Reconfiguring the RO for increased volumes of sap

[fireant911]

I have used a home-built RO machine for the previous two years and it has performed nicely. The current configuration is much like the unit detailed on the Mattatuck Madness Maple Syrup webpage using an Aquatec 8852 pump with four 150gpd RO membranes pumped in series. My father-in-law has expressed an interest in possibly increasing the number of trees that we tap - currently it is 25 and might be doubled to 50 trees.

Given this new scenario, I am curious about modding things up a little bit. Is it best to purchase a second Aquatec pump and replumb the system so that each pump can feed TWO membranes in series? Essentially this will be akin to running two independent systems simultaneously. It is understood that the concentrate will not be as high as that achieved from four membranes in series… but the output would be more than doubled. A second option would involve the two pumps being configured in parallel and the two outputs are connected to a wye branch which then feed the four membranes connected in series (is this last approach even doable?). Can the 150 gpd membranes handle this volume?

I do NOT want to go up to the next level of larger pumps and huge filters for cost reasons. Are there any pro’s or con’s to the layouts discussed above OR are there any other approaches that I should consider without spending much capital (assume my budget is $150 for this project).

One final question: I remember reading here on Maple Trader about an alternative to the AquaTec 8852 pump where someone had some very positive experiences. I searched but was unable to locate those threads... does anyone remember the name of the 'other' pump?

[82cabby]

I’ve used your exact setup for years and a larger version as well last season.

Honestly the setup you’re using should be pretty much what you need. Can you provide a few performance numbers like psi you’re running, %sugar on sap going in and concentrate coming out, gph of raw sap processed, etc? Maybe it’s not performing like it should.

For pumps, check the ones used at the RO bucket site or on http://www.roseummaple.com/. They are both incredibly knowledgeable about small sized ROs. But trouble shoot the current one first. It should work well for 50 taps.

[fireant911]

82cabby,
Yes, this setup worked well for the 25 trees I have tapped for the previous two years. Given the number of five-gallon buckets I have on-hand, I have to balance the storage of sap to the running of the RO machine with the current sap flow - this approach has worked nicely so that the previously gathered sap is not setting too long in the snow bank waiting to be processed AND that I am not over-run by the bags of sap actively being filled. Because I may be doubling the taps, I thought that maybe my existing setup may not be adequate in regards to time - it is usually a five to seven hour process with the 25 trees and I would like to keep it at that frequency, if possible.

I have all the statistics in my logbook but I am away from home currently - the current RO is doing an amazing job but I would rather not spend twice the time processing. I found the pump that I had referenced in my original post - Coronwater TYP-8900. Do you have any experience with this one?

[82cabby]

I used the Coronwater THP-8900 for the first time last season. I built a 5x400 gpd RO and it pushes that one just fine. You do need to source a proper power supply with that one as none of the ones that are listed on the website with it seem inadequate.

Given the budget you mentioned, you might want to look at sap and concentrate storage. I use 300 gallon ibc totes. If you have single containers that hold a lot more sap and concentrate you can set the RO running and take care of other tasks. With 5 gallon buckets the RO must go through them pretty quickly.

When you get a chance, post up the stats from your current RO. That will give folks a better idea what’s happening and where the real time savings can be found.

[DRoseum]

A couple quick concepts to always keep in mind when it comes to ROs:
(1) your membrane GPD rating is indicative of how much permeate they can produce under a given pressure.
(2) your pump flow rate (at that same pressure) needs to increase as you increase your total membrane GPD rating of your system
(3) increasing pump flow is done to keep "recovery rate" (permeate out flow / pump feed flow) as low as possible (which keep membranes performing optimatly).

Now to answer your questions
(1) yes you can run 2 pumps in parallel at the same pressure to increase feed flow rates. This wont directly increase your permeate rejection rate (which again is determined by your total GDP rating, which is 4 x 150 = 600 gpd on ypu system, which os near max capacity the aquatec 8852 can support with decent recovery rates).
(2) you can get higher feed flow pump like the coronwater 8900. I have used these pumps in two units with 5 x 500 gpd membranes with recirc (more about that below) and love them. I'd recommend a 12vdc transformer that is 10 - 15 amps (~150 watts)
(3) if you increase pump feed flow, then you can add a higher capacity membrane(s) in order to remove more permeate faster. I prefer membrane solutions membranes:

https://www.amazon.com/stores/page/F52DD3B0-BCA3-4BE4-A8B2-02EFC4C75251?maas=maas_adg_93A7FFB30C41A20B0D3842E 955AA8A5B_afap_abs&ref_=aa_maas&tag=maas

(4) you can add low pressure recirculation to keep feed flow higher and drive concentration % higher. Your total permeate outflow remains constant unless you add more membranes. You could probably add one more 150gpd and introduce recirc to keep recovery rates low and gain some performance improvement.

Recirc is done by splitting the concentrate output in 2 after the needle valve and looping one of them back to the inlet line to the pump.

I've got more details in a blog post and YouTube videos.

https://www.roseummaple.com/2020/01/diy-2-stage-portable-hobby-ro.html

https://youtube.com/playlist?list=PL6CwcmcTEWYxhYPQCMAWETg9gHWL7_RXw&si=4ruAI5sQko6zycW2

[fireant911]

DRoseum,
WOW! Thanks! All this is really helpful. I found an earlier thread where you linked the power supply you were using for the Coronwater TYP-8900 pump. That power supply had two separate output leads - does that indicate that one power supply could be used for two Coronwater pumps? Reference: 24V 400W LED Power Supply, IP67 Rainproof Waterproof Outdoor Driver,AC 90-140V to DC 24V Low Voltage Transformer, Adapter Converter for Outdoor Use https://a.co/d/c0M8fVo

[DRoseum]

No problem. Yes that 400W one can drive 2 of those pumps.

[82cabby]

Just to reiterate, bumping the pump up to a larger size will not, necessarily, give you more RO output. See #1 in D.Roseum’s first point. It’s tough to say without seeing data from what you are currently getting.

[TheNamelessPoet]

I don't know if this helps as I use an RO Bucket but I would think the concept is the same.

I have a large 65 gallon tank that I put the sap into. I run the concentrate back into that tank and the permeate into either buckets or another 35 Gallon tank if I have a ton of sap. I just let it keep recirculating until it us all up to about 4-5%. THEN I start putting into the 35 gallon tank (If I am not using ir for permeate) or into 5 gallon buckets.

My RO is the RB 10 (upgrading to an RB15 this year I think as I am at about 65-70 taps and would like the speed help.)

I start the RO the second I get up in the AM with any sap I have currently and just let it run until everything is done. Once I have 2 buckets of 8-10% concentrate (and everything is at about 4-5%, I start boiling while the RO is going. Usually they end up just about even as far as timing or the RO finished a little ahead of the evaporator.