which way is better to RO sap?

[red maples]

OK so here is a question on which way is better to RO sap which one would be less stressful on the membranes and more efficient.

Is is better to recirculate (for round numbers) a full batch of 1000 gallons of sap to lets say 15% or is it better to do that same 1000 gallons broken down to 250 gallons at at a time? considering you had proper tanks to do so and help to do so.

I was reading one of the RO papers on the issue (I think it was Steve Childs from cornell) he was talking about homemade RO's that he had done through the years as he got bigger he would RO in stages and they had stated that the when doing the smaller amount of the larger amount of sap that he had to the proper concentration it will take less time then, tranfser that to your feed tank and start boiling then start running the next batch through the RO which will in itself clean out some of the stuff in the membranes because its raw sap then repeat the process.

There was no comparison on doing it one way or the other.

I would think the only real thing that would be is timing since you are doing 2 things at once instead ROing everything at once then start boiling or your ROing while you boil.

Since its always just me boiling by myself I like to have everything concentrated then start boiling because then I can just concentrate on boiling and running the evaporator. I don't like to multitask too much while running to the evap.

I think its just a matter of preference and there really isn't better way but curious on what others thought about this.

[maple flats]

Since I don't have the tanks that I want to run stages in, I run thru the RO and send it to the head tank, from there I light the arch, but also open the valve to recirculate. I usually get about 7-8%, then I switch to recirculate. In that I often get to 12% +/- 2. My RO seems to plug if I go over 15%.
I think I may get more sap reduced faster if I lower the pressure a little on first pass, to get maybe 6%, then recirculate, but I haven't actuallt measured and timed it to be sure.

[S.S.S]

We run ours single pass through to our feed tank. 2 years ago we just had 1 membrane and it came out at like 10-12%. Last year we added a second membrane and now it comes out 20-23%

[bowhunter]

I'm a small producer so you can take my recommendation with a grain of salt. Your most efficient way to operate is to run both the RO and evaporator together. If you run the RO first you have to complete that step before you start boiling when you can be doing both at the same time. You have a good sized evaporator and I'm not sure about it's capacity but I know it will probably do over 50 gallons per hour. If you have 1000 gallons of sap and you can boil for 8 hours, you can boil 400 gallons of concentrate in an 8 hour day or 300 gallons of concentrate in a 6 hour day. You have a 300 gph RO which is probably capable of removing 2/3 of the water from 1000 of sap in a little over 3 hours. If it were me I would set the RO up to process 1000 gallons of sap in 6 hours yielding about 300 gallons of 6-8% concentrate. So the RO feed rate would be 165-170 gph of sap with the pressure just high enough to remove about 70% of the water and feeding concentrate directly through a small head tank into your evaporator. You can easily do it in two steps if running both the RO and evaporator at the same time is a problem, but I would not concentrate up to more than 8-10% otherwise you will only have 2-4 hours of concentrate to boil. It's much, much harder on the RO to run it up to 15%. The membranes foul much more quickly and you will have to run it at much higher pressure. And finally if you have to store concentrate the shelf life is shorter as you increase the sugar content.

[MapleMark753]

I too am a smallish producer, so x2 the above post relating to the grain of salt (lol...)
" help to do so " like the OP mentioned is key for me and us here. Most often its me doing the collecting, ROing, and boiling. No complaints, its good stuff/work. But I do acknowledge that just about everyone says to light the fire while you're ROing, and its much more efficient that way. Except for me probably. I've found that absent the extra help its much easier to make mistakes with both going. Embarrassing, but it is what it is. SO.... I just do it in stages. Collect. RO. Boil. One pass, or recirculate it to a bit more concentrated.
Good luck-- Mark

[maplemas]

I found it best to run my ro at equal gpm of perm/cons back in to my feed tank while I'm gathering then when I get ready to boil I crank it down to match my evaporation rate and send it to my head tank

[Russell Lampron]

I like to concentrate in batches of 300 gallons if I can. I run the first 300 through and when I get the concentrate output to 14% I open the valve from the raw sap tank and run another 300 gallons through. I let the concentrate mix and when the next 300 gallons is through it's first pass I recirculate the combined concentrate down to 14%. I send that to the head tank and start the next 300 gallons on it's first pass. On a normal night I will light the evaporator and by the time that I'm running out of sap in the head tank that next batch is ready to send up. If it's not ready I send up enough to keep the evaporator running and then recirc while I'm boiling that down and repeat the process until I'm out of sap. I find that the raw sap brings the flow rates back up and I can remove more water in a shorter amount of time than trying to process 900 gallons at once. I skip the sugar flush and rinse that I would normally have to do half way through processing a large batch because going back to raw sap after 300 gallons basically does the same thing.

[GeneralStark]

This will all certainly depend upon the type of machine you have and how much water it can remove on one pass and the tanks you have. I have found that my machine runs much more efficiently if I do not recirculate back to the raw sap tank. Now I am set up to concentrate from my raw sap tank to a dedicated concentrate tank and then from the conc. tank to the head tank. Using this method I can run at lower pressure and reduce the membrane fouling.

[DrTimPerkins]

There are several ways to do RO concentration depending upon your machine, membranes, rinsing/washing procedures, and work flow. Some like the recirculation method, some prefer single-pass, others will do 2-pass. Regardless, chat with your machine supplier and see what they suggest. Secondly, be aware that recirculating will raise the temperature of the sap/concentrate, which will increase the invert level, most likely resulting in darker syrup.

[red maples]

Secondly, be aware that recirculating will raise the temperature of the sap/concentrate, which will increase the invert level, most likely resulting in darker syrup.

Hmmm thanks doc. I never thought of that.

I do know that if you concentrate and boil at the same time its more time efficient thats a given.

What is recommended with my machine is to rinse out sugar every 3 hrs of continuous use. but if you are doing the batch method then it does cleanout the membranes like Russ said which was mentioned in the original article that I read.

I don't think there is a right or wrong way. when I am RO on the full batch recirc method I am usually bringing in wood, setting up the filter press, cleaning, maybe even making dinner for the wife and kids, then head out to boil. and since its just me by my self I can concentrate...(pun intented) on just boiling and not have to worry about the RO too. but I like the batch method Idea but as of right now I am not really set up to do that... yet(maybe by choice) not that I really need to be doing it that way yet anyway but If I were to increase taps which I can definitely handle more easily if time becomes more of an issue or on the rare occation like a few years ago when we had mega runs at the end of the season and folks were bringing me sap because they either couldn;t handle that amount of sap or were running low on wood.

Thanks for the input everyone!!!