UV water purification has been practiced for several decades. However, the evolution of water purification has taken time.
We have all known the link between water quality and health since the dawn of time. Indeed, clear water was considered clean water.
The oldest method of disinfection is to boil water. It is a “technology” used since humans could make fire!
The Romans, for example, used wine to disinfect their water. However, the origin of diseases have always been misinterpreted. Diseases were said to be a divine punishment or caused by polluted air.
After the microscope discovery and the bacteria and micro-organisms identification in the 17th century, it took another 2 centuries to identify the activity of pathogenic micro-organisms. This is when disinfectants such as chlorine were introduced.
For a century, we have been using disinfectants to prevent the spread of disease and improve water quality.
Water quality is not consistent
Achieving good water quality is an evolving concept. The pollutant loads and the hydraulic loads make the following characteristics vary permanently:
- physics
- chemical
- microbiological water.
The specific parameters of water quality must be analysed to find the right solution for each situation.
History of Chlorine in Water Treatment
The background of chlorine identification is complex. The Swedish chemist Carl Wilhelm Scheele discovered it in 1774.
In 1835, chlorine was used to remove odours from water. It was regarded as responsible for the transmission of diseases at that time.
It was not until 1890 that it proved to be an effective solution for disinfection. This will reduce the number of water-borne diseases.
Chlorination then began in Great Britain, before spreading around the world.
What are disinfection by-products?
When using chlorine or other chemicals, several by-products can be created during water disinfection. However, some compounds can be extremely harmful.
The main ones are trihalomethanes (THMs) and haloacetic acids (HAAs).
- Trihalomethanes (chloroform, bromodichloromethane, etc.) are mainly formed by reaction of chlorine. It is used to disinfect water, with natural organic matter (dead leaves, etc.). They are compounds consisting of a single carbon atom, linked to halogens, and of the general formula CHX 3, where X generally represents chlorine, bromine, or a combination of these two elements. THM concentrations depend on the organic matter content of the source water, and these compounds are associated with several types of cancer.
- Haloacetic acids (HAAs) are formed in the same way as trihalomethanes. It is a group of organic compounds based on the acetic acid molecule (CH3COOH). The main AHAs contained in drinking water are:
- monochloroacetic acid (MCA),
- trichloroacetic acids (TCA),
- Dichloroacetic acid (DCA),
Which issues are caused by disinfection by-products?
Disinfection by-products – primarily trihalomethanes and haloacetic acids – are carcinogens. They are thus associated with extremely harmful effects on the body.
- Chronic intoxication: These effects are produced following prolonged exposure to high doses of THM for example.
- Carcinogenic effects: Disinfection by-products are associated with several types of cancers. The main tumors observed are liver, kidney and colon cancer. Disinfection by-products are also associated with mutagenic effects.
These effects result from long-term exposure to products in domestic, wastewater or water bodies.
The absorption routes of disinfection by-products contained in water are diverse. Ingestion is an important route.
Specific uses of water can also contribute to the absorption of by-products contained through inhalation and dermal contact, as some are highly volatile and readily vaporize into the air.
UV treatment – An alternative without the addition of chemicals
Like chemical treatment, UV treatment eliminates pathogenic microorganisms (bacteria, viruses, etc.).
This technique avoids the addition of potentially harmful products that could cause health or environmental effects.
The UV disinfection method then appears to be a reliable and cost-effective solution. It also has the advantage of not altering the taste or smell of the water.
This solution uses ultraviolet radiation transmitted in the form of waves moving in all directions from the emitting source (UV lamp).
UV disinfection is therefore a particularly effective physical process at wavelengths for which the energy intensity is optimal. Even highly chlorine-resistant microbes such as Giardia and Cryptosporidium can be effectively disinfected with UV.
ÖNORM or NSF certified UV systems are becoming a popular alternative to chemical treatment for many applications.
The History of Ultraviolet and the Evolution of Water Purification
Egyptian doctors already used only boiled water to treat their patients. However, there was also another method of heating water in the sun.
It is certainly the oldest known and close application of UV disinfection technology. This process is ideal for disinfecting small quantities of water with good transparency. But it was not until 1910 that the first UV disinfection technologies actually appeared.
UV has a long history in water treatment. This has made them an effective alternative for non-chemical water disinfection.
Long recognized as an effective germicidal treatment, UV light has been installed in many large public drinking water and wastewater treatment plants around the world.
- In 1903, Niels Fensen received the Nobel Prize for his use of ultraviolet light to fight tuberculosis.
- In 1910, the first drinking water disinfection system was installed in Marseille, France.
- Since 1960, UVC disinfection has been increasingly used as commercial applications have been found.
FAQ
Is UV water treatment safer than chlorination?
Yes, UV treatment is considered safer because it does not generate any toxic chemical byproducts, unlike chlorination which produces compounds such as trihalomethanes (THMs) or haloacetic acids (HAAs), which are potentially carcinogenic. In addition, UV rays do not alter the taste or odour of the water and eliminate chlorine-resistant microorganisms such as Giardia or Cryptosporidium.
Is UV water treatment effective against all types of microorganisms?
UV treatment is very effective against the majority of pathogenic microorganisms: bacteria, viruses, cysts, protozoa, including chlorine-resistant ones. However, its effectiveness depends on the Water transparency : Water that is too cloudy or contains suspended particles can reduce the performance of UV radiation. One pre-filtration is often required.
Does UV completely replace chemicals in water treatment?
UV is an effective replacement for chemical disinfection, but does not treat chemical pollutants, heavy metals or organic matter. For a complete treatment, UV rays are often complemented by filtration, reverse osmosis or adsorption (activated carbon) steps as required. It is an ideal solution for disinfecting water without changing its chemical composition.
What are the side effects of chlorine byproducts in drinking water?
Chlorine by-products such as trihalomethanes (THMs) and haloacetic acids (HAAs) are associated with mutagenic and carcinogenic effects, especially in cases of chronic exposure. They can be absorbed by ingestion, inhalation (hot showers, steam) or skin contact. For this reason, alternatives such as UV are gaining popularity in modern disinfection systems.
How long does a UV system last and should it be maintained?
A UV system requires regular maintenance to remain effective. The UV lamp usually needs to be replaced every 9 to 12 months, even if it still works, because its intensity decreases over time. It is also necessary to Clean or replace the quartz sleeve that protects the lamp, as limescale or impurities build-up can reduce UV transmission.
