Waterborne Viruses Research Articles

Exploring waterborne viruses in groundwater: Quantification and Virome characterization via passive sampling and targeted enrichment sequencing

Aquifers, which provide drinking water for nearly half the world's population, face significant challenges from microbial contamination, particularly from waterborne viruses such as human adenovirus (HAdV), norovirus (NoV) and enterovirus (EV). This study, conducted as part of the UPWATER project, investigates the sources of urban groundwater contamination using viral passive sampling (VPS) and target enrichment sequencing (TES). We assessed the abundance of eight viral pathogens (HAdV, EV, NoV genogroup I and II, rotavirus, influenza A virus, hepatitis E virus and SARS-CoV-2) and investigated the virome diversity of groundwater in the aquifer of the Besòs River Delta in Catalonia. Over a period of 7 months, we collected 114 samples from the aquifer using nylon and nitrocellulose membranes to adsorb viruses over a 10-day period. Human faecal contamination was detected in nearly 50 % of the groundwater samples, with mean HAdV total counts ranging from 1.23E+02 to 3.66E+03 GC, and occasional detections of EV and NoV GI and GII. In addition, deep sequencing revealed a diverse virome in the aquifer, with detection of human pathogens, including adenovirus, astrovirus, calicivirus, enterovirus, herpesvirus, papillomavirus and rotavirus. Time-integrated sampling using VPS increases the likelihood of virus detection and, when combined with TES, can provide a deeper understanding of virus prevalence in this important water compartment. This approach is expected to streamline long-term monitoring efforts and enable small communities or water managers with limited resources to effectively manage their groundwater reservoirs.

Comparative Removal of Poliovirus, Rotavirus SA11 and MS2 Coliphage by Point-of-Use Devices used to Treat Drinking Water and Water Disinfectants: A Review.

Test protocols have been developed to test water treatment devices/systems for use for treating drinking water that are used at the individual and home level to ensure the removal of waterborne viruses. Current test procedures call for the use of poliovirus type 1 and/or rotavirus SA11. Recently we suggested that selected coliphages could be used as surrogates for poliovirus for testing of point-of-use (POU) water treatment devices, however, rotavirus was not used in those studies. The purpose of this review was to compare studies of POU devices which were tested with poliovirus type 1, simian rotavirus SA11 and coliphage MS2 to determine if the behavior of rotavirus SA11 was significantly different. In addition, an attempt was made to compare the relative resistance of these viruses by various disinfectants used to treat drinking water. In all cases SA11 was removed to an equal or greater degree than poliovirus. SA11 was found to be less resistant to halogens, although one study found it to be more resistance to chloramines than poliovirus and MS2. Based on this review, use of coliphages for testing POU devices appear justified. Additionally, data on chloramines for these viruses would be useful to determine if rotavirus is more resistant than poliovirus and MS2.

Characterization of low-pressure gaseous plasma radiation and its usage for inactivation of waterborne viruses

Water disinfection is a critical treatment step for removing harmful organisms from contaminated water sources. Vacuum ultra-violet (V-UV) radiation, generated by a low-pressure gaseous plasma discharge, consists of photons with high enough energy to break molecular bonds. In this work, we constructed and characterized a low-pressure capacitively coupled gaseous plasma and used it as a V-UV radiation source to inactivate MS2 bacteriophage, a surrogate for human enteric viruses. The treatment system allows for variation of gas composition inside the sample chamber and the modulation of V-UV radiation intensity. Both were used to separate the actual germicidal contribution of V-UV radiation from producing germicidal species by using virus inactivation to determine efficiency. OH* radical production was determined through the terephthalic acid chemical probe, which showed that when air was present in the sample chamber, it resulted in the highest OH* production and the best inactivation of MS2. Furthermore, we showcase that the OH* production rate was wavelength dependent and that ozone, generated by plasma treatment in the gas phase, leads to hydroxy terephthalic acid degradation, allowing us to determine better the actual OH* production rate with different treatment regimes. Lastly, by adding an OH* scavenger to the liquid, we were able to elucidate it as the primary inactivation agent in this setup while also providing evidence of its production in the bulk liquid by the transport and subsequent decomposition of the longer-lasting ozone molecule. This study demonstrates, for the first time, the applicability of low-pressure plasma radiation as a water treatment method.

Environmental virology linked to waterborne diseases and foodborne pathogens: Human and animal food viruses

Foodborne illnesses constitute a serious global one health issue. The transmission of foodborne viruses can occur due to inadequate hygiene of food, lack of basic sanitation, poor personal hygiene and consumption of raw or undercooked food. This study aims overview about environmental virology linked to waterborne diseases and foodborne pathogens in human and animal food viruses. Thus, epidemiological studies have proposed some emerging pathogens as possible transmitters of contaminated water ingestion based on biochemical properties and viral structures such as: Picornaviridae (polioviruses, enteroviruses, coxsakiviruses, hepatitis A viruses and echoviruses), Adenoviridae (adenoviruses), Caliciviridae (noroviruses, caliciviruses, astroviruses), and Reoviridae (reoviruses and rotaviruses). These viruses can cause gastrointestinal, liver and central nervous system disorders. In controlling foodborne infections, accurately identifying sources of contamination is a significant challenge, given the complexity of the food production chain. The lack of adequate monitoring and neglect of good health practices contribute to the spread of these infections. Large-scale immunization has contributed to the reduction of enteric outbreaks and eradication of cases in many regions of the world as a prevention of hepatitis A and poliomyelitis. However, challenges such as the lack of effectiveness in inspecting viruses in food increase the risk of outbreaks and epidemics, with emphasis on Noroviruses as the main causes of these infections today. Investment in vaccine research and development has been a fundamental strategy to reduce these statistics, especially in vulnerable groups. Moreover, the implementation molecular-based tools and wastewater-based epidemiology studies to high-throughput for aquatic biomonitoring should be up to date to avoid the risk and impact on public health and aquatic environments. Novel perspectives to control of waterborne viruses has been introduced in continuous surveillance programs for ecosystems monitoring.

Global investigation of the presence of adenovirus in different types of water resources: a systematic review.

Waterborne viruses such as adenoviruses cause major health problems in the world. Human adenoviruses are the second leading cause of childhood gastroenteritis worldwide. In recent years, the presence of the virus in aquatic resources has been shown in several studies. In this paper, the global presence of adenovirus in different types of water resources are reviewed through studying several surveys conducted in different countries worldwide. We designed one search study to collect the maximum number of related articles to this subject in international databases search engine via relevant keywords. After reviewing the articles, the most relevant ones were selected, and after classification and extracting the required information, they were reported in the tables presented in this study. In general, it was found that the highest rate of the presence of adenoviruses has been reported in sewage water, inlet, and outlet of the treatment plant while the lowest rate of the presence of adenovirus in the dam water. These findings demonstrate that treatment plant system has weakness in removing the adenovirus and are strongly recommended for treatment plants to use new and better protocols to remove this virus. In addition, appropriate diagnostic methods that combines molecular biological technique with infectivity assay should be implemented for detection of adenoviruses in water resources.

One-Year Investigation of Hepatitis A Virus and Rotavirus in Two Waste Water Treatment Plants in Egypt

Background: Waterborne enteric viruses are evolving source of disease outbreaks and represent a major threat to global public health. The repetitive assessment of water environments is necessary to manage enteric virus-mediated fecal infection and the probable emergence of different variants. Methods: Here, we detected human rotavirus and hepatitis A virus circulating in two wastewater treatment plants, for one year in sewage and sludge samples from two largest wastewater treatment plant (El-Gabal El-Asfar and Zenin) located in Egypt. For this purpose, we examine predefined viruses' prevalence in 72 samples (24 raw sewage samples, 24 treated effluent samples, and 24 sludge) collected from August 2022 to July 2023. Viral RNA was extracted and detected by nested Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) in case of HAV and by multiplex semi nested RT-PCR In case of rotavirus with the Results: Percentage of detection rate 58.3%, 25% 41.6%, 50%, 16.6%58.6%, 41.6%, 8.3%, 41.6%41.6%, 8.3% and 41.6% for inlet, outlet, sludge in WWTP zenin and WWTP El-Gabal El-Asfar for HAV, RV respectively. Using generic primer result indicated G1P8 was the most common although G2P [4], G1, G2, G3P? G9P [8], G9P [11], G1 P [4] were detected with different percentage. Conclusion: These results demonstrated that HAV and RV still remains in the environment after sewage treatment and could play an important role in maintaining the endemicity of HAV and RV infection. Routine and continuous monitoring of waterborne viruses are most useful approach to understand disease occurrence in communities.

Molecular Docking Analysis for Evaluating the Efficacy of Active Components of Essential Oils against Water-Borne Multi-Virulent Bacteria and Virus

Traditional Indian knowledge of Ayurveda mentions a large number of essential oils that contain many active compounds such as thymol, eugenol and cinnamaldehyde etc. which contemplate nontoxic for human being and have been used mostly in the field of medicine. An application of essential oils comprising antimicrobial activities was recently described in the SWASTIIK technology (Safe Water and Sustainable Technology Initiative from Indian Knowledgebase) in conjunction with cavitation/ intense mixing for drinking water treatment. Further, it is intended to demonstrate the efficacy of SWASTIIK technology to combat multi virulent bacteria and emerging viruses such as Escherichia coli and SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2) respectively with the help of in silico computational tools. Docking study indicated eugenol and thymol were the most effective ligands against the microorganisms, although SARS-CoV-2 performed better with a low binding affinity (-7.2 kcal/mol) than multi-virulent E. coli (-4.5 kcal/mol). SWASTIIK technology for eliminating harmful microorganisms is, therefore, expected to be more effective in combating viruses, including SARS-CoV-2. Further, favorable ADMET results suggest suitability of the active components for further clinical trials study or for possible health benefits of water treated using SWASTIIK technology. In view of lack of human studies, to evaluate the effectiveness and safety of essential oils for direct intake, clinical trials with more well-designed protocols are needed.

Effect of dissolved organic matter on the inactivation of bacteriophage MS2 by graphitic carbon nitride - based photocatalysis

Waterborne pathogenic bacteria and viruses are of great concern to environmental and public health. This study focused on the impact of dissolved organic matter (DOM) on photocatalytic inactivation of bacteriophage MS2 by utilizing a visible-light-responded photocatalyst composed of rGO-supported g-C3N4 (7.5%GCN). The results showed that the inactivation rate of MS2 by 7.5%GCN photocatalysis was 3.20 log at λ > 400 nm and 3.27 log at λ > 305 nm within 120 min. The presence of humic acid (HA) in the water matrix led to a decline in the inactivation rate of 2.19 log at λ > 400 nm and 2.08 log at λ > 305 nm, representing a reduction of 31.56% and 36.4%. During an 8 h inactivation process in ultrapure water using 7.5%GCN photocatalysis under λ > 400 nm, steady-state concentrations of 1O2, •OH, •O2- and H2O2 were measured to be 5.67 × 10-13, 8.56 × 10-7, 1.21 × 10-5 and 7.08 × 10-5 mol/L, respectively; When in presence of HA, the concentrations of ROSs were inhibited except for 1O2. The order of ROS steady-state concentration was found to be H2O2 > •O2-> •OH> 1O2 during 7.5%GCN photocatalysis, both within and without HA. Transmission electron microscopy (TEM) analysis revealed that the distortion in the morphology of MS2, potentially leading to the disclosure of RNA. Furthermore, protein analysis indicated that the protein structure was damaged, resulting in a decrease of approximately 90% in its concentration. This study may shed light on the impact of DOM during solar light-driven photocatalysis, offering a green, environment-friendly, and sustainable water treatment process.

Waterborne Virus Transport and Risk Assessment in Lake Geneva Under Climate Change

AbstractClimate changes influence lake hydrodynamics and radiation levels and thus may affect the fate and transport of waterborne pathogens in lakes. This study examines the impact of climate change on the fate, transport, and associated risks of four waterborne viruses in Lake Geneva. We used a coupled water quality‐microbial risk assessment model to estimate virus concentrations and associated risks to recreational water users for each month in 2019 and 2060. Long‐term hydrodynamic simulations suggested that although the annual hydrodynamic transport pattern of Lake Geneva will remain relatively stable, a 1.9°C increase of lake surface water temperature can be expected, while a slight decrease in lake current velocity may occur. The subsequent effect on the fate and transport of the four enteric viruses was found to vary by time of year. During warmer periods, the increase of virus inactivation due to higher water temperature and stronger solar radiation at the earth's surface will compensate for the additional virus discharge brought about by population growth over the time period considered, whereas during winter the virus concentration near the lake shore and the associated infection probabilities risks are likely to increase due to population growth. Additionally, the current estimation of virus inactivation rate shows significant variability, which has a more substantial effect on enteric virus concentrations in the lake compared with changing climate parameters. Overall, the study suggests that future risks posed by enteric viruses with recreational water users near popular beaches around Lake Geneva will likely remain similar to current risks and accurate estimation of the environmental inactivation of viruses is crucial for predicting the fate of enteric viruses in the aquatic system.

Research Progress on Inactivation of Bacteriophages by Visible-Light Photocatalytic Composite Materials: A Mini Review.

Infectious diseases caused by waterborne viruses have attracted researchers' great attention. To ensure a safe water environment, it is important to advance water treatment and disinfection technology. Photocatalytic technology offers an efficient and practical approach for achieving this goal. This paper reviews the latest studies on visible-light composite catalysts for bacteriophage inactivation, with a main focus on three distinct categories: modified UV materials, direct visible-light materials and carbon-based materials. This review gives an insight into the progress in photocatalytic material development and offers a promising solution for bacteriophage inactivation.

Somatic Coliphages as an Operational Tool to Assess Loss of Bathing Water Quality after Heavy Rain Events

Rapid population growth and coastal development has led to increased fecal contamination of coastal surface waters worldwide, enhancing the potential risk of waterborne human pathogens in bathing areas. More frequent heavy rainfall events, attributed to global warming, have further exacerbated the problem by causing sometimes sewer overflows into recreational waters. As traditional bacterial indicators have limited accuracy for predicting health risks associated with waterborne viruses, the additional use of viral indicators such as coliphages is recommended. In this study, we compared the behavior of bacterial and viral indicators of water quality at 10 Barcelona beaches during three bathing seasons, in dry conditions, and after four rainstorms that caused specific pollution events due to rain runoff with combined sewer overflows (CSO). Levels of all target indicators increased after the rainstorms, but compared to Escherichia coli and intestinal enterococci, somatic coliphages exhibited a slower decline and higher environmental persistence following a rain event. Daily continuous sampling carried out during the days following a rainstorm allowed not only the determination of the decay kinetics of each target indicator but also the day when the water quality recovered the values established in the current European regulation in approximately 2 -3 days after each CSO. These observations indicate that the combined use of bacterial and viral indicators can enhance the surveillance of microbial quality of bathing waters. Moreover, coliphages can swiftly provide insights into transient fecal pollution linked to rainfall episodes, thanks to available analytical techniques that enable same-day recommendations. The management of urban wastewater and recreational water regulations should consistently employ microbial indicators to address rainwater runoff or sewer overflows resulting from heavy rainfall.

The impact of anthropogenic climate change on pediatric viral diseases.

The adverse effects of climate change on human health are unfolding in real time. Environmental fragmentation is amplifying spillover of viruses from wildlife to humans. Increasing temperatures are expanding mosquito and tick habitats, introducing vector-borne viruses into immunologically susceptible populations. More frequent flooding is spreading water-borne viral pathogens, while prolonged droughts reduce regional capacity to prevent and respond to disease outbreaks with adequate water, sanitation, and hygiene resources. Worsening air quality and altered transmission seasons due to an increasingly volatile climate may exacerbate the impacts of respiratory viruses. Furthermore, both extreme weather events and long-term climate variation are causing the destruction of health systems and large-scale migrations, reshaping health care delivery in the face of an evolving global burden of viral disease. Because of their immunological immaturity, differences in physiology (e.g., size), dependence on caregivers, and behavioral traits, children are particularly vulnerable to climate change. This investigation into the unique pediatric viral threats posed by an increasingly inhospitable world elucidates potential avenues of targeted programming and uncovers future research questions to effect equitable, actionable change. IMPACT: A review of the effects of climate change on viral threats to pediatric health, including zoonotic, vector-borne, water-borne, and respiratory viruses, as well as distal threats related to climate-induced migration and health systems. A unique focus on viruses offers a more in-depth look at the effect of climate change on vector competence, viral particle survival, co-morbidities, and host behavior. An examination of children as a particularly vulnerable population provokes programming tailored to their unique set of vulnerabilities and encourages reflection on equitable climate adaptation frameworks.

Analysing the interplay of environmental virology, public health, and sanitation: a comprehensive review from a Kenyan perspective.

This comprehensive review examines the interplay between environmental virology, public health, and sanitation in the unique context of Kenya. The review sheds light on the specific viral threats faced by the country, including waterborne viruses, zoonotic infections, and emerging viral diseases, and their implications for public health. It explores the prevailing public health challenges in Kenya associated with environmental viromics, such as infectious viral diseases, and the rising burden of other infectious particles. The role of sanitation in mitigating viral infections is highlighted, emphasising the importance of clean water supply, proper waste management, and hygienic practises. The review also presents strategies for strengthening environmental virology research in Kenya, including enhancing laboratory capacities and leveraging technological advancements. Furthermore, the policy implications and recommendations derived from the review emphasise the need for multi-sectoral collaboration, evidence-based decision-making, and long-term investments in infrastructure and behaviour change interventions. Implementing these strategies can enhance the understanding of environmental virology, improve public health outcomes, and ensure sustainable sanitation practises in Kenya, ultimately contributing to the well-being of the population and sustainable development.

Data-driven systematic analysis of waterborne viruses and health risks during the wastewater reclamation process

Waterborne viral epidemics are a major threat to public health. Increasing interest in wastewater reclamation highlights the importance of understanding the health risks associated with potential microbial hazards, particularly for reused water in direct contact with humans. This study focused on identifying viral epidemic patterns in municipal wastewater reused for recreational applications based on long-term, spatially explicit global literature data during 2000–2021, and modelled human health risks from multiple exposure pathways using a well-established quantitative microbial risk assessment methodology. Global median viral loads in municipal wastewater ranged from 7.92 × 104 to 1.4 × 106 GC L−1 in the following ascending order: human adenovirus (HAdV), norovirus (NoV) GII, enterovirus (EV), NoV GI, rotavirus (RV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Following secondary or tertiary wastewater treatment, NoV GI, NoV GII, EV, and RV showed a relatively higher and more stable log reduction value with medians all above 0.8 (84%), whereas SARS-CoV-2 and HAdV showed a relatively lower reduction, with medians ranging from 0.33 (53%) to 0.55 (72%). A subsequent disinfection process effectively enhanced viral removal to over 0.89-log (87%). The predicted event probability of virus-related gastrointestinal illness and acute febrile respiratory illnesses in reclaimed recreational water exceeded the World Health Organization recommended recreational risk benchmark (5% and 1.9%, respectively). Overall, our results provided insights on health risks associated with reusing wastewater for recreational purposes and highlighted the need for establishing a regulatory framework ensuring the safety management of reclaimed waters.

Circulation of adenovirus and other viruses in urban drainage channels: an environmental surveillance in Belém, Amazon region, Brazil.

Urban channels in amazon cities are very polluted, with garbage and sewage disposal in these aquatic environments, favoring the high dissemination of waterborne viruses such as human adenovirus (HAdV). The aim of this study was to perform the detection and molecular characterization of adenovirus in urban channels and in a wastewater treatment plant located in a metropolitan city in the Amazon. Additionally, metagenomic analyses were performed to assess viral diversity. Samples were concentrated by organic flocculation, analyzed by quantitative real time PCR (qPCR) and sequenced (Sanger e next generation sequencing). Cell culture was performed to verify the viability of HAdV particles. A total of 104 samples were collected, being the HAdV positivity of 76% (79/104). Among the positive samples, 29.1% (23/79) were characterized as HAdV-F40 (87%, 20/23), HAdV-F41 (8.7%, 2/23), and HAdV-B (4.3%, 1/23). Average precipitation rates ranged from 163 to 614 mm, while the pH ranged from 6.9 to 7.6. Eight positive samples were inoculated into A549 cells and in 4 of these, was observed changes in the structure of the cell monolayer, alteration in the structure of the cell monolayer was observed, but without amplification when analyzed by PCR. The metagenomic data demonstrated the presence of 14 viral families, being the most abundant: Myoviridae (41% of available reads), Siphoviridae (24.5%), Podoviridae (14.1%), and Autographiviridae (6.9%) with more than 85% of the total number of identified reads. This study reinforcing that continuous surveillance may contribute to monitoring viral diversity in aquatic environments and provide early warning of potential outbreaks.

Waterborne viruses in urban groundwater environments

The proportion of global population using urban aquifers as drinking water sources increases every year and indeed the groundwater quality is not monitored adequately. Although norovirus has been identified as the first cause of groundwater-related outbreaks, the surveillance of waterborne viruses has been rather neglected. From ageing or disrupted sewer systems, occasional sewer discharges (e.g. combined sewer overflows, storm runoff), to poorly managed reclaimed water infiltration practices, multiple are the pathways that cause groundwater quality deterioration. This study revises the main viral contamination sources and the factors affecting viral contamination of groundwater bodies in terms of transport, inactivation, and survival of the viral particles. It also summarizes the methods used for those reporting the presence of human viruses in urban groundwaters. A total of 36 articles have been included in the method survey spanning a period of 24 years (1999–2022). There is a need of systematic monitoring considering representative set of waterborne pathogens. The evaluation of the presence of human adenovirus seems a useful tool to predict the presence of other waterborne pathogens in groundwater. Large volume sampling methods, but also new passive sampling methodologies applied to groundwater, coupled to target massive sequencing approaches may elucidate the range of pathogens capable of contaminating urban groundwaters for further evaluation of risk.

Material-engineered bioartificial microorganisms enabling efficient scavenging of waterborne viruses

Material-based tactics have attracted extensive attention in driving the functional evolution of organisms. In aiming to design steerable bioartificial organisms to scavenge pathogenic waterborne viruses, we engineer Paramecium caudatum (Para), single-celled microorganisms, with a semiartificial and specific virus-scavenging organelle (VSO). Fe3O4 magnetic nanoparticles modified with a virus-capture antibody (MNPs@Ab) are integrated into the vacuoles of Para during feeding to produce VSOs, which persist inside Para without impairing their swimming ability. Compared with natural Para, which has no capture specificity and shows inefficient inactivation, the VSO-engineered Para (E-Para) specifically gathers waterborne viruses and confines them inside the VSOs, where the captured viruses are completely deactivated because the peroxidase-like nano-Fe3O4 produces virus-killing hydroxyl radicals (•OH) within acidic environment of VSO. After treatment, magnetized E-Para is readily recycled and reused, avoiding further contamination. Materials-based artificial organelles convert natural Para into a living virus scavenger, facilitating waterborne virus clearance without extra energy consumption.

Interfacial mechanism and inactivation efficiency of bacteriophage MS2 by ozone in high turbidity and algal-laden water resource

With the onset of the COVID-19 epidemic and the measures implemented to curb the spread of the SARS-CoV-2 virus, there has been increasing attention on safe drinking water and waterborne viruses during water treatment processes. In this study, we investigate the impact of solution chemistry, including ionic strength (Na+ or Ca2+) pH, and natural organic matter (NOM), on the efficiency of MS2 bacteriophage inactivation by ozone in the presence of inorganic and organic particles (kaolinite (KAO) and microcystis aeruginosa (MA), respectively). The study results demonstrate that KAO has been found to adsorb MS2, but it does not significantly affect the inactivation of MS2 by ozone. In contrast, the inactivation of MS2 increased at low MA concentrations ranging from 105 to 106 cells/L due to MS2 dispersion, but decreased at higher concentrations ranging from 107 to 108 cells/L. The monovalent Na+ ion solutions (~200 mmol/L) maintain MS2 stability and dispersion irrespective of the presence of particles, and did not affect inactivation. Additionally, MS2 aggregates in divalent Ca2+ solutions, resulting in reduced inactivation with or without particles present. Increasing the solution's pH had a negative impact on inactivation, leading to ozone reduction and weakening of the inactivation. However, the presence of NOM poses a significant risk to the safety of drinking water by reducing MS2 inactivation.

Adsorption-enhanced photocatalytic waterborne virus inactivation by graphite carbon nitride conjugated with covalent organic frameworks

The increasing outbreaks of virus-related diseases drive the need to inactivate waterborne viruses efficiently and eco-friendly. Here, g-C3N4@COF heterojunction photocatalysts were synthesized for adsorption-enhanced photocatalytic inactivation of viral surrogates (phage MS2). The modified g-C3N4 outperformed g-C3N4 nanosheets in charge-carrier separation and quantum yield (with photocurrent intensity of 0.15 vs 0.02 μA and fluorescence lifetime of 11.6 vs 1.7 ns). COF exhibited a larger specific surface area (90.883 vs 20.801 m2/g) and less negative-charged surface (−13.8 vs −30.1 mV) than g-C3N4. Accordingly, modified g-C3N4 facilitated virus adsorption and improved the reactive species utilization efficiency, resulting in 7.36 times more efficient virus inactivation relative to g-C3N4. For g-C3N4@COF, the predominant reactive species causing virus inactivation through capsid destruction and genome degradation were superoxide radicals (•O2−) and photogenerated holes (h+). Interestingly, our study found the efficiency trade-offs that the appropriate adsorption of phage MS2 enhanced photocatalytic inactivation but over-adsorption affected the inactivation rate negatively. Overall, our study demonstrates that g-C3N4@COF heterojunction photocatalyst can simultaneously improve reactive species (RS) generation and utilization, which enhances the photocatalytic inactivation of waterborne viruses.

Dry-spun carbon nanotube ultrafiltration membranes tailored by anti-viral metal oxide coatings for human coronavirus 229E capture in water

Although waterborne virus removal may be achieved using separation membrane technologies, such technologies remain largely inefficient at generating virus-free effluents due to the lack of anti-viral reactivity of conventional membrane materials required to deactivating viruses. Here, a stepwise approach towards simultaneous filtration and disinfection of Human Coronavirus 229E (HCoV-229E) in water effluents, is proposed by engineering dry-spun ultrafiltration carbon nanotube (CNT) membranes, coated with anti-viral SnO2 thin films via atomic layer deposition. The thickness and pore size of the engineered CNT membranes were fine-tuned by varying spinnable CNT sheets and their relative orientations on carbon nanofibre (CNF) porous supports to reach thicknesses less than 1 µm and pore size around 28 nm. The nanoscale SnO2 coatings were found to further reduce the pore size down to ∼21 nm and provide more functional groups on the membrane surface to capture the viruses via size exclusion and electrostatic attractions. The synthesized CNT and SnO2 coated CNT membranes were shown to attain a viral removal efficiency above 6.7 log10 against HCoV-229E virus with fast water permeance up to ∼4 × 103 and 3.5 × 103 L.m−2.h−1.bar−1, respectively. Such high performance was achieved by increasing the dry-spun CNT sheets up to 60 layers, orienting successive 30 CNT layers at 45°, and coating 40 nm SnO2 on the synthesized membranes. The current study provides an efficient scalable fabrication scheme to engineer flexible ultrafiltration CNT-based membranes for cost-effective filtration and inactivation of waterborne viruses to outperform the state-of-the-art ultrafiltration membranes.