Reusing R/O waste water

[BigBBrew]

I've been thinking about what to do with our R/O wastewater. We have a 7bbl brewhouse and knockout is usually 15-20 minutes. I was thinking about taking an old, double wall plastic water tank we have and making it a cold water tank. I'd use it for knockout thru the first stage of the plate chiller? (We don't have a cold liquor tank). Has anyone tried this? I imagine there will be a lot of minerals just waiting to attach themselves to some nice, hot stainless plates.

Thanks

[dick murton]

Assuming you are brewing with RO, why aren't you using the RO for chilling the wort and recovering the heat? Far more efficient. Your proposal wastes all that good heat you could have recovered and then almost certainly ensures you will have to frequently clean the water side with acid because of excessive fouling (as you suspect) with the extra high mineral content waste water.

[MilepostWill]

Unfortunately, I don't have an answer. I came here with the same question. Our R/O filter is 1:1. Meaning for every gallon of "distilled" water for brewing, there is 1 gallon of waste "brine", which I assume is the water the original poster is talking about, loaded with the stripped out minerals. Our current system is small, but as we step up, i hate the idea of just sending hundreds of gallons down the drain each time i fill the HLT/kettle, etc. If i saved it and hauled it in a container, i bet it's unsuitable for animal watering, or irrigating plants, right?
Again, no answers, but interested in what people do with the run-off from their filters. Also, is 1:1 pretty normal for these filters, or do some produce less waste water?
will

[Rmiller]

As you didn't state what types of dissolved solids you have in your water it is difficult to determine what to do with the rejected brine. If you have that brine analyzed you can then decide how to best use it. Remember the brine is a concentrate of all the dissolved solids in your supply water. The brine will typically be corrosive and can cause other fouling. Depending on the chemical makeup of the brine it might not be suitable for grey water applications like landscaping irrigation. Once you know what you have in the rejected water you can better determine if you can make use of it or not.

Marks Design & Metalworks
Vancouver, WA
Marksdmw.com

[gitchegumee]

We use RO discharge water for flushing toilets in our pub.

[BuckeyeHydro]

The first thing I'd recommend any RO owner look at is the potential to recycle some of the concentrate. Before we recommend customers do this we look at their water chemistry and run it through some modeling software to identify the max concentrate that can be recycled.

Russ

[gitchegumee]

Don't want to hijack this thread, but to the OP's point of reusing reject water; what is the state of the art in blending RO to get a reasonable TDS for brewing liquor? Blending based on TDS transmitter?

[BuckeyeHydro]

Don't want to hijack this thread, but to the OP's point of reusing reject water; what is the state of the art in blending RO to get a reasonable TDS for brewing liquor? Blending based on TDS transmitter?

It is fairly simple to set up an inline TDS meter on the permeate line, and a needle valve to control the amount of feedwater added to reach your desired TDS level. Or are you looking for more of an automated solution?

[gitchegumee]

Automated for sure! Don't want to manually check TDS and manually adjust some valve constantly during the course of tank filling, which happens automatically. Sometimes at night. Nor do I want to batch this. Instead, I'd like to automatically blend in either reject water or borewell water to get a reasonable brewing liquor. It makes no sense to me to strip out all minerals and then add those minerals back in the form of food grade, purchased salts! Talk about wasteful with energy, money, and water! I can't be the only one who is faced with this.

I can handle the controller & mixing valve part, but was told that good online TDS transmitters were expensive due to trace amounts of iron fouling them. And is TDS the best way to monitor my brewing liquor? Would love to hear what sorts of solutions have been tried, and more importantly which ones work!

[BuckeyeHydro]

If you are using a commercial RO system, iron (along with a number of other contaminants like hardness and manganese) needs to be removed before the feedwater reaches the RO. You'd use the treated feedwater to blend with the permeate. So fouling or scaling of the probe of a controller (as well as the RO membrane) should not be a significant issue.

https://www.buckeyehydro.com/controllers-1/

[gitchegumee]

That's not the case with our commercial RO system. We have two units at 1,000 liters/hour and they use very hard feedwater with a descaling agent added. We do not, nor would we want, a salt-based water softener prior to our RO plant. Our plant discharge is salty enough without adding more salt. Appreciate the link for controllers, but it's not the controller, programming, logic, or loop I'm stuck on. It's the measurement probe/transmitter/sensor for TDS with standard 4-20 mA or other standard sensor signal that I'm being told is the difficult element to source. Our system might not be standard setup for US, but it works well. Just need to find a way to blend filtered, unstripped water back into the RO stream to gain minerals appropriate for brewing liquor. It would save us maybe 40% throughput on our RO units, along with associated energy costs, water saved, and the ridiculous waste of adding purchased food-grade minerals back to the RO water at mash-in.

[BuckeyeHydro]

Have you had issues with your membranes fouling from the anti-scalant?

Depending upon your water chemistry, you very well may have issues with untreated feedwater scaling/fouling the probe. The devil is in the details here.

The probes are not difficult to source in the USA... but I suspect it is an entirely different situation in Palau.

[BuckeyeHydro]

https://www.buckeyehydro.com/controllers-1/