What is UV-C ?

Light

People normally think of light as what we see when we open our eyes. Specifically, the light that lets us distinguish different colours and what makes the difference between day and night. But what we see on a daily basis is only part of the spectrum.

Light, in the scientific sense, is electromagnetic radiation. It consists of eight regions, depicted in the figure above. The most well-known regions are visible light, infrared, and ultraviolet light (UV light) The human eye can only see, as the name implies, visible light. This part contains all the colours in a rainbow. Infrared light and UV light are not visible to the human eye.

Ultraviolet light, which is literally “past violet,” has its own various regions. The first is UV-A light, this is also called blacklight. This light consists of long waves and is known for speeding up the ageing process. UV-B Light consists of middle length waves and causes sunburn and tanning.

UV-C light

UV-C Light is radiation with a short wavelength, from between 200 and 280 nanometers. This light is damaging to humans because it destroys skin cells. Luckily, natural UV-C light is completely blocked by our atmosphere. UV-C light is, however, very suitable for microbiological disinfection and is also a very clean technology.

Disinfection with UV-C

UV-C Light is able to disinfect water, air, and surfaces. Micro organisms are rendered harmless very effectively, without using any chemicals at all. Scent, colour, and taste don’t change, nor does the water composition itself. It’s actually very simple: micro organisms are “killed off”, even micro organisms that are resistant to chlorine, antibiotics, or organic biocides.

How does UV-C disinfection work?

Micro organisms, such as viruses, bacteria and moulds, absorb UV-C light naturally. But when the UV-C penetrates the micro organism, it breaks the DNA bonds of the cells. This changes the hereditary attributes of the cell, ensuring that the micro organisms can no longer multiply.
Low-pressure UV-C disinfection is performed on a wavelength of 254 nm, because micro organisms absorb the most at this wavelength.

The advantages of UV-C disinfection

The UV-C technology has more benefits than other disinfection methods such as chlorination or separation techniques such as filtering. The advantages are:

• It is not harmful to the environment
  UV-C light only effects the DNA of the micro organism and has no effect on other attributes.
• No chemicals are used
  Taste, colour, and scent of the medium (the carrier, such as liquids or surfaces) remain unchanged. Only light is used.
• – Micro organisms are treated effectively
  UV-C disinfection is aimed at killing off the organism. There is no residue.
• UV-C is versatile
  Along with disinfection, UV technology is also used for breaking down organic and inorganic components in water, such as chlorine, chloramines, ozone, micro pollutions, and organic, carbon based, compounds (TOC).

Advanced oxidation

A supplement to UV disinfection is advanced oxidation (AOP). This is a combined technology where UV-C light and hydrogen peroxide or ozone make powerful radicals that destroy micro pollutions. Advanced oxidation is used to destroy pesticides in irrigation water in horticulture, to destroy medicine residue in waste water or in water that is processed into drinking water and to destroy organic materials (TOC) in processed water, waste water, or ultra pure water. Advanced oxidation purifies water and results in no “disinfection by products”, like chlorine does.