Must a cheap RO be $5000+?

[bowhunter]

Howard,

I bought most of the major components from https://www.freshwatersystems.com/. There may be better options, but they seemed pretty reasonable.

Membrane Axeon NF- 4 2540 680 GPD Nanofiltration membrane (equivalent to Dow NF 90)
Axeon PVC membrane housing - 2.5 x 40 inch
Procon 140 GPH Pump
Procon Carbonator Motor - 1/2 HP 120 V
Procon V-band clamp - clamps motor to the pump
Pentak 10 " slim line water filter housing
10" 5 micron filters
0-300 psi filled pressure gauge
Blue White - F-440 Rotameter 0.025 GPM to .25 GPM for the Concentrate
Blue White - F-440 Rotameter 0.1 GPM to 1.0 GPM for the Permeate
3/8 " OD LLDPE Tubing
3/8" John Guest Fittings
2- 3/8 " brass needle valves ( bought these at local building supply store)
miscellaneous 3/8" copper fittings and tubing for needle valve manifold.

I don't have a sketch, but the flow is pretty simple. The sap flows out of the head tank and through the 5 micron filter. From the filter it flows into the pump. Out of the pump into the membrane housing (side connection). The concentrate flows out the side fitting on the other end of the membrane housing. I have the pressure gauge located on the concentrate tube out of the membrane housing. From the membrane housing the concentrate goes to a "tee" and splits with one stream going through a 3/8 " needle valve to the pump inlet and the other goes through a 3/8 " needle valve and through the concentrate rotameter. The permeate comes out one of the center ports on the membrane housing and through the permeate rotameter. I'll try to find pictures, but can't find them right now.

To operate the system make sure the pump is liquid full and both needle valves are open. Use the concentrate needle valve to control the flow of concentrate and the recycle needle valve to bring up the pressure. Try to keep the concentrate flow higher than target during the startup. Bring the pressure up slowly over the first 30 minutes and allow the system to line out before you make the final adjustment on pressure and concentrate flow. When you start up the permeate flow will be higher at the same pressure because the membrane is full of permeate from the previous permeate wash. Watch the sugar on the concentrate and try to keep it below 8 %. If you go too high too quickly the membrane will start to foul. The performance will naturally drop as you continue to process through the day so you will gradually have to increase the pressure to keep the split of concentrate and permeate.

The tubing and John Guest fittings worked really well. I ran up to 250 PSI with absolutely no problems

I tried to model the system in a spreadsheet using all the publicly available I could find. The one thing I couldn't model very well was how the sap fouled the membrane. It worked really well on water at different pressures and temperatures. In any case my system will consistently process 16-17 GPH of sap and take it from 2.5% to 7%. It des better right after a caustic wash and not quit as well when it's time to wash again. I feed the concentrate directly to the evaporator and I really like that approach. I did sometimes recirculate back to the sap tank, but I really don't like to store concentrate.

I have the good fortune to have my sugar house in a small two story barn so I have a 55 gallon drum on the second floor to feed the system. This worked well, but be prepared to change the filters after each day of processing. I didn't have any debris on the filter, but they still plug with fine material and slime from the sap.

Make sure you can flush at 2 GPM or so with permeate. My permeate tank was at floor level up on blocks and I didn't always have enough head pressure to overcome the filter fouling at the end of a run unless I changed the filter first.

Hope this helps. I can answer question on a private message or e-mail if you want.

[HowardR]

Thank you Bowhunter! Your parts list and description should enable me to put it all together. How did you end up mounting it so you could bring it in at night? A picture would be very helpful!

[HowardR]

Bowhunter,

The only thing I found confusing was exactly how you plumbed the recirculation connection between the 5 micron filter and the pump. I'm guessing that there was a checkvalve that you didn't mention there, otherwise the recirculating semi-concentrate from the 3/8 inch needle valve could have flowed backwards through the 5 micron filter toward the tank. In other words, I'm guessing the following:

Five Micron filter -> checkvalve ->Tee

with the other connections of that Tee: (1) going into your pump and (2) coming from the 3/8" needle valve that controlled your recirculation.

Could you describe your connection between the 5 micron filter and the pump a bit more fully?

[markct]

Why would it flow backwards if the pump was sucking it in? A checkvalve would only do anything when shutdown

[HowardR]

Mark, of course! Thank you.

[bowhunter]

I have a room in my barn that I can heat so I mounted it on the wall using I think it's called uni channel. It's a "U" shaped channel that's used to mount conduit in commercial or industrial construction. Some people mount the system on a hand dolly so they can move it around. I'm not a fabrication guy so I can't offer too many good options for mounting. I couldn't find pictures...I had some, but don't know where they went. I'll try to remember to send you a picture over the week-end. Also you can send me a private message with questions if you want.

Everyone asks about check valves and you can use them but for the most part they aren't necessary. You might want to use check valves where you tie in caustic wash or permeate wash so you don't get sugar back in those systems or vice versa. I disconnect the membrane from the system when I do a caustic wash so I don't have any back contamination.

[HowardR]

Bowhunter,

Thank you for the info about how you mounted it. Did you have to bring your nano membrane inside overnight so it wouldn't get damaged by frost?

I think I've found all of your parts on the freshwatersystems.com website. Could you let me know if I have made any mistakes:

1. Membrane Axeeon NF - 4 2540 g80 GPD Nanofiltration membrane (equivalent to Dow NF 90). Cost $204.74:

http://www.freshwatersystems.com/p-6...e-element.aspx

2. Axeon PVC membrane housing 2.5 x 40 inch. Cost $98.98:

http://www.freshwatersystems.com/p-6...e-housing.aspx

3. Procon 140 GPH Pump. Cost $107.54:

http://www.freshwatersystems.com/p-8...ief-valve.aspx

4. Procon Carbonator Motor - 1/2 HP 120V. Cost $155.33:

http://www.freshwatersystems.com/p-5...gle-phase.aspx

5. Procon V-Band Clamp. Cost $6.50:

http://www.freshwatersystems.com/p-5...and-clamp.aspx

6. Pentac 10" slim line water filter housing. Cost $15.19:

http://www.freshwatersystems.com/p-6...ump-no-pr.aspx

7. 10" 5 micron filters. Cost 2.97 if you buy one, or 1.83 each if you buy 50:

http://www.freshwatersystems.com/p-1...ter-5-mic.aspx

8. 0-300 psi filled pressure gauge. Cost $22.14:

http://www.freshwatersystems.com/p-4...ss-14-npt.aspx

9. Blue White - F-440 Rotameter 0.025 GPM to .25 GPM for the Concentrate. Cost $67.82:

http://www.freshwatersystems.com/p-3...rotameter.aspx

10. Blue White - F-440 Rotameter 0.1 GPM to 1.0 GPM for the Permeate. Cost 90.82:

http://www.freshwatersystems.com/p-3...rotameter.aspx

11. 3/8 " OD LLDPE Tubing. Cost 29 cents per foot:

http://www.freshwatersystems.com/p-8...ne-tubing.aspx

12. 3/8" John Guest Fittings:

http://www.freshwatersystems.com/c-7...-fittings.aspx

[bowhunter]

It looks like you've got everything. As with all plumbing jobs you will have to make several trips to the hardware store when you start putting it together. I kept the RO in a room with a milk house heater so I kept it above freezing, but to be clear you shouldn't leave it out where it will freeze. One more thing to keep in mind. RO's are very sensitive to sugar concentration so if you start out with 2% sap this unit will probably treat 22-24 GPH, but if it's 2.5% or higher the capacity will be down around 16 GPH. At the end of the day your target should probably be 6.5 -8% concentrate. If you try to go much higher with one of these homemade units you will dramatically reduce the capacity and the ProCon pumps are limited to 250 PSI.

Looks like you're from up in God's country....I lived just north of Pittsburgh for five years. Good luck. And let me know if you have more questions. I won't be checking the forum as often now, but if you leave me a private message I will get an e-mail.

[HowardR]

Bowhunter,

Thank you for the offer to answer questions by email that may come up when I put it together.

I think your design is brilliant. I like all these things about it:

1. Low cost -- professional parts at only twice the cost of a system that uses residential parts.

2. Simplicity -- you get from 2% to about 7% with one membrane, one motor, and one pass.

3. Engineering -- you don't give the motor too large a load or the membrane too low a flow.

4. Nano -- They do better when the sap is cold.

5. Ingenuity -- A brilliant and controlled way of recirculating the flow to get the right concentration, using just two valves.

[HowardR]

By the way, here's a little hand drawn schematic of Bowhunter's RO:

RO.jpg