Manganese is a common mineral substance in water that plays a key role in human nutrition. While small amounts of manganese is good for your body, quantities greater than 0.05 mg/L in well water can cause a problem, such as an unsightly brown appearance and an unappealing bitter metallic taste.
Excess levels of manganese can also lead to films on the surface of toilet water and pellet-like debris in your dishwasher.
Natural sources of iron and manganese are more common in deep wells where water has been in contact with rock for long periods of time. These metals may also occur from deep and surface mining activities.
Luckily, there are many different iron and manganese removal methods available today that can help you effectively remove these minerals from your water and we will be discussing the different methods in our article today.
What is Manganese?
Before we continue further, we need to first understand what is manganese. Manganese is a natural mineral that can be found in rocks, soil, and sediment. This is a beneficial metal that’s also present in various fruits, vegetables and grains. While the metal is an important nutrient in human diet, it can become unhealthy when consumed in large quantities.
When it comes to presence of manganese in water supply, this natural mineral is often found in deep water wells – some even up to 3ppm of mineral. However, it doesn’t take much manganese (0.05ppm and above) to begin staining and damaging your appliances at home.
Manganese and iron are often present together and these two metals combine to form deep brown staining and other negative effects.
Manganese can be present in water in two forms: manganous manganese and manganic manganese. Manganous manganese is completely soluble and dissolved in water, making it difficult to remove.
In order to remove this form of manganese, you’ll need to cause it to precipitate first before it can be filtered out of water. Water softeners are also a piece of effective equipment to help remove manganous manganese.
Are There Any Health Risks with Manganese?
Drinking a low concentration of manganese will usually not cause any negative impact on your health. However, ingesting manganese of higher concentration (0.05ppm or more) may lead to some health and neurological problems such as memory, motor skills, and attention issues.
Children and babies are especially at risk since they’re still at the development age and they may face problems with learning and behavior due to consumption of high concentration of manganese.
How Does Manganese Get Into Water?
Before looking at how to remove manganese from water, you need to first understand how the mineral enters your water. As mentioned before, manganese is naturally occurring and it gets into wells through surface water runoff and rainwater sources.
Water picks up metal as it seeps through soil and enters the well through the aquifer. In such occurrences, it is normal to see iron and manganese present together, especially in deep water wells where water has longer contact with rocks containing iron and manganese.
These two metals can be found in groundwater, which is why if you find iron in your water, there’s a high chance it also contains manganese.
Other than natural causes, human activity like traffic emissions could contribute to higher concentration of metal in air and ground. This can be seen in coal-mining regions where water sources typically have high concentrations of iron and manganese due to both surface mining and deep mining activities.
Is Manganese Safe? If not, What Is The Safe Level in Drinking Water?
Small concentrations of dissolved manganese are actually beneficial for human health and it can even be found in a number of food supplies. However, large concentrations of manganese will not only negatively affect the appearance and give a metallic taste to your water supply, it may also lead to potential health concerns.
Manganese concentrations of more than 0.05ppm will affect tap water quality, causing stains and other damages to your home’s fixtures. However, it’s still safe to consume such water as the safe manganese level in drinking water is approximately ten times this.
Nonetheless, the US Environmental Protection Agency (EPA) has come up with a set standard of recommendation for a person to not be exposed to more than 0.3 mg/L of manganese in drinking water throughout their lifetime.
Ensuring you do not consume anything with more than 0.3 mg/L of manganese will prevent neurological damage, and this is especially critical for children since they’re still in the development stage.
Is There a Way to Prevent Manganese from Entering My Well Source?
Since manganese comes from natural sources, it may be difficult to stop the mineral from getting into your water supply.
You need to also keep note that iron and manganese are often present together and may sometimes have higher dissolved concentration in some states. High dissolved iron concentrations and manganese concentrations are common in coal mining regions as these are areas with heavy traffic on the roads.
Since the manganese and iron concentrations depend on location and it may not be practical for you to move to an entirely new state just to solve the problem, there are many solutions available for manganese removal.
Nonetheless, if you’re noticing an unusually high quantity of iron and manganese in your water, you may want to take a look at your well design and check that it is structurally sound with no cracks or gaps in the seals, pump, or aquifer. Those with deep wells may also be more likely to have higher dissolved iron concentrations and manganese concentrations.
Ultimately, preventing manganese from entering your water supply is more fuss than it’s worth and relying on water treatment options for manganese removal has proven to be a much more practical solution.
Testing Manganese in My Well Water
You have your water tested by an accredited laboratory to quickly find out what is the manganese level in your water. What you’ll normally need to do is to just collect sample of your well water from your home’s point of entry and deliver it to a laboratory where they will conduct extensive tests to determine your water quality.
Having your water tested means that you can know exactly what’s in your water and the level of its presence. This way, you will know whether you’re at riskf or water contamination. We advise to regularly have your water source tested for chloride, sulfur, iron, manganese and corrosion every three years in case there are some changes to your water supply.
The two forms of manganese require different water treatment systems. Fortunately, a laboratory test can even indicate the different forms of manganese present in your water, helping you select the best water treatment method for manganese removal.
If you prefer to do the testing yourself at home, its possible too but it’s obviously not the most thorough option and it will only indicate the presence of manganese, not its levels.
Still, home test kits are useful to carry out between the more comprehensive laboratory testings to make sure your water’s manganese levels do no suddenly spike or to check whether the water treatment system’s manganese removal is working as expected.
Just like how you would do for a laboratory test, you should take a sample of your water from the home’s point of entry. Then dip the test strip into the water and leave it submerged for a few seconds. Then remove the strip and sinply wait for it to change color. The final color of the strip will indicate whether your water has manganese.
How to Remove Manganese From Water?
There are many factors that affects the manganese’s state, such as water’s pH and presence of other minerals, and different types of manganese will require different treatment methods. Despite that homeowners can still find a few effective treatments to remove manganese for safe drinking water supply.
Ion Exchange Water Softeners
Although water softeners were designed to help remove water hardness minerals like calcium and magnesium via an ion exchange process, they can also be effective in manganese and iron removal. The water softener’s ion exchange process involves replacing calcium and magnesium ions with sodium ions with a resin bed.
The ion exchange water softener can also use the same process to remove manganese and iron from your water. When the water passes through the sodium-saturated resin bed, manganese and iron will be attracted to the media bed while sodium is released into the water.
Once the resin tank is filled with manganese, the water softener will start its backwash process to flush the media and replace the sodium ions, allowing the process to take place over and over again for years.
Water softeners effectively reduce water hardness levels in your whole home and can even remove small amounts of manganese of between 3 and 20 grains per gallon (GPG). However, to effectively use a water softener to remove manganese, you need to make sure the following conditions are in place:
Low total dissolved solids (TDS)
Water softeners require low TDS for removing manganese. With high TDS, other minerals in the water will compete with manganese for space on the resin in water softeners and can even displace manganese that was already attached to the resin.
Low dissolved oxygen
High oxygen levels promote the precipitation of manganese into a physical form that’s hard for the water softener to handle. The opposite is true when using filter as a treatment.
pH lower than 8
The pH level of the water needs to be lower than 9 for removing manganese ions. High pH can lead to precipitation, which can be useful when using a filter as a treatment.
As is true with removing iron, treating manganese with water softeners is best paired with high salt dosage and to keep the running cycle short to avoid mineral build-u on the resin.
Your water softener may be ineffective at removing manganese in different water conditions since the manganese will be in a different state. This would make investing in a water softener not worth it if you’re purely looking to remove manganese with it. Hence, it is important to ensure frequent regeneration.
However, in the right conditions, a water softener is highly effective in helping you remove manganese. Still, you need to keep in mind that an increase in oxidised manganese and iron will eventually do more damage than good to your water softener.
So you will need to make sure that your raw water does not get in contact with a strong oxidising agent like chlorine or air before it gets into the water softener or this could damage the softener resin bed during the ion exchange process. For removing iron and manganese in their oxidised state, you can use a normal filtration system for removal.
Air Injection Oxidation
Air injection is also commonly known as aeration, is yet another effective water treatment to help remove manganese from your water. In addition to manganese, this method can also be used to remove iron and hydrogen sulfide. The water treatment system works by injecting air into water and does not require a filtering resin.
This system works by first feeding water into a tank before injecting air to aerate the water. The aeration process will help the dissolved metals to get oxidized and change state. The oxidized minerals will then stick to the media bed, which can be removed via backwashing of the tank. The tank is then replenished with a fresh air pocket during regeneration.
Maintenance for this type of water treatment will increase when there’s an increase in metal concentration in the water. The more manganese is present, the more frequent the system will require maintenance.
Air injection filtration system is effective when dealing with high concentrations of dissolved metals as this treatment system can help remove iron, sulfur, and manganese. On top of that, it even comes with relatively low cost to suit those with reduced budget.
Oxidation Media
Air injection oxidation water treatment separates the oxidation and filtering steps, whereas an oxidation media makes it possible to oxidize and filter manganese at the same time. Manganese greensand filters and birms are both popular filter media that can be used to remove manganese.
In manganese greensand filters, the filter media is coated with potassium permanganate to oxidize iron and manganese and trapping them in the filter media before getting flushed out of the system. Some systems may also use hydrogen peroxide or ozone instead.
However, a manganese greensand filter requires a lot of effort and maintenance on your part. The oxidation filtration media needs to be regenerated with potassium permanganate or ozone and then backwashed to remove the accumulated manganese from the media.
Nonetheless, manganese greensand fitlers are great drinking water treatment option for water supply with moderate amounts of manganese in both states. This oxidation filtration solution will work well for manganese or iron concentrations of around 2.5 to 10 mg/L. Keep in mind that the higher manganese concentration is in your water, the more often the system requires backwashing.
Similarly, a birm filter works to remove manganese but it has an extra advantage: no regeneration required. This is because the birm system uses oxygen from the water itself to oxidize the impurities. And in order for this system to be effective, the water needs to have high amount of dissolved oxygen with a pH of at leasy 7.5. Though it doesn’t require regeneration, you still need to backwash the birm filter to remove solid particles.
Reverse Osmosis
The last manganese water treatment system discussed in our article today is reverse osmosis. Reverse osmosis method is one of the most popular treatment options for drinking water since it’s able to effectively remove almost any impurity.
However, the reverse osmosis purification system requires several filter stages to ensure the water is treated effectively. These filter stages include the sediment filter cartridge membranes, activated carbon filter cartridge membranes, and post-filter membranes.
The main star of the treatment system is its semi-permeable membrane that contain small pores. Water is then pushed against the membrane to allow only very small water particles to pass through, leaving larger contaminants in the chamber that will be flushed away with wastewater.
Those with high concentrations of dissolved iron and manganese in their water source can consider getting a reverse osmosis filtration system, especially if you like the idea that the system can offer both reduction and purification benefits to other additional contaminants like lead, hydrogen sulfide, aesthetic impurities, chemicals, bacteria, arsenic, and VOCs.
The RO water system also does not need backwashing, it only needs filter membrane replacement once every six months. The semi-permeable membranes must be replaced every 2 years or so. Fortunately, you can easily buy the membranes and filters yourself online. The process of replacing the filter is also quite straightforward for DIY projects.
RO systems can be installed at your home’s point of entry. The system requires relatively high pressure to be efficient since it needs to push the water pass the semi-permeable membrane, so it’s recommended to purchase a pressure pump if you have low water pressure.
Although the entire RO system is quite expensive, many believes its worth the investment as it means cleaner and purer water for the entire house.
Other Methods to Remove Manganese
Biological Removal
Both iron and manganese can be removed biologically as there are certain bacteria which take their energy from the oxidation of such metals. However, you will need a very specific set of conditions for optimal microoriganism activity.
Biological treatments also require different environmental conditions for removing manganese and iron. Hence, it’s not a suitable method as a home treatment system for water.
Chemical Removal
Chlorination
Chlorine is a strong oxidizer and the water can undergo chlorination process to effectively get rid of manganese. The concept is the same as air injection but chlorination will require longer residence time. Chlorination can be performed via a pellet dropper (dry peller chlorinator) which drops calcium hypochlorite pellets directly into the well itself.
Alternatively, a feed pump can be used to inject liquid chlorine under pressure into the water line. If the pump method is used, you need to ensure that at least 20 minutes of residence time is added for the chlorine to do its work.
As with aeration, the chlorination process is followed by an iron filter. A good filter that works well with chlorination is carbon filter. Catalytic carbon works better than standard carbon and has the added advantage of removing both manganese and chlorine that was introduced in the step before.
Frequently Asked Questions on Manganese Removal
Can I remove manganese by boiling water?
No, boiling water does not remove manganese molecules. In fact, boiling water for too long will just evaporate the water and cause the manganese molecules and other metals to become even more concentrated. The best way to get rid of these contaminants is to use water softeners or filters discussed above.
Can I use chemical treatment for removing manganese?
Yes, chemical treatments are effective at removing manganese. You can use chemicals like chlorine to treat water with high manganese content. Chlorine is a strong, effective oxidizer and it works the same way as an air injection tank that uses oxygen to oxidize manganese. Once the manganese is oxidised, a filter will be used to remove the particles.
Chlorine oxidizing systems usually need a feed pump to deliver measured concentrations of chlorine into water in a tank. The water will also require about 20 minutes of contact time to be effectively oxidized by the chlorine. Chlorine chemical treatment is a good solution for removing manganese without backwashing.
Can I use catalytic carbon for removing manganese?
Yes, catalytic carbon is yet another effective method for removing manganese, but it’s advisable for you to pair it with an oxidizing process, such as an aeration tank, for maximum efficiency. Catalytic carbon treatment can also help to reduce or remove other aesthetic contaminants.
