Solid MnO2 media for Manganese (and iron) removal?

[new guy]

Symptoms – water runs clear, then turns hazy yellow-brown. Taste and smells like metal.


Lab results:

Manganese 0.5ppm
Iron 1.1ppm
PH 7.3
Hardness (caco3) 150ppm
TDS 200ppm
Turbidity 10.5ntu


Problem is Manganese (0.5ppm) and iron (1.1ppm). Everything else on lab results are excellent to acceptable IMO. I know first line of defence here would normally be a water softener but I don’t want to use a softener as I don’t want to add Na or K in my water or take out the Ca and Mg and who wants to be buying and hauling salt for the rest of their lives?

2nd option is getting an AIO iron filter with Birm or Katalox, but I’ve been reading these requires 8-9 PH for successful Mn removal and you guessed it, I also don’t want to be adding anything in the water to raise the PH.

So I’m now looking at setting up an AIO solid (75-85%) MnO2 media filter i.e. Filox, Pyrolox, etc. These apparently can work at lower PH than birm or katalox to remove iron, but would solid MnO2 media effectively reduce Mn at 7.3PH? Would it really be any better than katalox? I imagine injecting more air or O3 before the AIO filter would help in oxidizing more Mn at lower PH so I’m thinking I could add these on if I don’t get good results with just the AIO system.

Looking for anyone with real world experience or ideally real world numbers to give me an idea of what kind of Mn reduction I could expect to see at what might be less than ideal PH conditions? And also... Yes, I have sufficient GPM to backwash solid MnO2 media and no I don’t want a reverse osmosis or distilled water and no I don’t want to inject chlorine or permanganate before the filter either. (you know me, I’m super fussy with what chemicals I inject in my water!)

Thanks

 

[Aaroninnh]

Symptoms – water runs clear, then turns hazy yellow-brown. Taste and smells like metal.


Lab results:

Manganese 0.5ppm
Iron 1.1ppm
PH 7.3
Hardness (caco3) 150ppm
TDS 200ppm
Turbidity 10.5ntu


Problem is Manganese (0.5ppm) and iron (1.1ppm). Everything else on lab results are excellent to acceptable IMO. I know first line of defence here would normally be a water softener but I don’t want to use a softener as I don’t want to add Na or K in my water or take out the Ca and Mg and who wants to be buying and hauling salt for the rest of their lives?

2nd option is getting an AIO iron filter with Birm or Katalox, but I’ve been reading these requires 8-9 PH for successful Mn removal and you guessed it, I also don’t want to be adding anything in the water to raise the PH.

So I’m now looking at setting up an AIO solid (75-85%) MnO2 media filter i.e. Filox, Pyrolox, etc. These apparently can work at lower PH than birm or katalox to remove iron, but would solid MnO2 media effectively reduce Mn at 7.3PH? Would it really be any better than katalox? I imagine injecting more air or O3 before the AIO filter would help in oxidizing more Mn at lower PH so I’m thinking I could add these on if I don’t get good results with just the AIO system.

Looking for anyone with real world experience or ideally real world numbers to give me an idea of what kind of Mn reduction I could expect to see at what might be less than ideal PH conditions? And also... Yes, I have sufficient GPM to backwash solid MnO2 media and no I don’t want a reverse osmosis or distilled water and no I don’t want to inject chlorine or permanganate before the filter either. (you know me, I’m super fussy with what chemicals I inject in my water!)

Thanks

Your pH looks decent to me. Have you tested your ORP (oxidation-reduction potential)? Reasonably inexpensive tool to test it. If you get a good reading there, on paper you should be able to address that with Katalox, Filox etc, w/o an oxidizer. All depends on the levels.

If your ORP isn't good, you're gonna need to add an oxidizer I would suspect, and may want to anyways at 1.1ppm of Iron.

I reduced some manganese and iron for years with Filox with a pH of 7.0, but my ORP is real good. My levels are less than yours, but you don't have a ton of iron or manganese.

 

[Sponsor]

 

[new guy]

Your pH looks decent to me. Have you tested your ORP (oxidation-reduction potential)? Reasonably inexpensive tool to test it. If you get a good reading there, on paper you should be able to address that with Katalox, Filox etc, w/o an oxidizer. All depends on the levels.

If your ORP isn't good, you're gonna need to add an oxidizer I would suspect, and may want to anyways at 1.1ppm of Iron.

I reduced some manganese and iron for years with Filox with a pH of 7.0, but my ORP is real good. My levels are less than yours, but you don't have a ton of iron or manganese.

Thanks for the reply. It’s good to know that it works for you at 7PH! What iron and manganese levels are you dealing with? ORP wasn’t included on my lab report. I may be able to get it tested. Isn’t ORP directly related to dissolved oxygen levels i.e. more oxygen in water = more oxidation potential? I’m guessing I don’t have much oxygen in the water from the well since the water runs clear and oxidizes after sitting exposed to air.

I’m hoping I can deal with the issue with just an AIO but I’m leaving room to add air injection or ozone if more oxygen is required (if that makes sense). I guess the real question - Is Ph not important to manganese oxidation if enough oxygen is present? Maybe these are more chemistry questions than plumbing questions. lol

 

[Reach4]

Have you tested your ORP (oxidation-reduction potential)? Reasonably inexpensive tool to test it.

Interesting. I had not realize how low some of these are priced. I wonder if they are good. The cheapie pH meters seem to do remarkably well. I saw an ORP meter that looked like one of those, and wondered if it was a pH meter with a fake description.

https://www.emerson.com/documents/a...als-of-orp-measurement-rosemount-en-68438.pdf gets almost to where it explains the measurement method:

THE MEASUREMENT OF ORP
An ORP sensor consists of an ORP electrode and a reference electrode, in much the same fashion as a pH measurement.

THE ORP ELECTRODE
The principle behind the ORP measurement is the use of an inert metal electrode (platinum, sometimes gold), which, due to its low resistance, will give up electrons to an oxidant or accept electrons from a reductant. The ORP electrode will continue to accept or give up electrons until it develops a potential, due to the build up charge, which is equal to the ORP of the solution. The typical accuracy of an ORP measurement is ±5 mV.​

 

[Aaroninnh]

Thanks for the reply. It’s good to know that it works for you at 7PH! What iron and manganese levels are you dealing with? ORP wasn’t included on my lab report. I may be able to get it tested. Isn’t ORP directly related to dissolved oxygen levels i.e. more oxygen in water = more oxidation potential? I’m guessing I don’t have much oxygen in the water from the well since the water runs clear and oxidizes after sitting exposed to air.

I’m hoping I can deal with the issue with just an AIO but I’m leaving room to add air injection or ozone if more oxygen is required (if that makes sense). I guess the real question - Is Ph not important to manganese oxidation if enough oxygen is present? Maybe these are more chemistry questions than plumbing questions. lol

I am at about a tenth of your values for Iron and Manganese, although it varies.
My ORP is pretty high. My water runs clear as well.

I am not a chemist, there are people on here much smarter than I am that may be able to better answer your pH question, but most of the medias advertise that they will work reliably at lower pH than yours.

 

[Reach4]

https://www.watchwater.de/wp-content/uploads/2019/11/Part-2-ORP-use-of-H2O2.pdf says

Using an ORP-METER, any reading above a negative
170 millivolt (mV) indicates Katalox-Light® can be used
effectively without the use of additional oxidants in
most of the applications. Any reading below 170 mV
indicates oxidants will be required.​

There is an anomaly there, but I would think they missed the minus sign on -170 mv, since they actually spelled out negative in the first reference. But I don't know, and I could not find this discussed as much as I would expect. There is a big difference between 170 and -170.

 

[ditttohead]

I like your approach. Start with AIO, possibly add more oxidant injection later. A micronizer air injector or ozone later should do the trick. As to the pH/ORP calculations, we have used these numbers for years but they do not always work out as they claim. Ignore the specs from KL, they tend to be overly optimistic. Pyrolox specifications tend to be more conservative and reliable. Regardless, with iron and manganese reduction, simply be prepared to add more oxidant if necessary. How about H2o2? The byproduct is oxygen.

 

[new guy]

Ignore the specs from KL, they tend to be overly optimistic. Pyrolox specifications tend to be more conservative and reliable. .

I started ignoring specs from manufacturers after I noticed they give different specs for the same media.Lol... filox, pyrolox and mangox are all the same material yet have different specs so all this is really telling us is how honest a brand is! This is why I'm interessted in real world experience/numbers.

 

[ditttohead]

You got it, Pyrolox specifications would make Pyrolox appear to be the worst media, but because of these conservative specifications, people have the best luck with this media. More media, more contact time, higher pH, Lower ORP, etc... Other media claim to work as low as 6 pH... sigh.

 

[new guy]

https://www.watchwater.de/wp-content/uploads/2019/11/Part-2-ORP-use-of-H2O2.pdf says

Using an ORP-METER, any reading above a negative
170 millivolt (mV) indicates Katalox-Light® can be used
effectively without the use of additional oxidants in
most of the applications. Any reading below 170 mV
indicates oxidants will be required.​

There is an anomaly there, but I would think they missed the minus sign on -170 mv, since they actually spelled out negative in the first reference. But I don't know, and I could not find this discussed as much as I would expect. There is a big difference between 170 and -170.

according to filox specs ..... -170mV and above means you can "possibly" use it without extra oxidants. below -170mV then you need extra oxidant.

 

[new guy]

You got it, Pyrolox specifications would make Pyrolox appear to be the worst media, but because of these conservative specifications, people have the best luck with this media. More media, more contact time, higher pH, Lower ORP, etc... Other media claim to work as low as 6 pH... sigh.

Filox claims to remove 5ppm Mn while pyrolox makes no manganese claim. So IDK ... I'm hoping that if they claim 5ppm that it can at least handle .5ppm!

 

[Reach4]

Yes, I have sufficient GPM to backwash solid MnO2 media

How many backwash gpm are you planning, for what diameter tank? Make sure your valve will have plenty of backwashing throughput.

 

[new guy]

How many backwash gpm are you planning, for what diameter tank? Make sure your valve will have plenty of backwashing throughput.

most manufacturers are saying 30gpm/cuft backwash as their higher number. So I'm going with that. I should have ca. 15gpm available according to pump curve... this should be good for 1 or 1.5 cu/ft media in a 9" or 10" tank? I'm looking at clack ws1 for the valve, I know they're rated for 27gpm.

 

[Bannerman]

The chart linked below, shows the appropriate backwash rate for Filox & Pyrolox to be 20-30 GPM per square foot (ft2).

30 GPM ft2 calculates to 16 gpm in a 10" tank (1.5 ft3) or 13 gpm for a 9" diameter tank appropriate for 1 ft3 media.

https://view.publitas.com/impact-water-products/2018-catalog-final/page/154-155

 

[new guy]

https://fluxtekeurope.com/pdf/en/iron-removal.pdf
According to this... ideal PH for Mn removal with MnO2 media is 7.8 and they say up to 1ppm at these "ideal" conditions... so this sounds way more plausible than claims of 5ppm!?! maybe they have stricter laws on what you can claim in the EU. lol

 

[new guy]

https://www.canada.ca/content/dam/h...ent-manganese/pub-manganese-0212-2019-eng.pdf
I've been reading this. It's very informative on different manganese removal techniques and on how they work. Unfortunately they do not go over MnO2 media in great detail compared to other methods.