Ultraviolet Disinfection System Research Articles

Financial assessment of groundwater and rainwater treatments for school clean water supply

The global primary school population has experienced a significant increase, in line with the pursuit of Sustainable Development Goal number 4 which strives to ensure inclusive, equitable, and high-quality education, fostering lifelong learning opportunities for all. However, not all schools, especially in developing countries, have access to a sufficient supply of clean water. For example, a 2021 World Bank study found that almost half (47%) of schools in Indonesia have no access to soap and flowing water, which is critical to disease prevention. In this study, we featured a case study of a school in Indonesia that mainly obtains its clean water supply from pumped underground water and treats it with reverse osmosis technology. This study analyzed the potential financial savings from adding combinations of a rainwater harvesting system, an adsorption–filtration system, an ultraviolet radiation disinfection system, and solar photovoltaics to the existing underground water pumping system in a case study school. We utilize local data encompassing factors such as rainfall intensity, facility investment, operation, and maintenance costs in the evaluation of financial performance for each scenario, employing methods such as net present value (NPV), benefit–cost ratio (BCR), and payback period. The findings indicate that the adoption of constructed scenario 1, incorporating an adsorption filtration system and UV disinfection, yields superior financial outcomes in this study. Scenario 1 results in 167,890 IDR NPV over its 12-year lifespan, 1.10 BCR, and a payback period as short as 2 months. The results from this study provide knowledge about the potential financial gains and technological alternatives for other schools in developing countries without access to a centralized clean water or energy supply.

Dose Distribution Scaling and Validation of Ultraviolet Photoreactors Using Dimensional Analysis.

Ultraviolet (UV) disinfection is commonly applied in the treatment of drinking water and wastewater. The performance of UV disinfection systems is governed by the UV dose distribution delivered to the fluid, which is an intrinsic characteristic of the reactor under a given operating condition. Current design and validation approaches are based on empirical methods that are expensive to apply and provide limited information about the UV photoreactor behavior. To address this issue, a dose distribution scaling method was developed based on dimensional analysis (i.e., application of the Buckingham-π theorem). Three dimensionless groups representing UV dose, reactor geometry, and UV absorption behavior were defined. Using these groups, the approach was applied for the analysis of 15 operating conditions, defined by process variables of volumetric flow rate, UV transmittance, and lamp power. The approach was demonstrated to allow scaling of the dose distribution with these critical, dimensionless variables and yielded close agreement between predictions of disinfection efficacy against MS2 and E. coli based on the scaling approach with conventional CFD-E' modeling results. The approach thus provides a low-cost, rapid method for predicting the performance of UV disinfection systems across a wide range of operating conditions and against essentially any microbial challenge agent.

Disinfection of Phi6, MS2, and Escherichia coli by Natural Sunlight on Healthcare Critical Surfaces.

Ultraviolet (UV) radiation systems, commonly used to disinfect surfaces, drinking water, and air, stem from historical practice to use sunlight to disinfect household items after contagious illness. Currently, it is still recommended in viral outbreak contexts such as COVID-19, Ebola, and Marburg to expose soft surfaces to sunlight after washing with detergent or disinfecting with chlorine. However, sunlight that reaches the Earth's surface is in the UVA/UVB wavelengths, whereas UV disinfection systems typically rely on biocidal UVC. Our goal was to fill the evidence gap on the efficacy of sunlight disinfection on surface materials common in low-resource healthcare settings by seeding four surfaces (stainless steel, nitrile, tarp, cloth) with three microorganisms (viral surrogate bacteriophages Phi6 and MS2 and Escherichia coli bacteria), with and without soil load, and exposing to three sunlight conditions (full sun, partial sun, cloudy). We conducted 144 tests in triplicate and found: solar radiation averaged 737 W/m2 (SD = 333), 519 W/m2 (SD = 65), and 149 W/m2 (SD = 24) for full sun, partial sun, and cloudy conditions; significantly more surfaces averaged ≥4 log10 reduction value (LRV) for Phi6 than MS2 and E. coli (P < 0.001) after full sun exposure, and no samples achieved ≥4 LRV for partial sun or cloudy conditions. On the basis of our results, we recommend no change to current protocols of disinfecting materials first with a 0.5% chlorine solution then moving to sunlight to dry. Additional field-based research is recommended to understand sunlight disinfection efficacy against pathogenic organisms on healthcare relevant surfaces during actual outbreak contexts.

Improved disinfection performance for 280 nm LEDs over 254 nm low-pressure UV lamps in community wastewater

Ultraviolet (UV) disinfection has been incorporated into both drinking water and wastewater treatment processes for several decades; however, it comes with negative environmental consequences such as high energy demands and the use of mercury. Understanding how to scale and build climate responsive technologies is key in fulfilling the intersection of UN Sustainable Development Goals 6 and 13. One technology that addresses the drawbacks of conventional wastewater UV disinfection systems, while providing a climate responsive solution, is UV light emitting diodes (LEDs). The objective of this study was to compare performance of bench-scale 280 nm UV LEDs to bench-scale low pressure (LP) lamps and full-scale UV treated wastewater samples. Results from the study demonstrated that the UV LED system provides a robust treatment that outperformed LP systems at the bench-scale. A comparison of relative energy consumptions of the UV LED system at 20 mJ cm−2 and LP system at 30 and 40 mJ cm−2 was completed. Based on current projections for wall plug efficiencies (WPE) of UV LED it is expected that the energy consumption of LED reactors will be on par or lower compared to the LP systems by 2025. This study determined that, at a WPE of 20%, the equivalent UV LED system would lead to a 24.6% and 43.4% reduction in power consumption for the 30 and 40 mJ cm−2 scenarios, respectively.

An aluminum-based reflective nanolens array that enhances the effectiveness of a continuous-flow ultraviolet disinfection system for livestock water

Climate change has worsened droughts and floods, and created conditions more likely to lead to pathogen contamination of surface water and groundwater. Thus, there is a growing need to disinfect livestock water. Ultraviolet (UV) irradiation is widely accepted as an appropriate method for disinfecting livestock water, as it does not produce hazardous chemical compounds and kills pathogens. However, UV-based disinfection inevitably consumes electricity, so it is necessary to improve UV disinfection effectiveness. Aluminum-based reflective nanolens arrays that enhanced the effectiveness of a continuous-flow UV water disinfection system were developed using electrochemical and chemical processes, including electropolishing and two-step anodization. A continuous UV disinfection system was custom designed and the parts were produced using a three-dimensional printer. Electropolished aluminum was anodized at 40 and 80 V in 0.3 M oxalic acid, at 120 and 160 V in 1.0 M phosphoric acid, and at 200 and 240 V in 1.5 M citric acid. The average nanolens diameters (D) of the aluminum-based reflective nanolens arrays prepared using 40, 80, 120, 160, 200, and 240 V anodization were 95.44, 160.98, 226.64, 309.90, 296.32, and 339.68 nm, respectively. Simple UV reflection behind irradiated water disinfected Escherichia coli O157:H7 in water more than did the non-reflective control. UV reflection and focusing behind irradiated water using an aluminum-based reflective nanolens array disinfected E. coli O157:H7 more than did simple UV reflection. Such enhancement of the UV disinfection effectiveness was significantly effective when a nanolens array with D 226.64 nm, close to the wavelength of the irradiated UV (254 nm), was used.

Design of UVA Ultraviolet Disinfection System for Nutrient Solution Residual Liquid and Development of Microbial Online Monitoring System

If the nutrient solution used in the hydroponic system is recycled and reused without disinfection, the plant diseases are likely to spread. The current disinfection system still cannot conduct online monitoring of microorganisms at the same time as disinfection. In this paper, a UVA ultraviolet disinfection system and an online microbial monitoring system are proposed, which can conduct online monitoring at the same time as disinfection. This system includes the design of the disinfection system, the microbial online detection system and the microfluidic chip. The practical performance of the disinfection system and the microfluidic chip was verified by means of simulation and experiment. The relationship between the working power (P) of the UVA ultraviolet sterilizer used and its irradiance (Ee) is P = 29.98 Ee. The direct influencing factor of the ultraviolet disinfection rate of the nutrient solution residual liquid was the ultraviolet light irradiation dose. When the power of the ultraviolet lamp (radiation flux) is 30 W, the optimum wavelength is close to 300 nm, and the absorbance value is approximately 0.07. The error between bioluminescence detection and laboratory culture detection error is 0.002. The disinfection method and microfluidic chip proposed in this paper can be used in a greenhouse hydroponic system to reduce the impact of harmful microorganisms in the nutrient solution return on plants, and improve the effect of the return solution.

Ultraviolet disinfection of water in recirculating aquaculture system: a case study at sturgeon caviar fish farm

In this report, we present a practical example of ultraviolet (UV) water disinfection in an aquaculture facility for sturgeon caviar production. Among the methods of water disinfection in recirculating aquaculture systems, the technical approaches using ozonation or ultraviolet radiation in combination with other methods are the most effective. However, improper use of ozonation can result in excessive ozone concentrations that can cause serious harm to fish and be harmful to the environment and personnel. Therefore, we describe an example of a reagent-free ultraviolet water disinfection system. Preliminary results show that filtration followed by ultraviolet irradiation inactivates microorganisms in fish tank water. Total microbial count, total coliform bacteria, and E. coli (CFU/m3) did not exceed the permissible values. The described UV system provides an irradiance of 180 W/m2. For a pool with a water volume of 300 m3, bacteriological purity of the water was achieved with 480 W of UV-light.

Comparative Life Cycle Assessment of Water Disinfection Processes Applicable in Low-Income Settings.

Access to safe, sufficient water for health and sanitation is a human right, and the reliable disinfection of water plays a critical role in addressing this need. The environmental impact and sustainability of water disinfection methods will also play a role in overall public health. This study presents an investigation of the environmental life cycle impacts of four ultraviolet disinfection systems utilizing ambient solar radiation directly and indirectly for water disinfection in comparison to chlorination and water delivery for application in low-income settings. Product inspection and existing literature were used to define a life cycle functional unit of 1 m3 of water for each system, which allowed quantification of material use, infrastructure requirements, and life cycle of the original components of each system and those needed to keep them operational for the studied lifespans (1, 5, 10, and 20 years) and scales (30, 100, 500, and 1000 L per day). For all studied cases, chlorine had the lowest impact in all impact categories, but end-user acceptance of chlorine in some settings is low, driving interest in low-impact alternatives. Disinfection based on low-pressure mercury lamps had the next lowest normalized impact in most categories and may represent a viable alternative, particularly for long-term (10+ years), high production (500+ liters per day) scenarios.

Selective Disinfection Based on Directional Ultraviolet Irradiation and Artificial Intelligence

Ultraviolet disinfection has been proven to be effective for surface sanitation. Traditional ultraviolet disinfection systems generate omnidirectional radiation, which introduces safety concerns regarding human exposure. Large scale disinfection must be performed without humans present, which limits the time efficiency of disinfection. We propose and experimentally demonstrate a targeted ultraviolet disinfection system using a combination of robotics, lasers, and deep learning. The system uses a laser-galvo and a camera mounted on a two-axis gimbal running a custom deep learning algorithm. This allows ultraviolet radiation to be applied to any surface in the room where it is mounted, and the algorithm ensures that the laser targets the desired surfaces avoids others such as humans. Both the laser-galvo and the deep learning algorithm were tested for targeted disinfection.

Uncertainty quantification and sensitivity analysis of an ultraviolet water disinfection photo-reactor

In recent years, computational fluid dynamics (CFD) has been utilized as a powerful simulation tool to design and analyze the ultraviolet (UV) disinfection systems. A fact that is ignored in deterministic simulations is that most of industrial problems are associated with inevitable uncertainties in input parameters. In the present study, a non-deterministic CFD simulation of the UV disinfection process using non-intrusive polynomial chaos expansion method is performed to quantify the impact of uncertain input parameters on the performance of an annular photo-reactor. Five input variables with their probability distribution functions are determined as the uncertain inputs to evaluate their effects on the quantities of interest for different working conditions. Besides, the contribution of each uncertain variable is quantified by a sensitivity analysis using the Sobol’ indices method. The results show that the disinfection process of contaminated water with higher UV transmittances and lower flow rates is associated with more uncertainty.

Assessment of indigenous surrogate microorganisms for UV disinfection dose verification

AbstractThis study aimed to isolate waterborne heterotrophic organisms indigenous to water treatment processes with suitable ultraviolet (UV) dose–response profiles for estimation of the UV doses delivered by operational UV disinfection systems. The UV dose–response profiles of two isolated organisms, Flavobacterium succinicans and Sphingopyxis chilensis, were determined. S. chilensis has a UV dose–response with potential for use as an indigenous surrogate for Cryptosporidium inactivation, up to 2.2‐logs in the dose range 2–7 mJ/cm2 of monochromatic UV light at 253.7 nm. F. succinicans was more sensitive and tailing was observed above 4 mJ/cm2 making it unsuitable for UV dose verification above this dose. As a single species in the water samples used in this study, S. chilensis is unlikely to be present in sufficient numbers for routine use as an indigenous surrogate. However, the Sphingomonadaceae family to which it belongs is abundant in various drinking water sources and warrants further investigation.

Studies on ultraviolet C (UVC) radiation intensity of the high performance UVC disinfector using a newly developed UVC radiation sensor

To evaluate the effect of the ultraviolet (UV) disinfection system on controlling microorganisms on the surface of medical devices, it is essential to measure the intensity of UV radiation intensity. However, a sensor that can easily measure it has not yet been developed. Thus, we developed a new sensor that can measure the UVC radiation dose, and conducted a study to clarify the detailed UV dose and effective microbial inactivation conditions by the UVC irradiation device that have been practically used. A UV irradiation sensor consisted of a zinc oxide photoconductive element and multi-logger acquisition software was developed in collaboration with a company. The UV irradiation sensors were installed at several locations in the model hospital room including frequently touched areas, environmental surfaces and blind spots. The UVC radiation intensity was measured simultaneously and continuously at multiple locations. Radiation intensity varied with distance and height even in the effective radiation range of the device, and attenuation was significant in blind spots such as upward direction and shadows. Our results indicated that the effectiveness of UV radiation varies depending on the radiation location.

A Critical Review on Ultraviolet Disinfection Systems against COVID-19 Outbreak: Applicability, Validation, and Safety Considerations.

The global health-threatening crisis from the COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), highlights the scientific and engineering potentials of applying ultraviolet (UV) disinfection technologies for biocontaminated air and surfaces as the major media for disease transmission. Nowadays, various environmental public settings worldwide, from hospitals and health care facilities to shopping malls and airports, are considering implementation of UV disinfection devices for disinfection of frequently touched surfaces and circulating air streams. Moreover, the general public utilizes UV sterilization devices for various surfaces, from doorknobs and keypads to personal protective equipment, or air purification devices with an integrated UV disinfection technology. However, limited understanding of critical UV disinfection aspects can lead to improper use of this promising technology. In this work, fundamentals of UV disinfection phenomena are addressed; furthermore, the essential parameters and protocols to guarantee the efficacy of the UV sterilization process in a human-safe manner are systematically elaborated. In addition, the latest updates from the open literature on UV dose requirements for incremental log removal of SARS-CoV-2 are reviewed remarking the advancements and existing knowledge gaps. This study, along with the provided illustrations, will play an essential role in the design and fabrication of effective, reliable, and safe UV disinfection systems applicable to preventing viral contagion in the current COVID-19 pandemic, as well as potential future epidemics.

Deactivation of SARS-CoV-2 with pulsed-xenon ultraviolet light: Implications for environmental COVID-19 control.

Prolonged survival of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on environmental surfaces and personal protective equipment may lead to these surfaces transmitting this pathogen to others. We sought to determine the effectiveness of a pulsed-xenon ultraviolet (PX-UV) disinfection system in reducing the load of SARS-CoV-2 on hard surfaces and N95 respirators. Chamber slides and N95 respirator material were directly inoculated with SARS-CoV-2 and were exposed to different durations of PX-UV. For hard surfaces, disinfection for 1, 2, and 5 minutes resulted in 3.53 log10, >4.54 log10, and >4.12 log10 reductions in viral load, respectively. For N95 respirators, disinfection for 5 minutes resulted in >4.79 log10 reduction in viral load. PX-UV significantly reduced SARS-CoV-2 on hard surfaces and N95 respirators. With the potential to rapidly disinfectant environmental surfaces and N95 respirators, PX-UV devices are a promising technology to reduce environmental and personal protective equipment bioburden and to enhance both healthcare worker and patient safety by reducing the risk of exposure to SARS-CoV-2.

Wastewater Treatment Plant Upgrades to Ultraviolet Disinfection System

OpflowVolume 46, Issue 8 p. 36-36 Departments Wastewater Treatment Plant Upgrades to Ultraviolet Disinfection System First published: 04 August 2020 https://doi.org/10.1002/opfl.1416Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume46, Issue8August 2020Pages 36-36 RelatedInformation

On-site rainwater harvesting and treatment for drinking water supply: assessment of cost and technical issues.

This study assessed the performance of rainwater-harvesting systems installed for selected public utilities in the northern provinces of Vietnam where rainwater was collected, stored in stainless steel tanks, and treated with a complex filtration unit and Ultraviolet (UV) disinfection system (full system). Results from an operation of over 5years show that the untreated rainwater could not be used directly for drinking purposes as it was contaminated with bacteria (total coliforms TC = 200-300CFU/100ml, Pseudomonas aeruginosa PA = 40-160CFU/100ml), and turbidity = 2-4 NTU. Most of the heavy metals detected were found below the standard limits. Phenol and its derivatives were detected occasionally as higher than the standard value (1μg/L). After treatment, all parameters met the drinking water standards. The capital costs of the rainwater systems were approximately US$200/m3 and US$180/m3 for a full system and simplified system (without complex filtration unit), respectively, while the operation and maintenance (O&M) costs were 3 cents/L and 0.8 cents/L on average for a full system and simplified one, correspondingly.

Disinfection behavior of a UV-treated wastewater system using constructed wetlands and the rate of reactivation of pathogenic microorganisms.

The use of constructed wetlands as a wastewater treatment system is a feasible solution for rural areas. However, these systems do not efficiently eliminate pathogenic microorganisms. Therefore, it is necessary to implement disinfection systems such as ultraviolet (UV) disinfection systems in constructed wetlands. To evaluate the behavior of a UV system, a pilot system of artificial wetlands connected to one such disinfection system was operated. The results show that when the total suspended solids (TSS) of the influent (already treated by the system of constructed wetlands) reached values of 26.7 mg/L, a reduction of 2.03 uLog in fecal coliforms was obtained. However, when the TSS increased to 34.7 mg/L, the reduction was only 0.33 uLog. In addition to the influence of the TSS on the fecal coliform reduction efficiency, there is a direct relationship between the transmittance and the sizes of the particles present in the influent. After UV treatment, the microorganisms showed a peak in photoreactivation of 27.8% at 4 h after irradiation with visible radiation, while under conditions of darkness, no reactivation was observed.

Evoqua buys UK's ATG UV

Evoqua Water Technologies has acquired ATG UV Technology Ltd, a UK manufacturer of ultraviolet (UV) light disinfection systems serving the municipal, marine, food and beverage, oil and gas, aquatics and aquaculture markets.

Development and experimental validation of a mathematical model for the irradiance of in-duct ultraviolet germicidal lamps

An ultraviolet (UV) germicidal lamp installed in a ventilation duct (in-duct) is one of the most effective means for disinfecting pathogens circulated inside ventilation duct. We presented a new mathematical model based on the view factor approach, which was first developed to calculate the irradiance (Ir) of a typical in-duct UV lamp consisting of short and double luminous tubes within a full-scale ventilation duct system. The model predicted both of the emissive irradiance (Ire) of in-duct UV lamp and the diffuse reflection from the ventilation duct wall. Validation experiments were conducted by measuring Ire for 1/4, 1/2 and full UV lamp luminous length in a full-scale ventilation system. The efficacy (η) of the in-duct 1/2 luminous length UV lamp in disinfecting Escherichia coli (E. coli) was also experimentally and numerically studied. The results showed that the predicted Ire matched the measurement data well. The irradiance decreased accordingly as the luminous length of the UV lamp shrank.The disinfection efficacy declined as the air supply velocity increased and the highest measured η was 67.1% for a 1/2 luminous length in-duct UV lamp on E. coli, with 3 m/s air supply velocity. The results suggested that in-duct UV lamp is an efficient way to inactivate the airborne E. coli. The developed model facilitates the prediction of the irradiance including the diffuse reflection and can prompt the application for in-duct UV disinfection systems.

Effectiveness of ultraviolet disinfection in reducing hospital-acquired Clostridium difficile and vancomycin-resistant Enterococcus on a bone marrow transplant unit.

To determine the effectiveness of ultraviolet (UV) environmental disinfection system on rates of hospital-acquired vancomycin-resistant enterococcus (VRE) and Clostridium difficile. Using active surveillance and an interrupted time-series design, hospital-acquired acquisition of VRE and C. difficile on a bone marrow transplant (BMT) unit were examined before and after implementation of terminal disinfection with UV on all rooms regardless of isolation status of patients. The main outcomes were hospital-based acquisition measured through (1) active surveillance: admission, weekly, and discharge screening for VRE and toxigenic C. difficile (TCD) and (2) clinical surveillance: incidence of VRE and CDI on the unit. Bone marrow transplant unit at a tertiary-care cancer center.ParticipantsStem cell transplant (SCT) recipients.InterventionTerminal disinfection of all rooms with UV regardless of isolation status of patients. During the 20-month study period, 579 patients had 704 admissions to the BMT unit, and 2,160 surveillance tests were performed. No change in level or trend in the incidence of VRE (trend incidence rate ratio [IRR], 0.96; 95% confidence interval [CI], 0.81-1.14; level IRR, 1.34; 95% CI, 0.37-1.18) or C. difficile (trend IRR, 1.08; 95% CI, 0.89-1.31; level IRR, 0.51; 95% CI, 0.13-2.11) was observed after the intervention. Utilization of UV disinfection to supplement routine terminal cleaning of rooms was not effective in reducing hospital-acquired VRE and C. difficile among SCT recipients.