Impact of COVID-19 and viruses on UV disinfection design dose

While virus effluent limits are yet to be promulgated through wastewater discharge permits, consideration for regulations and their resulting impact on current and future wastewater disinfection systems have long preceded the SARS-CoV-2 pandemic. Further, the pandemic has prompted significant pubic interested in the presence and threat of pathogens in waterways. The wastewater industry has proven its adaptability through the implementation of influent monitoring to predict coronavirus outbreaks and the SARS-CoV-2 pandemic has ushered in a new perspective on both virus monitoring and potential regulation. As a result, disinfection projects occurring during the pandemic have been privy to the influence of virus-based control considerations, irrespective of official discharge regulations impacting the UV design dose for secondary effluent applications. Copyright © 2022 Water Environment Federation.

Automatic Environment Protection Using Mixed Signal Processor for Covid-19

Now a days, the merciless covid-19 is threatening the world in everywhere. And, people are instructed to protect themselves from the virus infections. So, our proposed work will monitor the area around the person with the help of multiprocessor. In this method, particular area's temperature will be monitored by the advanced multiprocessor and the moisture level of the room around the person checked/ verified. And, spraying sanitizer will sanitize automatically, if it is necessary. Moreover, this system reduces the man power and protects the environment from the affects of covid-19. With the use of MSP, we can monitor the temperature and clean up mechanism will run automatically. From this method, we will permit the secured and sanitized people into the crowd places such as stock market, shops and stations. The vital recognition of this method is that fully automated procedure. Hence, it will replace physical labor and save time and also control the virus from spreading one to one another. © 2022 IEEE.

Verifiable Surface Disinfection Using Ultraviolet Light with a Mobile Manipulation Robot †

Robots are being increasingly used in the fight against highly-infectious diseases such as the Novel Coronavirus (SARS-CoV-2). By using robots in place of human health care workers in disinfection tasks, we can reduce the exposure of these workers to the virus and, as a result, often dramatically reduce their risk of infection. Since healthcare workers are often disproportionately affected by large-scale infectious disease outbreaks, this risk reduction can profoundly affect our ability to fight these outbreaks. Many robots currently available for disinfection, however, are little more than mobile platforms for ultraviolet lights, do not allow fine-grained control over how the disinfection is performed, and do not allow verification that it was done as the human supervisor intended. In this paper, we present a semi-autonomous system, originally designed for the disinfection of surfaces in the context of Ebola Virus Disease (EVD) that allows a human supervisor to direct an autonomous robot to disinfect contaminated surfaces to a desired level, and to subsequently verify that this disinfection has taken place. We describe the overall system, the user interface, how our calibration and modeling allows for reliable disinfection, and offer directions for future work to address open space disinfection tasks. © 2022 by the authors.

UV Disinfection Robots: A Review.

The novel coronavirus (COVID-19) pandemic has completely changed our lives and how we interact with the world. The pandemic has brought about a pressing need to have effective disinfection practices that can be incorporated into daily life. They are needed to limit the spread of infections through surfaces and air, particularly in public settings. Most of the current methods utilize chemical disinfectants, which can be laborious and time-consuming. Ultraviolet (UV) irradiation is a proven and powerful means of disinfection. There has been a rising interest in the implementation of UV disinfection robots by various public institutions, such as hospitals, long-term care homes, airports, and shopping malls. The use of UV-based disinfection robots could make the disinfection process faster and more efficient. The objective of this review is to equip readers with the necessary background on UV disinfection and provide relevant discussion on various aspects of UV robots.

Can Autonomous UV Disinfection Robots Sterilize a Room? A Review

The coronavirus disease 2019 pandemic has forced us to improve hygiene. Sterilizers have been widely used in public and private homes. Ultraviolet (UV) robots with different designs, biological interactions, and features have been widely used as sterilizers. The dose issued is only based on theoretical calculations under optimal conditions without considering other environmental factors. This ideal condition is unsuitable to apply in real conditions. Factors such as room temperature and room airflow could affect the effectiveness of UV sterilizers. This review aims to propose an ideal design for UV sterilizer robot by adding a feedback system to minimize external disturbances. The development of UV robots is necessary for future design improvements to be effective and efficient. © 2022 UPM Press. All rights reserved.

Evaluation of an Air Cleaning Device Equipped with Filtration and UV: Comparison of Removal Efficiency on Particulate Matter and Viable Airborne Bacteria in the Inlet and Treated Air.

Since the COVID-19 pandemic, improving indoor air quality (IAQ) has become vital for the public as COVID-19 and other infectious diseases can transmit via inhalable aerosols. Air cleaning devices with filtration and targeted pollutant treatment capabilities can help improve IAQ. However, only a few filtration/UV devices have been formally tested for their effectiveness, and little data is publicly available and UV doses comparable. In this research, we upgraded a particulate matter (PM) air filtration prototype by adding UV-C (germicidal) light. We developed realistic UV dose metrics for fast-moving air and selected performance scenarios to quantify the mitigation effect on viable airborne bacteria and PM. The targeted PM included total suspended particulate (TSP) and a coarse-to-fine range sized at PM10, PM4, PM2.5, and PM1. The PM and viable airborne bacteria concentrations were compared between the inlet and outlet of the prototype at 0.5 and 1.0 m3/s (low and high) air flow modes. The upgraded prototype inactivated nearly 100% of viable airborne bacteria and removed up to 97% of TSP, 91% of PM10, 87% of PM4, 87% of PM2.5, and 88% of PM1. The performance in the low flow rate mode was generally better than in the high flow rate mode. The combination of filtration and UV-C treatment provided 'double-barrier' assurance for air purification and lowered the risk of spreading infectious micro-organisms.

Systematic review for low-cost and automatic packaging machine with UV disinfection applied to food industry

This paper evaluates the integration of the UV ray applied to disinfection in food industry with an automatic packaging machine, instead of traditional methods. This systematic review allows to evaluate the most appropriate solution to the selection of the automatic process and devices involved, in order to reduce the bacterial and virus with UV treatment by a schematic development and its verification through modeling and simulation software. The results obtained demonstrate the ability to control the intensity of UV rays emitted by an OSRAM TYPE UVC lamp with a range between 200-280 nm. It is appropriated for a complete disinfection of food products. And also, that the Proportional-Integrative Control system regulates the set-point in a rise time of 24 ms, settlement of 87.8 ms and overshoot of 13.8%. Our findings are the the control time, efficiency, accuracy and uniformity to be integrated into the packaging process;compared to thermal disinfection methods;with a settlement error of ± 1.48 and its ability to counteract Covid-19. © 2022 IEEE.

Implication of cell culture methods and biases on UV inactivation of viruses.

Inactivation of human respiratory viruses in air and on surfaces is important to control their spread. Exposure to germicidal ultraviolet (UV-C) light damages viral nucleic acid rendering them non-infectious. Most of the recent viral inactivation studies have not considered potential artifacts caused by interactions between UV-C light and culture media used to suspend and deposit virus on surfaces. We show that the reactive oxygen and nitrogen species (ROS and RNS) form when commonly used virus culture media is exposed to 265 nm irradiation from light emitting diodes (LEDs) at UV-C doses (4 or 40 mJ/cm2) commonly considered to achieve multiple log-inactivation of virus. Surface viral inactivation values were enhanced from 0.49 to 2.92 log10 of viruses in DMEM, EMEM or EMEM-F as compared to absence of culture media (only suspended in Tris-buffer). The mechanisms responsible for the enhanced surface inactivate is hypothesized to involve photo-activation of vitamins and dyes present in the culture media, deposited with the virus on surfaces to be disinfected, which produce ROS and RNS. Given the rapidly growing research and commercial markets for UV-C disinfecting devices, there is a need to establish surface disinfecting protocols that avoid viral inactivation enhancement artifacts associated with selection and use of common cell culture media in the presence of UV-C light. This study addresses this weak link in the literature and highlights that inadequate selection of virus suspension media may cause a bias (i.e., over-estimation) for the UV-C dosages required for virus inactivation on surfaces.

A simple multiparametric analysis to guide, compare and optimize the design of "lensless" LED illuminators

LED lighting is becoming increasingly pervasive in many areas ranging from ambient lighting, up to applications such as microscope illumination, UV-LED curing and, UV disinfection for air, surfaces, and water. Irradiance uniformity is often a fundamental parameter for guiding the design, comparison, and optimization of the illuminator. To this end, many methods and procedures have been proposed to guide the arrangement of the LED sources, as well as to guide the design of ad-hoc lenses. Nevertheless, there are many applications in which it is important to be able to consider other aspects as well as the uniformity of the irradiance. For this purpose, we propose both a method that allows calculating the irradiance generated by the used LED sources and, performance indicators for guiding the design and comparing different optical layouts.

Far-UVC Disinfection with Robotic Mobile Manipulator

The COVID-19 pandemic has demonstrated the need for a more effective and efficient disinfection approach to combat infectious diseases. Ultraviolet germicidal irradiation (UVGI) is a proven mean for disinfection and sterilization and has been integrated into handheld devices and autonomous mobile robots. Existing UVGI robots which are commonly equipped with uncovered lamps that emit intense ultraviolet radiation suffer from: inability to be used in human presence, shadowing of objects, and long disinfection time. These robots also have a high operational cost. This paper introduces a cost effective germicidal system that utilizes UVGI to disinfect pathogens, such as viruses, bacteria, and fungi, on high contact surfaces (e.g. doors and tables). This system is composed of a team of 5-DOF mobile manipulators with end-effectors that are equipped with far-UVC excimer lamps. The design of the system is discussed with emphasis on path planning, coverage planning, and scene understanding. Evaluations of the UVGI system using simulations and irradiance models are also included. Please see the project's website for videos and simulations of the robot.1 © 2022 IEEE.

Evaluation of the effectiveness of UV-C dose for photoinactivation of SARS-CoV-2 in contaminated N95 respirator, surgical and cotton fabric masks.

As part of efforts to combat the Covid-19 pandemic and decrease the high transmissibility of the new coronavirus, SARS-CoV-2, effective inactivation strategies, such as UV-C decontamination technologies, can be reliably disseminated and well-studied. The present study investigated the susceptibility of a high viral load of SARS-CoV-2 in filtering facepiece respirators (FFR) N95, surgical mask, cotton fabric mask and N95 straps under three different doses of UV-C, applying both real-time PCR (qPCR) and plaque formation assays to quantify viral load reduction and virus infectivity, respectively. The results show that more than 95% of the amount of SARS-CoV-2 RNA could be reduced after 10 min of UV-C exposure (0.93 J cm-2 per side) in FFR N95 and surgical masks and, after 5 min of UV-C treatment (0.46 J cm-2 per side) in fabric masks. Furthermore, the analysis of viable coronaviruses after these different UV-C treatments demonstrated that the lowest applied dose is sufficient to decontaminate all masks ([Formula: see text] 3-log10 reduction of the infective viral load, > 99.9% reduction). However, for the elastic strap of N95 respirators, a UV-C dose three times greater than that used in masks (1.4 J cm-2 per side) is required. The findings suggest that the complete decontamination of masks can be performed effectively and safely in well-planned protocols for pandemic crises or as strategies to reduce the high consumption and safe disposal of these materials in the environment.

Numerical model of the irradiance field surrounding a UV disinfection robot.

Objective.New technologies, including robots comprising germ-killing UV lamps, are increasingly being used to decontaminate hospitals and prevent the spread of COVID-19 and other superbugs. Existing approaches for modelling the irradiance field surrounding mobile UV disinfection robots are limited by their inability to capture the physics of their bespoke geometrical configurations and do not account for reflections. The goal of this research was to extend current models to address these limitations and to subsequently verify these models using empirically collected data.Approach.Two distinct parametric models were developed to describe a multi-lamp robotic UV system and adapted to incorporate the effects of irradiance amplification from the device's reflectors. The first model was derived from electromagnetic wave theory while the second was derived from conservation of energy and diffusion methods. Both models were tuned using data from empirical testing of an existing UV robot, and then validated using an independent set of measurements from the same device.Results.For each parameter, predictions made using the conservation of energy method were found to closely approximate the empirical data, offering more accurate estimates of the 3D irradiance field than the electromagnetic wave theory model.Significance.The versatility of the proposed method ensures that it can be easily adapted to different embodiments, providing a systematic way for researchers to develop accurate numerical models of custom UV robots, which may be used to inform deployment and/or to improve the accuracy of virtual simulation.

UV inactivation of Semliki Forest virus and E. coli bacteria by alternative light sources.

The quick spreading of the SARS-CoV-2 virus, initiating the global pandemic with a significant impact on economics and health, highlighted an urgent need for effective and sustainable restriction mechanisms of pathogenic microorganisms. UV-C radiation, causing inactivation of many viruses and bacteria, is one of the tools for disinfection of different surfaces, liquids, and air; however, mainly mercury 254 nm line is commonly used for it. In this paper, we report our results of the experiments with newly elaborated special type polychromatic non-mercury UV light sources, having spectral lines in the spectral region from 190 nm to 280 nm. Inactivation tests were performed with both Escherichia coli (E.coli) bacteria and Semliki Forest virus (SFV) as a representative of human enveloped RNA viruses. In addition, the effect of prepared lamps on virus samples in liquid and dry form (dried virus-containing solution) was tested. Reduction of 4 log10 of E.coli was obtained after 10 min of irradiation with both thallium-antimony and arsenic high-frequency electrodeless lamps. High reduction results for the arsenic light source demonstrated sensitivity of E. coli to wavelengths below 230 nm, including spectral lines around 200 nm. For the Semliki Forest virus, the thallium-antimony light source showed virus inactivation efficiency with a high virus reduction rate in the range of 3.10 to > 4.99 log10 within 5 min of exposure. Thus, the new thallium-antimony light source showed the most promising disinfection effect in bacteria and viruses, and arsenic light sources for bacteria inactivation, opening doors for many applications in disinfection systems, including for pathogenic human RNA viruses.

An IoT Approach for Monitoring UV Disinfection Robots

The use of ultraviolet germicidal irradiation (UVGI) technology as a means of disinfecting hospitals and other frontline settings has increased significantly in the wake of the COVID-19 pandemic. Although the science of UVGI is well established, it can be difficult to determine in practice if sufficient levels of UVC has been irradiated to kill the target microbes in a room. This research presents the development of a low-cost wireless UVC sensor that can be used to systematically track the UV irradiation dose on target surfaces during a UV disinfection procedure. We present key elements of the design of this device, which included a custom PCB, enclosure, operating software, and graphical user interface. The applicability of the system was assessed through an experiment where the devices were placed at 12 locations in a CT scan treatment room that was subject to a UVGI disinfection procedure using an autonomous UV robot. Over the course of three cleaning sessions, each lasting approximately 10 minutes, it was found that each site location received an average UVC dose of 13mJ/cm2, which is more than published D90 values for SARS-Cov-2, influenza, and a number of known pathogens that are commonly found in hospital settings. This study provides early validation of the potential effectiveness of low-power wireless UV level monitoring technology, which may form part of future distributed room sensing networks or as part of smart wearable devices carried by relevant hospital staff. © 2021 IEEE.

A UV-LED module that is highly effective at inactivating human coronaviruses and HIV-1.

Ultraviolet (UV) light has previously been established as useful method of disinfection, with demonstrated efficacy to inactivate a broad range of microorganisms. The advent of ultraviolet light-emitting diodes provides advantages in ease of disinfection, in that there can be delivery of germicidal UV with the same light unit that delivers standard white light to illuminate a room. Herein we demonstrate the efficacy and feasibility of ultraviolet light-emitting diodes as a means of decontamination by inactivating two distinct virus models, human coronavirus 229E and human immunodeficiency virus. Importantly, the same dose of ultraviolet light that inactivated human viruses also elicited complete inactivation of ultraviolet-resistant bacterial spores (Bacillus pumilus), a gold standard for demonstrating ultraviolet-mediated disinfection. This work demonstrates that seconds of ultraviolet light-emitting diodes (UV-LED) exposure can inactivate viruses and bacteria, highlighting that UV-LED could be a useful and practical tool for broad sanitization of public spaces.

Focused multivector ultraviolet (FMUV) technology rapidly eradicates SARS-CoV-2 in-vitro: Implications for hospital disinfection of COVID-19 environments.

Focused Multivector Ultraviolet technology rapidly killed the SARS-CoV-2 coronavirus in-vitro. Plates were inoculated with a mean of greater than 106 plaque forming units of USA-WA1 Washington index patient strain of SARS-CoV-2 and exposed to ultraviolet, resulting in mean reductions of 99.99% within 30 seconds, 99.999% within 60 seconds, and 99.9999% within 90 seconds. These results support the effectiveness of Focused Multivector Ultraviolet technology for SARS-CoV-2 disinfection.

Handheld Multispectral Fluorescence Imaging System to Detect and Disinfect Surface Contamination.

Contamination inspection is an ongoing concern for food distributors, restaurant owners, caterers, and others who handle food. Food contamination must be prevented, and zero tolerance legal requirements and damage to the reputation of institutions or restaurants can be very costly. This paper introduces a new handheld fluorescence-based imaging system that can rapidly detect, disinfect, and document invisible organic residues and biofilms which may host pathogens. The contamination, sanitization inspection, and disinfection (CSI-D) system uses light at two fluorescence excitation wavelengths, ultraviolet C (UVC) at 275 nm and violet at 405 nm, for the detection of organic residues, including saliva and respiratory droplets. The 275 nm light is also utilized to disinfect pathogens commonly found within the contaminated residues. Efficacy testing of the neutralizing effects of the ultraviolet light was conducted for Aspergillus fumigatus, Streptococcus pneumoniae, and the influenza A virus (a fungus, a bacterium, and a virus, respectively, each commonly found in saliva and respiratory droplets). After the exposure to UVC light from the CSI-D, all three pathogens experienced deactivation (> 99.99%) in under ten seconds. Up to five-log reductions have also been shown within 10 s of UVC irradiation from the CSI-D system.

UV Inactivation of SARS-CoV-2 across the UVC Spectrum: KrCl* Excimer, Mercury-Vapor, and Light-Emitting-Diode (LED) Sources.

Effective disinfection technology to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can help reduce viral transmission during the ongoing COVID-19 global pandemic and in the future. UV devices emitting UVC irradiation (200 to 280 nm) have proven to be effective for virus disinfection, but limited information is available for SARS-CoV-2 due to the safety requirements of testing, which is limited to biosafety level 3 (BSL3) laboratories. In this study, inactivation of SARS-CoV-2 in thin-film buffered aqueous solution (pH 7.4) was determined across UVC irradiation wavelengths of 222 to 282 nm from krypton chloride (KrCl*) excimers, a low-pressure mercury-vapor lamp, and two UVC light-emitting diodes. Our results show that all tested UVC devices can effectively inactivate SARS-CoV-2, among which the KrCl* excimer had the best disinfection performance (i.e., highest inactivation rate). The inactivation rate constants of SARS-CoV-2 across wavelengths are similar to those for murine hepatitis virus (MHV) from our previous investigation, suggesting that MHV can serve as a reliable surrogate of SARS-CoV-2 with a lower BSL requirement (BSL2) during UV disinfection tests. This study provides fundamental information on UVC's action on SARS-CoV-2 and guidance for achieving reliable disinfection performance with UVC devices. IMPORTANCE UV light is an effective tool to help stem the spread of respiratory viruses and protect public health in commercial, public, transportation, and health care settings. For effective use of UV, there is a need to determine the efficiency of different UV wavelengths in killing pathogens, specifically SARS-CoV-2, to support efforts to control the ongoing COVID-19 global pandemic and future coronavirus-caused respiratory virus pandemics. We found that SARS-CoV-2 can be inactivated effectively using a broad range of UVC wavelengths, and 222 nm provided the best disinfection performance. Interestingly, 222-nm irradiation has been found to be safe for human exposure up to thresholds that are beyond those effective for inactivating viruses. Therefore, applying UV light from KrCl* excimers in public spaces can effectively help reduce viral aerosol or surface-based transmissions.

Kinetics and Monte Carlo simulation of UV disinfection of B. subtilis spores and SARS-CoV-2 in dried saliva droplets.

Surfaces can be contaminated by droplets produced through coughing or sneezing. In this exploratory work, the UV disinfection results of Bacillus subtilis spores in dried saliva droplets were fitted to a three-parameter kinetic model (R2 ≥ 0.97). This model has a disinfection rate constant for single organisms and a smaller one for aggregates found in droplets. The fraction of organisms found in aggregates (ß) could account for the effects of different-sized droplets in the experimental work. Since a wide spectrum of droplet sizes can be produced, and some of the rate constants were uncertain, Monte Carlo simulation was used to estimate the UV inactivation performance in dried saliva droplets in a variety of conditions. Using conservative distribution for ß, the model was applied to the UV disinfection of SARS-CoV-2 in dried saliva droplets. It was shown that a one-log reduction of SARS-CoV-2 was very likely (p>99.9%) and a two-log reduction was probable (p=75%) at a dose of 60 mJ/cm2. Aggregates tend to be variable and limit the log reductions that can be achieved at high UV doses.

Effectiveness of solar water disinfection in the era of COVID-19 (SARS-CoV-2) pandemic for contaminated water/wastewater treatment considering UV effect and temperature.

Long is the way and hard, that out of COVID-19 leads up to light. The virus is highly contagious and spread rapidly and the number of infections increases exponentially. The colossal number of infections and presence of the novel coronavirus RNA in human wastes (e.g. Excreta/urine) even after the patients recovered and the RT-PCR tests were negative, results in massive load of the viral in water environments. Numerous studies reported the presence of SARS-CoV-2 in wastewater samples. The risk of contaminating water bodies in the regions which suffer from the lack of proper sanitation system and wastewater treatment plants (mostly in developing countries) is higher. Since solar water disinfection (SODIS) is usually used by people in developing countries, there is a concern about using this method during the pandemic. Because the SARS-CoV-2 can be eliminated by high temperature (>56 °C) and UVC wavelength (100-280 nm) while SODIS systems mainly work at lower temperature (<45 °C) and use the available UVA (315-400 nm). Thus, during a situation like the ongoing pandemic using SODIS method for wastewater treatment (or providing drinking water) is not a reliable method. It should be reminded that the main aim of the present study is not just to give insights about the possibilities and risks of using SODIS during the ongoing pandemic but it has broader prospect for any future outbreak/pandemic that results in biological contamination of water bodies. Nevertheless, some experimental studies seem to be necessary by all researchers under conditions similar to developing countries.