UV Disinfection Research Articles

Comparative life cycle assessment of non-thermal plasma for the removal of pharmaceuticals from wastewater

Wastewater effluents are a continuous source of pharmaceuticals in water bodies, which pose a serious environmental threat to aquatic ecosystems. This work provides a comprehensive technical, environmental and cost assessments of different advanced quaternary treatments for wastewater effluents, with special focus on novel Non-Thermal Plasma technology. For this porpouse Non-Thermal Plasma, Sand Filtration + Ozonation, Ultrafiltration, Ultrafiltration + Nanofiltration and Ultrafiltration + Reverse Osmosis technologies were compared with UV disinfection-based technology. This work applies the Life Cycle Analysis tool for the impact environmental assessment using both ReciPE 2016(H) method and, for a more detailed analysis of the contribution of pharmaceuticals to freshwater ecotoxicity category of impact, the USETOX method, which was integrated with 7 new characterisation factors. The results obtained showed overall removal efficiency of pharmaceuticals always higher than 80%, with performances in descending order of Ultrafiltration + Reverse Osmosis > Sand Filtration + Ozonation > Ultrafiltration + Nanofiltration > Non-Thermal Plasma, being Sand Filtration + Ultraviolet disinfection and standalone Ultrafiltration comparatively not suitable for pharmaceuticals removal. Regarding the target pharmaceuticals proposed on the EU Directive 271/91 revision, the Non-Thermal Plasma perform better towards venlafaxine than Sand Filtration + Ozonation, and towards diclofenac and carbamazepine than Ultrafiltration + Nanofiltration. Ultrafiltration + Nanofiltration and Non-Thermal Plasma showed better environmental performance than Sand Filtration + Ozonation and Ultrafiltration + Reverse Osmosis in 7 out of 18 categories of impact (ReciPe method), with Ultrafiltration + Nanofiltration being more advantageous than Non-Thermal Plasma in human and ecotoxicity-related categories of impact, and Non-Thermal Plasma more advantageous in Global Warming, Fossil Resource Scarcity, and Fine Particulate Matter Formation. Regrading Freshwater Ecotoxicity (USEtox method), the quaternary treatment configuration and its energy demand affect the Freshwater final value of impact more than the presence of pharmaceuticals. Under the conditions tested, the Non-Thermal Plasma provided the lower OPEX (0.24 € m−3) than other tested technologies, showing an interesting compromise between pharmaceuticals removal efficiency, environmental impacts, and economic operational cost.

Potential for synergism of sequential UV-NaClO disinfection on ARGs removal in municipal sewage: Effectiveness, kinetics, and mechanisms

Conventional disinfection technologies have limitations in effectively addressing the challenges posed by the emerging pollutant of antibiotic resistance genes (ARGs). To reduce the risk of antibiotic resistance in wastewater treatment plant (WWTP) effluent, this study investigated the effectiveness of ultraviolet (UV) irradiation followed by Sodium hypochlorite (NaClO) (sequential UV-NaClO) disinfection in removing six classes and 18 subtypes of ARGs in the secondary effluent of a municipal WWTP. The study showed that UV disinfection could reduce tetracycline ARGs (TCs-ARGs) subtype tetQ by 0.98 log, while it was ineffective in removing sulfonamide ARGs (SAs-ARGs). NaClO disinfection was very effective in removing ARGs. Increasing the disinfectant dosage is more effective than extending the disinfection time. The highest removal was observed for the SAs-ARGs subtype sul1 with 4.15 log and the β-lactams-ARGs(β-LACs-ARGs) subtype blaCTX-M1 with 3.87 log. Sequential UV-NaClO disinfection has the potential for synergistic effects in disinfection. Sequential UV-NaClO disinfection with a UV dosage of 15 mJ/cm2 and a NaClO dosage of 10 mg/L can effectively remove 1.46 log of the total 18 subtypes of ARGs, which is 0.73 log higher than the removal achieved by standalone UV irradiation at a fluence of 100 mJ/cm2, and equivalent to the results obtained with NaClO disinfection alone at a dose of 30 mg/L. Additionally, sequential UV-NaClO disinfection can reduce the repair efficiency of ARGs. The proposed modified Hom model can be used to analyze the kinetics of sequential UV-NaClO disinfection synergy. Analysis of microbial community structure and co-occurrence of ARGs showed synchronized and consistent removal of ARGs and their potential bacterial hosts. Sequential UV-NaClO disinfection could achieve 99 % removal of more than half of the genera. Overall, our results indicate that sequential disinfection is a promising disinfection technology for disinfecting municipal wastewater and reducing the spread and transfer of ARGs.

Ultraviolet radiation inhibits mitochondrial bioenergetics activity.

Mitochondria play an important role in cellular function, not only as a major site of adenosine triphosphate (ATP) production but also by regulating energy expenditure, apoptosis signaling, control of the cell cycle, cellular growth, cell differentiation, transportation of metabolites, and production of reactive oxygen species. Interaction with electromagnetic waves can lead to dysregulation or alterations in the patterns of energy activities in the mitochondria. Ultraviolet light (UV) can be found in sunlight and artificial sources, such as lamps. UV radiation can cause damage to DNA, proteins, and lipids. Besides that, UV radiation is largely used in microorganism disinfection. To establish possible alterations in mitochondrial bioenergetics, this study proposes to investigate the UV (at two distinct intervals) effects on isolated mitochondria from mice liver to obtain direct responses and selective permeability of the internal membrane information. UVA-371 and UVC-255 nm lamps were used to irradiate, at different doses varying from 22.5 to 756 mJ/cm2, isolated mitochondria samples. Mitochondrial respiration pathways were investigated by high-resolution respirometry, and possible mitochondrial membrane damages were evaluated by mitochondrial swelling by spectrophotometer analysis. UVC irradiation results (in the higher dose) indicate decrease in 75% of mitochondrial bioenergetics capacity, such as limitation of oxidative phosphorylation in 60% and increased energy dissipation in 30%. Mitochondrial swelling experiments (spectrophotometer) indicated inner membrane damage, and consequently a loss of selective permeability. Direct correlation between irradiation and effect responses was observed, mitochondrial bioenergetics is severely affected by UVC radiation, but (UVA) radiation did not present bioenergetic alterations. These alterations can contribute to improving the knowledge behind the cell death mechanism in disinfection UV light and UV therapy such as phototherapy.

Greywater recycling for diverse collection scales and appliances: enteric pathogen log-removal targets and treatment trains

In light of increasingly diverse greywater reuse applications, this study proposes risk-based log-removal targets (LRTs) to aid the selection of treatment trains for greywater recycling at different collection scales, including appliance-scale reuse of individual greywater streams. An epidemiology-based model was used to simulate the concentrations of prevalent and treatment-resistant reference pathogens (protozoa: Giardia and Cryptosporidium spp., bacteria: Salmonella and Campylobacter spp., viruses: rotavirus, norovirus, adenovirus, and Coxsackievirus B5) in the greywater streams for collection scales of 5-, 100-, and a 1000-people. Using quantitative microbial risk assessment (QMRA), we calculated LRTs to meet a health benchmark of 10-4 infections per person per year over 10’000 Monte Carlo iterations. LRTs were highest for norovirus at the 5-people scale and for adenovirus at the 100- and 1000-people scales. Example treatment trains were designed to meet the 95% quantiles of LRTs. Treatment trains consisted of an aerated membrane bioreactor, chlorination, and, if required, UV disinfection. In most cases, rotavirus, norovirus, adenovirus and Cryptosporidium spp. determined the overall treatment train requirements. Norovirus was most often critical to dimension the chlorination (concentration × time values) and adenovirus determined the required UV dose. Smaller collection scales did not generally allow for simpler treatment trains due to the high LRTs associated with viruses, with the exception of recirculating washing machines and handwashing stations. Similarly, treating greywater sources individually resulted in lower LRTs, but the lower required LRTs nevertheless did not generally allow for simpler treatment trains. For instance, LRTs for a recirculating washing machine were around 2-log units lower compared to LRTs for indoor reuse of combined greywater (1000-people scale), but both scenarios necessitated treatment with a membrane bioreactor, chlorination and UV disinfection. However, simpler treatment trains may be feasible for small-scale and application-scale reuse if: (i) less conservative health benchmarks are used for household-based systems, considering the reduced relative importance of treated greywater in pathogen transmission in households, and (ii) higher log-removal values (LRVs) can be validated for unit processes, enabling simpler treatment trains for a larger number of appliance-scale reuse systems.

Utilization of Ultraviolet C Light-Emitting Diodes for the Deactivation of SARS-CoV-2 in Human Breath

Ultraviolet light has a long track record when it comes to use for deactivating harmful microorganisms. With recent developments in LED technology in terms of generating electromagnetic waves from this specific spectral range, new applications have emerged. In this study, the possibility of constructing an effective miniature UV barrier for deactivating the SARS-CoV-2 virus in both exhaled and inhaled air is investigated. Our findings demonstrate that utilizing commonly available UVC diodes operating at the wavelength of 275 nm makes it possible to attain an adequate level of deactivation that fulfills the standards specified for commercial devices. Full Text: PDF References N.G. Reed, "The History of Ultraviolet Germicidal Irradiation for Air Disinfection", Public Health Rep. 125(1), 15 (2010) CrossRef S. Oliveira De Souza, A. Cardoso, A. Sales, C. Sarmento, F. D'errico, "Effectiveness of a UVC air disinfection system for the HVAC of an ICU", Eur. Phys. J. Plus 137, 37 (2022), CrossRef N. Trivellin et al., "UV-Based Technologies for SARS-CoV2 Inactivation: Status and Perspectives", Electronics 10, 4 (2021), CrossRef R. S. Bergman, "Germicidal UV Sources and Systems", Photochem. Photobiol. 97(3), 466 (2021), CrossRef M. Shatalov, R. Jain, T. Saxena, A. Dobrinsky, M. Shur, "Chapter Two - Development of Deep UV LEDs and Current Problems in Material and Device Technology", Semiconductors and Semimetals 96, 45 (2017). CrossRef W. Kowalski, Ultraviolet Germicidal Irradiation Handbook UVGI for Air and Surface Disinfection, 1 (2009), CrossRef P. Sobotka, M. Przychodzki, K. Uściło, T.R. Woliński, M. Staniszewska, "Effect of Ultraviolet Light C (UV-C) Radiation Generated by Semiconductor Light Sources on Human Beta-Coronaviruses’ Inactivation", Materials 15(6), 2302 (2022), CrossRef Y. Gerchman, H. Mamane, N. Friedman, M. Mandelboim, "UV-LED disinfection of Coronavirus: Wavelength effect", J. Photochem. Photobiol. B Biol. 212, 112044 (2020), CrossRef R.M. Mariita, J.W. Peterson, "Not all wavelengths are created equal: disinfection of SARS-CoV-2 using UVC radiation is wavelength-dependent", Access Microbiology 3(11), 1 (2021), CrossRef Polio laboratory manual, 4th ed., World Health Organization 2004. DirectLink J.V. Maizel, D.O. White, M.D. Scharff, "The polypeptides of adenovirus: I. Evidence for multiple protein components in the virion and a comparison of types 2, 7A, and 12", Virology 36(1), 115 (1968), CrossRef H. Inagaki, A. Saito, H. Sugiyama, T. Okabayashi, S. Fujimoto, "Rapid inactivation of SARS-CoV-2 with deep-UV LED irradiation", Emerging Microbes and Infections 9(1), 1744 (2020), CrossRef

Combined performance of upper-room UVGI and ceiling-mounted air cleaners for removing active bioaerosol

Upper-room ultraviolet germicidal irradiation (UR-UVGI) and ceiling-mounted air cleaner (CM-AC) technologies contribute to curbing the spread of infectious diseases such as COVID-19. However, there is a lack of detailed studies on the performance differences between these two control technologies for reducing viral concentrations and infection risk in isolation ward environments with different ventilation modes, especially when used alone versus in combination. Therefore, this study performed numerical simulations under three ventilation modes, namely, downward ventilation (DWV), stratum ventilation (SV), and displacement ventilation (DV), by the Eulerian-Lagrangian method combined with the UV inactivation model. The viral disinfection performance of UR-UVGI and CM-AC was parametrically analyzed. The effectiveness of the combined application of these two control technologies in wards was evaluated. The results showed that expanding the irradiation range was more effective in enhancing the UR-UVGI performance with the same total UV flux. When using UR-UVGI only, DWV disinfected better at the same irradiation flux. In CM-AC cases, the viral aerosol removal efficiency was the greatest in DV. UR-UVGI and CM-AC had advantages in active bioaerosol removal in overall and localized indoor spaces, respectively. The combined application was recommended to maximize the air cleanliness. Under the role of UR-UVGI, a high level of disinfection could be achieved using CM-AC with low ventilation rates. When the CM-AC ventilation rate was 150 m3/h and the UV irradiance was 30 μW/cm2, the viral disinfection of DV exceeded 90%, while that of DWV was also close to 90%. The findings could provide insights to further lower the transmission risk of infectious diseases.

Global transcriptional analysis for molecular responses of Alicyclobacillus acidoterrestris spores in drinking water after low- and medium-pressure ultraviolet irradiation

Ultraviolet (UV) irradiation can effectively disinfect water contaminated with pathogens. However, the biological mechanisms of inactivation by different types of UV irradiation are unknown. The present study investigated the inactivation mechanisms of Alicyclobacillus acidoterrestris spores in water by low-pressure UV (LPUV) and medium-pressure UV (MPUV) using a quasi-collimated beam apparatus. Global transcriptomic data obtained by RNA-seq revealed 291 shared differentially expressed genes (DEGs) that damaged DNA, reduced biofilm formation, and had other reactions. The individual downregulated DEGs (n = 123) mainly related to cell motility, membrane transport, and metabolism were induced by LPUV, and in turn contributed to energy-saving and metabolic activity inhibition, forcing bacteria into a viable but non-culturable (VBNC) state. The individual upregulated DEGs (n = 244) following MPUV treatment were mainly enriched in cell motility, membrane transport, metabolism, DNA replication and repair, and spore germination pathways. This results in high-energy consumption, severe damage to genetic material, and enhanced spore germination accelerated cell death. Additionally, hub genes in the protein-protein interaction network were mainly involved in transcription and translation. These findings contribute to the comprehensive understanding of the inactivation mechanisms of different types of UV irradiation, and will improve applications of UV disinfection in the treatment of water.

Fate of emerging contaminants in an advanced SBR wastewater treatment and reuse facility incorporating UF, RO, and UV processes

A critical factor for widescale water reuse adoption is the capability of advanced wastewater treatment facilities to consistently produce high-quality water by efficiently removing various pollutants, including emerging contaminants (ECs). This study monitored the fate of seventeen ECs (which included pesticides, antibiotics and other pharmaceutically active compounds) over six months in an advanced wastewater reuse facility situated in the United Arab Emirates. The facility integrates a sequencing batch reactor (SBR) based sewage treatment plant (STP) with a water recycling facility featuring ultrafiltration (UF), reverse osmosis (RO), and ultraviolet (UV) disinfection. ECs were detected and quantified at the influent and effluents of the various treatment stages, using an ultra-high-performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS). The STP exhibited variable removal efficiencies, achieving >90 % removal for compounds like caffeine and acetaminophen, while others, such as carbamazepine and thiabendazole, displayed poor removal (<10 %). UF treatment broadly resulted in limited removal, with ECs in permeate typically persisting in the 1–10 ng/L range. Subsequently, after undergoing RO treatment, eight ECs were still detected in the RO permeate, albeit at <1 ng/L, except for imidacloprid (2.5 ng/L). Conversely, the final UV disinfection step led to concentration increases of certain ECs, namely imidacloprid, thiabendazole, sulfamethoxazole, sulfamethazine and caffeine. Overall, the total EC concentration levels decreased considerably from 2300 ng/L in the STP influent to 5.2 ng/L in the RO permeate. However, a subsequent increase to 27.5 ng/L was observed after UV disinfection. While the study underscores the effectiveness of advanced treatment processes, notably RO, in reducing EC concentrations, it also demonstrates the importance of continuous EC monitoring in such facilities as many compounds persist post treatment. Additionally, the potential for processes like UV disinfection to increase certain EC concentrations highlights the need to optimize treatment trains to minimize EC concentration rebound.

Silica Sand, Activated Carbon, and Manganese Zeolite for Clean Water Filtration

The General Background Water is essential for human life, but many rural areas still lack access to clean drinking water that meets health standards. In Sumbergedang Village, Pandaan, local water sources are often contaminated by dissolved metals and bacteria, posing risks to community health. Current filtration methods in the area are insufficient, and limited studies explore the combined use of silica sand, activated carbon, manganese zeolite, and UV sterilization for improving rural water quality. This study aims to evaluate the performance of these filtration materials and UV sterilization in producing safe drinking water for the village. The results show that the filtration system increased the pH of the water from 7.94 to 7.98, within acceptable drinking water standards. The novelty of this research lies in the integration of filtration materials with UV sterilization to address both chemical and microbial contaminants, offering a comprehensive solution for water purification. The findings suggest that, while the system effectively improves most water quality parameters, additional treatments may be required to reduce aluminum levels to meet national drinking water standards. These results have important implications for water management in rural areas facing similar challenges. Highlihts: The study combines mangan zeolite, silica sand, and activated carbon with UV sterilization for effective water purification. Filtration and UV treatment significantly reduced turbidity, odors, and bacterial contamination in spring water. Aluminum levels exceeded permissible limits, indicating the need for further modifications to the filtration system. Keywords: Water quality, filtration, UV sterilization, rural communities, aluminum levels

Modelling of radiation and flow fields in in-duct ultraviolet germicidal irradiation systems with and without ribs

In-duct ultraviolet germicidal irradiation systems (ID-UVs) is a promising technology for the development of biosecure buildings. This study explored the Computational Fluid Dynamics (CFD) method for accurately predicting the inactivation efficiency of ID-UVs. The results showed that the setting of ‘Divisions’ is crucial to the accuracy of radiation field modelling, and 15 × 15 was considered to be a reasonable value in this study. In addition, residence time and deposition ratio are two crucial parameters determining the average UV dose (AD) received by microbial particles, thereby influencing the inactivation efficiency. For ID-UVs without ribs, the Renormalization Group (RNG) [Formula: see text] model largely overestimated these two parameters, while the Reynolds Stress Model (RSM) with correcting fluctuation velocity improved the predictive accuracy of AD by 10.0%. For ID-UVs with ribs, the RNG [Formula: see text] model overestimated the eddy size and AD by 28.6% and 12.0%, respectively. The RSM model provided results closer to the Large Eddy Simulation. Adding 0.10 H (H: duct height) ribs increased the inactivation efficiency for MS2 Bacteriophage by 19.0%–64.3%, with an additional pressure drop of only 3.3 Pa. These findings contributed to a reliable CFD framework and provided novel ideas for improving inactivation efficiency.

Applications of robot-assisted UV disinfection in dentistry.

Maintaining a microbial-free environment in healthcare facilities is more widely recognized as an essential component of therapies to minimize transmission of viruses associated with healthcare sector. The global spread of COVID-19 and recent outbreaks have presented humanity with previously unheard-of challenges. The development of autonomous disinfection robots seems to be necessary given the urgent need for constant sterilization in the face of a labor shortage. Due to their automated and perceived cost advantages by eliminating cleaning staff, these robots are being advertised more and more as an easy solution to immediately disinfect rooms and operating areas. The use of these services lowers the danger of infection, and expense of traditional cleaning and, most significantly, builds trust and security in medical facilities. Currently, routine (manual) cleaning is not replaced by disinfection robots; rather, they may support it. Additional hospital and device design alterations are necessary to address the overshadowing (visibility) issue allowing Ultraviolet disinfectant (UV-D) robots move freely in the medical environment. More technical developments and clinical studies in a variety of hospitals are needed to overcome the current challenges and find ways to integrate this unique technology into hospitals now and in the future. Thus, we present a review that includes detailing all elements required for it to function, as well as both its advantages and disadvantages. To the best of our knowledge, very limited studies have collected an in- depth data on the sterilization effect using a disinfection robot in the field of dentistry. We believe that this data will work as a foundation in more advanced uses at diverse sites that require disinfection and will highlight unsolved challenges and potential research avenues for UV robot operational concerns in dental hospitals. The goal of this work is to offer a comprehensive manual for UV-D robots covering pertinent information on traditional Ultraviolet germicidal irradiation (UVGI) system along with advancements in UV-D robots and thereby focusing on in-depth application in medical and dental facilities.

Assuring reclaimed water quality using a multi-barrier treatment train according to the new EU non-potable water reuse regulation

In this study, we evaluated the ability of various pilot-scale treatment train combinations to meet the microbial requirements of the new European non-potable water reuse regulation 2020/741. The study utilized non-disinfected secondary effluent from the wastewater treatment plant in Schweinfurt, Germany, as feedwater for two pilot-scale treatment trains. The first, a reference treatment train (Train A), consisted of filtration and UV disinfection as specified for reclaimed water class A in the EU regulation. The second, an advanced treatment train (Train B), included ceramic ultrafiltration (UF), ozonation, biological activated carbon filtration (BAC), and final UV disinfection. Based on a Monte Carlo simulation for Train A, the EU requirements for pathogen removal were not met when an average UV dose of 400-600 J m−2 was applied. This shortcoming was likely due to a moderate transmittance range (50–65 %), resulting in decreased UV fluence. These findings suggest that operational conditions for disinfection should be more clearly specified to ensure consistent pathogen inactivation both during validation and regular operation. In contrast, treatment train B successfully met the requirements of the EU regulations by reducing pathogens to below the detection limit. The UF membrane demonstrated a positive effect on the overall log reduction values (LRVs) throughout the water reclamation system. It also enhanced the efficiency of downstream processes, such as ozonation and UV disinfection, by lowering total suspended solids and turbidity. However, even without the UF membrane, treatment train B was still able to meet the pathogenic EU requirements for non-potable reuse applications. Furthermore, the study observed that the inclusion of biologically activated carbon (BAC) filtration requires a final disinfection step (e.g., UV disinfection) to prevent the potential occurrence of heterotrophic bacteria that proliferate in the BAC filter. For process validation it is recommended to use at least two different virus surrogates (MS2 and PhiX174), rather than just one or total coliphage as required in the EU regulation.

Preloading Long-Chain Quaternary Ammonium Groups to Synthesize a High-Efficient Anion-Exchange Resin for Eliminating Bacterial Contaminants in Drinking Water.

Bacterial contamination in drinking water is a global health concern, necessitating the development of highly efficient treatment techniques. Anion-exchange resins (AERs) have long been employed for removing anionic contaminants from drinking water, but their performance for bacterial contamination is poor. Here, we develop a novel AER (AER6-1) with exceptional bactericidal effects and ultrafast adsorption rates of extracellular DNA (eDNA) (2.2- and 11.5-fold compared to other AERs) achieved through preloading quaternary ammonium groups (QAGs) with hexyl chain (-C6-N+-) on the resin exterior and successively grafting QAGs with a methyl chain (-C1-N+-) inside a resin pore. The AER6-1 outperforms other commercial AERs and ultraviolet disinfection, exhibiting superior elimination of total bacteria, potential pathogens (Escherichia coli and Pseudomonas aeruginosa), eDNA, and antibiotic resistance genes (mexF, mexB, and bacA) in actual drinking water, while maintaining a comparable anion exchange capacity with other commercial AERs. Theoretical calculations of density functional theory and xDLVO combined with XPS elucidate the crucial roles of hydrogen bonding and hydrophobic force provided by the resin skeleton and -C6-N+- in cleaving the bacterial cell membrane and increasing the adsorption kinetics on eDNA. This study broadens the scope of AERs and highlights an effective way of simultaneously removing bacterial and anionic contaminants from drinking water.

Evaluation of the effectiveness of ultraviolet light disinfection of a chemotherapy preparation robot

Evaluation of the effectiveness of ultraviolet light disinfection of a chemotherapy preparation robot

Evaluation of two household decontamination methods on protective mask materials and disinfection effects

Abstract In order to find affective disinfection methods for general public to reuse protective mask, which could address supply shortages in the period of epidemic, household ovens and household ultraviolet disinfection cabinets were used as decontamination tools, and the influence of decontamination process on the protective performance of masks including PFE and TIL, as well as virus (PV I and MHV) inactivation effect were completely evaluated. It was found that the dry heat and UVGI decontamination with household devices had a little impact on PFE or TIL of masks, which indicated that two process had little effect on mask material and face seal fit. The virus inactivation results showed that dry heat decontamination could effectively inactivate the virus on the masks, and UVGI decontamination could not completely inactivate the virus caused by the special shape of masks, which could be concluded that dry heat decontamination with household oven was a feasible method to reuse the mask, and UVGI decontamination was not recommended. This study had guiding significance for the decontamination and reuse of masks by the general public.

NIR-driven intense UV upconversion films for non-contact high-efficiency prevention of bacterial infections

Bacterial infections on wounds imposes a significant limitation to the wound healing. Although the conventional drug antibacterial dressing is employed for hindering bacterial infection, the inevitable microbial resistance and secondary damage severely limit the quality and speed of wound healing. Herein, the NIR-driven intense UV upconversion (UC) BaLu2F8:80%Yb3+/0.5%Tm3+ microcrystals are, for the first time, designed and fabricated into solid sterilization film to protect the wounds from infections. Equipped with excessive Yb3+ sensitizers, the emission of Yb3+/Tm3+ co-doped monoclinic BaLu2F8 matrix achieve a 175-fold enhancement at the UV band. The UV UC microcrystals was further fabricated into a NIR-to-UV sterilization film with a diameter of 1.5 cm and a thickness of 150 μm using solution casting method, which can efficiently destroy 97 % of E. coli with a NIR irradiation of 5 minutes. Due to the outstanding penetrability of NIR irradiation, the sterilization film under 4 layers gauze dressing can be activated to produce UV photons. The in-vivo mouse tests demonstrate the well-designed NIR-to-UV sterilization film can speed up the wound healing by high-efficient inhibiting E. coli infection under the irradiation of 980 nm NIR laser. The non-contact NIR-driven UV sterilization film require no more drugs and dressing exchange, thus entirely eliminating the effect of microbial resistance and secondary damage from conventional drug dressing. Our work provides a new alternative for constructing highly-efficiency sterilization dressing through the utilization of NIR-to-UV optical conversion materials.

Real-time water quality monitoring using AI-enabled sensors: Detection of contaminants and UV disinfection analysis in smart urban water systems

This study introduces a novel method for assessing water quality, employing a cutting-edge sensor system integrated with artificial intelligence (AI) technologies. Addressing the global challenge of water scarcity and pollution, the research focuses on the innovative use of spectroscopic analysis for real-time water quality monitoring. The study evaluates the effectiveness of this system in distinguishing between clean, contaminated, and UV-disinfected water samples, highlighting its precision in detecting variations in water quality. Central to the research is the deployment of advanced machine learning algorithms, including Random Forest, Support Vector Machines (SVM), and Neural Networks, to process and classify spectral data. These models demonstrate remarkable accuracy in real-time classification, underscoring the synergy between AI and environmental science in addressing critical public health issues. Significantly, the study showcases the potential of UV disinfection in water treatment, as evidenced by the spectral changes observed in disinfected water samples. This aspect of the research emphasizes the role of spectral analysis in verifying the efficacy of water treatment processes. Overall, this study paves the way for more sophisticated and accessible water quality monitoring systems, offering a promising solution to one of the most pressing environmental challenges. The integration of AI and spectral analysis in this research offers a breakthrough in ensuring a safe water supply and effective water resource management. This study utilizes advanced machine learning algorithms, including Random Forest, Support Vector Machines (SVM), and Neural Networks, for water quality assessment. These models process and classify spectral data with high precision, highlighting variations in water quality.

An energy efficiency and cost analysis of utilizing high-intensity profile UVC systems on air handling unit under cool-humid climate

The feasibility of the ultraviolet germicidal irradiation (UVGI) application has been proven over the past few decades, especially in disinfection performances; however, a small number of studies were found that explored the energy efficiency improvement and cost savings of real buildings by implementing the UVC systems on cooling coils. The goal of this study is to verify the energy efficiency improvements and cost savings of AHU in a real building environment by removing biofilms on the cooling coil surfaces with the UVC irradiation techniques that can provide higher lamp output (300 μW/cm2) as well as higher intensity levels (1000–4000 μW/cm2) on the cooling coil surfaces. A series of experiments were conducted in an AHU in a medical center located in Michigan, US, to estimate energy efficiency improvement of cooling coils, chiller, and fan with UVC application. The results show that after 7 weeks of UVC operation increased coil overall enthalpy-based thermal conductance by 15.62 %, achieved chiller-side energy savings by up to 28.2 %, reduced pump energy by 32.1 %, and fan energy by 17.7 %. A return on investment (ROI) based only on energy savings is estimated to be 43 % and has a payback period of 2.32 years. When the labor, chemical, and water-saving costs for coil cleaning were included, the ROI was increased to 49 % and reduced the payback period to 2.04 years. When it comes to UVC's disinfection performances, six pathogens showed a more than 99 % removal rate while Klebsiella pneumoniae and Clostridium difficile showed a relatively lower 94 % removal rate.

Breathing Clean Air: Navigating Indoor Air Purification Techniques and Finding the Ideal Solution.

The prevalence of airborne pathogens in indoor environments presents significant health risks due to prolonged human occupancy. This review addresses diverse air purification systems to combat airborne pathogens and the factors influencing their efficacy. Indoor aerosols, including bioaerosols, harbor biological contaminants from respiratory emissions, highlighting the need for efficient air disinfection strategies. The COVID-19 pandemic has emphasized the dangers of airborne transmission, highlighting the importance of comprehending how pathogens spread indoors. Various pathogens, from viruses like SARS-CoV-2 to bacteria like Mycobacterium (My) tuberculosis, exploit unique respiratory microenvironments for transmission, necessitating targeted air purification solutions. Air disinfection methods encompass strategies to reduce aerosol concentration and inactivate viable bioaerosols. Techniques like ultraviolet germicidal irradiation (UVGI), photocatalytic oxidation (PCO), filters, and unipolar ion emission are explored for their specific roles in mitigating airborne pathogens. This review examines air purification systems, detailing their operational principles, advantages, and limitations. Moreover, it elucidates key factors influencing system performance. In conclusion, this review aims to provide practical knowledge to professionals involved in indoor air quality management, enabling informed decisions for deploying efficient air purification strategies to safeguard public health in indoor environments.

UV electromagnetic irradiation sensing by GQDs sensitized ZnO/GaN heterostructure for wearable dosimetry

Sensing of Ultraviolet (UV) Electromagnetic Irradiations (EIs) for wearable dosimetry is promulgated universally by reserving their place in precise calibration for the controlled exposure of UV-EIs for the betterment of humankind. In other words, the controlled exposure of incident optical power density (OPD) of UV-EIs found advantageous and numerous noble healthcare applications such as beta-endorphin molecule (provide feel-good factor to the brain) level augmentation, adequate vitamin D (physical strength) level formation, in skin treatment like eczema and dermatitis, sensing important biomolecules like Uric Acid (responsible for critical disease related with kidney and heart). Moreover, the controlled exposure of OPDs also significantly impacts UV disinfection technologies, which provide a defensive shield against critical respiratory syndrome coronavirus 2 (SARS-CoV-2), which belongs to the COVID-19 pandemic. Therefore, by understanding the importance of limited exposure to these vital UV-EIs, the present study showcased the GQDs-sensitized ZnO/GaN heterostructured UV sensor utilized to explore the impact of UV-EIs OPDs on their performance. This study helps to develop and utilize the UV sensor-based wearable dosimetry for in-house diagnostics of critical healthcare parameters. This report also divulged an interesting core mechanism (band bending, tunneling through narrowed hole injection under increased negative bias) involved in affecting the performance of the UV-EIs sensor by a function of growing OPDs with the help of a suitable band diagram. The impact of increasing OPDs on fabricated UV-EIs sensors can be well understood by the fact that, by varying the OPDs up to ∼550%, the Gain (G), responsivity (R), external quantum efficiency (EQE) and noise equivalent power (NEP) significantly increases up to (156.7 to 332.4) ∼300%, (118 A W−1 to 3200 A W−1) 2700%, (∼870% to 12 × 103%) 1400% and (1.3 pWHz−1/2 to 50 fWHz−1/2) 10,000% respectively at an applied bias of −6 V. Furthermore, the time-correlated transient photoresponse is also dramatically improved with increasing OPDs, wherein the increment in rise and decay time is estimated as (159 ms to 7.86 ms) ∼2000% and (68.7 ms to 12.4 ms) ∼500%, respectively.