Waste RO Water?

[iced98lx]

Mine goes into the sump hole. During the winter it gets pumped into the drain, with any other ground water that makes its way in there. For the summer I'm working on a storage vat setup outdoors, and to use the water the sump pumps out (ground water that leaches intot he drain field, waste RO water, water from dehumidfier and A/C unit, etc) to water everything from the grass to the flowers. A jet pump can provide plenty of power to run a regular in ground sprinkler system for $500. I'm planning to start with a 1000 gallon tank and add more if I fill it during the wet time (spring) and hopefully I'll be able to water the yard during the dry times with it.

[kinkylizard]

My waste water goes straight to my blood thirsty lawn!

[MNewman]

My waste water goes to two 275 gallon rain totes, that are also plumbed to catch most of my rain water from the roof. I have a high pressure pump thats on a timer to water all plants around the house using PEX tubing and irrigation valves.

[hogfish]

other issues with ro waste water include the concentrations of impurities are contained in the wastewater. I had a business where we produced ro water and we were checked up on by the environmental inspectors yearly and quizzed about how much ro water we created because of the potential harm caused by the run off...

[mussel and hate]

Worst case scenario the waste water is routed to drain, eventually evaporates and is precipitated... What is the concern again?

[11purewater]

Get a permeate pump.Its like a turbo for a car .It takes the concentrate(waste water) and forces it through the membrane again and boosts water pressure which produces more permeate(good stuff) and no power requirement ,

[BuckeyeFS]

Originally Posted by 11purewater

Get a permeate pump.Its like a turbo for a car .It takes the concentrate(waste water) and forces it through the membrane again and boosts water pressure which produces more permeate(good stuff) and no power requirement ,

??

Permeate pumps are intended for systems using a pressurized storage container/tank.

[BuckeyeFS]

Originally Posted by northbay-reefer

You could send the waste line to another membrane and reduce the waste ratio to about 2-1 or less depending on the water pressure.

First - remember that what folks call "waste water" really would be better thought of as "flush water" in that this water serves the important purpose of internally flushing the surface of the semipermeable membrane to keep the membrane from fouling/scaling.

When you configure a system with two membranes in series (the waste from the first membrane going to the "in" port on the second membrane), for this discussion let's say it's two 75 gpd membranes, the system behaves like you have a single long (75 gpd x 2) 150 gpd membrane.

Now - if you use a proper flow restrictor, that is, one for a 150 gpd membrane, you'll have about a 4:1 waste to product ratio. Sounds familiar, right?

If however you don't change the flow restrictor - meaning you keep using the same restrictor you were using when you just had one 75 gpd membrane, then you'll see a waste to product ratio much lower than 4:1. But remember that the recommendation for a ~4:1 ratio comes from the membrane manufacturer. They are telling you that you need about a 4:1 ratio to keep the membrane flushed and keep the membrane from fouling or building up scale. Run the system with a lower ratio and you will foul/scale the membrane(s) quicker than would have otherwise been the case.

Instead of adding a second membrane to lower that ratio, you could have just changed out your flow restrictor ($4) instead. A much less expensive approach to get you to the same endpoint in terms of saving on waste water.

Now, to confuse things just a bit. Filmtec specs call for the 4 to 1 ratio on the basis of assumptions about the water that will be supplied to the membrane. If you have very soft water you MAY be able to get a decent service life from the membrane running at a ratio lower than 4 to 1 (e.g., 3 to 1). Remember that the waste water from the first membrane is about 25% harder than your tap water.

Bottom line: If what you are after is reduced waste water, experiment with a different flow restrictor for $4 instead of messing around with a second membrane plumbed in series.

As a side note, you can also lower the ratio by increasing the pressure delivered to the membrane (with a booster pump), because flow restrictors are sized assuming you are providing factory spec conditions (50 psi and 77 degrees for Filmtec membranes). Increase the pressure and you'll drive more water through the membrane and viola - less waste water. But as I mentioned above, if you do this (just like over-restricting a membrane) - the lower the waste to product ratio, the shorter the lifespan on the membrane.

Makes sense?

Russ

[mordibv]

I use ro containers . One for RD/Di and the other for the rejected water that I feed to my square foot vegetable garden .

[firebirdude]

Depends on the size of the tank you have. Anything under 30 gallons usually means you're not making more than 5 gallons of DI at a time. In that case, it's almost not worth worrying about the waste. If you have a 100 gallon tank, and you're making 20 gallons of DI at a time, then it starts to be quite a bit of waste water. I think filling the washing machine is the best use of the water, for me anyway. I use well water to water my lawn/bushes/etc. The pump is on a timer that runs every other day. Plus it rains in FL every other day. So no need for anymore water out there...

[ReefPharmer]

some great ideas here but i do have a follow up question. When you are "filling" your washing mashine, do you just let the water fill up the machine until its full? half full? then you run it off into the train until you wash the clothes and start the process over?

I am having a hard time figuring out how you "fill the machine" without overfilling.

I have 2 180 gallon tanks and a 120 (for now) so i have quite a bit of waste water.

Thanks

[sawcreatives]

Waste RO water is great for watering plants. The acidity is great for them.