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How do ultraviolet light lamps work?

Ultraviolet light in water treatment: From large industries to simple household equipment, ultraviolet light has been used in water treatment. But what does an ultraviolet lamp actually do?

We all know that light has different spectra that are invisible to us, ranging from infrared light to gamma rays. Within these spectrums of light there is a range called UV which, just last century, was discovered to be for batteries what radioactivity is for us. It destroys the genetic information of microorganisms, bacteria and some viruses.

Microorganisms that are exposed to a certain frequency of light, with a certain intensity and at a specific time are sterilized and in some cases even roasted. And here is a fact that we must keep in mind. The UV rays of a STERILIZER, what they do is to prevent bacteria and viruses from reproducing, very different from a UV biocide, whose purpose is to kill these microorganisms.

What bacteria and viruses are affected by UV?

It usually depends on the equipment, size and brand. But good brands usually have a visible catalog of all the microorganisms their equipment affects. Trojan and Sterilight have them on their pages.

Interesting Fact: UV often works where chlorine does not. There are some bacteria that are immune to chlorine because they have a shell that inhibits the oxidizing effect of chlorine.

Limitations of ultraviolet light

One of the limitations of ultraviolet systems is that they only act on what passes through the chamber. That is to say, if at the exit of the chamber there is a recontamination, the UV no longer works. Unlike chlorine, which is in contact with the water all the time, it does not have this limitation.

To exemplify this, we attended a laboratory that complained about our uv sterilizer because it did not work. He had a valve connected to a PVC pipe that came out to a socket from where he took his samples (it should be noted that the valve and the PVC pipe were after the UV equipment). The valve was large and had air inlets, PVC is not recommended because it is porous and allows bacteria to settle there and reproduce. When the water samples were taken, microorganisms were present because both the pipe and the valve were contaminated and the UV was before them.

As mentioned above, it is not advisable to use uv equipment to treat water to be stored in a tank, as it will be re-contaminated.

Some limitations of this equipment are:

That the bulb or ballast may be damaged.
The frequency at which the focus radiates may be wrong.

If you have any doubts, we recommend the advice of one of our engineers when installing them.

When to decide between an ultraviolet lamp and Osmosis?

Uv is for sterilization and osmosis is to concentrate the solids in a rejection stream and have less conductivity. The case where it is necessary to evaluate which one to use is for domestic use. But this is very simple, if the water analysis complies with NOM 127, only a UV is needed, which is also usually cheaper. Otherwise, it is recommended to install an osmosis system.