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Post by motorsports on Oct 16, 2023 19:15:52 GMT
Have had some issues with Feed Water quality at more than two of our locations recently.
One is high city water pH - 8.6-9.3 - what effect does that have on carbons (specifically exchangeables) and the conductivity of the RO product water. Can exchangeable carbons not handle higher pH? There is a single exchangeable lignite carbon post softener (pre carbon) also. Still have high pH post all carbons (9.3), a lower pH post booster pump (city water 8.6) and high product water conductivity requiring DI polish. No one can explain this sudden issue on a less than 2 yr old CWP system. Can carbon be bad right from the mfr? We needed to add the DI polish a few days after a carbon exchange took place.
The other is algae in a 1micron, pre RO filter and housing. No algae in the 5 micron pre filters. Exchangeable carbons as well. Gray opaque hoses across all pretreatment tanks. I have never seen algae growth in a pretreatment system. Annnd, this is the only water room I have seen with windows. Could the semi-opaque softener and carbon tanks be growing algae because of the windows?
We are waiting for some mfr. test results on the pH issue. We have been told algae can grow in the gray tubing at the other location. I wish we had a real water expert we could consult with. If anyone knows of any, please share.
Thanks!
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Post by Chuck Weddle on Oct 16, 2023 20:19:05 GMT
Have had some issues with Feed Water quality at more than two of our locations recently. One is high city water pH - 8.6-9.3 - what effect does that have on carbons (specifically exchangeables) and the conductivity of the RO product water. Can exchangeable carbons not handle higher pH? There is a single exchangeable lignite carbon post softener (pre carbon) also. Still have high pH post all carbons (9.3), a lower pH post booster pump (city water 8.6) and high product water conductivity requiring DI polish. No one can explain this sudden issue on a less than 2 yr old CWP system. Can carbon be bad right from the mfr? We needed to add the DI polish a few days after a carbon exchange took place. The other is algae in a 1micron, pre RO filter and housing. No algae in the 5 micron pre filters. Exchangeable carbons as well. Gray opaque hoses across all pretreatment tanks. I have never seen algae growth in a pretreatment system. Annnd, this is the only water room I have seen with windows. Could the semi-opaque softener and carbon tanks be growing algae because of the windows? We are waiting for some mfr. test results on the pH issue. We have been told algae can grow in the gray tubing at the other location. I wish we had a real water expert we could consult with. If anyone knows of any, please share. Thanks! You need to start at the beginning and make contact with your municipal water supplier and find out why the pH is so high. Municipalities are mandated by the EPA to regulate the pH in order to mitigate corrosion and leaching of lead from old plumbing but not as high as you're seeing. If the high pH is permanent and not an "oopsie!", you will likely need to add an acid feed system to your pretreatment. The high pH does affect the ability of carbon to react with and remove chlorine. Do you get your carbon from a company that specializes in dialysis or from Joes Water Conditioning and Septic Service? GAC for dialysis is supposed to be acid-washed because of this. Your booster pump won't affect the pH so why it would be lower after the pump I have no idea. The lignite carbon after the softener is there as an organic scavenger and shouldn't affect the pH. The high pH could be allowing calcium to come out of solution and not be removed by the softener. This calcium precipitate could theoretically be getting to causing scale and damage to the RO membranes. Your algae issue sounds easier to solve but not pleasant. Its likely a combination of things all contributing to it. After taking care of the causes, you then have to get rid of what you already have. 1. As you stated, the windows allowing UV light. Cover them. 2. If the lights are florescent, put them on a motion detector so they turn off or change them to LED. 3. Get rid of any tanks and filter housings that are opaque. With algae, light is the enemy. One of the best pieces of advice I can give you is to get a copy of Water Treatment for Dialysis from NANT. |
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Post by dave74 on Oct 16, 2023 22:44:41 GMT
I can only speak to some of the issues.
When we used exchange carbons, the vendor did not properly prepare the carbon. The pH would go high for several days, and the RO percent rejection would drop. It is possible to get inferior grade carbon from a water vendor.
I worked in an acute unit that had a water treatment system located in what was once a patient room. Sun would come in there so bright, you almost needed sunglasses. Algae was a big problem there. Cover the windows and use motion detector lights.
We also had problems with algae and the home patient systems. The connectors on the carbon tanks were semiopaque. Algae was a problem in home systems where there was light.
Become friends with at least one person at the water department. Dialysis facilities may send out a generic letter, but it helps if you actually someone there who can answer your questions and keep you informed as to what is going on.
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dts
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Post by dts on Oct 18, 2023 16:51:21 GMT
As for the effect on the RO product quality, I’ve been given to different explanations.
First, the high pH causes the membranes to swell, thus resulting in lower rejection.
Second, a pH approaching 9 will produce an alkalinity, not being a salt will pass through the membranes. The alkalinity will be picked up by the conductivity monitor and result in a higher product conductivity.
From past experience, the latter seems to be the best explanation.
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Post by Chuck Weddle on Oct 18, 2023 19:00:35 GMT
As for the effect on the RO product quality, I’ve been given to different explanations. First, the high pH causes the membranes to swell, thus resulting in lower rejection. Second, a pH approaching 9 will produce an alkalinity, not being a salt will pass through the membranes. The alkalinity will be picked up by the conductivity monitor and result in a higher product conductivity. From past experience, the latter seems to be the best explanation. I would think that if the membrane swelled, the "pores" would become tighter and allow less to pass through resulting in lower recovery but better quality (lower conductivity). High alkalinity actually lowers conductivity and high acidity increases it...... "Of the common ions, the most mobile cation is the Hydrogen ion and the most mobile anion is the Hydroxyl ion. So, you see that strongly acidic solution will have high conductivity since the pH is a measure of the concentration of the Hydrogen [and the Hydroxyl] ions, for an acidic solution, the lower the pH the greater the conductivity will be." Source: edubirdie.com/examples/electrical-conductivity-and-ph |
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dts
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Post by dts on Oct 18, 2023 22:55:24 GMT
I’m certainly not an expert in chemistry and couldn’t even begin to remember the source’s for those explanations. However, in the past 45+ years I’ve installed numerous systems and on a few occasions I’ve experienced higher feed pH with higher than expected product conductivity. And by lowering the pH resulted in better product quality. Not sure, could be the water composition at that particular site
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Post by motorsports on Oct 19, 2023 16:12:51 GMT
Thank you all for your response - I agree with the effects of pH on the high conductivity. And I get it that vendors could not prepare the carbon properly. I have a hard time assuming the vendor may have a poor quality or the wrong carbon in the exchangeables because they are specific to Dialysis Quality Water Service and definitely know better. We were told the lignites would resolve any pH issues and they have helped out consistently. It's the introduction of the new carbons that created the sudden high pH in pretreated water and condo spike in product water. The vendor doesn't agree. They insist something changed with our feed water. City water treatment manager states absolutely not- Same source and same municipal water treatment practices as always.
Kind of the same goes for the algae situation. We need to contact city water for that location to verify no changes in source or treatment practices. Vendor states it is normal to find green foreign matter in our prefilter.
I am curious about water composition. Hoping vendors samples will explain more and the pretreatment system can be modified to resolve future issues with carbon exchanges.
I would still appreciate any recommendations for water experts. Didn't we have a couple of them on the old RenalWeb forum?
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Post by Chuck Weddle on Oct 19, 2023 17:03:52 GMT
Your posts are confusing. In your initial post, you said "high city water pH - 8.6-9.3" but now you're saying that it's your pretreated water.
New carbon, even acid-washed can TEMPORARILY cause an increase in pH if not adequately flushed. But as I posted before, alkalinity will cause a decrease in conductivity not an increase.
The pH and conductivity may be separate problems and not related.
1. What is the pH of the water coming directly from a sink?
2. What is the pH after each component of the pretreatment?
3. What is the pH immediately after the RO?
4. What is the conductivity of the water entering the RO?
5. What is the conductivity of the RO product water?
6. Can you verify the conductivity with a independent device?
7. Will your lab do an AAMI analysis on a tap water sample? (I know Ascend does and Spectra doesn't)
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Post by dave74 on Oct 19, 2023 17:45:49 GMT
A man named Larry Alexander owned a water treatment consulting business. He used to post on RenalWeb. He was also a member of the AAMI Renal Disease and Detoxification Committee. He disappeared, and I can't remember the name of his company. Sorry. I think it was Florian, but a Google search didn't turn up anything.
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Post by stephenccarr on Oct 23, 2023 15:19:45 GMT
I also wondered what happened to the Florian posts. While sometimes disagreeing with him, I found Larry's posts brought in a font of knowledge and expertise beyond what a technician would likely know. It was very sad that all the Renalweb postings disappeared. I sometimes wonder if the major corporate interests actually tried to suppress independent discussion of the cash cow known as dialysis.
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Post by Amber on Nov 15, 2023 16:12:06 GMT
We had that same issue with a new water system. Conductivity running high at around 60us. They ended up putting in a dealkalizer that took care of the high pH and conductivity issue. In fact it worked too well, and caused the pH to be to alkaline. This in turn caused fluoride to be able to "slip" through the RO membranes and show up high when I did my AAMI on the product water. The reason explained to me was that the RO couldn't "see" that specific ion due to the alkalinity of the water. I ended up having to open the bypass valve for the dealkalizer slightly until my pH reading, post the dealkalizer, was neutral around 7. Just something to keep in mind should you go that route.
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