything kind of like a pressure washer on your driveway washing away the dirt.. Hope this helps.
I was thinking that dirt got down inside the membrane, but if I'm understanding you correctly then the dirt just stays on top of the membrane (the outside) and the open valve flushes the dirt away.Quote:
Originally Posted by hodorskib
If you think of a membrane like paper towels. The material is in a long sheet and there are millions of microscopic holes so small that only water molecules can fit through. Then it is rolled up and looks very similar to a roll of paper towels. There is a plastic cover placed on the outside and when pressure is applied the liquid is forced through all of these layers of the material. What goes through is pure water - permeate and what cannot pass through is concentrate. Here is short video that I have used to help my students understand the process - It is using salt water instead of sap but it is the same principal.
https://www.youtube.com/watch?v=4RDA_B_dRQ0
I also have a question with regards to the washing/rinsing - this will be my 2nd year with my homebuilt RO. During the season I do a permeate rinse after each day and then a rinse with our soft well water (I know some will say not to do use this, but our water is pretty good and honestly I think better than the permeate which might have a small amount of sugar in it) before each run or every other day when not running just to keep things fresh. I completed a soap wash with H20 Biomembrane at the end of the year and stored the membranes in a vessel of sodium solution. Just pulled them out and they were pretty good, slight odor - I probably could have used more solution or else changed it after 6 months. I ran a rinse and I'm now re-running a soap wash. Any benefit or harm/foul to leaving the soap in the RO/membranes until I am ready for first run this season and then rinsing it out before starting to concentrate? Would this help prevent bacteria growth before I run next time? Otherwise, my plan is to rinse out and then continue as if we were between runs, passing some clean water through it every other day until we start.
Great thread - appreciate everything. I’m jumping in on the RO bandwagon this year! With that, can any of you offer me some advice on the height placement of the pump? I’m reading some say it should be below the sap and watching videos where it is above the sap. In your opinions does it matter? Thanks for any advice you can offer.