RO Bucket or similar setup

[eddy6963]

Those of you who use the RO bucket kit or have made your own that is similar in setup. Can you post pictures of your setup and if you could change things around what would they be. Thanks. Just trying to get ideas on the best way to assemble mine.

[therealtreehugger]

I ordered the RO 10 bucket kit. I got the kit so I would have the option of adding on in the future. The idea was to make it portable, so when I was not using it, I could pick it up and bring it inside. I left all the tubing attached and coiled it into a bucket so I just had to carry it and the bucket inside. I intended to put a handle on the back of the plywood, but haven't got there yet. I like the bottom plywood ledge not only to screw the pump onto, but the idea was to have it be able to stand up by itself.

[littleTapper]

I took the easy route with the RB20 kit and mounted it on some 3/4" plywood on 2x4s bolted to a furniture dolly to easily roll it around. Some pics here: http://mapletrader.com/maplegallery/g678-2020-season.html

[gbeneke]

Try looking at my post under "home made, portable RO". That may help you. Have now gone to 5 -400GPD membranes in series to see if that works better, but this system worked well for me last year.

[vtbackyardmaple]

I'll show you mine... Just built it. One huge question I had was should the membranes be in line or individual. I asked my MIT nerd and he said individual but recycle sugar line back to main sugar tank and run it 24/7.
... getting pic... 21660
youtube.... https://www.youtube.com/watch?v=95JzleyG3Jc

Hope this helps.
oh, membranes are 150gpd and I have 2 of them attached. I could get another pump and 2 more membranes on other side to double my output but need to live test it to see how fast I get a 5 gal bucket of sap at 10%.
10% is my minimum goal.
I might need to add an inline heater to accomplish this.

[wobbletop]

I'll show you mine... Just built it. One huge question I had was should the membranes be in line or individual. I asked my MIT nerd and he said individual but recycle sugar line back to main sugar tank and run it 24/7.
... getting pic... 21660
youtube.... https://www.youtube.com/watch?v=95JzleyG3Jc

Hope this helps.
oh, membranes are 150gpd and I have 2 of them attached. I could get another pump and 2 more membranes on other side to double my output but need to live test it to see how fast I get a 5 gal bucket of sap at 10%.
10% is my minimum goal.
I might need to add an inline heater to accomplish this.

A couple things...

10% is probably unlikely with that setup. This guy:
https://sites.google.com/view/mattatuckmadnessmaplesyrup/homemade-reverse-osmosis?authuser=0
has been doing this a long time and usually maxes out at 8%. Still pretty good! I believe these consumer membranes start to clog/underperform as you get close to 8%

Second, I used to cycle the concentrate back to the feed tank, but found my performance decreased as opposed to going though the whole sap bucket before repeating. I think the issue is the input has to be at the bottom of the feed tank, and as the concentration goes up, the higher concentration goes to the bottom. So you are continually trying to concentrate the highest concentrated sap. At least that's my theory. Doing a couple passes seem to perform better, but of course it's a little more work.

[vtbackyardmaple]

Good point about the sugar going to the bottom. I'll use an empty bin then recirculate it.

[vtbackyardmaple]

I also noticed his has his membranes in line. This doesn't work well as the last membranes will gunk up fast and hurt overall final numbers. That's what my MIT guy was stressing. He did his doctorate on RO efficiency.
I might flush the system after the first round and see what numbers I get on the second output-if it goes up... I'll do it again for the 3rd. I don't know if it will actually make any difference at all in the end. My sap the past 3 yrs averaged 3.5% out of the trees. Anyways, thanks for the input and I see what you mean about heavies going to the bottom. Might add a bobber or something to keep it from falling down all the way to the bottom of the tank and process the lighter stuff on top.

[carls47807]

If you really want to try and push 10%, set your pump head to get at least 150psi, and keep the sap as cold as possible. Osmotic pressure is temperature dependent (direct relationship), and you are going to want to keep it as low as possible. The flow rate will be extremely slow, but you can get there..

Series is also a lot better if you want to push higher concentrations. Having as much sap pass through the system as possible will decrease membrane fouling (and decrease recovery across the membrane). Two membranes in parallel decreases your flux and increases recovery by a factor of 2.

The last membrane in a series setup would basically see the same sap as EVERY membrane in a parallel setup, but the flow rate across the last membrane will be higher (which is why series is advantageous).

[vtbackyardmaple]

Someone should prove this in series or parallel. My MIT nerd who did his doctorate says in parallel is better. I trust him.
If I have to run it 3x's that fine with me. It's better than bricking the last membrane which halts the system.
If I don't get there-I'll spend more on pumps and higher pressure membranes. I might be able to do my own study and post it.
I'll do 1/2 bin parallel - flush the system and 1/2 in series. Take a brix reading and let you all know.

[vtbackyardmaple]

After thinking about it perhaps doing 2 parallel then 1 or 2 in series after might be the best all round solution. Unghh.. testing. Need sap first but thanks for all the info you have.

[Gord]

Maybe some pumps are different. For the pump I got from Carl, vtbackyardmaple's pump would be backwards. If I'm looking at the pic of his setup correctly, he has the IN port aiming at the prefilter and the OUT port going to his sap barrel. But, like I said, it might be just how it looks in the pic. Maybe the hose to the prefilter is going behind the pump.

[wobbletop]

After thinking about it perhaps doing 2 parallel then 1 or 2 in series after might be the best all round solution. Unghh.. testing. Need sap first but thanks for all the info you have.

Along with the website I posted above, here is the forum discussion regarding his setup. It's almost 30 pages so there is a lot of information and discussion and would probably be worthwhile to go through. Here's his quote on parallel vs series:

http://mapletrader.com/community/showthread.php?28349-hodorskib-s-Small-Scale-RO-Build&p=381183#post381183


sorry my account had been suspended for some reason. I have run my 6 membrane system in series, parallel and a combination of both. To process lets say 150 gallons of sap from 1.5% sugar to 7.5-8% it takes the same amount of time in all three setups the only difference is when running in parallel or combination you have to recirculate. I do not do this because I have found that the more times the sap runs through the pump the more it heats up and the lower quality of syrup I make. This has been my experience over the past 7 years.

[vtbackyardmaple]

Gord - thanks you're correct... I'll flip it upside down. Man what a disaster that would have been lol. Chance to put the 3rd membrane in.

[vtbackyardmaple]

wobbletop-Thanks for forwarding that thread. Good Stuff!!!!!Carl thanks too man... saving me hours of testing.

[Gord]

Gord - thanks you're correct... I'll flip it upside down. Man what a disaster that would have been lol. Chance to put the 3rd membrane in.

You would have made a lot of bubbles in your sap barrel at least!

[carls47807]

In any typical RO system, where the booster pump is not the limiting factor, parallel would probably be the best (in no way am I saying your MIT guy is wrong!). You could maintain a low % recovery by running the waste side at 75%, permeate at 25%, and achieve adequate pressures across all membranes in parallel.

The issue with our maple systems is that the pumps are always the limiting factor. We can't run waste (concentrate) at 75%, permeate at 25%, and maintain 100psi because the pumps can't handle that volume and maintain pressure. In addition, we don't want to run those percentages because we want to pull as much water as possible. If you want to up the permeate percentage, you have to increase the flux across the membrane somehow (by running it in series with other membranes to get the total flow of the system up). Once you do this, each membrane produces a fraction of the overall permeate, but they all flow the TOTAL amount of concentrate.

[vtbackyardmaple]

@ Gord -roflmao.... you got that right. Who is farting???

[vtbackyardmaple]

So after reading all this-put 4 membranes in series and corrected the flow (smacks head). Not sure if my tubes are correct-water /sap. Haven't done it yet so I don't know which one will release water. Once I find out-I'm going to label it somehow probably on the membrane cannister.

[littleTapper]

So after reading all this-put 4 membranes in series and corrected the flow (smacks head). Not sure if my tubes are correct-water /sap. Haven't done it yet so I don't know which one will release water. Once I find out-I'm going to label it somehow probably on the membrane cannister.

The outlet in the center will be permeate; off-center will be concentrate. If you have fittings for those locations that have o-rings to help seal, use them on the concentrate side since those will see the highest pressure; and any that are just thread tape sealed, use on the permeate side.

That valve between your pump and filter will almost certainly leak under pressure needed to run the RO.

[carls47807]

plumbing looks correct. You won't need a shut off valve on the permeate line, run that open all the time. Also, you have check valve fittings on your permeate outlets. If you have regular ones it might work a bit better. Looks great, nice work.

[wobbletop]

^^^ Also apparently those plastic ball valves do not give enough control over the concentrate pressure. You'll need a needle valve.

[randolphvt]

I replaced the one on the output of concentrate with needle valve. Do I really need one by the pump?

[randolphvt]

there is no check valve. The insert is the reducer. I can see how you might interpret that as a check valve but I never bought one.

[randolphvt]

Pump-valve-reducer-filter-T-ro-ro-ro-ro-valve
that's the sequence.

[carls47807]

Got it, usually the fittings with the pink ring have a check valve (stainless plunger with a spring).

You do not need the shut off valve directly after the pump. You only need to throttle the concentrate outlet after your last membrane.

What kind of 1/4" hose are you using (vinyl? or HDPE?) It looks really flexible.

[randolphvt]

Carl-again you're correct. Jeepers. I didn't know they were check valves. Thank god I looked. I removed it from the membrane housing and it does have a check valve. Thank god you mentioned that. Thank You a TON! Just ordered replacements from amazon.

[randolphvt]

Everyone-What do you 'wash' your membranes out with? Was waiting for Tim to reply but he's probably insanely busy.

[randolphvt]

Someone asked me what tubes I was using. hkp is labeled on the side of the tubes.https://www.homedepot.com/p/UDP-1-4-in-O-D-x-0-170-in-I-D-x-25-ft-Natural-Polyethylene-Tubing-T16007001/304185139

[DrTimPerkins]

Membranes are typically "washed" with RO soap, essentially lye, a strong caustic. This removes the biological films that build up on the membranes and reduce sap flow through the RO. So the process is:

- concentrate sap until flow slows down
- purge sugar from the membrane with permeate
- wash membranes with RO soap
- rinse membranes with permeate
- concentrate sap

Citric acid is used to dissolve minerals that build-up at times or to try to "tighten" membranes that leak sugar. We've rarely have used citric acid, but some people do find it helpful. Probably depends upon sap chemistry and soil chemistry.

[randolphvt]

Where can I buy it? I went to cdl and they no longer ship it. Any anyone help me there?https://www.etsy.com/listing/219353858/sodium-hydroxide-10-ounces-fine-powder?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=food+grade+lye&ref=sr_gallery-1-13&frs=1

Looking at buying this.

[randolphvt]

Tim on the tail end of the process how many gal approx should I flush the system with water? If I get 40 gal of sap/day I'll only have about 30 gal of perm. I can always use water from the house. I just want to be sure it's surely flushed out. Maybe just running it for 10 min or something.

[DrTimPerkins]

You don't need to wash until you notice flow start to noticeably drop off. Even then, try flushing with permeate first to see if flow rates are restored.

I should have noted that it is best to use buffered RO soap. Membranes have specifications, but generally exceeding the pH limits on the low (acid) or high (caustic) sides can be damaging. If the soap isn't buffered, measure the pH of the solution and keep it within the specs of the membrane. RO soap is VERY caustic....wear gloves and handle with care.

The BEST way to determine how much permeate to use is to test the pH of the rinse water after it exits the system. Initially it will be very caustic (high pH), but should drop down to near the same pH as the permeate when sufficient rinsing has occurred. While you can do this with a cheap pH meter, the easiest and cheapest way to do it is with pH test strips. They never run out of batteries or need calibration. Just be sure to store them properly (away from caustic or acidic materials).

Note that the soap will work better if the solution is slightly warm.

With a system that small, a few gal of permeate should provide enough of a rinse (that permeate should be discarded). With larger systems, the rule of thumb is to rinse (with permeate) whatever amount of sap the RO is rated to process in an hour. Best practice is to neutralize the washwater from the RO. https://vermontmaple.org/client_media/files/Procedures-for-neutralizing-maple-wash-water.pdf

[randolphvt]

Thanks Tim.