NON-CHEMICAL APPROACH TO DISINFECTION
About ultraviolet light as a disinfectant and germicidal bodies, based on UV-C light
Some aspects of disinfection
Classic disinfection
The use of chlorine as a disinfectant is usually accepted worldwide. People are becoming more and more concerned about the by-products of chlorine as it reacts with other organic compounds to produce different compounds, such as trihalomethanes (THM). THMs are documented as probable or possible human carcinogens.
Other disadvantages of chlorination are how it changes taste and odors, the need for additional equipment, such as tanks, to ensure adequate contact time, and the monitoring needed to ensure adequate concentration levels.
Chlorination is known to provide poor disinfection performance against viruses such as enterovirus and hepatitis A and microorganisms such as Giardia and Cryptosporidium.
Another type of disinfectant currently used is that based on benzalkonium chloride (BAK) https://natth.org/blog/ and which is the most common active ingredient in many disinfectants used regularly in hospitals, households and factories. food processing to protect against a wide range of viruses and bacteria – including all strains of SARS-CoV-2, which leads to the appearance of COVID-19 – but its toxicity, raises problems in achieving concentrations. It has recently been shown that by UV-C radiation the toxicity of this chemical can be neutralized.
UV disinfection
Exposure to UV light in the 200 – 400 nm wavelength spectrum harms genetic molecules (DNA and RNA) and other molecules inside a microorganism.
Bacteria, protozoa, viruses, fungi, algae are all sensitive to UV light. Due to differences in shape, they are sensitive to different wavelengths.
The application of UV light leaves no residue in the water, which is an advantage over chemical disinfection methods. UV has been shown to be very effective in inactivating Giardia and Cryptosporidium with a very low dose but also SARS-CoV-2.
Advantages of UV-C light over chemicals:
no residue results
no disinfection by-products result
it has no effects on color, taste, smell
does not require storage of chemicals
effective against all microorganisms, including Giardia and Cryptosporidium
environmentally friendly and human
About UV
Ultraviolet rays, also called UV rays, are electromagnetic radiation with a wavelength shorter than that of light radiation perceived by the human eye.
Natural sunlight contains, among other things, ultraviolet rays.
The discovery of ultraviolet rays came from the experiments of blackening silver salts under the action of sunlight. In 1801, the German physicist Johann Wilhelm Ritter observed that the silver chloride layer darkens outside the realm of visible rays, these invisible radiations being called “oxidizing rays”. UV and infrared rays will be called “chemical rays” throughout the nineteenth century.
The spectrum of ultraviolet rays is between the wavelengths of 10 – 380 nm (1 nanometer = 10-9 m).
UV-C, from 100 nanometers (nm) to 280 nm
UV-B, from 280 nm to 315 nm
UV-A, from 315 nm to 400 nm
UV-A and UV-B are found in sunlight, being the ones that help us tan but can also cause burns. UV-B is responsible for the formation of vitamin D, which strengthens our bones.
UVC rays are found in the Sun but do not reach the Earth’s surface because they are completely absorbed by the atmosphere. UV-C light, is an invisible light, stretches between 100-280 nm, it has strong germicidal properties.
UV-C light is germicidal – that is, it deactivates the DNA of bacteria, viruses and other pathogens, destroying their ability to multiply and cause disease. Practically under the action of UV-C light, structural distortions of the DNA take place, followed by the interruption of the RNA transcription and the replication of the DNA, finally causing the cell mutagenesis or the death of the virus.
According to: ISO 15858: 2016 (en) (UV-C Devices – Safety information – Permissible human exposure):
UVC radiation is a form of low UV penetration compared to UVA or UVB radiation. Human tissue measurements show that 4% to 7% of UVC radiation, along with a wide range of wavelengths from 250 nm to 400 nm, are reflected and absorbed in the first 2 µm of the stratum corneum. Therefore, the amount of UVC transmitted through the epidermis is minimized.
The skin damage consists of erythema, a reddening of the skin similar to sunburn, but without tanning. The maximum effect of erythema occurs at a wavelength of 297 nm in the UVB band. UVC radiation at a wavelength of 254 nm is less effective in causing erythema.
Ultraviolet technology is a non-chemical approach to disinfection. This method of disinfection does not use other substances, the process being simple, cheap and requires very little maintenance. Abbreviated is called UVGI.
Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses shortwave ultraviolet light (ultraviolet C or UV-C) to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them in inability to perform vital cellular functions. UVGI is used in a variety of applications, such as food, air and water purification (https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation)
NatLUX germicidal bodies for disinfection are not medical devices and should not be used in hospitals. Germicidal bodies are electronic devices that can be used by individuals to disinfect private spaces. The particularities of a medical device are presented below, according to NAMMD.
The Romanian National Agency for Medicines and Medical Devices says:
Medical device – any instrument, apparatus, equipment, software, material or other article, used separately or in combination, including software intended by its manufacturer to be used specifically for diagnosis and / or for therapeutic purposes and necessary for its proper functioning of the medical device intended for use by the manufacturer for the purpose of:
a) diagnosis, prevention, monitoring, treatment or amelioration of a disease;
b) diagnosis, monitoring, treatment, amelioration or compensation of an injury or a disability;
c) investigation, replacement or modification of the anatomy or of a physiological process;
d) design control,
and which does not fulfill its main action for which it was intended in or on the human body by pharmacological, immunological or metabolic means, but whose functioning can be assisted by such means;
In the production of germicidal bodies, we use the most efficient UV-C lamps
The lamps used in the production of germicidal bodies are low pressure lamps produced by the German company Osram, which together with Philips and USHIO, is one of the most important lamp manufacturers.
OSRAM germicidal lamps provide extremely efficient UV-C irradiation at 254nm, which ensures efficient disinfection of surfaces without the use of toxic chemicals. These lamps are ideal for both air and water purification systems. PURITEC HNS lamps are reliable and efficient sources with a long service life of over 8,000 hours. In addition, the outer tube is made of a special glass that absorbs shorter wavelengths, suppresses the formation of ozone and ensures environmentally friendly sterilization.
Osram Pluritec, used in our applications,
Respect:
Restriction of Hazardous Substances Directive 2002/95 / EC, RoHS, short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, which is a European Union directive adopted in February 2003 [1] and which applies on equipment placed on the market from 1 July 2006. The Directive (2002/95 / EC) restricts the use of six substances (lead, mercury, cadmium, hexavalent chromium and two brominated flammable agents, PBB and PBDE).
In the case of these lamps, the skin and eyes should not be exposed to direct or reflected and unfiltered radiation as they may cause sunburn and conjunctivitis (see this site – About UV-C).
In the case of each gender device, NatLUX germicidal body, a check is made of the UV-C light intensity of both the lamp and the germicidal body at the end, using a UV512C (UVC Digital Light Meter) meter produced by the US company GENERAL.
This meter allows the measurement of UV-C light in the range of 220-275 nm.
In the production of air purification systems, we use for professional air quality verification, the PCE-RCM 10 professional meter produced in Germany.