some people use 'gray water' to wash laundry, or have a tub so that laundry water is used a few times and then discarded. I guess the flush could be used for laundry somehow unless it was extremely hard
Reverse Osmosis Water
- Thread starter Potterychef
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A pretty-much-standard RO system produces 4 parts flush water for one part pure. That suggests that the TDS of that flush water will be roughly 25% higher than the incoming supply. Depending upon the starting concentration and what the dissolved solids are, that might not be so much after all, meaning it's perfectly usable for other, less sensitive plants.
If your RO system goes into a pressurized tank (most "plant people" use an open tank, so this doesn't apply), as the tank fills, the back-pressure on the membrane is increased, slowing the production of the pure water, but the flush water keeps flowing so the "waste" ratio increases. That can be overcome by employing a "permeate pump" that uses the flush water flow to draw a slight vacuum on the membrane, so it never sees that back-pressure.
Candace, it is possible to decrease the flush
ure ratio, but at the cost of replacing the membrane more frequently. If you pay for water or water+sewer, or if you want to be particularly conservative in your water consumption, it's worth it. My new 200gpd system is just a shade over 2:1, and I'm sure I can get it lower, but I'm using it as a test-bed for membrane repacement.
I just did a cost comparison for another forum:
It seems the average cost of water is somewhere between $0.0015 and $0.0020 per gallon in the US (I used the $0.0020 in my calculations). Santa Fe NM was the highest I could find, at $0.0123 for their costliest residential bracket.
Using the most-expensive, standard configuration I sell (5-stage, 100 gpd, 1:4 pure:flush), and using a true output of half that (most get more, depending upon temperature and pressure of the incoming line), adding the municipal water cost drives the price per gallon to $0.034 for the US average, and up to $0.086 for Santa Fe - still a long way from the $1/gallon store price.
If I assume that the sewer cost is equal to the water cost - most are less - those costs/gallon are $0.044 and $0.147, respectively. Still a relative bargain.
I then reran the numbers doubling the rate (and cost) of membrane replacement, and assumed a 1:2 pure:flush ratio (I honestly don't know if they would need to be replaced twice as often with that ratio - the company that sells 1:1 systems recommends replacing membranes annually, so that's what I did here) and the cost comes down for Santa Fe, to $0.105 per gallon RO, while being unchanged for the US average.
If your RO system goes into a pressurized tank (most "plant people" use an open tank, so this doesn't apply), as the tank fills, the back-pressure on the membrane is increased, slowing the production of the pure water, but the flush water keeps flowing so the "waste" ratio increases. That can be overcome by employing a "permeate pump" that uses the flush water flow to draw a slight vacuum on the membrane, so it never sees that back-pressure.
Candace, it is possible to decrease the flush
ure ratio, but at the cost of replacing the membrane more frequently. If you pay for water or water+sewer, or if you want to be particularly conservative in your water consumption, it's worth it. My new 200gpd system is just a shade over 2:1, and I'm sure I can get it lower, but I'm using it as a test-bed for membrane repacement.I just did a cost comparison for another forum:
It seems the average cost of water is somewhere between $0.0015 and $0.0020 per gallon in the US (I used the $0.0020 in my calculations). Santa Fe NM was the highest I could find, at $0.0123 for their costliest residential bracket.
Using the most-expensive, standard configuration I sell (5-stage, 100 gpd, 1:4 pure:flush), and using a true output of half that (most get more, depending upon temperature and pressure of the incoming line), adding the municipal water cost drives the price per gallon to $0.034 for the US average, and up to $0.086 for Santa Fe - still a long way from the $1/gallon store price.
If I assume that the sewer cost is equal to the water cost - most are less - those costs/gallon are $0.044 and $0.147, respectively. Still a relative bargain.
I then reran the numbers doubling the rate (and cost) of membrane replacement, and assumed a 1:2 pure:flush ratio (I honestly don't know if they would need to be replaced twice as often with that ratio - the company that sells 1:1 systems recommends replacing membranes annually, so that's what I did here) and the cost comes down for Santa Fe, to $0.105 per gallon RO, while being unchanged for the US average.
B
biothanasis
Guest
Thanks Charles!!
Very valuable info!! Thanks Ray!!
Very valuable info!! Thanks Ray!!
One more thing to consider, besides cost: the use of a pure water source has invariably resulted in reports of better, "brighter" and "cleaner" growth.
We invest a lot to keep our 'chids happy, so maybe this is just one more way.
We invest a lot to keep our 'chids happy, so maybe this is just one more way.
K
keithrs
Guest
I wonder if anyone here has use a Nanofiltration membrane for removing hardness.
M
Mike
Guest
I have considered this as an option. Sizing and flow rates are my biggest concerns, but if you are running this into an open tank, I think you can get pretty good clearance of minerals with these filters. Because they don't pull everything out of the water they tend to give you water between 20 and 50ppm in the product stream.
I have also looked at the TAC (Template Assisted Crystallization) systems, but I cannot tell with this method if there is accumulation of available minerals and salts. These systems use a media to bind the minerals and flush them out of the pipes without causing the scale problems in hard water systems. I cannot determine if the TAC molecules can be taken up into plant tissues. It would be great if these TACs precipitated and could be filtered out. Has anyone had experience with these TAC systems?
I have also looked at the TAC (Template Assisted Crystallization) systems, but I cannot tell with this method if there is accumulation of available minerals and salts. These systems use a media to bind the minerals and flush them out of the pipes without causing the scale problems in hard water systems. I cannot determine if the TAC molecules can be taken up into plant tissues. It would be great if these TACs precipitated and could be filtered out. Has anyone had experience with these TAC systems?
K
keithrs
Guest
I have not... In fact I have not even heard of this system intel now. From what I have read in a short research study is that TAC media causes certain elements that are in water to bind into crystals "balls" or "seeds". I'm not sure if these crystals seeds are usable to plants with out being broken down by bio life is soil. TAC is a anti-scale media and not a filter. It doesn't remove any thing in the water, only transform it so it can't "stick" to a water pipe ect. That being said.... I'm not sure why you would need this media unless you have scale problems in your water heater or boiler. You may be able to filter the seeds out?!?!?
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