Water purification evolution

UV water purification has been practiced for several decades. However, it took a long time for water purification to evolve.

The connection between water quality and health has been known since the beginning of time. Actually, clear water was considered as pure water.

The most ancient method of disinfection is boiling water. It is a “technology” used since humans could make fire!

Romans, as an 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 constant

Getting good water quality is an evolving concept. The pollutant loads and the hydraulic loads make the following characteristics vary permanently:

  • physics
  • chemical
  • microbiological water.

Water quality specific parameters must be analyzed to find the right solution for each situation.

Historically, chlorine has been used 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 odors 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 content of the source material, and these compounds are associated with several types of cancers.
  • 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 primary HAAs 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 present in domestic water, wastewater or water bodies.

There are various pathways for the absorption of disinfection by-products from water. Ingestion is an important route.

Specific water uses may also contribute to the absorption of the contained byproducts through inhalation and skin contact, as some are highly volatile and readily vaporize into the air.

UV treatment - An alternative without adding chemicals

Like chemical treatment, UV treatment eliminates pathogenic micro-organisms (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 does not alter 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 physical process that is particularly effective at wavelengths where the energy intensity is optimal. Even highly chlorine-resistant microbes such as Giardia and Cryptosporidium can be effectively disinfected by UV.

ÖNORM or NSF certified UV systems are becoming a popular alternative to chemical treatment for many applications.

Ultraviolet history and the evolution of water purification

Egyptian doctors already used boiled water to treat their patients. However, there was also another method of heating water in the sun.

This is certainly the oldest known application of UV disinfection technology. This process is ideal for disinfecting small quantities of water with good transparency. But it was only in 1910 that the first real UV disinfection technologies appeared.

UV has a long history in water treatment. They have become an effective alternative for non-chemical water disinfection.

Known as an effective germicidal treatment, UV light has been used in numerous public drinking water and wastewater treatment systems 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 used more and more as commercial applications were found.
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