Just a few RO questions

[Ms Ellis]

Niter and RO System


Wed 2022-04-13 8:59 Pm

Hello Everyone,

I am posting from PEI, my family and i have only been making syrup for about four years so we are still learning. we tap about 150 trees and this year we added a RO system and an urn with a thermostat for bottling. We have run into a problem with niter that we have not experienced before. We do a lot of filtering and in the past had no issues making a really clear bottle of syrup. Now since we added two new elements we have a niter issue. We strain the sap from the woods, we filter with a pre filter and felt cone filter and two additional layers of felt filters as it comes out of the evaporator, we finish on the stove and then filter again with pre filter, felt cone filter and two extra layers of felt filters and then one last time through a piece of pre filter before it goes into the bottle. This is in addition to the filter and four membranes from the RO system. So i am not sure how the niter can get through all of that. We are new to RO systems and this is our first try so we suspect it maybe connected to the level of sugar and how long its in the evaporator, or we have no real idea. Does anyone have any suggestions on what is happening? and how to fix it?


I thank you in advance for your time and expertise.

[DRoseum]

A few things to remember
(1) niter is formed above 195F. All the prefiltering of sap won't have an effect on final amount of niter.
(2) you probably don't need so many stages of filtering. Just do it after your final finish boil. You are creating more when you finish it anyways and losing product in the intermediate filtering.
(3) some years are worse than others when it comes to niter.
(4) sometimes niter is incredibly fine and gets thru just about every kind of filter. I had this happen a couple years ago. Tons of pre-filters, multiple fine orlon filters and was still getting very fine niter that was settling out of my syrup over time.
(5) filtering with DE (via a press or vacuum filter) should help overall clarity and efficiency.

[Swingpure]

Swingpure,
I am curious if you have any update to your first RO run (as you and I are 'first-seasoners' with Reverse Osmosis!).

My first run went well - 44 gallons of raw sap in and 17 gallons of concentrated sap out. Incoming sap Brix was 2.6% and concentrate was at 5.6% Brix. Final boiling yielded about 3/4 gallon of syrup that looked and tasted WONDERFUL! There was a tremendous learning curve as not only was this my first usage of the RO, my father-in-law has a new CDL wood-fired evaporator; however, overall, things went nicely albeit slower than expected. I am just waiting for things to warm up so we can tackle our second batch.

My Aquatec Pump never worked from day one. After trying to get Amazon to replace it, I am not working with Aquatec to cover it under warranty. I have finished my season, so hopefully will have it for next season. Can you wait a year for my answer?

I could have used it and made the 930 gallons seem like 465 gallons and the five face cords I burnt more like 2.5 face cords.

[DRoseum]

Gary- did you ever take the pump head off and look at the diaphragm?

[Swingpure]

Gary- did you ever take the pump head off and look at the diaphragm?

I didn’t, because I didn’t want to void any warranty and also I was hoping I could return it. If in the end I can’t get any warranty satisfaction, I will check it out and get it repaired.

I suspect it is something very minor.

[Ms Ellis]

Hello D Roseum

Thank you for the tips, do you think extra niter is created in the RO process? I read that somewhere. Do you think even the best of syrup producers end up with niter some times?

Ms Ellis

[DRoseum]

Not sure - will defer to Dr. Tim Perkins and if there has been research conducted on this topic.

[DrTimPerkins]

… do you think extra niter is created in the RO process? I read that somewhere. Do you think even the best of syrup producers end up with niter some times?

RO does not increase niter. It does concentrate minerals as well as sugar, so the RATE of niter formation during boiling will increase proportional to the syrup production rate, but the total amount for a given amount of sap doesn’t change.

[Swingpure]

Two RO questions.

How many gallons of concentrate will two 400 gpd membranes produce per hour?

As long as you flush the membranes after each daily use, is that all you have to do to maintain them during the season?

Thanks

[DrTimPerkins]

How many gallons of concentrate will two 400 gpd membranes produce per hour?

It is highly dependent on the sugar level in your sap, how high you're concentrating to, and the sap temperature.

As long as you flush the membranes after each daily use, is that all you have to do to maintain them during the season?

No...membranes should be periodically "washed" with RO sap (a strong alkaline solution) to reduce/remove microbial buildup and restore high flow rates. Other conditions may dictate an acid wash (much less common).

You'd probably benefit from reading the section on RO concentration in the Third Edition of the North American Maple Syrup Producers Manual. Lots of general info in there on ROs, how they work, how to operate them, and how to clean them.