29ppm Clear Iron Well Water - Please help

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Darrell Kresge

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Hi folks,

Long time listener, first time caller here.

TL;DR How do we correct for a well producing 29 ppm dissolved Iron, 5.6 pH, 0.684 ppm Mn, 150 NTU Turbidity

With many thanks for your suggestions, here's the long version:

Background:
Well drilled 1995 on Eastern Shore of MD w/ usage of 50-60 GPD​

Long history of rusty, "stinky" water controlled by frequent softener
backwash. Recent labs show 28.7 mg/L ferrous iron. Tried a couple things,
skeptical about the local provider's recommendation, have a few ideas, but
looking for solution.​

Water test:
Conducted 14 Aug 2020 @ http://www.finsup.net/NTL-913225.pdf (details also at bottom of post)​

Equipment (in order):
Stenner Peroxide injector
42MHP2 pump w/ 7% H2O2 set max flow (3.0 GPD)
32 gal pressure vessel
38-58psi cutin/out
Flow rate 8GPM​

Durawater AIO system
10in x 54in tank w/ Fleck 5600SXT
1.5 ft^3 Centaur Catalytic Carbon​

Simplus 744( Sulfur Remover
0.5 ft^3 MnO w/ Cl Regen​

AN / Softener Combo
Master Water NS30T "Combo Concept 30/40" w/ Autotrol 168
Upper tank 0.5 ft^3 80% Calcite / 20% MgO "NS-Mix"
Lower tank 30k grain standard resin​

Notes:
The presence of the AIO & H2O2 is, umm, unconventional. We installed the AIO system in 2019 before completely understanding the scale of the problem and subsequently added the H2O2 with the goal of increasing the oxidation potential. All other equipment was installed in '95 based on water tests at the time.​

Recent events:
Water quality was great following installation of H2O2/AIO but recently plummeted. We've since bypassed the AIO tank and stopped the H2O2 drip.​

A local water company was out, tested (after multiple dilutions) 64ppm Iron with drops. Stated the Iron levels in the region are too high to filter and recommended the installation of a 132k grain softener. Possibly two of them.​

I suggested that nothing be done until we get proper labs and talk to the good folks at terrylove.com​

My thoughts/questions:
The AIO backwash frequency and H2O2 injection rate were never set based on actual data. I suspect the unit is completely fouled. Knowing what we know now, and assuming we shouldn't, in fact, be installing a giant water softener, I'm thinking that/wondering if:​

1) The H2O2 applied rate should be increased to 0.97 GPD of 34% H2O2​

2) Calgon states max Iron is 10ppm for Centaur. So the media bed of the AIO tank (which we're basically trying to use as a sediment filter / contact tank) is likely insufficient -- maybe replace with KL? Need different backwashing filter? Inline static mixer for H2O2?​

3) Well w/ 8GPM places potential pressure and volume limits on media backwash​

4) High Turbidity with normal TDS implies what?​

I've read lots of posts here about similarish situations, and hope that we're finally on the right track. If you've made it this far, thank you for reading. And thank you for any advice you can offer!

-----

Watercheck "Problem Check" results of 14 Aug 2020:
('*' denotes excessive)

[Microbiologicals]
Iron Bacteria ABSENT

[Metals] [Physical Factors] [Inorganic]
Calcium 23.700 mg/L Alkalinity/CaCO3 (ND) Nitrates as N (ND)
Copper 0.009 mg/L Corrosivity -4.451 SI Nitrite as N (ND)
*Iron 29.331 mg/L Hardness 170.0 mg/L Sulfate 15.0 mg/L
*Iron-Dissolved 28.748 mg/L *pH 5.6 Tannin/Lignin 16.0 mg/L
Magnesium 27.930 mg/L TDS 190.0 mg/L
*Manganese 0.684 mg/L *Turbidity 150.0 NTU
Potassium 7.000 mg/L
Silica 15.100 mg/L
Sodium 40.000 mg/L
 
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Reach4

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Dang.
I've read lots of posts here about similarish situations,
Standing out to me is Langelier corrosivity of -4.451. That is unusual I think -- very corrosive. I guess your low pH is a big part of that. Avoid metal for your fittings and pipe.
Plus your Manganese is high, but the thing that takes care of the iron may take care of that.

Tannin/Lignin 16.0 mg/L -- I don't know, but that sounds high.

And the iron, as you pointed out, is impressively high. I don't remember people posting with similar water.

My suspicion is that something like H2O2 or chlorine injection followed by a good contact tank with blowoff valve for sediment removal might be a good start. But I anticipate more than one stage is going to be needed. I am not a pro. Good luck.
 

Darrell Kresge

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Thanks for the reply and for calling that to my attention @Reach4 -- As NTL kindly put a big green checkmark next to the Corrosivity value, I can't say I paid it much notice. Until now. I'll do some more reading on that. Thankfully almost everything is CPVC (and I believe the AN is doing its job), but it might explain an earlier failure of a galvanized hose barb fitting.

We have H2O2 injection (probably set too low given recent findings) but may need to have more contact time. If that is, in fact, the right approach, I'm just not clear on what product is best able to filter the sheer volume of solids. Is my AIO tank sufficient given a proper amount of a proper media?

And I should have probably said "I've read a lot of posts. Some similar." - this one was the closest:
[URL]https://terrylove.com/forums/index.php?threads/60-ppm-iron.54107/[/URL]

Also thanks @DIYMissus -- While the long ago primary motivation for the softener was "because it was recommended to remove iron", I thought the GPG would be 9.94 (170 ppm / 17.1 ppm/g) which is pretty hard, no? Have I goofed?

Thank you both!
 

Reach4

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As NTL kindly put a big green checkmark next to the Corrosivity value, I can't say I paid it much notice.
I had presumed that was the Langelier corrosivity number. It rated a green checkmark, then that -4.51 number must have been some other kind of reading.

We have H2O2 injection (probably set too low given recent findings) but may need to have more contact time. If that is, in fact, the right approach, I'm just not clear on what product is best able to filter the sheer volume of solids. Is my AIO tank sufficient given a proper amount of a proper media?
I suggest you add "baffle factor" to searches. https://view.publitas.com/impact-water-products/2018-catalog-final/page/152 Flexcon Mixmaster looks good to me. I think it has 3 ports, with one a purge (blowoff) port for dumping sediment. Treated water comes out of the top.

You would want to have a faucet letting you sample the output of the contact tank to let you measure the residual H2O2. Based on that level, you would adjust your injection rate. Then you would remove the residual H2O2 with a carbon tank.

Depending on how you neutralize the pH, the softener could become more important. Some neutralizing methods add hardness.
And I should have probably said "I've read a lot of posts. Some similar." - this one was the closest:
https://terrylove.com/forums/index.php?threads/60-ppm-iron.54107/
I had missed that one. The first response was interesting: move or new well.
 
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Darrell Kresge

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I had presumed that was the Langelier corrosivity number. It rated a green checkmark, then that -4.51 number must have been some other kind of reading.

Nope - you're right -- I called and it's LSI. The checkmark just indicates that it was below the minimum detection level (which doesn't apply for range values). It's a bit misleading in my opinion. Iron + Manganese + low pH likely contributory. I think if I solve the Iron issue, everything else will likely fall into place.

I suggest you add "baffle factor" to searches. https://view.publitas.com/impact-water-products/2018-catalog-final/page/152 Flexcon Mixmaster looks good to me. I think it has 3 ports, with one a purge (blowoff) port for dumping sediment. Treated water comes out of the top.

Thank you! That's the critical bit I was missing. I didn't realize that the contact tank existed for more than simply "more contact" but would also act as the sediment accumulator.
 

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Also thanks @DIYMissus -- While the long ago primary motivation for the softener was "because it was recommended to remove iron", I thought the GPG would be 9.94 (170 ppm / 17.1 ppm/g) which is pretty hard, no? Have I goofed?

Thank you both!

Your are welcome
TDS is all the dissolved solids including sodium.
Hardness is Calcium and Magnesium
The TDS of ones hard and softened water is usually the same same since Calcium and mag. ions are swapped for sodium ions
The 170 hardness looks like Calcium 24, magnesium 28 and Iron ( 29 x4 ) = 168 mg/l Calcium and mag. = 52 / 17.1 = ~3.5 gpg

A softener is designed to remove Calcium and Magnesium . A softener can remove a small amount of iron but not efficiently and the iron "fouls" the media requiring regular feedings of iron out and reducing its lifespan. You don't have a small amount of iron and it should be removed by equipment for that specific purpose. imo
 

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The 170 hardness looks like Calcium 24, magnesium 28 and Iron ( 29 x4 ) = 168 mg/l Calcium and mag. = 52 / 17.1 = ~3.5 gpg
Thanks again @DIYMissus ! I especially appreciate your assertion that specialized equipment should be used. I've watched my folks deal with this for years and it's really hard to not perpetually second guess myself.

And while I *really* don't want to derail this thread from "solving their Iron problem", I'm not sure I follow the math and, as a newbie, would very much like to understand.
In your statement ".. and Iron ( 29 x4 )", from where does the [4 ppm hardness per ppm Fe] originate? When they reopen tomorrow I plan to call the lab to find out how they derive their Hardness number, but I don't _think_ it includes any Iron. As I understand it(*), the CaCO3 equivalence factor is 2.5 for Ca++ and 4.1 for Mg++ which would result in a total hardness CaCO3 equivalent of ((23.7 * 2.5) + (27.93 * 4.1)) == 174 mg/L (which is close). Fe++ (ferrous) has a CaCO3 equivalent of 1.79, and Fe+++ (ferric) is 2.69 -- so if they included Iron, it seems the Hardness number would be closer to 227 ppm?

(*) https://www.necoindustrialwater.com/conversions-and-guides-water-chemistry-caco3-equivalents/
 

ditttohead

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I removed the info that is not critical to simplify this one.

*pH 5.6 Very low and this should be treated. A simple Calcite filter may be adequate, since all your plumbing is CPVC, be sure to replace any older fixtures to prevent lead leaching. You may want to have the treated water tested after a few months for lead to make sure your plumbing is not being leached...
*Manganese 0.684 mg/L
*Iron-Dissolved 28.748 mg/L excessive but it should be fairly easy to treat. I would recommend dosing at about 20 PPM H2o2 into a Katalox Light system. A baffled contact tank would help tremendously.

Hardness 170.0 mg/L Moderate, a softener would be nice but certainly not mandatory. I would definitely have one myself at this level.


Tannin/Lignin 16.0 mg/L Tannins are tricky, wait until the water is treated for iron, hardness etc... then decide if you want to treat. You can also retest later.

*Turbidity 150.0 NTU This number will likely come down after the KL system...
 

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Sodium hydroxide plays nice with chlorine bleach. I wonder about injecting such a mix. Two birds....

Yes, it would take experimenting to tune the mix.
 

Darrell Kresge

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Thanks @dittohead for the reply! As mentioned, there are already a calcite filter and water softener installed, so I'll focus on the Iron issue. @Reach4 mentioned the possibility of using a contact tank with a blowoff valve -- basically allowing the Ferric Iron to precipitate out and periodically discharging the waste. I'm not sure if your suggestion of a Katalox Light system complements this proposal or replaces it? Assuming the goal is to clean up any residual ferrous iron, could I simply use KL in lieu of the Centaur Catalytic Carbon that currently lives in the bottom of the AIO injection tank?
 

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Thanks again @DIYMissus ! I especially appreciate your assertion that specialized equipment should be used. I've watched my folks deal with this for years and it's really hard to not perpetually second guess myself.

And while I *really* don't want to derail this thread from "solving their Iron problem", I'm not sure I follow the math and, as a newbie, would very much like to understand.
In your statement ".. and Iron ( 29 x4 )", from where does the [4 ppm hardness per ppm Fe] originate? When they reopen tomorrow I plan to call the lab to find out how they derive their Hardness number, but I don't _think_ it includes any Iron. As I understand it(*), the CaCO3 equivalence factor is 2.5 for Ca++ and 4.1 for Mg++ which would result in a total hardness CaCO3 equivalent of ((23.7 * 2.5) + (27.93 * 4.1)) == 174 mg/L (which is close). Fe++ (ferrous) has a CaCO3 equivalent of 1.79, and Fe+++ (ferric) is 2.69 -- so if they included Iron, it seems the Hardness number would be closer to 227 ppm?

(*) https://www.necoindustrialwater.com/conversions-and-guides-water-chemistry-caco3-equivalents/
I'm not one of the experts . I assumed and maybe I was wrong that hardness value was the number to be used as the H (hardness) setting on a softener, once converted to gpg . Ca + Mg 23.7 + 27.93 = ~52 mg/l Iron, being much harder for the softener to remove is often multiplied by 4 ( I have seen between 3 and 5 used as the multiplier)~ 29 x 4 = 116. 116 + 52 = 168 ppm. I'm interested in hearing how they calculated the hardness.
 

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Iron is not considered during the hardness lab test or Hach 5-B test. If the softener is to be used for iron removal, you create a compensated hardness by summing (4x or 5x the iron in ppm as grains of hardness) with the actual hardness to get the compensated number.

There is also a high-hardness compensation too.

You would not consider using the softener as the primary iron remover with 29 ppm of iron, but the softener is going to be dealing with any bleedthrough of iron from the primary iron treatment.
 

ditttohead

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AIO and 30 PPM of iron is similar to towing a 30 foot boat with your Honda Civic. Technically it may work, but your poor Civic will be scrap metal in no time.

Your calcite/corosex qty is probably not even close to adequate. The design is "neat", but calcite and corosex need contact time. If your water flow is very low, never exceeding 1 gpm, then this might be adequate.

Your system seems like someone just started throwing pieces of equipment that sounded neat together in hopes of cleaning up the water.

In general, we would want to raise the pH first. Then oxidant injection, then iron reduction/oxidant removal, then softening. Your system has the pH correction at the end. Low pH and iron is good if you are using softening for iron reduction. Using KL requires higher pH for adequate iron reduction. Ignore the KL specs they list, these are typically under perfect conditions.
 

Darrell Kresge

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AIO and 30 PPM of iron is similar to towing a 30 foot boat with your Honda Civic. Technically it may work, but your poor Civic will be scrap metal in no time.

Which is why we added the H2O2 injection, but then it became a filtration issue.

Your calcite/corosex qty is probably not even close to adequate. The design is "neat", but calcite and corosex need contact time. If your water flow is very low, never exceeding 1 gpm, then this might be adequate.

I'll be "onsite" tomorrow so I can check the post AN pH.

Your system seems like someone just started throwing pieces of equipment that sounded neat together in hopes of cleaning up the water.

Not far from the truth. Sulfur and Combo AN/Softener "came with the house". AIO was added blindly and H2O2 added after learning enough to be dangerous.

In general, we would want to raise the pH first. Then oxidant injection, then iron reduction/oxidant removal, then softening. Your system has the pH correction at the end. Low pH and iron is good if you are using softening for iron reduction. Using KL requires higher pH for adequate iron reduction. Ignore the KL specs they list, these are typically under perfect conditions.

The pH adjustment is currently prior to softening, but as you noted, is possibly insufficient. I'm reluctant to just start over (but will if necessary). Prior to moving to KL (and all the system replacement/rerouting that would entail), would it make any sense at all to test the outcome of installing a contact tank w/ blowoff immediately following the pressure tank? It's not ideal, it's not proportional, and it might require periodic flushing of the pressure tank, but it's a component I'm going to need anyway, and perhaps the carbon bed in the AIO (nee, filter) tank will handle the residual?
 

Darrell Kresge

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I'm not one of the experts . I assumed and maybe I was wrong that hardness value was the number to be used as the H (hardness) setting on a softener, once converted to gpg . Ca + Mg 23.7 + 27.93 = ~52 mg/l Iron, being much harder for the softener to remove is often multiplied by 4 ( I have seen between 3 and 5 used as the multiplier)~ 29 x 4 = 116. 116 + 52 = 168 ppm. I'm interested in hearing how they calculated the hardness.

Hey, no worries, I'm just thankful for the feedback of this community, and happy to be learning. I just now spoke w/ NTL/watercheck -- they stated it's calculated as I hypothesized.
 
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