DIY RO DI 1:1 waste????

[Roland Jacques]

First test

First off, I did not get 1:1. I got 1 part clean water to about 0.75 waste,

I forgot to run the carbon first and bypass the membranes when I ran this test, oops. I will flush the membranes and run the test again. I don’t imagine it will improve that much.

Other problems

1. A couple of small leaks. No biggy

2. I bypass my pressure reg for the house and my tap water pressure pegged my 100psi gauge. (This is a temporary gauge, im trying to find a inexpencive digital gauge.)

After the prefilters the needle came off the peg. Guessing no more than 115 psi. I not sure but I would think the membranes could take that high of a pressures with out damaging them right????

3. My inline tds meter is not reading anything.

you can see the darker color in the waste water, carbon i should have flushed first.

 

[cres]

Sweet setup.

It looks like you have two sets of prefilters in parallel and parallel dual DI filters. Did you go this way for capacity or for longevity?

And, I'm guessing you are getting close to 300 GPH out of this setup.

I've been considering the extra RO membrane and maybe doubling my DI. Thanks for this experiment.

 

[Roland Jacques]

The first prefilter are in series the second set is .5 micron carbon parallel. I use a lot of water so partly capacity but mainly to minimize the pressure drop across these .5 micron filters. I did not no that my tap water pressure was that high when I built it.

I think the addition of the membranes is a good mod. I got the info and idea from this thread. jim, from thefilterguys did a lot of the testing for this type of set up it convinced me it worth doinghttp://reefcentral.com/forums/showthread.php?s=&postid=7676017#post7676017

Im not positive on the daily output yet but I m thinking 300 at that psi

 

[bergzy]

wow!

now that is a ro set up!!!

if you are trying to get zero waste...

i use this unit!

Zero Water RO Unit

pricey, small output and not for everyone...

 

[Roland Jacques]

yeah Ben
i looked at that zero waste. but i could not fully understand it. i can see how it works, but it seems like it would have some limiting factors. (How much waste water can you house plumbing/waterheater except before you flush your toilet...) it seem like it would be great for low water use in a apartment with shared plumping. do you no what kind of performance number your geting out of it? TDS, GPD, membrane life?

 

[bergzy]

<a href=showthread.php?s=&postid=7678464#post7678464 target=_blank>Originally posted</a> by yourfishman
do you no what kind of performance number your geting out of it? TDS, GPD, membrane life?

i finally got a tds meter a few months ago and the input water reads 3-4ppm as of today with a two year old membrane and one year old sediment and carbon filter. socal water here is very high in tds.

gpd sucks as it only generates about 20-25gpd.

thus, it must be because of the low production that the pump can pump waste water back into the hot water line without any noticeable effect on things like my hot water heater (i use a tankless system btw) and toilets the such.

even on my 180g reef and 125g fo tanks...this system is more thanenough as i do not make my sw for water changes...i am very lucky to live near a facility that gives research nsw away for FREE! and who could ask for the best product for such a great price!

 

[Roland Jacques]

FREE Salt Water!!!!!!!!!!!!! where do you live?

your zero watse unit sounds good. i would think 25 gpd would be enough for 95% of hobbyest out thier.
no water heater. see this is what i dont get. unless the booster pump is able to over come the city water pressure it should only be able to produce water while you are using water, right? do you know how much pressure that booster pump can do?

 

[bergzy]

yeah,

i am lucky to live in southern cal where there is a place that has a spigot for nsw for public use. the parameters are perfect (as nsw should be) and i tested it for zero nitrates and phosphate...

i dont know the pressure the pump can create but from what i gather from this unit...the pump is able to overcome city water pressure and pump the waste water downstream from the ro source water.

 

[Roland Jacques]

That zero waste system raises more questions to me.

Since the zero waste water pushes water back into the city water system does your meter run backwards when it doing this?

In my case my city water pressure is 120psi that means my house plumbing is also pressured that high. I would think that would stress some household plumbing the water heater tank in particular. Kind of cancels the function of the home pressure regulator.

How often dose your pump run? Continuously while you are making water?

 

[bergzy]

i havent checked if my water meter runs backwards and here is a huge caveat about the zero waste system.

my hot water tank did spring a leak about 6 months into using it...

coincidence or just the water heater being old...

the water heater i had was there (i am the third owner) when we bought the house and also with the previous owners who lived there for 7 years...

so i am guessing that the hot water tank was a min of ten years old.

i have no more tank worries as i went to a tankless system where the water is heated on demand.

the pump does start running once you start emptying the ro tank.

how long does the pump last and does it burn out? i dunno...but i have ran for 10 days straight without any problems.

 

[Roland Jacques]

thanks Ben,

Thats a lot of good info. i think i now understand the zero waste RO better.

 

[cres]

bergzy: Do you have a TDS meter on the input size of your system?

My concern with zero waste is that without other demand (e.g. toilets flushing, people showering, laundry, etc.) the slightly higher TDS on the ouput side will make it's way back to the input size of the filter.

So, if you leave for the day and the system is making water, will the input TDS slowly build up, 95% or 98% of it being rejected by the RO membrane, and 2-5% of an increasing TDS making to the DI (therefore using a little more of it).

It then becomes a question of water conservation and cost reduction balanced against DI resin conservation and cost reduction.

As a whole, your house is using water while you make water (at a rate equal to production), so, I doubt any water is pushed back into the city lines.

 

[BeanAnimal]

Your water meter is not going to run backwards. If the system does indeed make enough pressure to push water back into the city water system, then you are still paying for the water. On another note, I certainly don't like the idea of an end user pushing water back into the system... I am sure your local water company would not be happy about it either.

Most setups that use similar technology require an expansion tank on the hot water heater.

That said, while this unit is running, it is putting water into your system as you take water out of the system. There should be no real pressure gain. As long as the pressure pump is strong enough to overcome your line pressure, then the water is put back into the hot water heater to mix with the rest of the water. It is a closed loop with a pressure regulated "top off" (the city water supply). As the system runs you are drawing clean water off of it (at 1:4) ratio. The 4 parts of dirty water go back into the hot water tank and mix with what was alread there PKUS 1 new part of clean water. BUT WAIT... we are drawing water from the COLD NOT THE HOT SIDE! Yes, but they are connected together right before the water heater, so they are under the same pressure.....

NOW here is the problem, without the expansion tank, the water you are pushing INTO the hot water heater must go someplace. It gets pushed back out the COLD WATER INPUT side of the heater, into the COLD WATER SUPPLY LINE and then to your faucet or RO/DI unit. Not very efficient because your water heater now has to cycle to reheat the tank (becuase you are pushing cold water into it) and also has to compensate for the loss of heat you are pushing into the cold water supply line.

So.... add it all up and the unit is really to good to be true.

Hope this makes sense.

 

[bergzy]

the system to me makes perfect sense...

but again...to let the numbers speak for themselves rather than analytical, hypotheical and non-empirical research interjections...

please read my earlier post about my ro tds output at 3-4 ppm (hard water here in socal) without a membrane change for two years and sediment and carbon change in over a year...

if i was getting 'extra' contaminated water (higher tds) then i would expect premature membrane failure and sediment filters clogging which would show on my tds input meter. as far as i know...3-4ppm tds output is pretty good even if the membranes, sed filters etc were brand spanking new...but, again, the numbers speak for themselves.

also, as i have written earlier and needing to repeat myself again...

i dont run a hot water tank, i dont worry about hot water mixing with cold as my system is tankless...so, efficiency of the hot water tank is irrelevant to 'my situation'. i am writing about 'my' experiences. if one reads my first post to this thread...there is a line that says 'not for everyone'...and i believe this to be true still.

i run into the same 'i am smarter than the engineers who designed this piece of crap' discussion all the time. it's like the engineers at the company said 'hey, let's make something that doesnt work and is too good to be true...let's keep making it regardless if it doesnt work, ruin our reputation (watts has an incredible reputation btw) and, what the heck, let's spend a bazillion dollars to patent the design as well'

anyway, if it is too good to be true and my numbers are there to prove it...i guess i a sucker now, arent i?

 

[BeanAnimal]

1) If you push water back into the city lines, you pay for it anyway (you actually pay for it twice).

2) Again if the water leaving the unit is pushed into the "hot water" line, it still has to go someplace. While the unit is in operation, the waste water is being pushed back into the hot water line. It travels backwards into the TEE that connects it to the cold water side where it mixes with the cold water. From there it takes the path of least resistance which is back to the input of hte RO/DI unit.

Was there really a need for you to act like a child over that explanation? It's a fairly simple concept and no different than a recirculation pump feeding the waste directly back into the input... The one major difference is that the waste gets mixed with some new city water each cycle. Running the unit in short bursts will result in MOSTLY city water being processes. Run the unit long enough (without running other taps in the house) and the input TDS will start climb acponetially. This will happen as soon as the volume of otherwise "standing" water in the supply pipes is exhausted. Again very simple concept. With each "loop" 1 part of clean city water will mix with 4 parts of waste water. The waste water concentration will rise with each loop. Again a very simple concept.

Those with hot water tanks will process much less TDS due to the larger pool of water to mix with. However their problem becomes one of pushing (back flushing) crud out of their water heaters (and the cost of the heater cycling).

Again, with the tankless setup, you are better off with regards to the "problems" associated with the heater, but will certainly process a LOT more tds per gallon of clean water. With proper membrane maintenance, this should be cost effective as long as your runs are short and the inptu TDS is not allowed to skyrocket (working the membrane and DI MUCH harder).

Maybe next time you could just read the post with regards to facts and keep the tantrums to yourself. If you want math to go along with any of these explanation, I (or many of us) can provide it. RO/DI setups are very simple mechanical devices that must follow the laws of physics. No magic, just fluids at work.

Enjoy

 

[Qwiv]

Just wanted to post a note on these systems as I have built a few.
First, you can't pump water back into the city main. There are back flow preventers on all water lines.
Second, the device does just what it says, it pumps the water back into your plumbing. It doesn't build up any incredible preasure because it it removing more water from the system then it is putting back. Example, if it makes a gallon or water an hour and rejects 4 gallons and hour, it removed 5 gallons from the system and put back four. That is a net usage of 1 gal. per hour. If you left this running in your house while on vacation your water usage would be 1 gal. per hour. The preasure on your house water lines would be the same as when you left.

 

[BeanAnimal]

exactly

 

[Roland Jacques]

Yeah Qwiv,
Bean made that very clear; I had a brain fart with that one thanks for clearing that up.

Bean is right again, with the fact that unless you’re using water at the same time you are making water; you do end up recirculation waste water. (Without an expansion tank or a diluted version with a water heater tank.) If you only use a little top off water daily (like Ben) from that type of zero waste units that is no problem. that is probabley why you don't any 100 gallons per day units

Back to my original question will 120 psi on the membranes have any bad effects? Or should I try to find a pressure reg to bump it down to 100 psi.

And 2 does anyone sell an inexpensive digital pressure gauge?

 

[fahz]

Here's the operating limits for 75 GPD FilmTec membranes.

Membrane Type Polyamide Thin-Film Composite
Maximum Operating Temperature 113°F (45°C)
Maximum Operating Pressure 300 psig (21 bar)
Maximum Feed Flow Rate 2.0 gpm (7.6 lpm)
pH Range, Continuous Operationa 2 - 11
pH Range, Short-Term Cleaning (30 min.)b 1 - 13
Maximum Feed Silt Density Index (SDI) 5
Free Chlorine Tolerancec < 0.1 ppm

 

[Roland Jacques]

I can’t believe I did not run water through the carbon (rinse/flush) before I ran the system.

I did have a small flood in my basement as I discover a hairline crack in the PVC tee fitting I used to tie into the sprinkler system water. It was such a fine mist of water I did not catch it until the next morning