H2S Slippage; SRB's in Centaur Carbon Bed

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Beets

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I've been using my water treatment system with H2O2 for about 2 years; and before that I used it with chlorine for about +15 years. I've had occasions where I've had H2S slippage, but this is fast becoming one of my most challenging. I'm looking for advise.

My water treatment consists of adding H2O2 to incoming water, running through a large pressure tank and large pressurized holding tank, then through a 10x54 back washing centaur carbon filter. I have H2S in the incoming water, and the critters that make the H2S also live in the water (hereafter referred to as SRB's). I've sanitized the well in the past, but the SRB's and H2S come back in days. Consequently, I focus on water treatment from the house onwards.

A couple weeks ago, there was H2S slippage. I checked the H2O2 residual entering the carbon filter and it was around 5 ppm, and I bypassed the carbon filter for several days. When I bypassed the carbon filter and sent the H2O2 water throughout the house and the smell went away. That suggested the source of the H2S was the carbon filter itself! I sanitized my entire water system with bleach last week (everything downstream of the well) by passing the carbon filter and running the chlorine throughout the house and letting it sit for 4 to 6 hours. I then back washed the carbon filter with bleach and put it back into service with a large dose of bleach upstream of it. The smell went away for about 3 or 4 days, but it is back. H2O2 residual entering the centaur carbon filter is 25 ppm at the moment.

Several thoughts in my mind. Is there any harm in just by-passing the carbon filter forever? What sort of H2O2 residual can I have before it is harmful to humans, drinking water, septic tank, etc?

If I rebed the carbon filter, is there a filter medium that is less hospitable to SRB's than centaur carbon, but still helps removes residual H2S (there are times when I have 25 ppm residual H2O2, but still get H2S to the carbon filter) and removes residual H2O2.

If I rebed the carbon filter, is there any harm in putting only 1 cu ft of carbon in it as compared to the 1.5 cu ft it can hold? My theory is that I have SRBs living in the filter, and I can't seem to get chlorine or peroxide in sufficient concentrations to them during the back wash to kill them off. However, I don't need much carbon because the H2O2 is already taking care of most of the smell, so perhaps reduce the bed height.

I would appreciate any thoughts.
 

Reach4

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When I bypassed the carbon filter and sent the H2O2 water throughout the house and the smell went away. That suggested the source of the H2S was the carbon filter itself!
Another interpretation would be that the plumbing after the carbon filter was producing after the carbon filter was growing SRB, and letting the H2O2 reach and kill the SRB.

But the Centaur carbon (CC) being the source of the smell would also make sense. I was under the impression that the life of Centaur Carbon was around 7 years. I am not sure of that. I am not sure what happens to H2O2 in the CC. I am not sure what happens to chlorine in the CC. I have a filter with 1.5 cuft of CC, installed 9 years ago. So the topic interests me.
I've been using my water treatment system with H2O2 for about 2 years; and before that I used it with chlorine for about +15 years.
How did your chlorine get injected, and how does your H2O2 get injected? Into the brine port of the valve from a solution tank? So my chlorine is only drawn during regeneration, and then gets flushed out. That is how my chlorine gets in. I recently noticed the draws were taking less solution each time. I cleaned the injector, and that got the flow back to where it was originally. I suspect your H2O2 gets injected via micronizer or pump.

I think the sanitizing of well and plumbing with an enhanced procedure gave me an effect lasting longer. You might consider sanitizing your well and plumbing when the weather permits. https://terrylove.com/forums/index....izing-extra-attention-to-4-inch-casing.65845/ is my writeup. It may be overkill, but that was my intention. We are going for years and not days.
 
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ditttohead

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If you have bacterial issues, use bleach, not h2o2. H2o2 can feed the bacterial problems since the byproduct is oxygen. You need to do very high dosing in order for h202 to properly disinfect.
 

Beets

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Thank you. The H2O2 is injected into the system via a Stenner pump. Pump is activated when there is power to the submersible pump in the well. The addition of chlorine is manual. There are two ways I do this. I have a filter housing upstream of the pressure tank. I don't have a filter in it. I simply use it for a place where I can open the system up, and add chlorine. The other way I add chlorine is by isolating the retention tank, draining a couple liters of water off the bottom of it, and then adding chlorine to the top of that tank. I wait 10 or 15 minutes for the chlorine to disperse, and then I will back wash or sanitize the house with the mixed water. I often do both i.e. add chlorine to the filer housing AND add it to the retention tank.

I have little doubt the plumbing is "growing" bacteria as I've seen that before. I have never seen it so quickly after a heavy chlorination though, which is why I'm leaning towards the centaur carbon being the issue.

I'm not familiar with a "brine port". Maybe that is something I should be looking into. Would my back washing carbon filter have this?

I'm really tempted to empty my centaur carbon filter, sanitize it, and refill it with 0.5 ft^3. That is 1/3 of what I would normally fill it with. I have a suspicion that on back wash, I would have better contact with the bacteria than I currently have and perhaps less problems.

I appreciate the thoughts. Please keep them coming!
 

Reach4

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I'm not familiar with a "brine port". Maybe that is something I should be looking into. Would my back washing carbon filter have this?
Yes and no, but mostly no. The valve housing would have the place, and but it would be plugged. Also you would be missing the injector to let you draw brine or solution.

I'm really tempted to empty my centaur carbon filter, sanitize it, and refill it with 0.5 ft^3. That is 1/3 of what I would normally fill it with. I have a suspicion that on back wash, I would have better contact with the bacteria than I currently have and perhaps less problems.
Interesting idea. I think you are saying that you have a retention/contact tank. Does that have a drain to let you blow out sediment? And is that retention tank upstream or downstream of the pressure tank. I presume the injector is before the pressure tank, but am not sure.

Anyway, if your carbon tank is only there to get rid of residual H2O2, you could use cheaper coconut GAC rather than Centaur Carbon. Yet I am not totally sure. Maybe the Centaur Carbon gets rid of the peroxide via catalytic action and lasts longer, than GAC. I am really fuzzy on that area, among others.

Heat is another way to kill bacteria. In sewer plant use, they rejuvenate the Centaur Carbon with heating, maybe with steam, to high temperatures. So I am not prescribing an action here. Just bringing up stuff I have seen in searches.
 

Beets

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The retention tank is downstream of the pressure tank, and I can isolate it, drain fluid off the bottom and add chlorine in from the top manually when desired. The H2O2 injection is upstream of the pressure tank. During a back wash, I'm simply backwashing with the water + H2O2 that is in the retention tank. If I've added chlorine to the retention tank, that is what the back wash is done with.

I wish I had a source of steam.....that sounds like a good idea.

I just completed a back wash at the highest H2O2 setting. I am getting roughly 100 ppm H2O2 to the inlet of the carbon filter with the Stenner set at 10. I also just added chlorine to the top of the retention tank and to the filter pod upstream of the pressure tank. I can hear the chlorine "fizzing" when I add it to the retention tank. It's possible the reaction between the chlorine and the H2O2 in the water might be reducing the efficacy of the chlorine. I just started another back wash. Hopefully this will clean things up, as I don't know what more I can do besides replace the centaur. I've wondered about using different media, but I do think I need the H2S capability of the Centaur at times.
 

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I've wondered about using different media, but I do think I need the H2S capability of the Centaur at times.
Peroxide reacts with H2S, so I am thinking that gets rid of the H2S. I expect there is some S compound that precipitates out.
 

Beets

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Thank you,

First question: Does anyone know the difference between Centaur NDS 12 x 40 and Centaur 12 x 40? I was guessing that "NDS" might mean "non-drinking water", but both data sheets show them being useful for drinking water.

Second question. How often do you back wash and for how long? Has anyone seen some guidance on that?

I did a lot of backwashing yesterday with H2O2 and with chlorine. No H2S smell this morning. I didn't sanitize the house lines, so that would support my theory that the H2S was coming from the carbon filter (this time). It will be interesting to see how long I go before I have slippage again.....
 

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My DLFC is a 500.....Fleck 2510 valve. I'm guessing this is 5 GPM. Wondering if I should be 7 GPM for Centaur? I'm back washing every 12 days for 10 minutes. 4 minute rapid rinse cycle.
 

Bannerman

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the difference between Centaur NDS 12 x 40 and Centaur 12 x 40?
The product info I have seen, consistently mentions acid wash when referring to the NDS version of Centaur CC. This leads me to suspect the performance for NDS was further enhanced by acid washing. In comparing the Iodine removal performance for both products, the NDS version is rated at 900 mg/g whereas the non-NDS type is 825 mg/g.

Both chlorine and hydrogen peroxide will be rapidly neutralized by the carbon, so don't expect either chemical to saturate and sanitize the entire volume of media. As you said you did not sanitize the house plumbing after the water treatment devices, suggest bypassing the filter system to sanitize all of the plumbing within the home.

As most now maintain the hot water in storage at 120°F to prevent scalding incidents, that temperature is insufficient to reduce bacteria within the water heater, but can act as an incubator to promote bacteria growth. Periodically raising the water temperature above 140°F for several hours will allow sanitation of the tank interior. Because the hotest water will rise to the top of the storage tank, suggest raising the temperature setting to at least 160°F to ensure 140°F at the tank bottom. To sanitize the hot water plumbing downstream from the heater, allow the 160°F water to flow to all hot faucets throughout the home before resetting the temperature to 120.

The recommended backwash rate for 12x40 carbon media is 8-12 gpm per square foot. For a 10" diameter tank, this calculates to 4.3-6.5 gpm depending on water temperature. Suggest increasing the backwash frequency.

Chart showing recommended backwash rates for various media:. https://view.publitas.com/impact-water-products/2018-catalog-final/page/155
 

Reach4

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Second question. How often do you back wash and for how long? Has anyone seen some guidance on that?
My system that uses Centaur Carbon (CC below) is different than yours, but I regenerate every 3 days. My BW is 10 and RR is 5, but my RR also serves to rinse out the chlorine that I draw during backwash. Not an ideal rinse, but it's what is available.

When you backwash, did you ever watch the drain line for visible color? An empty tank has about a 16 gallon capacity. Some of that is displaced by media. But at 5 gpm backwash, I think most discoloration observed would be in the first 2 minutes.

Have you measured residual H2O2 after the CC tank? In city water, the maximum chlorine allowed to show up at a house is 4 ppm, which would be noticeable and annoying at best I think. I think the comparable number with H2O2 is about 25 ppm.
 

Beets

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Thank you. Sounds like I have enough backwash rate. I've never seen much for visible color on backwash. Residual H2O2 after the carbon filter is zero. Even with 100 ppm at inlet. I have set to backwash every 6 days. Still no smell, so I did some good the other day. Will have to see how long it lasts. I never thought of that hot water tank trick. I will have to keep that in mind. I've had issues in the distant past where it was only the hot water affected.
 

WellOff

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Running too high of a concentration of H2O2 into the carbon tank is taxing the carbon- it'll degrade the carbon (that is my understanding): anything that works will expend itself doing that work.

I've always heard that injection should happen AFTER the pressure tank. I have injection post pressure tank and going into a contact tank: H2O2 needs to break down my IRB [Iron Reducing Bacteria] in order to then break down the iron. My well is shallow, so bacteria isn't unexpected: many claim that H2O2 won't deal with bacteria, but that's not what I've found- I have never had any bacteria show up in water tests [lab]. I flush my contact tank every day (set up on a valve with timer). I flush my backwash filter (Centaur carbon) every two days: water use is low, roughly 100 gallons per day. Post contact tank I aim for 1ppm of residual H2O2. Once a quarter (or perhaps 4 months) I shock my water piping: I have an empty filter housing that I fill with H2O2 and discharge into the delivery lines to the house and inside the house. I cannot use chlorine because my water may have tannins- mixing with chlorine is BAD. But, even IF I could use chlorine I wouldn't: water is just so much better with H2O2 (the extra maintenance is worth it to me).
 

Reach4

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Running too high of a concentration of H2O2 into the carbon tank is taxing the carbon- it'll degrade the carbon (that is my understanding): anything that works will expend itself doing that work.
I don't know the mechanism in catalytic carbon. In GAC, I think the mechanism is adsorption, and that filling up the spaces would degrade the carbon. But with catalytic action, I am not so sure. If you had citations that would be interesting. I have seen the writing of rejuvenation for sewer plants. I am not arguing a point, but am interested in discussions on the topic.

I have considered longer+stronger bleach backwashing of my media. I have also considered the same with Iron Out. I would suck in enough solution to fill the tank, remove power while in brine draw, and then put the unit into bypass for a couple of hours. Then while the valve is still unpowered and stopped in brine draw, take the unit out of bypass. That would produce a nice slow rinse. I would monitor the drain line for rust color.

I was told to expect about 7 years out of my media, and it has been in service for 9 years.

I understand that we each have different wells and equipment.

I've always heard that injection should happen AFTER the pressure tank. I have injection post pressure tank and going into a contact tank: H2O2 needs to break down my IRB [Iron Reducing Bacteria] in order to then break down the iron.
After the pressure tank is better, but it requires a proportional flow sensor and a proportional pump. If you use an adjustable fixed injection, injection needs to be before the pressure tank. Before the pressure tank, the water flow rate is fairly consistent while the pump is running, so the pressure switch can control the injection pump.
 
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