Ultraviolet (UV) disinfection is an effective technology for the inactivation of pathogens in water and is of growing interest for industrial application. A new UV source - ultraviolet light-emitting diode (UV-LED) - has emerged in the past decade with a number of advantages compared to traditional UV mercury lamps. This promising alternative raises great interest in the research on application of UV-LEDs for water treatment. Studies on UV-LED water disinfection have increased during the past few years. This article presents a comprehensive review of recent studies on UV-LEDs with various wavelengths for the inactivation of different microorganisms. Many inconsistent and incomparable data were found from published studies, which underscores the importance of establishing a standard protocol for studying UV-LED inactivation of microorganisms. Different UV sensitivities to UV-LEDs and traditional UV lamps were observed in the literature for some microorganisms, which requires further investigation for a better understanding of microorganism response to UV-LEDs. The unique aspects of UV-LEDs improve inactivation effectiveness by applying LED special features, such as multiple wavelengths and pulsed illumination; however, more studies are needed to investigate the influencing factors and mechanisms. The special features of UV-LEDs offer the flexibility of novel reactor designs for a broad application of UV-LED reactors.

Public health concerns such as multi- and extensive drug-resistant tuberculosis, bioterrorism, pandemic influenza, and severe acute respiratory syndrome have intensified efforts to prevent transmission of infections that are completely or partially airborne using environmental controls. One such control, ultraviolet germicidal irradiation (UVGI), has received renewed interest after decades of underutilization and neglect. With renewed interest, however, come renewed questions, especially regarding efficacy and safety. There is a long history of investigations concluding that, if used properly, UVGI can be safe and highly effective in disinfecting the air, thereby preventing transmission of a variety of airborne infections. Despite this long history, many infection control professionals are not familiar with the history of UVGI and how it has, and has not, been used safely and effectively. This article reviews that history of UVGI for air disinfection, starting with its biological basis, moving to its application in the real world, and ending with its current status.

Ultraviolet light emitting diodes (UV LEDs) are a promising technology for the disinfection of water and wetted surfaces, but research into these applications remains limited. In the drinking water field, UV LEDs emitting at wavelengths ranging from 254 nm to 285 nm (UVC LEDs) have been shown to be effective for the inactivation of numerous pathogens and pathogen surrogate organisms at UV doses comparable to conventional germicidal UV lamps. Surface disinfection with UV light, from UVC LEDs or from conventional UV lamps, is not as well understood. As the technology underlying the design and construction of UV LEDs matures and their energy efficiency improves, it is likely that they will become ubiquitous in small scale water treatment applications and surface disinfection in various industries, including the medical and dental fields. A simple, easily replicated methodology was developed and optimized to grow, irradiate, and recover biofilms from coupons. It was hypothesized that higher UV doses would be required to inactivate biofilm-bound bacteria than planktonic (free-floating) bacteria because the biofilm would provide some degree of protection from the effects of UVC irradiation. Indeed, UV LED irradiation at 265 nm achieved 1.3 ± 0.2 log inactivation of biofilm-bound Pseudomonas aeruginosa at a UV dose of 8 mJ/cm2. This inactivation level is lower than those that have been reported by researchers using UVC LEDs to inactivate planktonic P. aeruginosa, a finding that can be explained by the higher resistance of biofilm-bound bacteria to UV inactivation. A dose-response curve was developed and fitted to three disinfection models: the Chick-Watson model, the multi-target model, and the Geeraerd model. This last, which posits a subpopulation of organisms that are resistant to treatment, was a good fit to the dose-response data. ATP results obtained using the biomass recovery ATP method (ATPBR), a method that includes a 4 h incubation period after treatment, was well correlated to the results of conventional plate counts.

Ultraviolet (UV) disinfection is an early discovered technology that is currently and widely used for water treatment and food hygiene treatment. A newly emerging technology of UV disinfection, that is, UV light-emitting diodes (UV-LEDs), has aroused considerable research attention. UV-LEDs feature numerous advantages compared with traditional UV mercury vapor lamps and are expected to replace traditional UV lamps. Researchers currently perform studies to obtain data and develop methods for UV-LED water treatment systems. This article analyzes the latest research status and discusses the types of inactivation factors, such as the wavelength selectivity of UV light source, control of UV dose, effect of inactivation rate constant (K) (cm²/mJ), working mode of water sample, external auxiliary system, and UV sensitivity of pathogenic bacteria in water. The wavelengths of approximately 260 and 280 nm normally feature strong inactivation characteristics. When compared with the approximately 260 nm wavelength chip, the around 280 nm wavelength chip proves to be a better choice as its higher wavelength light power can result in faster disinfection capacity of bacteria. UV dose can also be used as the reference value for disinfection of drinking water, whereas the inactivation rate constant (K) (cm²/mJ) varies with different microorganism internal structures. Changing the working mode or adding an auxiliary system can also enhance the inactivation effect in water treatment system settings. In addition, we can compare the inactivation capacities of several pathogens as follows: ΦX174 > Escherichia coli > T type bacteriophage >Bacillus subtilis > MS2 or Qβ > human adenovirus. The in-depth investigation and discussion of inactivation factors and the mechanism of action in UV-LEDs water treatment systems will establish a more efficient UV-LED disinfection method in the future, provide a guiding direction, and promote the standardization and normalization of pathogen inactivation mechanism in UV-LED water treatment systems.

The inactivation rate constants (k-value) of pathogenic viruses, bacteria and protozoa and indicator or model microorganisms for monochromatic UV253.7 radiation have been calculated from literature studies describing experiments of seeded microorganisms in collimated beam apparatus with low-pressure lamps. Results show that data of most studies fitted well in the first-order Chick-Watson disinfection kinetics. Viruses require the highest UV fluence and the double-stranded DNA adenovirus is by far the most persistent species with an UV fluence requirement of 125 mJ/cm2 for 3 log inactivation. Translation of these k-values to full-scale UV systems requires accurate fluence assessment in these continuous flow systems with fluence distribution, variations in water quality (UV transmittance) and operational aspects like lamp age and fouling. Determination of the reduction equivalent fluence or REF with seeded model organisms is an accepted methodology to validate UV systems. Frequently used model organisms F-specific RNA phage MS2 and spores of Bacillus subtilis have low k-values. For validation of systems with low fluence requirement to inactivate UV sensitive organisms, alternative model organisms are suggested. Further research is needed to verify the potential of REF verification of full-scale systems by monitoring inactivation of indigenous spores (anaerobic or aerobic) with large volume sampling.

Ensuring access to safe drinking water is a key global priority. However, conventional disinfection methods often produce toxic disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs), which pose significant carcinogenic and environmental risks. Cold atmospheric plasma (CAP) has emerged as a promising alternative disinfection approach that generates reactive species <i>in situ</i>, without the need for added chemical reagents. It utilizes reactive oxygen and nitrogen species (RONS), ultraviolet (UV) radiation, and transient electric fields to effectively inactivate a wide range of waterborne pathogens. CAP disrupts microbial membranes, damages nucleic acids, and induces oxidative stress, rapidly inactivating bacteria, viruses, and fungi. A notable advancement in plasma-based water disinfection is microbubble-enhanced cold atmospheric plasma (MB-CAP), which significantly improves plasma-liquid interactions. Microbubbles (MBs) act as efficient carriers for RONS, greatly increasing the gas-liquid interfacial area and enhancing the mass transfer of RONS. This results in faster removal of pathogens compared to conventional CAP systems. Furthermore, MB-CAP offers localized and targeted treatment capabilities, making it particularly suitable for decentralized water systems, hospital wastewater, and high-load industrial effluents. This review thoroughly examines the mechanisms of microorganism inactivation by MB-CAP, reactor configurations, MB generation techniques, and disinfection performance. This review also discusses key challenges such as energy efficiency, scalability, and regulatory compliance. Future research should focus on developing hybrid CAP systems, integrating renewable energy sources, and implementing real-time monitoring tools to optimize treatment efficacy. Overall, the review highlights the transformative potential of MB-CAP as a next-generation sustainable water disinfection technology.

Introduction. Drinking water supplied to the population must be safe in epidemic terms. However, some viruses and parasites are resistant to the disinfecting effect of traditionally used agents for water treatment. The use of UV irradiation ensures the microbiological safety of water, but there are factors affecting its effectiveness. The purpose of the review was to systematize scientific data on the effectiveness of the use of UV irradiation in relation to drinking water. Materials and methods. The search for scientific publications was carried out using literature databases MedLine/PubMed, Scopus, and Science Direct. The total number of publications was one thousand six hundred forty-six. The criteria for including the report in the systematic review were: publications in Russian or English with an available full-text version; samples for the study are water from centralized water supply systems or specially prepared microorganisms; any type of research evaluating the effectiveness of a wide range of doses of UV irradiation against microorganisms. Results of the analysis of publications. A systematic review included 17 reports about the effect of UV irradiation on bacteria and viruses. The subject of several studies was the resistance of protozoan cysts and helminth eggs to different doses of UV irradiation. According to the results presented in the publication, pathogenic viruses and bacteria, giardia cysts possess of the least resistance to UV irradiation (100% inactivation). 4 log-inactivation was established for Mycobacteia. E. coli and coliphages demonstrate a wide range of indicators of the resistance to ultraviolet radiation due to the diversity of the studied strains. Conclusion. UV disinfection should be used as an additional method in combination with traditional reagents methods of water treatment. It is necessary to study the effect of UV irradiation on helminth eggs and protozoan cysts.

Disinfection of Drinking Water". Ground Water and Drinking Water. Washington, D.C.: EPA. 2024-06-24. Electrochemcially Generated Oxidant Disinfection Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources (such as rivers, lakes, and wells) for drinking purposes. Their main function is to eliminate pathogens, and often also suspended solids and some unpalatable or toxic compounds. These units provide an autonomous supply of drinking water to people without access to clean wate Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources (such as rivers, lakes, and wells) for drinking purposes. Their main function is to eliminate pathogens, and often also suspended solids and some unpalatable or toxic compounds. These units provide an autonomous supply of drinking water to people without access to clean water supply services, including inhabitants of developing countries and disaster areas, military personnel, campers, hikers, and workers in wilderness, and survivalists. They are also called point-of-use water treatment systems and field water disinfection techniques. Techniques include heat (including boiling), filtration, activated charcoal adsorption, chemical disinfection (e.g. chlorination, iodine, ozonation, etc.), ultraviolet purification (including sodis), distillation (including solar distillation), and flocculation. Often these are used in combination.

[Use of UV rays for the disinfection of water. III. UV sensitivity of Legionella pneumophila of different ages in cold and warm drinking water]. In drinking water the sensitivity of L. pneumophila serogroup 1 type Philadelphia and L. pneumophila serogroup 5 type Dallas were studied with a flowthrough u.v. light treatment apparatus. By washing purified cells from broth cultures were used as inoculum directly ( = young cultures) or kept 2-3 weeks in drinking water in the dark ( = old cultures). A decrease of 99,9999% was found after u.v. treatment by 19 mWs/cm2 for young cultures and by 15 mWs/cm2 for old cultures. Reductions of 99,9999% were obtained by 16 mWs/cm2 in cold drinking water (13-16 degrees C) and by 13 mWs/cm2 in warm drinking water (45-47 degrees C). L. pneumophila serogroup 1 and L. pneumophila serogroup 5 show a very similar susceptibility to u.v.-irradiation. Reductions of 99,9999% were obtained by 14 mWs/cm2 and 15 mWs/cm2, respectively. Thus L. pneumophila-suspensions proved to be more sensitive to u.v.-irradiation than E. coli oder E. faecium in earlier experiments.

Disinfection of oral rehydration solutions by sunlight. The use of a salt/sugar oral solution for rehydration in cases of diarrhea is being encouraged by the World Health Organization for developing areas. 1 problem so far with this treatment has been a question as to their safety when prepared with contaminated water or stored in contaminated vessels. An experiment was tried in which the recommended solution was mixed with contaminated water. Some of the containers were exposed to direct sunlight, some kept in the dark, and some stored in normal room conditions. Although the heat in the containers stored in sunlight did not rise significantly, the solutions were found to be purified. It is speculated that the germicidal action resulted from solar radiation near the ultraviolet range. The solution, itself, did not change composition. The microorganisms were not able to regrow within 24 hours after solar irradiation. 50 additional experiments confirmed the findings. It is concluded that this technique of solar irradiation of contaminated solutions will be effective. All types of containers were effective. Published in Lancet (London, England) (1980)