Pursanova -- RO/S Water

 

(This post is a year late in publishing.  Following soon will be another post with updated information on our experience with RO/S water in 2022)

     Reverse Osmosis-Structured water (RO-S)!  Is it a hoax?  Well, we are finally going to get a hands on experience to determine it's value, beyond just the printed material that's available.  It's taken about two years since the concept was originally discussed in our Bio Farming group, to reach the point where we are starting to use the water product on our operation.  The unit is designed to be set up at different operations where there is a water source (~10gpm)  and 240v, single phase, three wire electrical service.    Water enters the system through a garden hose, goes through a filter bank, a Pursanova disc, and into a 500gal holding tank which feeds the four tube reverse osmosis (RO) unit. Once the water passes through the RO unit, it passes through another Pursanova disc and through two Pursanova structure tubes, then the water proceeds to it's final destination tank.   The water being held in the destination tank can then recirculated back through the Pursanova disc and structure tubes until the treated water is used, or the unit is shut down.  The unit is ~50-60% efficient, meaning that 8-10gpm goes into the unit with 4-6g going into the storage tank and 3-5g is wasted to other purposes.  Early on we were told that we could recycle the waste for more efficiency but found that the RO membranes quickly fouled with the concentration of minerals we were removing from the water.  We are now adding a small dose of scale inhibitor to the RO unit for the purpose of extending the life of the membranes.   We were instructed to clean our equipment and holding tanks by filling them with the RO structured water and storing for 24 hours, then draining them out to remove the built up deposits, --then refill for use.  The unit has safety/float switches, so, once running it will shutoff/turn-on as water is used from the supply and holding tanks so you don't have to sit with the unit while processing.  Our net production is about 5gpm, giving ~7200g of processed water in a 24hr period.  We have been told that this processed water will hold it's "structure" for about two weeks without any circulation.  Beyond that time some small water movement should be incorporated to hold the "structure"in the destination tank.  

     Why are we even considering using this RO/S equipment.  There is ~$50K in this unit, and annual maintenance will ≥$1K.  What is the payback?  In our case we have hard water ranging 136-207mg/l, with a 7.5-8.0pH depending on which well we use.  This hardness is termed moderate to high, and the high pH can compound the problem of chemical efficacy.  The literature includes enticements of more effective weed control from half to two thirds the chemistry, along with better crop response from foliar applications.  If results even come close to the reported savings, the return on investment will be a year or less for us.  I haven't had that kind of ROI since we purchased our Raven AccuBoom system for the sprayer back in the 1990's.

    We are just starting to get too know the system.  The equipment is cleaned and we are starting our fall spraying operation under some very bad conditions of excessive heat 95-105ºF for ~ 30days, no rain for 60 days, and low humidity.  Our deep soil moisture is keeping the targeted plants growing but they are hardened off.   I have spent some time checking out our water quality, spray surfactants,  and AMS replacements, to determine the coverage we may expect.  A few things are showing some direction, (or maybe a change in direction).  

     Anateck Lab test on the RO/S sample showed non-detectable for Al, Fe, & Mg.  A low level of Ca remained.  I did not have the "hardness" test done, --a mistake!  I expect it would have been very low, but I don't have a number for comparison.

    I have a HACH Test Kit for fish farming that I use on rare occasions to check our pond water.  I found it useful for this project to get numbers for pH, and hardness.  Elements that are important for fish health were not of interest to me for this project.

     The question that does interest me though is RO/S relationship to surfactants and other additives we use to make our chemistry work.  We put a lot of money into these additives.  I mixed up various rates of M90 (surfactant) and Downrigger (a AMS replacement-plus), in well water (WW), RO/S, and RO water to see if there was a difference.  The pic to the left shows from left to right, WW, RO/S, and a light rate of Downrigger in RO/S, and a light rate of M90 in RO/S.  Enlarge this pic and you will see that the surface tension on the WW (left) is greatest and the M90-RO/S (right) has the least.  What I don't understand, is that 8oz/100g mix showed less surface tension than 32oz/100gal of M90.  I did that test 3 times with the same result.  That's weird to me.

     The pic to the left show results 20+ minutes after droplets were deposited.  Until I was doing this narrative I didn't recognize the discrepancy in labeling in the pic.  All SW should have RO attached, and Outrigger should be Downrigger.  I find the slide on the right side interesting as relates to spread and drying.  At this point, this is the only instance where I have seen a difference between RO and RO/S water.  This pic is 20min after the droplets were deposited and it shows that the M90 at 2pt/100g dried similar to M90 at 8oz/100g mix.  High magnification does show a little difference.