The cheapest way to remove manganese from well water includes; Using pretreatment oxidation filters, using a water softener, or extracting manganese with a filter.
Manganese deposited in well water at rates over 0.05 mg/L will make the water appear unsightly brown plus it has a bitter taste. Also, the manganese will leave debris in the dishwasher.
The high manganese levels in well water (causing brown and black staining) come from sediment, rocks, and soils but these will benefit vegetables and grains.
Method 1: Oxidation or Pre-treatment Filters
a. Oxidation Using Permanganate
Manganese removal will be simpler with that filter with the iron present. Working like a strong oxidizer, Potassium Permanganate will be applied with greensand-medium filters.
Permanganate will be sucked into your filter in that regeneration stage. Despite being challenging to maintain (unsuitable for homes), Greensand filters will easily remove odors, iron, and manganese.
- Further, hydrogen peroxide and Ozone will also oxidize manganese but the ingredients are rarely used for residential water treatment.
Manganese oxidation using permanganate is prevalent in some US states. The permanganate dosage must be adequate for the oxidation of all the manganese to the insoluble state.
- The permanganate dosage must not be excessive causing pink coloration to the water-distribution. Compared to chlorination and aeration, permanganate-oxidation is more effective.
After backwashing, the granular manganese greensand is effectively charged with the permanganate. Thus, the permanganate oxidation will be finished in your filter – and also prevents pink water.
b. Oxidation through Chlorination
Chlorine will effectively oxidize manganese and iron in well water – generating manganese dioxide and ferric hydroxide – and the precipitate will be filtered easily.
You’ll experience rapid oxidation if you use loads of chlorine (the average is 1: 2 as the ratio for chlorine: iron). However, the chlorine will demand additional “residence time” compared to aeration.
You can conduct chlorination using that dry-pellet chlorinator (calcium hypochlorite dropper) to the well or get that feed pump to inject the pressurized liquid chlorine into the water-line.
For use of the pressure pump, employ some retention tanks as this enables the chlorine to function for about 20 minutes for residence manganese chlorination.
- After chlorination, you must undertake iron filtration (just like in aeration) – don’t use the Birm filters but other standard filters will be effective.
- Catalytic carbon will be more effective compared to regular carbon – but all the carbon will work well for small amounts of manganese – removing it plus the chlorine.
With chlorine pumped into the chlorination chambers, you can inject (plus the chlorine) soda ash to work in increasing the pH.
Forms of Manganese:
1. Manganous manganese – This manganese type fully dissolves just like salt and sugar do in the water. So, manganese precipitation is needed but you can also use a water softener (ion exchanger).
2. Manganic manganese – Following the precipitation process, this manganese turns from liquid to solid – may make the water become black – the Manganic manganese is easily removed with filters.
- Being ion exchangers, a water softener will remove all un-precipitated ions but filters won’t remove either un-precipitated iron or un-precipitated manganese.
c. Oxidation through Aeration
You can pre-treat the well water using air in several ways – such as the “venturi” installation – this involves setting up the system before the pressure tank – drawing air to the water-line.
After the venturi, you’ll require a tiny vent tank to allow the air enough time for manganese oxidation and remove excess air. Finally, manganese will be removed in the filtration stage.
- But you may undertake a more aggressive aeration using larger tanks for the treatment – feed air from a compressor to the tanks.
- The compressed air will be feed into 1/3 of the treatment tank (the top section) allowing manganese oxidation to happen as the water drops via the compressed air.
After the aeration tank, there will be a filter – but there may also be aeration at your filter tank – alternative for compressed air. Aeration provides oxygen enabling the removal of manganese.
You may add some calcite tank before the filter but inject caustic soda, and soda ash – to raise pH. Thus, adequate air pre-treatment and provided a suitable pH enhancer, manganese will be removed.
See Also: Do Water Purification Tablets Expire?
Method 2: Remove Manganese with a Water Softener
Water softeners, with the right conditions, will work well in manganese removal. It’ll remove huge manganese amounts but the manganese must be un-precipitated all through.
Besides damaging the softener, precipitated manganese won’t also easily remove manganese. Below I discuss the conditions that significantly affect the performance of softeners.
a. pH (Potential of Hydrogen);
The water softener will operate at best when the pH is under 8 to remove manganese ions. The lower pH hinders precipitation – which is not the same with filter manganese removal.
Just like in iron-removal, using the water softener for manganese removal requires an elevated salt dosage – and also avoids the build-up of mineral (with regular regeneration) on the resin.
See Also: Distilled Water vs. Purified Water
b. Dissolved Oxygen;
The dissolved oxygen in the water is an excellent ion-exchange agent to remove manganese.
Don’t use oxidizers (permanganate, hydrogen peroxide, or ozone) or chlorinate for manganese removal with softener.
The TDS (total dissolved solids) must be low to guarantee manganese removal with softeners. or high TDS, various minerals will race with manganese at the resin.
Method 3: Removing Manganese with a Filter
Get enough oxygen content and high pH to allow fitting manganese removal – the conditions allow precipitation. With pH amendment, you can use oxidizers like ozone, air, or chlorine for pretreatment.
a. Catalytic Media
For manganese that is un-precipitated (and low concentration), plus there are high pH and oxygen content, you can use a filter media (catalysts) to remove the manganese (make it precipitated).
The Catalox, Filox, and Birm Media turn manganese into the physical form for filtration of the manganese in its precipitated form.
Filter backwashing will rinse off the contaminants that are trapped and also helps restore that filter bed. The manganese must be less than iron – you may use the catalytic media + oxidizer.
b. Simple Filter
You may use simple filters + manganic manganese to remove the manganese from your well water. You may use the sediment filter (the cartridge-type) for small manganese amounts.
But for huge manganese amounts, back-washing filters with some multi-media like anthracite, garnet, and sand – or Micro Z, Zeolite, and Filter Ag to reduce sediment.
See Also: Do Water Purification Tablets Work?
So, the removal of manganese from your well water must involve a consideration of pH – you’ll require higher pH to remove manganese using a filter compared to iron removal.