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What is Permanganate and Why is it Important for Water Treatment?
Wednesday, May 22, 2019

Potassium permanganate dates back to 1659 and a German chemist named Johann Rudolf Glauber.

But what is potassium permanganate and why is it useful? Read on to find out.

What is Potassium Permanganate?

Potassium permanganate is a point-of-entry treatment option for water. It is sold as a dry, purple-tinted solid.

It oxidizes dissolved bits of iron, hydrogen sulfide, and manganese so that the solid particles can be easily filtered out of water.

It's important to note that potassium permanganate is not a good disinfectant. You also don't want to allow a residual amount of permanganate because it will likely give water a pink tinge that no one wants coming out of their pipes.

Why is Potassium Permanganate Useful?

There are many uses for potassium permanganate. It is mostly used as a pre-treatment.

It is better at getting rid of the smell of sulfide than chlorine. Potassium permanganate is often used to control taste and odors, remove color, control biological growth in treatment plants, intake structures, and pipelines.

Potassium permanganate is used in wells to control iron bacteria and other biological growth. It also keeps well water's taste and smells under control.

How Potassium Permanganate Works

Generally, a device injects potassium permanganate into the water in between the pump and holding tank.

When treating a well, a concentration of 3.8 to 7.6 grams per gallon helps to remove iron bacteria. After the mixture has been fed into the well, agitation will make the treatment even more effective.

You can agitate the well by turning it on and off. This forces the water to come up through the casing and then splash back down.

During large-scale water treatment processes, potassium permanganate is usually added early on at the raw water intake.

After, permanganate oxidation, there could be chlorine disinfection, granular activated carbon (GAC), or membrane filtration.

It can also be added at the rapid mix tank at the same time as coagulants. Potassium permanganate is always added before filtration.

Steps in Potassium Permanganate Water Treatment

There are three simple steps in order to use potassium permanganate water treatment successfully.

Step 1

First, do a water sample test to check the water's pH, temperature, manganese and iron levels. Monitoring the pH of water is important to do all the time.

You'll need 0.94mg of potassium permanganate per milligram of iron and 1.92mg per milligram of manganese for oxidation.

Follow the manufacturer's instructions for dose when treating water for odor and taste.

You can also buy pre-made tablets if you don't want to calculate dosage.

Step 2

Next, filter the drinking water to remove the manganese dioxide and the elemental sulfur precipitate.

You may want to pair this treatment with a "greensand" resin bed system.

Step 3

Keep your leftover potassium permanganate in an air-tight container. Store it in a cool, dry area that is well away from acids, peroxides, and combustible and oxidizable materials.

Final Thoughts

Thanks for reading. We hope that this article has given you the info you need to successfully treat your water with potassium permanganate.

Did you know that you can monitor permanganate without sensor contamination? Learn more about a gas-phase approach to permanganate measurement.

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