Activated carbon for filtering tap water: benefits, limitations and effective alternatives
In this article, we take a look at a method of tap water filtration relatively popular: activated carbon. No, it's not the charcoal you use for your barbecues, but rather a 'turbo' version of it, specially designed for water purification.
But as you know, no method is perfect. So what are the advantages of activated carbon and, similarly, what are its limits ? Finally, are there any more effective alternatives ?
What is activated carbon?
Activated carbon is a form of carbon treated to have small, low-volume poresbut with a high adsorption surface area.
It is these pores that trap impurities and particles.This makes it a great ally for purifying a variety of substances, including air and, for our purposes here, water.
How is it obtained?
You're probably wondering how you go from "ordinary" coal to activated carbon? Well, the process is quite fascinating!
Activated carbon is generally obtained from carbon-rich organic mattersuch as woodthe coconut shells or even some types of coal.
This material is first carbonised and then "activated" by a chemical treatment or thermalcreating a porous structure. Now you have activated charcoal ready to capture all sorts of impurities!
General use in tap water treatment
When it comes to water purification or filtration, activated carbon remains a popular choice. It is often used in domestic water filters to remove impurities such as chlorine and sediments, thus eliminating bad tastes and odours from the water.
For example, if you have already used a carafe filter in your kitchenThere's a good chance that it has an activated carbon filter. There's a reason why 'activated carbon water' is often referred to as a winning combination!
How does the activated carbon filter work?
Having discovered what activated carbon is, the next logical question is: how does it work? Don't worry, we're here to enlighten you!
Operating principle
We touched on the subject earlier in the article, but activated carbon filters water through a process called "purification".adsorption"(not to be confused with "absorption"!).
In this process, the contaminant molecules become attach themselves to the surface of the activated carbon. Imagine that every pore in the coal is like a small car park where impurities are parked.
So, when the water passes through the filter, contaminants are captured and withheldThis gives the water a better smell, taste and, above all, quality.
If your tap water has a chlorine tasteAn activated carbon filter can therefore help to eliminate this unpleasant taste.
Types of activated carbon filter
There is not one but several types of activated carbon filter, each with its own advantages and disadvantages.
- Granular activated carbon filter As the name suggests, this type of filter uses granular carbon. It is fairly effective at removing large particles, but less so for small ones.
- Activated carbon block filter activated carbon: here, the activated carbon is compressed into a solid block, providing better filtration for small particles.
- Powdered carbon filter Rarely used in domestic systems, this type of filter is more common in industrial treatments.
Focus on binchotan coal
We couldn't write an article on the subject without mentioning the star in the field: binchotan coal. Binchotan is a special form of activated carbon. of Japanese origin.
It is made from branches of ubamegashi oak, a native Japanese oakThese are slowly carbonised in a kiln at temperatures of up to 1,200°C, then rapidly cooled, giving the coal a high porosity.
Binchotan is said to have the ability to capture and retain a wide variety of contaminants present in water, such as chlorine, heavy metals and organic chemicals.
As well as filtering out impurities, binchotan has the ability to release minerals such as calcium, magnesium and iron in the water, enriching its mineral composition. One notable advantage of binchotan carbon over other types of activated carbon is its longevity. Some manufacturers claim that binchotan lasts longer than other types of activated carbon.
However, binchotan is not a miracle solution It also has a number of setbacks that we invite you to discover in our article : Binchotan carbon to filter tap water, from dream to reality.
Practical applications
Filter jugs
Indeed, as mentioned above, many filter jugs employ cartridges filled with activated carbon to purify tap water.
These cartridges are generally designed to retain impurities, chloramines, heavy metals and other contaminants, while improving the taste and odour of the water. Well-known brands such as Brita and Berkey use this technology.
Read also: Filter carafes: a good idea?
Domestic water filters
Domestic water filtration systems often use activated carbon to filter tap water.
These systems, which generally include several types of filtercan be installed under the sink or on the tap are effective at eliminating contaminants and improving water quality.
Water treatment plants
Activated carbon is used in some water treatment plants on a large scale to eliminate organic compounds and disinfectant residues. It is often used in the form of powdered activated carbon (PAC) or granular activated carbon (GAC) in these applications.
Filters for hikers
From portable filters with activated carbon are also available for hikers and campers. These lightweight, compact filters purify water from natural sources, making it drinkable. Some hiking water bottles also have a built-in filter of this type.
Refrigerator filters
Some fridges have built-in water filters that use activated carbon to purify the water used for drinking and for making ice cubes.
Charcoal sticks (Binchotan or other...)
Sticks or activated carbon sticks are a natural, environmentally-friendly method of water purification.
They are placed directly into a bottle or a jug of water, where they absorb impurities and release beneficial minerals. This type of filtration is a sustainable solution that allows you to reduce the use of plastic bottles.
Steps for filtering water with an activated carbon stick
1 - Cleaning the activated carbon
Before using for the first timeRinse the activated carbon stick under cold water to remove any carbon residue.
Bring to the boil the activated charcoal stick in a pan of water for 10 minutes to sterilise it and open its pores. Then leave it to cool.
2 - Place the stick in the water
Fill a carafe or bottle with tap water.
Place the activated carbon stick in the water.
Close the carafe or bottle with a lid or stopper to prevent contamination.
3 - Leave to rest
Leave the water to stand with the activated carbon stick for a few minutes. at least 1 hour for minimum filtration. For better purification, it is recommended to leave to stand for 4 to 8 hours.
4 - Enjoying purified water
Once the resting time has elapsed, your water is ready to drink. If all goes well, you'll notice an improvement in the taste of the water, with an impurity reduction and chlorine.
Maintenance of the charcoal stick :
Regular cleaning Boil the stick once a month to clean it and open its pores.
Service life A stick generally lasts about 3 months. After that, it needs to be replaced.
Recycling Once the stick has been used up, it can be recycled in a variety of ways, for example as an air freshener in the fridge or cupboard, or incorporated into the compost.
Advantages of activated carbon filtration
Now you know the principle behind activated carbon and how it is used. Now let's get down to business and explore the benefits of activated carbon in water treatment!
Effective in removing certain contaminants
The use of activated carbon in tap water treatment is particularly effective in removing specific contaminants, such as chlorinethe organic particlesand even certain types of heavy metals.
If your water has the smell of a municipal swimming poolIt's probably because of the chlorine. An activated carbon filter can greatly improve the situation by eliminating this undesirable taste and odour.
Activated carbon is therefore of interest forimproved organoleptic properties water (colour, taste and smell).
It's economical
Another advantage is that relatively low cost of this method. Activated carbon filters are generally less expensive than other advanced filtration technologies.
Easy to install and use
Finally, the installation and use of an activated carbon filter is generally very cost effective. simpleeven though, as we have seen, there is a a number of steps to be followed. There's no need to call in an engineer or spend a fortune on installation.
Limits of activated carbon filtration
This type of filter certainly has certain advantages, but they are not without fault. Knowing the limits is essential to making an informed choice when it comes to water purification.
Contaminants not eliminated
Firstly, it is crucial to understand that not all contaminants are eliminated by activated carbon.
For example, the nitratesthe bacteria and certain types of heavy metals are not effectively filtered. If these contaminants are a concern for you, you will need to consider additional treatment methods.
Filter replacement frequency
Another aspect to take into account is the filter life. Activated carbon saturates after a certain time, which reduces its effectiveness. It is therefore necessary to replace carbon filters regularlyThis is usually done every one to six months, depending on the volume of water filtered. This applies to all types of filter: on sink, under sink or cartridges for carafe filters.
Maintenance and purification time for the activated carbon rod
The use of an activated carbon stick requires prior maintenance, including the rinse and the sterilisation by boiling, and for optimum purification, theThe water should be left to stand with the charcoal for 4 to 8 hours.
Risk of bacterial proliferation in filters
Yes, you read that right. Activated carbon filters can become a home to bacterial proliferation if they are not properly maintained. This problem can actually worsen water quality rather than improve it. (To find out more: https://www.quechoisir.org/actualite-carafes-filtrantes-inutiles-voire-pire-n25672)
Environmental restrictions
Finally, activated carbon also has an environmental cost. Its manufacture, use and even disposal can have an impact on the environment. So it's important to look for filters that are made responsibly and, if possible, to recycle them.
Alternatives to activated carbon filtration
Reverse osmosis
Activated carbon is not the only option on the market for purifying your water. If you're looking for a more complete or specific filtration method, there are several alternatives available to you.
This technique removes up to 99% of dissolved contaminants from water, including those that activated carbon cannot filter out. However, we do not recommend it: it is dear and removes all the essential minerals from your water. For further information : What is a water osmosis unit used for?
Ceramic filtration
Ceramic filtration is effective at eliminating bacteria and parasites, making it a good choice for the home. complement or an alternative to activated carbon.
Certain domestic filtration systems combine activated carbon with ceramic filtration for better results.
UV-A radiation
Our speciality! Water purifiers using UV-A radiation eliminate bacteria and viruses without the addition of chemicals. A solution ecological and very effective.
UV-A radiation offers a number of advantages over activated carbon filtration. It eliminates a wide range of micro-organisms, including those resistant to chlorine, while remaining a very environmentally-friendly solution. And of course there's 0 maintenance !
In 15 minutesThe result is pure water, better than bottled water !
To find out more about LaVie water purifiers : https://lavie.bio/technologie-uv-a-purification-eau/
Read also: The most common water filtration methods: advantages and disadvantages
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Using LaVie on video
Conclusion: coal for water = useful?
As you can see, purifying tap water with activated carbon is a very effective way of protecting the environment. cost-effective solutionbut partially effective.
This method offers major disadvantagesparticularly with regard to certain contaminants not removed and the frequency of carbon filter replacement.
Now that you're armed with comprehensive information on activated carbon for water treatment, you can make an informed choice. Take stock, assess your specific needs and don't hesitate to explore the alternatives to find the water purification system that suits you best.
Read also: Water purifier: the complete guide
Article written on 26/09/2023 by Pascal Nuti - CIO Solable - Passionate about energy, I'm constantly on the lookout for new targets for improvement, exploring cross-disciplinary paths using novel methods.
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