Help: need help with well water treatment

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Hydrocynus

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Hello, I am in South Florida and I get my water from the sandstone aquifer at about 95 feet. I have a system that I use now for 6 months. It was installed professionally and consists of an air drawn system (10X54 air injected), 1.35 ft^3 of Calgon Centaur catalytic with 5 pounds of KDF-85 followed by a water softener. The softener gets cleaned by back flushing every other day and my air drawn filter gets cleaned every day between 1 and 4am.

I still get some iron deposits and a very light smell of sulfur (will analyze). My water has no ferrous iron per analysis. It is hard water and has 2.4ppm of sulfides. TDS is about 480-750 ppm depending on the season. I use the green back for the salts in my softener.

The water treated reacts with SOS cleaning pads creating a black smoke reaction in the water and black stains. This reaction does not happen when I use untreated well water or RO water. So, it is coming from my filtration system.

To address the sulfides, I would like to add an aeration tank with solenoid valves and sprinklers. I am thinking using this tank AFTER the softener to i) get rid of the remainder of the sulfides and ii) be able to use water during the blackout period from 1 am to 4 am.

Let me know. I want to stay away from whole house RO.

Cheers to all.
 

ditttohead

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Can you post a lab report water test? As to the 5 pounds of KDF, this is likely done more for marketing than actual function. If you consider that tKDS requires 30 GPM per ft2 of bed area to properly backwash and carbon typically uses 10 GPM per ft2 to backwash, these two medias are not a good fit for mixing as the KDF simply does not get backwashed. it wont hurt anything but it also wont help anything.

If you do not have a full real water report, leas get one, use the link below and get the well standard.
NTLWATERTEST
 

Reach4

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My water has no ferrous iron per analysis. It is hard water and has 2.4ppm of sulfides.
I have never before seen a numeric test result for sulfides. At first I thought you meant sulfates, but your low number lead me to rethink that. My Centaur Carbon based H2s+iron filter regenerates every 3 days, running a bleach solution through after backwash. But my H2S is very low level. High enough that I wanted it gone, but low enough to be not noticeable for many. Yours has to be impressively noticeable if that is mostly H2S.

https://www.who.int/water_sanitation_health/dwq/hydrogensulfide.pdf says
In water, the taste and odour thresholds for hydrogen sulfide are estimated to be between 0.05 and 0.1 mg/litre. The taste and odour threshold for sulfides is about 0.2 mg/litre (5).​

That sentence confuses me a bit in that I have not thought about gaseous sulfides other than H2S. Iron sulfide is a solid, and I don't know that it has a smell in water. I don't know that it does not. I think iron sulfide is the black sediment in the bottom of water heaters, but having no iron in your test would be another way that our waters are very different.

Did your system work well initially?
 

Hydrocynus

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I have never before seen a numeric test result for sulfides. At first I thought you meant sulfates, but your low number lead me to rethink that. My Centaur Carbon based H2s+iron filter regenerates every 3 days, running a bleach solution through after backwash. But my H2S is very low level. High enough that I wanted it gone, but low enough to be not noticeable for many. Yours has to be impressively noticeable if that is mostly H2S.

https://www.who.int/water_sanitation_health/dwq/hydrogensulfide.pdf says
In water, the taste and odour thresholds for hydrogen sulfide are estimated to be between 0.05 and 0.1 mg/litre. The taste and odour threshold for sulfides is about 0.2 mg/litre (5).​

That sentence confuses me a bit in that I have not thought about gaseous sulfides other than H2S. Iron sulfide is a solid, and I don't know that it has a smell in water. I don't know that it does not. I think iron sulfide is the black sediment in the bottom of water heaters, but having no iron in your test would be another way that our waters are very different.

Did your system work well initially?

Thank you all for your answers. That does not really answer my original question as it seems that your answers elude to eventually changing the filtration medium. I have tested my own water using bench equipment in my lab. For the suflides and the iron, I used HACH test kits and used either a Cary 100 spectrophotometer with a standard curve or the colorimeter that came with the HACH kit. The sulfides were analyzed less than 30 minutes after sampling and I had to dilute the sample by 10 because my kit is on the more sensitive range.

For nutrients, I ran them on my auto analyzer (TP, TN, NOx, NH4, PO43-). The TDS were either deducted from the water conductivity (in microS/cm) or actually during the real mass measurement following the standards methods (which is my preferred method).

Again, I am in South Florida in a karstic environment getting the water at 95 feet. I do have a CSV valve not too long ago because I had issues with my pump being oversized for my pressure tank.

Well water as measured at the end of the rainy season (November 2020)
TDS: 475 ppm
Suflides: 2.4ppm
Hardness: 385ppm CaCO3eq or 22.4 gpg
pH: 7.39
Temp: 26.41C
ORP: -137.3
DO% 16.93
DO: 1.42 ppm
Ferrous iron: undetected
Fluoride, copper, chlorine, bromine, cyanuric acid: undetected
E. coli and Entero not detected. Coliforms were detected but they cover a broad range of bacteria
TP: 0.084 ppm, TN: 0.953 ppm, NH3 0.504 ppm, NO2: 0.0075 ppm, NO3: 0.0020 ppm, PO4: 0.02378 ppm.

Apparently, the company I have hired to install the well has several air drawn systems like mine installed all over my region. The KDF and Calgon are not layered but all mixed because I do not have any ferrous iron. I wanted to retrofit an ozone drawn system because I never felt that my system fully get rid of the sulfides which maybe some sulfur oxidizing bacteria are passing the filters and use the iron on my fixtures that they oxidize and create iron oxides and hydroxide rust.

So, maybe an UV treatment would kill such bacteria but I still would have an issue with the mild sulfides which smell a bit even passed my on demand RO filter. I am the only one drinking the RO water in the family.

So, What do you think guys? Would a an aerator placed after the water softener help with the sulfides? I could eventually do a H2O2 injection but then we are getting pretty far...

Thanks for your tips. Will try to find the time to measure the sulfides in the inhouse water if I get time next week.
 

Reach4

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Thank you all for your answers. That does not really answer my original question as it seems that your answers elude to eventually changing the filtration medium.
I did not think I was providing answers, but I will say that changing the medium was not what I had in mind. I was wondering about modifying your system to suck something from a solution tank rather than sucking air. While I suck chlorine bleach solution, H2O2 (hydrogen peroxide) might be a better choice. So I did provide my thoughts. I think an aerator earlier might be good. If the H2S appears more after the water sits above ground than when water is used a lot, I would suspect bacteria is producing H2S. I have a Ceranode powered anode on my WH to prevent H2S production in my WH. I do not have UV, and expect to sanitize my well and plumbing this spring or summer; it has been 5 years.
Maybe UV to prevent bacteria coming in could prevent bacterial action once you sanitized the downstream water to kill the preexisting bacteria.

I am not a pro. I have only the one system installed 2012. That will likely need a media changeout at some point, since I am passed the original 8-year estimate, but my levels are low. I was interested that your system uses Centaur Carbon too.

Apparently, the company I have hired to install the well has several air drawn systems like mine installed all over my region. The KDF and Calgon are not layered but all mixed because I do not have any ferrous iron. I wanted to retrofit an ozone drawn system because I never felt that my system fully get rid of the sulfides which maybe some sulfur oxidizing bacteria are passing the filters and use the iron on my fixtures that they oxidize and create iron oxides and hydroxide rust.

Did your system work initially?
 
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Hydrocynus

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I did not think I was providing answers, but I will say that changing the medium was not what I had in mind. I was wondering about modifying your system to suck something from a solution tank rather than sucking air. While I suck chlorine bleach solution, H2O2 (hydrogen peroxide) might be a better choice.

I am not a pro. I have only the one system installed 2012. That will likely need a media changeout at some point, since I am passed the original 8-year estimate, but my levels are low. I was interested that your system uses Centaur Carbon too.



Did your system work initially?

Well, I do not want to mess with the system that is already in place. I did think about an ozone drawn retrofit system as 100% O3 is a much better oxidant than 21% O2 (air drawn). However, that means that I need to lower the grade of my clack valve. H2O2 also does not come out cheap, hence the idea of a double treatment air drawn and aerator which would also allow me to have a water reserve when the filters are being back flushed from 1 to 4 am every day. I do sometimes have to hit the road at 4am to do field work...

I am curious to see what the others are saying.
 

ditttohead

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As to the Ozone system mounted on the valve, this only generates ozone during the regeneration process which is great for keeping the bed sanitary. Bacteria and oxygen can make for a nasty situation as opposed to ozone. You would need either a proprietary clack valve capable of ozone regen or a 4 button EE valve to use the ozone properly. As to the KDF and carbon being mixed, it is more likely the KDF is simply a clumped up ball of kdf in the bottom of the tank. KDF requires 30 GPM per ft2 to b backwashed properly. Carbon typically requires 1/3 of that. H2o2 injection is relatively cheap and easy to maintain.
 

Hydrocynus

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As to the Ozone system mounted on the valve, this only generates ozone during the regeneration process which is great for keeping the bed sanitary. Bacteria and oxygen can make for a nasty situation as opposed to ozone. You would need either a proprietary clack valve capable of ozone regen or a 4 button EE valve to use the ozone properly. As to the KDF and carbon being mixed, it is more likely the KDF is simply a clumped up ball of kdf in the bottom of the tank. KDF requires 30 GPM per ft2 to b backwashed properly. Carbon typically requires 1/3 of that. H2o2 injection is relatively cheap and easy to maintain.
Thanks.

Looks like the H2O2 would have to be placed before the well water enters the filter media. Costs of H2O2 a month seems to be about $25-$30 a month (about 2 gallons of 7% H2O2). So, it looks like this is going to be moderately expensive.
I will test my H2S this week but it seems to me that since they are hardly noticeable, an aeration tank placed after the softener should get rid of the remaining H2S. I might want to treat the pipes in my house by adding H2O2 and to open each faucet individually. I do believe I have some sulfur oxidizers in my lines.
 
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