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4040 RODI filtration system - sense check?

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JDR

JDR

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Location
Banbury
Hi,

I'm new to this forum. I am a car valeter and detailer.

I bought a trolley based RO setup off a local window cleaner, who was upgrading his system chasing after a higher throughput system.

I am a complete newbie at this setup, however, I have had it a few months. I  want to call on the more experienced to ensure that I am not missing a trick or opportunities to improve efficiency, reduce waste, etc.

So, my system is three stage: a 20" Carbon block, a 4040 (40"?) RO membrane which has a pump pressurising water to 145PSI (editted), and a DI filter. There is a flow control valve controlling the waste water port from the 4040. I was instructed as to where to keep the dial. I have calculated that this equates to 60% wasted water, leaving 40% from the pure outlet. After a while I noted that the pure water was registering 15ppm with my domestic water supply typically being around 300ppm. 

Last weekend I changed the Carbon block filter, the DI resin with MB-115 and flushed and cleaned everything out. I have now done some more tests and with 300ppm input I am achieving 0ppm output. I also took a reading directly after the RO filter, i.e. before the DI filter and seen 11ppm, so seems the RO filter itself is removing 96.3% of TDS. Does this sounds right? I am managing to process just over 100 litres an hour and currently filling up my 1000Litre IBC.

I have calculated that to fill a 1000Litre IBC with pure water I will consume 2500 litres of water.  Is this a lot/atypical? Could I tweak the flow control valve to reduce water consumption? If so, what is the trade-off? I am assuming shorter life of the RO filter and more frequent changes of the DI resin? Or, thinking outside my box, is there another filter stage I could add to help reduce consumption? Btw, I measured the TDS of the waste water to be 563ppm and I am thinking out agricultural uses!

Just for completeness of documenting my setup: I have installed a 13,000 litre per hour bilge pump into my IBC and use a 1" pipe which is 30 metres long to dispense water into my 400 litre tank in my van. Takes just a couple of minutes to fill up! I have used a smart plug so that I can turn off the bilge pump from my van, which I thought was a nice touch ?

edit: Just one more question. I flush the system by fully opening the control valve for ten minutes every 4 hours of usage and at the end, is this right?

TIA, Jonathan @ Autograph Valeting and Detailing 

 
Last edited by a moderator:
Looking at your points it looks as if the pump is your main problem in performance.

Do you have a photo of the pump with part number etc..

 
JDR said:
Hi,

I'm new to this forum. I am a car valeter and detailer.

I bought a trolley based RO setup off a local window cleaner, who was upgrading his system chasing after a higher throughput system.

I am a complete newbie at this setup, however, I have had it a few months. I  want to call on the more experienced to ensure that I am not missing a trick or opportunities to improve efficiency, reduce waste, etc.

So, my system is three stage: a 20" Carbon block, a 4040 (40"?) RO membrane which has a pump pressurising water to 45PSI, and a DI filter. There is a flow control valve controlling the waste water port from the 4040. I was instructed as to where to keep the dial. I have calculated that this equates to 60% wasted water, leaving 40% from the pure outlet. After a while I noted that the pure water was registering 15ppm with my domestic water supply typically being around 300ppm. 

Last weekend I changed the Carbon block filter, the DI resin with MB-115 and flushed and cleaned everything out. I have now done some more tests and with 300ppm input I am achieving 0ppm output. I also took a reading directly after the RO filter, i.e. before the DI filter and seen 11ppm, so seems the RO filter itself is removing 96.3% of TDS. Does this sounds right? I am managing to process just over 100 litres an hour and currently filling up my 1000Litre IBC.

I have calculated that to fill a 1000Litre IBC with pure water I will consume 2500 litres of water.  Is this a lot/atypical? Could I tweak the flow control valve to reduce water consumption? If so, what is the trade-off? I am assuming shorter life of the RO filter and more frequent changes of the DI resin? Or, thinking outside my box, is there another filter stage I could add to help reduce consumption? Btw, I measured the TDS of the waste water to be 563ppm and I am thinking out agricultural uses!

Just for completeness of documenting my setup: I have installed a 13,000 litre per hour bilge pump into my IBC and use a 1" pipe which is 30 metres long to dispense water into my 400 litre tank in my van. Takes just a couple of minutes to fill up! I have used a smart plug so that I can turn off the bilge pump from my van, which I thought was a nice touch ?

edit: Just one more question. I flush the system by fully opening the control valve for ten minutes every 4 hours of usage and at the end, is this right?

TIA, Jonathan @ Autograph Valeting and Detailing 
Click to expand...
The tds of your tap water is quite high at 300ppm so your pure output quality is about right. You really need to play around with the waste valve (closing it and opening it a tad) and see if you can improve water quality, but I doubt there will be much of an improvement. Our water is around 132ppm and our 4040 works best at 55% waste to 45% pure. It was once recommended by a supplier that water over 250ppm needs a waste to pure ratio of 3 to 1. But at 3:1 your pressure will be much lower on the membrane as the easiest route is to waste.

What you are looking for is the r/o producing the purest water before di. In my experience your r/o is performing within spec (96.3%) even although you haven't mentioned how old the membrane is or who has manufactured the membrane.

45psi is operating at the low end of the water pressure requirement. I'm also questioning what pump you have pressurizing your membrane, as is @doug atkinson.

If we look at Axeon they produce two membrane variants. An HF4 best operates at 80 to105psi. There are numerous manufacturers who came to have low pressure membranes or even an ultra low pressure membrane that best operate at the same or higher psi - one at 120psi. The other variant that Axeon manufacturer is an HF5 low pressure membrane which works best at 50 to 80psi.

Our water pressure is 50psi and our 4040 produces about 120 litres of pure an hour. When the sediment filter starts to clog up, water going through the prefilters slows and the pressure on the membrane drops. At about 45psi my pure goes up from 3ppm to 4ppm. While that is nothing coming from a low base, it actually 33.3%.

When I first purchased my HF5 8 years ago I was getting a rejection rate of 98%. Its now 97%. A supplier once hinted that 94% was the time to start thinking about a new membrane.

As with all these things, it's about "economies of scale." If you are on a water meter, the cost of running an r/o to spec could cost you more on water than you would spend increasing the longevity of your membrane. There was a windie once who advised that he ran his r/o at around 20% waste to 80% pure. His membrane would last a year and he would use more resin, but the saving on his reduced water bill justified his action.

I use 20" Fibredyne carbon block filters which are rated at 75700 litres of chlorine removal (waste + pure.) For us that's a change cycle of about every 3 months for the amount of water we use. Someone on the other forum had a go at me for replacing these filters as often. He stated that replacing prefilters every 6 months would reduce the longevity of the membrane, but the cost saving on every second filter set would off-set that. TBH, his argument does make sense, but as we will never have a "sliding doors" scenario, we can never know which is best as we can't run our experiment together under the identical conditions.

As regarding flushing, many just flush once before producing water. I'm the worst when it comes to this, and I often don't bother for weeks at a time, and when I do, it's less than 5 minutes. Many years ago, June from GAPS Water did say that flushing isn't as important as some make it out to be. But then our water has very little calcium content.  If I lived in Hartlepool with their water at 550ppm, I would flush much more often and would also consider a commercial water softener.

 
Last edited by a moderator:
spruce said:
The tds of your tap water is quite high at 300ppm so your pure output quality is about right. You really need to play around with the waste valve (closing it and opening it a tad) and see if you can improve water quality, but I doubt there will be much of an improvement. Our water is around 132ppm and our 4040 works best at 55% waste to 45% pure. It was once recommended by a supplier that water over 250ppm needs a waste to pure ratio of 3 to 1. But at 3:1 your pressure will be much lower on the membrane as the easiest route is to waste.

What you are looking for is the r/o producing the purest water before di. In my experience your r/o is performing within spec (96.3%) even although you haven't mentioned how old the membrane is or who has manufactured the membrane.

45psi is operating at the low end of the water pressure requirement. I'm also questioning what pump you have pressurizing your membrane, as is @doug atkinson.

If we look at Axeon they produce two membrane variants. An HF4 best operates at 80 to105psi. There are numerous manufacturers who came to have low pressure membranes or even an ultra low pressure membrane that best operate at the same or higher psi - one at 120psi. The other variant that Axeon manufacturer is an HF5 low pressure membrane which works best at 50 to 80psi.

Our water pressure is 50psi and our 4040 produces about 120 litres of pure an hour. When the sediment filter starts to clog up, water going through the prefilters slows and the pressure on the membrane drops. At about 45psi my pure goes up from 3ppm to 4ppm. While that is nothing coming from a low base, it actually 33.3%.

When I first purchased my HF5 8 years ago I was getting a rejection rate of 98%. Its now 97%. A supplier once hinted that 94% was the time to start thinking about a new membrane.

As with all these things, it's about "economies of scale." If you are on a water meter, the cost of running an r/o to spec could cost you more on water than you would spend increasing the longevity of your membrane. There was a windie once who advised that he ran his r/o at around 20% waste to 80% pure. His membrane would last a year and he would use more resin, but the saving on his reduced water bill justified his action.

I use 20" Fibredyne carbon block filters which are rated at 75700 litres of chlorine removal (waste + pure.) For us that's a change cycle of about every 3 months for the amount of water we use. Someone on the other forum had a go at me for replacing these filters as often. He stated that replacing prefilters every 6 months would reduce the longevity of the membrane, but the cost saving on every second filter set would off-set that. TBH, his argument does make sense, but as we will never have a "sliding doors" scenario, we can never know which is best as we can't run our experiment together under the identical conditions.

As regarding flushing, many just flush once before producing water. I'm the worst when it comes to this, and I often don't bother for weeks at a time, and when I do, it's less than 5 minutes. Many years ago, June from GAPS Water did say that flushing isn't as important as some make it out to be. But then our water has very little calcium content.  If I lived in Hartlepool with their water at 550ppm, I would flush much more often and would also consider a commercial water softener.
Click to expand...
Thanks for your reply Spruce. I did buy another TDS meter to double check my readings and it confirmed that my water supply is around 300ppm. Today its at 293ppm. My carbon block filter also quotes 75000Litres. I don't know the make of the RO filter but I was told that it should be replaced in twelve months time. I think its about 6 months old. I am on a water meter also. What's the sediment filter?

IMG_20210919_173935.jpg

IMG_20210919_173942.jpg

 
I've now produced 1000 litres of pure water. Taking off the flushing times it does actually work out to throughput of 138 litres an hour ?

So just the 11ppm which is suggested to be not the best from the membrane, given 300ppm, what is the ideal PPM to aim for? Does 11ppm mean I will have to change the resin more often? I don't really want to waste more water as said I am on a water meter. Thank you all for your replies.

 
That is not for a 40 inch membrane but that pump would do around 160 litres in a hour with a 4040 membrane.  
 

However it can only do 40 psi with the 4040 membrane. Based on the results you are getting it may be a high pressure membrane in there.

I wouldn’t worry too much as 011ppm is okay.

 
JDR said:
Thanks for your reply Spruce. I did buy another TDS meter to double check my readings and it confirmed that my water supply is around 300ppm. Today its at 293ppm. My carbon block filter also quotes 75000Litres. I don't know the make of the RO filter but I was told that it should be replaced in twelve months time. I think its about 6 months old. I am on a water meter also. What's the sediment filter?

View attachment 25604

View attachment 25605
Click to expand...
Good old Brodex; they haven't changed. Still only fitting 1 prefilter. Yes, you can use the carbon block as a sediment prefilter doing both jobs. However, if your water supply gets contaminated with sediment from a mains repair, this will block up the carbon filter and render it useless. We have another filter before the carbon block. A sediment filter isn't expensive and basically protects the carbon block filter. At times in the past I've had to replace my sediment twice before replacing both at 75600 litres. A sediment filter was around £5 where a Fiberdyne is about £37.00.

Resin polishes off the dissolved solids in the water the membrane can't remove. The higher the pure tds output is from the r/o, the more resin you will use.

For us, we deplete 6.5 litres of Tulsion MB115 resin a year. The windie near us (now retired) had an old, inefficient Merlin r/o. His pure tds was 10ppm from the same water supply. He changed his resin approx 3 times a year. At the time we were using a little more water a month than he was., although not by very much.

This is our r/o in a heated cabinet in the garage. The sediment filter is the first one and the second is the carbon block.

Ro 1.jpg

 
Last edited by a moderator:
doug atkinson said:
That is not for a 40 inch membrane but that pump would do around 160 litres in a hour with a 4040 membrane.  
 

However it can only do 40 psi with the 4040 membrane. Based on the results you are getting it may be a high pressure membrane in there.

I wouldn’t worry too much as 011ppm is okay.
Click to expand...
Thanks Doug.

 
spruce said:
Good old Brodex; they haven't changed. Still only fitting 1 prefilter. Yes, you can use the carbon block as a sediment prefilter doing both jobs. However, if your water supply gets contaminated with sediment from a mains repair, this will block up the carbon filter and render it useless. We have another filter before the carbon block. A sediment filter isn't expensive and basically protects the carbon block filter. At times in the past I've had to replace my sediment twice before replacing both at 75600 litres. A sediment filter was around £5 where a Fiberdyne is about £37.00.

Resin polishes off the dissolved solids in the water the membrane can't remove. The higher the pure tds output is from the r/o, the more resin you will use.

For us, we deplete 6.5 litres of Tulsion MB115 resin a year. The windie near us (now retired) had an old, inefficient Merlin r/o. His pure tds was 10ppm from the same water supply. He changed his resin approx 3 times a year. At the time we were using a little more water a month than he was., although not by very much.

This is our r/o in a heated cabinet in the garage. The sediment filter is the first one and the second is the carbon block.

View attachment 25611
Click to expand...
Thanks for filling the blanks for me Spruce. Nice and neat system there. Something for me to aspire to. 

 
JDR said:
Thanks for your reply Spruce. I did buy another TDS meter to double check my readings and it confirmed that my water supply is around 300ppm. Today its at 293ppm. My carbon block filter also quotes 75000Litres. I don't know the make of the RO filter but I was told that it should be replaced in twelve months time. I think its about 6 months old. I am on a water meter also. What's the sediment filter?

View attachment 25604

View attachment 25605
Click to expand...
Just looking at this be  mindful that daylight uv will promote algae growth within an uncovered IBC outdoors and it's best to cover it or your water quality and IBC cleanliness will deteriorate quickly.

Also be mindful of winter being around the corner and especially the RO and filter housings will need wrapping up from the frost when the weather dips into winter. Even if storing the RO in a garage over night 

A frost damaged RO is an expensive mistake 

 
Apw1210 said:
Just looking at this be  mindful that daylight uv will promote algae growth within an uncovered IBC outdoors and it's best to cover it or your water quality and IBC cleanliness will deteriorate quickly.

Also be mindful of winter being around the corner and especially the RO and filter housings will need wrapping up from the frost when the weather dips into winter. Even if storing the RO in a garage over night 

A frost damaged RO is an expensive mistake 
Click to expand...
Thank you Apw1210 for your suggestions. I shall get an IBC blanket/coat/cover. I am currently insulating my shed and installing a heater.

 
JDR said:
Thank you Apw1210 for your suggestions. I shall get an IBC blanket/coat/cover. I am currently insulating my shed and installing a heater.
Click to expand...
My best tip is to get 2x cheap tesco double duvets, cut them length ways in half and they are the same height as an IBC, wrap them around twice and secure with gaffa tape then wrap the IBC with black or green pallet wrap or landscaping geo textile fabric 

Great affordable installation and light blocking 

 
Pjj said:
Sounds like an episode of blue Peter ???
Click to expand...
Haha! Reminds me of my son watching 'The A Team' when he was about 8. I used to say "Look at that! They go into a barn. Find a bent nail a piece of string and a rusty bucket and come out with an armoured car!.." Shut up, Dad!" was his usual annoyed reply. ?

 
Last edited by a moderator:
Davy G said:
Haha! Reminds me of my son watching 'The A Team' when he was about 8. I used to say "Look at that! They go into a barn. Find a bent nail a piece of string and a rusty bucket and come out with an armoured car!.." Shut up,
Dad!" was his usual annoyed reply. ?
Click to expand...
Yeah, that, and a dozen men firing fully automatic machine guns and no blood. I watched it when growing up though. lol. 

 
JDR said:
Yeah, that, and a dozen men firing fully automatic machine guns and no blood. I watched it when growing up though. lol. 
Click to expand...
A team, Chips, blue thunder, street hawk, Knight rider all my favourite TV shows growing up thank god for colour tv's my Sanyo Black and white with the round aerial was awful 

 

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