If I buy a machine, can I set it up to save the waste to feed to my plants?
Doesn't the waste get trapped in filters and filter media?
No. RO units waste between 8-12 gallons of water to produce 1 gallon of RO water. It's a pressure thing. .
My RO system produces around 5 gallons of "waste" for every gallon of RO water. But to call it waste is silly - it's in fact carbon filtered, delicious water that has a slightly higher mineral content than the source. I use it for everything from making tea to watering plants without any issues at all. Water is cheap (.5 cents per gallon here in MN), so I can make a gallon of RO water for 2.5 cents. Compare that to what grocery stores charge and you will see why getting an RO system makes so much sense for those of you with difficult water to brew with.
The reason they cut down on waste is because systems that use pressure tanks with out booster pumps are poorly designed WRT recovery. They are usually small systems from which a few GPD is the maximum that is likely to be demanded. If you have such a system you can increase recovery by running the permeate to an atmospheric rather than a pressure tank. Your HLT could be that tank. Eliminating the pressure tank may lead to other inconveniences however. Efficient systems collect to an atmospheric tank and then pump from the atmospheric tank to a pressure tank if pressurized water is needed. Needed or not it certainly is handy.A permeate pump dramatically cuts down on waste water as well as reducing regeneration time.
The reason they cut down on waste is because systems that use pressure tanks with out booster pumps are poorly designed WRT recovery. They are usually small systems from which a few GPD is the maximum that is likely to be demanded. If you have such a system you can increase recovery by running the permeate to an atmospheric rather than a pressure tank. Your HLT could be that tank. Eliminating the pressure tank may lead to other inconveniences however. Efficient systems collect to an atmospheric tank and then pump from the atmospheric tank to a pressure tank if pressurized water is needed. Needed or not it certainly is handy.
But the essence of high recovery is the feed booster pump and concentrate line restriction. By restricting the flow of concentrate one forces the pressure across the membrane higher for more permeate at the same time cutting down on what goes to the drain. Many systems have an adjustable needle valve as the concentrate restriction device. By adjusting this one can set up for a wide range of recoveries. I run my system at 50%, for example i.e. 1L of concentrate for each liter of permeate.
It is possible to go even higher recovery by recirculating a portion of the concentrate back to the pump inlet. This is, of course, at the cost of lower system rejection.
Enter your email address to join: