The bottle in the water purifier
UV water filters: UV-A, UV-B, UV-C, what are their effects on water, micro-organisms and health?
Table of contents
Before we talk about UV filters for tap water treatment in particular, let's start with a bit of scientific background.
What is ultraviolet radiation?
The ultraviolet rays are a form of electromagnetic radiation emitted by the sun and other sources. They are classified into three main types according to their wavelength. The UV-A, UV-Band UV-C are all happy photons of the light spectrum. These are electro-magnetic wavesbut our eyes cannot see them. They are at the very bottom of the spectrum, opposite infrared.
UV-A
First of all, let's start with the most abundant by far: the UV-A ! UV-A rays have the longest wavelengths of all UV rays, ranging from around 320 to 400 nanometres (nm). They represent 5 % of solar radiation. Harmless, they can help combat skin diseases.
Besides, they are essential to our overall balanceThey cause only a slight tanning of the skin after a few hours' exposure. On the other hand, exposure for more than a few hours a day is not recommended, even though its long-term harmfulness is not clearly known.
They are widely used in industrial products: polymerisation of glues, drying in printing and screen printing, drying and polymerisation of nail varnish, fluorescent light in nightclubs, etc.
UV-B
Then, the rays UV-B have wavelengths ranging from approximately 280 to 320 nm. UV-B is clearly carcinogenic in high dosesThis has led to increasingly strict regulations on tanning booths, particularly in view of the cases of skin cancer.
They are responsible for "sunburnThis can happen after just 30 minutes' exposure for fragile skin. UV-B can also damage cellular DNA, which can increase the risk of skin cancer.
The atmosphere filters out much of itThis means we can face the midday sun without too much risk.
They are very rarely found in commercial products, except for a few reptiles (for reptiles kept in captivity, it is essential to provide appropriate UV-B lighting in order to reproduce their natural environment) and the tanning booths.
UV-C
And finally.., UV-C rays have the shortest wavelength, ranging from around 100 to 280 nm. UV-C is lethal to humans and just about everything else on the planet. There are none on earth, because the ozone layer blocks them (Let's hope it stays there, otherwise we'll have to live underground...).
Man is able to produce them with the power of mercury lamps or ledsmainly for their effects onBacterial DNA.
Find out more about UV : https://fr.wikipedia.org/wiki/Ultraviolet
Effects of UV water treatment on microorganisms
So.., in the tradeWhen people talk to you about uv water treatment, they're almost always talking about sterilisers that use a UV-C lamp.
With that in mind, let's focus on water and the microorganisms inside.
UV-C is used in sterilisationbecause they can affect theBacterial DNA and mutate it. This blocks bacterial division.
If you drink water containing bacteria that has been exposed to UV-C light, so you drink these bacteria, most of them alivebut with the guarantee that these bugs will not reproduce during digestion.
So you will be "saved", but you won't improve the taste, l'smell or physico-chemical aspects of water. That's why we talk about sterilisation and not filtration (And even then, to kill bacteria using a UV steriliser, you need to triple the dose, and for some viruses multiply it by 10).
It should also be noted that the effect of UV-C on bacteria is unevenThe vast majority can no longer reproduce, but they are able to do so. a small minority become "supercharged".is more active and dangerous, and retains the ability to divide or multiply.
You can therefore buy a UV-C bottle (or UV steriliser) if you want to use thelake water or a river. Provided it is not loaded with chemicals, pesticides, traces of medication, etc.
Some brands advertise them as water purifiers, but this is entirely false.
Effects of UV treatment on bad tastes and odours in tap water
UV-B and UV-C
And as for the poor taste and the bad smell of tap water in the home, they are due to the chlorine and its 500 by-products. But did you know that some of these chlorine by-products are proven carcinogens? And the UV-C "flashes" won't affect them in the slightest!
In this respect, even a "vulgar" carafe filter with a active charcoal filter does much better!
In fact, although the major players in the treatment of drinking water in France use UV-C for its rapid action, they only do so for the following reasonsat the end of treatmentjust before the chlorination for transmission to the public network.
But when I see French companies equipping themselves with under-sink LED UV-C treatment at 1300€There are no bacteria in tap water in France, so there's no point in trying to eliminate them...
It's as bad as buying a water softener (€1,000, very polluting) to improve the taste of water: who prefers to drink salty water that has been passed through resins and plastic to avoid absorbing calcium? The calcium ion has no taste...
So, one last reminder: UV-C rays cannot "purify" waterUnless you believe that purification means killing a bacterium to drink it dead? I'll leave you to conclude.
It should be noted that lUV-B is hardly ever used for water treatmentbecause plastics and glass are opaque.
Read also: What are the environmental impacts of plastic water bottles and how can they be avoided?
UV-A light for real water treatment
UV-A is used for its properties bactericide in various applications such as the SODIS (solar disinfection) developed by theEAWAG and widely used in developing countries.
This is a method for disinfect water using only the sun's rays and polyethylene terephthalate (PET) bottles.
This solar disinfection water works by exposing plastic bottles to the sun for several hours to eliminate pathogenic germs. So that chis greatly reduces cases of dysenteryfor example.
What do LaVie water purifiers offer?
Now that we've had a good look at the subject of UV water treatmentLet's take a look at what the solution proposed by LaVie has an innovative approach.
First of all, let's be clear, using UV-A for its bactericidal properties is not patentablebecause it's been known to people in the art for decades. So we have patented something else.
So fasten your seatbelts and let's get diving in this magnificent setting. innovation. However, we'll have to go through a quick explanation of what a advanced oxidation processa family to which LaVie belongs.
Advanced oxidation processes (AOP)
First and foremost, you need to know that advanced oxidation processes (POA) refer to a range of techniques (Ozonation, Peroxidation, UV radiation and electro-oxidation) used to treating water and wastewater. Their main objective is to destroy or transform the organic and certain inorganic pollutants present in water.
In fact, water companies use these very costly processes to eliminate persistent substances from wastewater: female hormones (beta estradiol in the contraceptive pill), endocrine disrupters, pesticides, traces of medicines, etc.
The system proposed by LaVie
Water purifiers LaVie therefore uses an advanced oxidation process, with the UV radiation of water. But, as you will have realised, a UV-A radiation !
In fact, what's new is flash the chlorine contained in tap water with UV-A radiation, which transforms it into oxidising radicals (O, O3, H2O2, H-, CL-). This UV-A bombardment of chlorine generates radicalswhich, by rebound, will break down everything that is not water into simple, harmless elements. And, all the while, making the chlorine disappear too: it was worth thinking about 🙂
What's more, living organisms (bacteria, viruses, etc.) are riddled with holes created by these violent exchanges and cannot come out of the treatment alive or in one piece.
1. Fill in
Your LaVie bottle of tap water
2. Insert
3. Wait
Time taken for UV-A light to activate chlorine photolysis (15 minutes)
4. Enjoy!
And enjoy the real taste of healthy water!
UV water treatment for private customers
To tell the truth, no-one had ever thought of using this type of treatment for tap water, even less so with UV-A instead of UV-C. And much less with active ingredient the chlorine contained in tap water !
So we created the the first domestic advanced oxidation process. It's risk-free and just as effective as its ancestors.
Conclusion on UV for treating tap water
UV water treatment is a vast field with a wide range of effects and applications. Visit UV-A, UV-Band UV-C all play distinct roles, but it is essential to understand their specific characteristics if they are to be used appropriately and effectively.
While UV-C have traditionally been associated with water sterilisationLaVie brilliantly demonstrates theUV-A efficiency in a process ofadvanced oxidation. This is a first for the domestic water treatment.
In short, thanks to this innovationit is now possible toeffectively eliminate pollutants andimproving the quality of tap water without risk to health. In a world where drinking water is a precious resource, it's vital to turn to safe, environmentally friendly solutions. innovative solutions and sustainable like the one offered by LaVie.
But some will say that protecting oneself from micro-pollutants in this way can no doubt be interpreted as a way of "protecting" oneself. precautionary principle. But would you think of drinking medicines or pesticides, even in very small quantities?
Similarly, do you think that drinking chlorine of your favourite drink, a biocide contained in tap waterhas no effect on the bacteria in your trachea?
And once again: So avoid UV-C-based products.. You don't need it if you're not a fan of camping cars and wild camping, or if you live in a country where the drinking water is untreated! It's up to you to judge.
Article written on 18/08/2023 (updated on 25/04/2024) 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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