Comparative enteric viruses and coliphage removal during wastewater treatment processes in a sub-tropical environment

From sewage to genomes: Expanding our understanding of the urban and semi-urban wastewater RNA virome

Wastewater is a hotspot for viral diversity, harboring various microbial, plant, and animal viruses, including those that infect humans. However, the dynamics, resilience, and ecological roles of viral communities during treatment are largely unknown. In this study, we explored RNA virus ecogenomics using metagenomics from influent and effluent samples across three wastewater catchment areas in Chile, with a population of 7.05 million equivalent inhabitants. We identified 14,212 RNA-dependent RNA polymerase (RdRP)-coding sequences from the Orthornavirae kingdom, clustering into 4989 viral species. Using extensive databases of 14,150 family-level representative sequences, we classified 90 % of our sequences at the family level. Our analysis revealed that treatment reduced viral richness and evenness (Shannon index), but phylogenetic diversity remained unchanged. Effluents showed lower richness and evenness than influents with similar phylogenetic diversity. Species turnover, influenced by catchment area and treatment, accounted for 54 % of sample dissimilarities (Weighted Unifrac). Biomarker analysis indicated that families like Astroviridae and Fiersviridae were more abundant in influents, while Reoviridae and Virgaviridae dominated effluents. This suggests that viral resistance to treatment varies and cannot be solely attributed to genome type, size, or morphology. We traced viral genomes through time and space, identifying sequences like the Pepper Mild Mottle Virus (PMMoV) from the Virgaviridae family over large distances and periods, highlighting its wastewater marker potential. High concentrations of human pathogens, such as Rotavirus (Reoviridae) and Human Astrovirus (Astroviridae), were found in both influents and effluents, stressing the need for continuous monitoring, especially for treated wastewater reuse.

A comprehensive review on human enteric viruses in water: Detection methods, occurrence, and microbial risk assessment

Human enteric viruses, such as norovirus, adenovirus, rotavirus, and enterovirus, are crucial targets in controlling biological contamination in water systems worldwide. Due to their small size and low concentrations in water, effective virus concentration and detection methods are essential for ensuring microbial safety. This paper reviews the typical and innovative methods for concentrating and detecting human enteric viruses, highlights viral contamination levels across different water bodies, and discusses the removal efficiencies of virus through various treatment technologies. The application and current gaps of quantitative microbial risk assessment (QMRA) for evaluating the risks of human enteric viruses is also explored. Innovative methods such as digital polymerase chain reaction and isothermal amplification show promise in sensitivity and convenience, however, distinguishing between infectious and non-infectious viruses should be a key focus of future detection techniques. The highest concentrations of human enteric viruses were detected in wastewater, ranging from 103 to 106 copies/L, while drinking water showed significantly lower concentrations, often below 102 copies/L. QMRA studies suggest that exposure to human enteric viruses, whether through contaminated drinking water, occupational contact, or accidental wastewater discharge, could result in a life expectancy of 1.96 × 10-4 to 4.53 × 10-1 days/year.

Virus Removal from Real Wastewater as an Environmental Management Approach

The increased presence of resistant microorganisms in water promotes the need for supplementary measures to mitigate the water source's contamination. Traditional treatments are inefficient in wastewater management at removing some emerging contaminants. Corbicula fluminea, an invasive species, can be used in the treatment due to their resistance and biofiltration capacity, working as a pest management strategy. In this study, this bivalve was used to promote the virus disinfection from the municipal wastewater treatment plant (MWTP) that enters (influent) and after the secondary treatment (effluent leaving the plant). JC virus, norovirus (GI, GII), and hepatitis A (HAV) were identified. C. fluminea promoted norovirus GI and GII removal after 72 h and a slight decrease in the JC virus concentration. These results prove the potential of this pest management approach to be used in virus removal. Furthermore, infectivity assays using mengovirus confirmed the correlation between the presence of the genome detected by PCR and the infectious virus particles. This highlights the potential of PCR as a reliable indicator of the infectious virus's presence. However, such an infectivity assay proved that even when PCR results are undetectable, a reduced number of viruses may remain viable and able to infect susceptible cells in culture.

Unveiling the genomic diversity and ecological impact of phage communities in hospital wastewater

Phages are pivotal in shaping microbial communities and biogeochemical cycles, while our understanding of the diversity, functions potential, and resistance gene carriage of phages in hospital wastewater (HWW) remains limited. We collected influent and effluent samples from the 3 hospital wastewater treatment plants (HWTPs) to assess the diversity and fate of phages, the interactions between phages and hosts, and the presence of resistance genes and auxiliary metabolic genes (AMGs) encoded by phages. Compared to influent, effluent showed reduced phage abundance and altered composition, with decreases in Microviridae and Inoviridae. The gene-sharing network highlights that many phages in HWW are not classified in known viral genera, suggesting HWW as a rich source of new viruses. There was a significant association between phages and microorganisms, with approximately 32.57 % of phages expected to be capable of infecting microbial hosts, characterized primarily by lytic activity. A total of 8 unique antibiotic resistance genes, 13 unique metal resistance genes, and 5 mobile genetic elements were detected in 3 HWTPs phageomes. Phage AMGs have the potential to influence carbon, nitrogen, phosphorus, and sulfur metabolism, impacting biogeochemical cycles. This study reveals the genomic diversity and ecological role of phages in HWTPs, highlighting their environmental and ecosystem impact.

Modelling and optimization of membrane process for removal of biologics (pathogens) from water and wastewater: Current perspectives and challenges

As one of the 17 sustainable development goals, the United Nations (UN) has prioritized "clean water and sanitation" (Goal 6) to reduce the discharge of emerging pollutants and disease-causing agents into the environment. Contamination of water by pathogenic microorganisms and their existence in treated water is a global public health concern. Under natural conditions, water is frequently prone to contamination by invasive microorganisms, such as bacteria, viruses, and protozoa. This circumstance has therefore highlighted the critical need for research techniques to prevent, treat, and get rid of pathogens in wastewater. Membrane systems have emerged as one of the effective ways of removing contaminants from water and wastewater However, few research studies have examined the synergistic or conflicting effects of operating conditions on newly developing contaminants found in wastewater. Therefore, the efficient, dependable, and expeditious examination of the pathogens in the intricate wastewater matrix remains a significant obstacle. As far as it can be ascertained, much attention has not recently been given to optimizing membrane processes to develop optimal operation design as related to pathogen removal from water and wastewater. Therefore, this state-of-the-art review aims to discuss the current trends in removing pathogens from wastewater by membrane techniques. In addition, conventional techniques of treating pathogenic-containing water and wastewater and their shortcomings were briefly discussed. Furthermore, derived mathematical models suitable for modelling, simulation, and control of membrane technologies for pathogens removal are highlighted. In conclusion, the challenges facing membrane technologies for removing pathogens were extensively discussed, and future outlooks/perspectives on optimizing and modelling membrane processes are recommended.

A new understanding of somatic coliphages belonging to the Microviridae family in urban wastewater

Somatic coliphages (SC) and F-specific RNA coliphages (FRNAPH) have been included in regulations or guidelines by several developed countries as a way of monitoring water safety and the microbiological quality of shellfish harvesting waters. SC are highly diverse in their morphology, size and genome. The Microviridae family contains three genera of phages (Alphatrevirus, Gequatrovirus, and Sinsheimervirus), all having a capsid of similar morphology (icosahedral) and size (25-30 nm in diameter) to that of common pathogenic enteric viruses. Three PCR assays specific for each genus of Microviridae were designed to study these phages in raw and treated wastewater (WW) in order to gain knowledge about the diversity and prevalence of Microviridae among SC, as well as their inactivation and removal during WW treatments. Among the four wastewater treatment plants (WWTPs) monitored here, two WWTPs applied disinfection by UV light as tertiary treatment. First, we noticed that Microviridae represented 10 to 30 % of infectious SC in both raw and treated WW. Microviridae appeared to behave in the same way as all SC during these WW treatments. As expected, the highest inactivation, at least 4 log10, was achieved for infectious Microviridae and SC in both WWTPs using UV disinfection. PCR assays showed that the highest removal of Microviridae reached about 4 log10, but the phage removal can vary greatly between WWTPs using similar treatments. This work forms the basis for a broader evaluation of Microviridae as a viral indicator of water treatment efficiency and WW reuse.

Partitioning and inactivation of enveloped and nonenveloped viruses in activated sludge, anaerobic and microalgae-based wastewater treatment systems

Anaerobic and microalgae-based technologies for municipal wastewater treatment have emerged as sustainable alternatives to activated sludge systems. However, viruses are a major sanitary concern for reuse applications of liquid and solid byproducts from these technologies. To assess their capacity to reduce viruses during secondary wastewater treatment, enveloped Phi6 and nonenveloped MS2 bacteriophages, typically used as surrogates of several types of wastewater viruses, were spiked into batch bioreactors treating synthetic municipal wastewater (SMWW). The decay of Phi6 and MS2 in anaerobic and microalgae-based reactors was compared with the decay in activated sludge batch reactors for 96 h (Phi6) and 144 h (MS2). In each reactor, bacteriophages in the soluble and solids fractions were titered, allowing the assessment of virus partitioning to biomass over time. Moreover, the influence of abiotic conditions such as agitation, oxygen absence and light excess in activated sludge, anaerobic and microalgae reactors, respectively, was assessed using dedicated SMWW control reactors. All technologies showed Phi6 and MS2 reductions. Phi6 was reduced in at least 4.7 to 6.5 log10 units, with 0 h concentrations ranging from 5.0 to 6.5 log10 PFU mL-1. Similarly, reductions achieved for MS2 were of at least 3.9 to 7.2 log10 units, from starting concentrations of 8.0 to 8.6 log10 PFU mL-1. Log-logistic models adjusted to bacteriophages' decay indicated T90 values in activated sludge and microalgae reactors of 2.2 and 7.9 h for Phi6 and of 1.0 and 11.5 h for MS2, respectively, all within typical hydraulic retention times (HRT) of full-scale operation. In the case of the microalgae technology, T99 values for Phi6 and MS2 of 12.7 h and 13.6 h were also lower than typical operating HRTs (2-10 d), while activated sludge and anaerobic treatment achieved less than 99 % of Phi6 and 50 % of MS2 inactivation within 12 h of typical HRT, respectively. Thus, the microalgae-based treatment exhibited a higher potential to reduce the disinfection requirements of treated wastewater.

Diurnal changes in pathogenic and indicator virus concentrations in wastewater

Wastewater-based epidemiology (WBE) has been commonly used for monitoring SARS-CoV-2 outbreaks. As sampling times and methods (i.e. grab vs composite) may vary, diurnal changes of viral concentrations in sewage should be better understood. In this study, we collected untreated wastewater samples hourly for 4 days at two wastewater treatment plants in Wales to establish diurnal patterns in virus concentrations and the physico-chemical properties of the water. Simultaneously, we also trialled three absorbent materials as passive samples as a simple and cost-efficient alternative for the collection of composite samples. Ninety-six percent of all liquid samples (n = 74) and 88% of the passive samplers (n = 59) were positive for SARS-CoV-2, whereas 87% and 97% of the liquid and passive samples were positive for the faecal indicator virus crAssphage, respectively. We found no significant daily variations in the concentration of the target viruses, ammonium and orthophosphate, and the pH and electrical conductivity levels were also stable. Weak positive correlations were found between some physico-chemical properties and viral concentrations. More variation was observed in samples taken from the influent stream as opposed to those taken from the influent tank. Of the absorbent materials trialled as passive samples, we found that tampons provided higher viral recoveries than electronegative filter paper and cotton gauze swabs. For all materials tested, viral recovery was dependent on the virus type. Our results indicate that grab samples may provide representative alternatives to 24-h composite samples if taken from the influent tank, hence reducing the costs of sampling for WBE programmes. Tampons are also viable alternatives for cost-efficient sampling; however, viral recovery should be optimised prior to use.

Prevalence and Genetic Diversity of Cross-Assembly Phages in Wastewater Treatment Plants in Riyadh, Saudi Arabia

The most common DNA virus found in wastewaters globally is the cross-assembly phage (crAssphage). King Saud University wastewater treatment plant (KSU-WWTP); Manfoha wastewater treatment plant (MN-WWTP); and the Embassy wastewater treatment plant (EMB-WWTP) in Riyadh, Saudi Arabia were selected, and 36 untreated sewage water samples during the year 2022 were used in the current study. The meteorological impact on crAssphage prevalence was investigated. CrAssphage prevalence was recorded using PCR and Sanger sequencing. The molecular diversity of crAssphage sequences was studied for viral gene segments from the major capsid protein (MCP) and membrane protein containing the peptidoglycan-binding domain (MP-PBD). KSU-WWTP and EMB-WWTP showed a higher prevalence of crAssphage (83.3%) than MN-WWTP (75%). Phylogenetic analysis of MCP and MP-PBD segments depicted a close relationship to the Japanese isolates. The MCP gene from the current study's isolate WW/2M/SA/2022 depicted zero evolutionary divergence from 3057_98020, 2683_104905, and 4238_99953 isolates (d = 0.000) from Japan. A significant influence of temporal variations on the prevalence of crAssphage was detected in the three WWTPs. CrAssphage displayed the highest prevalence at high temperatures (33-44 °C), low relative humidity (6-14%), and moderate wind speed (16-21 Km/h). The findings provided pioneering insights into crAssphage prevalence and its genetic diversity in WWTPs in Riyadh, Saudi Arabia.

Integrating life cycle assessment with quantitative microbial risk assessment for a holistic evaluation of sewage treatment plant

An integrated approach was employed in the present study to combine life cycle assessment (LCA) with quantitative microbial risk assessment (QMRA) to assess an existing sewage treatment plant (STP) at Roorkee, India. The midpoint LCA modeling revealed that high electricity consumption (≈ 576 kWh.day^-1) contributed to the maximum environmental burdens. The LCA endpoint result of 0.01 disability-adjusted life years per person per year (DALYs pppy) was obtained in terms of the impacts on human health. Further, a QMRA model was developed based on representative sewage pathogens, including E. coli O157:H7, Giardia sp., adenovirus, norovirus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The public health risk associated with intake of pathogen-laden aerosols during treated water reuse in sprinkler irrigation was determined. A cumulative health risk of 0.07 DALYs pppy was obtained, where QMRA risks contributed 86 % of the total health impacts. The annual probability of illness per person was highest for adenovirus and norovirus, followed by SARS-CoV-2, E. coli O157:H7 and Giardia sp. Overall, the study provides a methodological framework for an integrated LCA-QMRA assessment which can be applied across any treatment process to identify the hotspots contributing maximum environmental burdens and microbial health risks. Furthermore, the integrated LCA-QMRA approach could support stakeholders in the water industry to select the most suitable wastewater treatment system and establish regulations regarding the safe reuse of treated water.

Statistical Analysis of SARS-CoV-2 Using Wastewater-Based Data of Stockholm, Sweden

An approach based on wastewater epidemiology can be used to monitor the COVID-19 pandemic by assessing the gene copy number of SARS-CoV-2 in wastewater. In the present study, we statistically analyzed such data from six inlets of three wastewater treatment plants, covering six regions of Stockholm, Sweden, collected over an approximate year period (week 16 of 2020 to week 22 of 2021). SARS-CoV-2 gene copy number and population-based biomarker PMMoV, as well as clinical data, such as the number of positive cases, intensive care unit numbers, and deaths, were analyzed statistically using correlations and principal component analysis (PCA). Despite the population differences, the PCA for the Stockholm dataset showed that the case numbers are well grouped across wastewater treatment plants. Furthermore, when considering the data from the whole of Stockholm, the wastewater characteristics (flow rate m3/day, PMMoV Ct value, and SARS-CoV gene copy number) were significantly correlated with the public health agency's report of SARS-CoV-2 infection rates (0.419 to 0.95, p-value < 0.01). However, while the PCA results showed that the case numbers for each wastewater treatment plant were well grouped concerning PC1 (37.3%) and PC2 (19.67%), the results from the correlation analysis for the individual wastewater treatment plants showed varied trends. SARS-CoV-2 fluctuations can be accurately predicted through statistical analyses of wastewater-based epidemiology, as demonstrated in this study.

A review on disinfection methods for inactivation of waterborne viruses

Water contamination is a global health problem, and the need for safe water is ever-growing due to the public health implications of unsafe water. Contaminated water could contain pathogenic bacteria, protozoa, and viruses that are implicated in several debilitating human diseases. The prevalence and survival of waterborne viruses differ from bacteria and other waterborne microorganisms. In addition, viruses are responsible for more severe waterborne diseases such as gastroenteritis, myocarditis, and encephalitis among others, hence the need for dedicated attention to viral inactivation. Disinfection is vital to water treatment because it removes pathogens, including viruses. The commonly used methods and techniques of disinfection for viral inactivation in water comprise physical disinfection such as membrane filtration, ultraviolet (UV) irradiation, and conventional chemical processes such as chlorine, monochloramine, chlorine dioxide, and ozone among others. However, the production of disinfection by-products (DBPs) that accompanies chemical methods of disinfection is an issue of great concern due to the increase in the risks of harm to humans, for example, the development of cancer of the bladder and adverse reproductive outcomes. Therefore, this review examines the conventional disinfection approaches alongside emerging disinfection technologies, such as photocatalytic disinfection, cavitation, and electrochemical disinfection. Moreover, the merits, limitations, and log reduction values (LRVs) of the different disinfection methods discussed were compared concerning virus removal efficiency. Future research needs to merge single disinfection techniques into one to achieve improved viral disinfection, and the development of medicinal plant-based materials as disinfectants due to their antimicrobial and safety benefits to avoid toxicity is also highlighted.

CrAssphage as an indicator of human-fecal contamination in water environment and virus reduction in wastewater treatment

Viral indicators of human-fecal contamination in wastewaters and environmental waters have been getting much attention in the past decade. Cross-assembly phage (crAssphage) is the most abundant DNA virus in human feces. Recently, the usefulness of crAssphage as a microbial source tracking and water quality monitoring tool for human-fecal contamination has been highlighted. Here, we conducted a comprehensive review on crAssphage in water, focusing on detection methodology, concentration range in various waters and wastewaters, specificity to human-fecal contamination, and reduction in wastewater treatment systems. This review highlights that crAssphage is globally distributed in wastewaters and various fecal-contaminated water bodies at high concentrations without seasonal fluctuations. CrAssphage is highly specific to human-fecal contamination and is rarely found in animal feces. It also has a good potential as a performance indicator to ensure virus reduction in wastewater treatment systems. Accordingly, crAssphage could be an effective tool for monitoring of human-fecal contamination and potential presence of fecal pathogenic microbes in environmental waters. Bridging the research gaps highlighted in this review would make crAssphage a powerful tool to support the control of water-related health risks.

Quantification of human adenovirus in irrigation water-soil-crop continuum: are consumers of wastewater-irrigated vegetables at risk?

Because of health concerns regarding the presence of enteric viruses in wastewater effluents, this study was designed to investigate the occurrence of human adenovirus (HAdV) in the irrigation water-soil-crop continuum. Viral particles were extracted from wastewater and wastewater- or water-irrigated soil and crop samples and analyzed using real-time PCR. Concentration of fecal indicator bacteria (FIB) were also determined. Quantitative microbial risk assessment was performed to determine the HAdV illness risk associated with the consumption of wastewater-irrigated vegetables. HAdV-F was detected in 74% of wastewater effluent samples with a mean concentration of 38 Genomic Copy (GC)/mL. HAdV was also detected in wastewater-irrigated soil (2 × 102 GC/g) and crop (< 10 GC/g) samples, with no statistically significant difference in concentrations between wastewater- and freshwater-irrigated samples. The results showed no correlation between concentrations of FIB and HAdV in the analyzed samples. Mean probability of illness risk from consumption of wastewater-irrigated vegetables was 4 × 10-1 per person per year (pppy) which was about two orders of magnitude higher than the proposed value by WHO (10-3 pppy) for safe reuse of wastewater. This finding suggests that the wastewater reuse for irrigation of vegetables eaten raw could pose a threat to human health with respect to the risk of viral illness, signifying stricter management of wastewater reuse. However, because of uncertainties in the QMRA model, particularly the ratio of infectious to non-infectious virus particles, more data is required to validate the predicted risk. This information is especially important in arid and semi-arid regions where high temperatures, UV radiation intensity, and desiccation can efficiently inactivate microorganisms in the environment.

Effectiveness of two wastewater disinfection strategies for the removal of fecal indicator bacteria, bacteriophage, and enteric viral pathogens concentrated using dead-end hollow fiber ultrafiltration (D-HFUF)

Primary influent and final effluent samples were collected from wastewater treatment plants using either chlorination or ultraviolet (UV) disinfection biweekly for one year. Paired measurements were determined for fecal indicator bacteria (Escherichia coli and enterococci), cultivated bacteriophages (somatic, F+, and CB-390 coliphage and GB-124 Bacteroides phage), human-associated viral markers (human polyomavirus [HPyV] and crAssphage), enteric pathogens (adenovirus, noroviruses genogroups I and II) as well as total infectious enteric virus. To increase the probability of detecting low concentration targets, both primary (10L) and final effluent wastewater samples (40-100 L) were concentrated using a dead-end hollow-fiber ultrafilter (D-HFUF). Despite seasonal temperature fluctuations, concentration shifts of FIB, bacteriophages, human-associated viruses, and viral pathogens measured in primary influent samples were minimal, while levels of infectious enteric virus were significantly higher in the spring and fall (P range: 0.0003-0.0409). FIB levels measured in primary influents were 1-2 log₁₀ higher than bacteriophage, human-associated viral markers (except crAssphage) and viral pathogens measured. FIB displayed the greatest sensitivity to chlorine disinfection, while crAssphage, adenoviruses and infectious enteric viruses were significantly less sensitive (P ≤ 0.0096). During UV treatment, bacteriophages F+ and GB-124 were the most resistant of the culturable viruses measured (P ≤ 0.001), while crAssphage were the most resistant (P ≤ 0.0124) overall. When UV lamps were inactive, infectious enteric viruses were significantly more resilient to upstream treatment processes than all other targets measured (P ≤ 0.0257). Similar to infectious enteric viruses and adenoviruses; GB-124, F+, and crAssphages displayed the highest resistance to UV irradiation, signaling a potential applicability as pathogen surrogates in these systems. The use of D-HFUF enhanced the ability to estimate removal of viruses through wastewater treatment, with the expectation that future applications of this method will be used to better elucidate viral behavior within these systems.

Sources, fates and treatment strategies of typical viruses in urban sewage collection/treatment systems: A review

The ongoing coronavirus pandemic (COVID-19) throughout the world has severely threatened the global economy and public health. Due to receiving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a wide variety of sources (e.g., households, hospitals, slaughterhouses), urban sewage treatment systems are regarded as an important path for the transmission of waterborne viruses. This review presents a quantitative profile of the concentration distribution of typical viruses within wastewater collection systems and evaluates the influence of different characteristics of sewer systems on virus species and concentration. Then, the efficiencies and mechanisms of virus removal in the units of wastewater treatment plants (WWTPs) are summarized and compared, among which the inactivation efficiencies of typical viruses by typical disinfection approaches under varied operational conditions are elucidated. Subsequently, the occurrence and removal of viruses in treated effluent reuse and desalination, as well as that in sewage sludge treatment, are discussed. Potential dissemination of viruses is emphasized by occurrence via aerosolization from toilets, the collection system and WWTP aeration, which might have a vital role in the transmission and spread of viruses. Finally, the frequency and concentration of viruses in reclaimed water, the probability of infection are also reviewed for discussing the potential health risks.

A review of the potential of conventional and advanced membrane technology in the removal of pathogens from wastewater

Consumption of pathogenic contaminated water has claimed the lives of many people. Hence, this scenario has emphasized the urgent need for research methods to avoid, treat and eliminate harmful pathogens in wastewater. Therefore, effective water treatment has become a matter of utmost importance. Membrane technology offers purer, cleaner, and pathogen-free water through the water separation method via a permeable membrane. Advanced membrane technology such as nanocomposite membrane, membrane distillation, membrane bioreactor, and photocatalytic membrane reactor can offer synergistic effects in removing pathogen through the integration of additional functionality and filtration in a single chamber. This paper also comprehensively discussed the application, challenges, and future perspective of the advanced membrane technology as a promising alternative in battling pathogenic microbial contaminants, which will also be beneficial and valuable in managing pandemics in the future as well as protecting human health and the environment. In addition, the potential of membrane technology in battling the ongoing global pandemic of coronavirus disease 2019 (COVID-19) was also discussed briefly.

Potentialities of a mesoporous activated carbon as virus detection probe in aquatic systems

Enteric viruses are widely spread in water environments, some being harmful for human communities. Regular epidemics highlight the usefulness of analysing such viruses in wastewaters as a tool for epidemiologists to monitor the extent of their dissemination among populations. In this context, CNovel™ Powdered Activated Carbon (PAC) was chosen for its high porosity and high adsorption capacity to investigate sorbent ability to be used as part of of virus detection probes. Self-supported PAC Foils (PAC-F), PAC coated Brushes (PAC-B) and PAC Sampler (PAC-S) were used to prospect PAC efficacy in virus adsorption and above all, the feasibility of virus retrieval from them, allowing to further analysis such as molecular analysis quantification. Aiming at the development of a field-operational tool, PAC saturation and reusability were also investigated, as well as PAC-polarisation effect on its adsorption capacity. Our results pointed out that sorbent-based probes exhibited a high adsorption efficacy of spiked Murine Norovirus (MNV-1) in bare 0.1 M NaCl solution (>90 % for PAC-B and >86 % for PAC-F at ≈10⁷ genome unit virus concentration), with no saturation within our experimental framework. On the other hand, polarisation assays using PAC-F as electrode, did not demonstrate any adsorption improvement. Experiments on PAC probes reusability suggested that they should be used three times at the most for a maximum efficiency. Values of virus retrieval were low (up to 11 % with PAC-B and up to 14 % with PAC-F in 0.1 M NaCl virus suspensions), illustrating the need for the techniques to be improved. A preliminary field assay using PAC-S, demonstrated that our catch-and-retrieve protocol yielded to the detection of autochthonous human Norovirus Genogroup I (NoV GI) and Adenovirus (AdV), in wastewaters suggesting its promising application as virus detection tool in such high loaded and complex waters.

A review on detection of SARS-CoV-2 RNA in wastewater in light of the current knowledge of treatment process for removal of viral fragments

The entire globe is affected by the novel disease of coronavirus 2019 (COVID-19 or 2019-nCoV), which is formally recognised as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The World Health Organisation (WHO) announced this disease as a global pandemic. The presence of SARS-CoV-2 RNA in unprocessed wastewater has become a cause of worry due to these emerging pathogens in the process of wastewater treatment, as reported in the present study. This analysis intends to interpret the fate, environmental factors and route of transmission of SARS-CoV-2, along with its eradication by treating the wastewater for controlling and preventing its further spread. Different recovery estimations of the virus have been depicted by the detection of SARS-CoV-2 RNA in wastewater through the viral concentration techniques. Most frequently used viral concentration techniques include polyethylene glycol (PEG) precipitation, ultrafiltration, electronegative membrane, and ultracentrifugation, after which the detection and quantification of SARS-CoV-2 RNA are done in wastewater samples through quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The wastewater treatment plant (WWTP) holds the key responsibility of eliminating pathogens prior to the discharge of wastewater into surface water bodies. The removal of SARS-CoV-2 RNA at the treatment stage is dependent on the operations of wastewater treatment systems during the outbreak of the virus; particularly, in the urban and extensively populated regions. Efficient primary, secondary and tertiary methods of wastewater treatment and disinfection can reduce or inactivate SARS-CoV-2 RNA before being drained out. Nonetheless, further studies regarding COVID-19-related disinfectants, environment conditions and viral concentrations in each treatment procedure, implications on the environment and regular monitoring of transmission need to be done urgently. Hence, monitoring the SARS-CoV-2 RNA in samples of wastewater under the procedure of wastewater-based epidemiology (WBE) supplement the real-time data pertaining to the investigation of the COVID-19 pandemic in the community, regional and national levels.

The occurrence and control of waterborne viruses in drinking water treatment: A review

As the coronavirus disease 2019 continues to spread globally, its culprit, the severe acute respiratory syndrome coronavirus 2 has been brought under scrutiny. In addition to inhalation transmission, the possible fecal-oral viral transmission via water/wastewater has also been brought under the spotlight, necessitating a timely global review on the current knowledge about waterborne viruses in drinking water treatment system - the very barrier that intercepts waterborne pathogens to terminal water users. In this article we reviewed the occurrence, concentration methods, and control strategies, also, treatment performance on waterborne viruses during drinking water treatment were summarized. Additionally, we emphasized the potential of applying the quantitative microbial risk assessment to guide drinking water treatment to mitigate the viral exposure risks, especially when the unregulated novel viral pathogens are of concern. This review paves road for better control of viruses at drinking water treatment plants to protect public health.

Virological Characterization of Roof-Harvested Rainwater of Densely Urbanized Low-Income Region

Roof-harvested rainwater (RHRW) is considered relatively clean water, even though the possible presence of pathogens in the water may pose human health risks. In this study, we investigated the occurrence of enteric viruses in the first flush (10 mm) of RHRW from a densely populated and low-income urbanized region of Rio de Janeiro. One hundred samples (5 L) were collected from 10 rainfall events between April 2015 and March 2017. RNA and DNA viruses were concentrated using the skimmed milk flocculation method and analyzed using the TaqMan® quantitative RT-qPCR and qPCR. Human adenoviruses, noroviruses, rotaviruses A, and avian parvoviruses were detected in 54%, 31%, 12%, and 12% of the positive samples. JC polyomavirus, also targeted, was not detected. Virus concentrations ranged from 1.09 × 10¹ to 2.58 × 10³ genome copies/Liter (GC/L). Partial nucleotide sequence confirmed the presence of HAdV type 41, norovirus genotype GII.4, and avian parvovirus 1. The results suggest that the first flush diversion devices may not adequately remove enteric virus from the rainwater. Additional treatment of RHRW is required to mitigate potential health risks from potable use of captured water.

Detection and molecular characterization of enteric adenovirus in treated wastewater in the Brazilian Federal District

Human enteric viruses, such as enteric adenoviruses (HAdV), are known to be involved with gastrointestinal disorders, especially acute gastroenteritis. Several studies have used HAdV as an indicator of water quality, since they are considered highly stable and widely distributed viruses in water matrices. The aim of this study was to detect and genotype HAdVs in water matrices impacted by discharges of treated effluents from wastewater treatment plants (WWTPs). Wastewater treatment plants from the sanitary system of the Brazilian Federal District were assessed in 2018 and 2019. Samples were collected upstream and downstream from discharge points for each WWTP. Viral concentration based on adsorption-elution and conventional PCR was used for molecular detection, and positive samples were sequenced for phylogenetic analysis. Pluviosity data for the period in which the samples were collected were obtained. Our results demonstrated the presence of HAdVs in 27.2% (61/224) of the samples. The positivity was significantly higher in downstream samples compared to upstream. Moreover, the HAdV positivity was higher in downstream samples collected from receiving water bodies impacted by secondary-level WWTPs in comparison with those impacted by tertiary-level WWTPs. Phylogenetic analysis demonstrated the presence of genotypes 40 and 41, with prevalence of HAdV genotype 41. Despite the predominance of HAdV-41, an increasing frequency of the HAdV-40 was associated with higher pluviosity. In conclusion, this study is the first documentation in the Brazilian Federal District dealing with the prevalence and diversity of HAdVs in several WWTP, along with their correlation with rainfall index.

Where do we stand to oversee the coronaviruses in aqueous and aerosol environment? Characteristics of transmission and possible curb strategies

By 17 October 2020, the severe acute respiratory syndrome coronavirus (SARS-CoV-2) has caused confirmed infection of more than 39,000,000 people in 217 countries and territories globally and still continues to grow. As environmental professionals, understanding how SARS-CoV-2 can be transmitted via water and air environment is a concern. We have to be ready for focusing our attention to the prompt diagnosis and potential infection control procedures of the virus in integrated water and air system. This paper reviews the state-of-the-art information from available sources of published papers, newsletters and large number of scientific websites aimed to provide a comprehensive profile on the transmission characteristics of the coronaviruses in water, sludge, and air environment, especially the water and wastewater treatment systems. The review also focused on proposing the possible curb strategies to monitor and eventually cut off the coronaviruses under the authors' knowledge and understanding.

Investigating awareness, fear and control associated with norovirus and other pathogens and pollutants using best-worst scaling

Pollutants found in the water and air environment represent an ever-growing threat to human health. Contact with some air-, water- and foodborne pathogens (e.g. norovirus) results in gastrointestinal diseases and outbreaks. For future risk mitigation, we aimed to measure people's awareness of waterborne and foodborne norovirus relative to other environment-associated pollutants (e.g. pesticides, bioaerosols, antibiotic resistant bacteria) and well-known risks (e.g. diabetes, dementia, terrorist attack). We used an online survey, which included a best-worst scaling component to elicit personal levels of control and fear prompted by norovirus relative to 15 other risks. There was a negative correlation between levels of fear vs. control for all 16 measured risks. Perceived infection control levels were higher amongst women compared to men and correlated with age and the level of qualification in both groups. Participants who had sought advice regarding the symptoms caused by norovirus appeared to have more control over the risks. Norovirus is associated with high levels of fear, however, the levels of control over it is low compared to other foodborne illnesses, e.g. Salmonella. Addressing this deficit in the public's understanding of how to control exposure to the pathogen in an important health need.

Make it clean, make it safe: A review on virus elimination via adsorption

Recently, the potential dangers of viral infection transmission through water and air have become the focus of worldwide attention, via the spread of COVID-19 pandemic. The occurrence of large-scale outbreaks of dangerous infections caused by unknown pathogens and the isolation of new pandemic strains require the development of improved methods of viruses' inactivation. Viruses are not stable self-sustaining living organisms and are rapidly inactivated on isolated surfaces. However, water resources and air can participate in the pathogens' diffusion, stabilization, and transmission. Viruses inactivation and elimination by adsorption are relevant since they can represent an effective and low-cost method to treat fluids, and hence limit the spread of pathogen agents. This review analyzed the interaction between viruses and carbon-based, oxide-based, porous materials and biological materials (e.g., sulfated polysaccharides and cyclodextrins). It will be shown that these adsorbents can play a relevant role in the viruses removal where water and air purification mostly occurring via electrostatic interactions. However, a clear systematic vision of the correlation between the surface potential and the adsorption capacity of the different filters is still lacking and should be provided to achieve a better comprehension of the global phenomenon. The rationalization of the adsorption capacity may be achieved through a proper physico-chemical characterization of new adsorbents, including molecular modeling and simulations, also considering the adsorption of virus-like particles on their surface. As a most timely perspective, the results on this review present potential solutions to investigate coronaviruses and specifically SARS-CoV-2, responsible of the COVID-19 pandemic, whose spread can be limited by the efficient disinfection and purification of closed-spaces air and urban waters.

Evaluation of two rapid ultrafiltration-based methods for SARS-CoV-2 concentration from wastewater

Quantitative measurements of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in raw wastewater have been implemented worldwide since the beginning of the pandemic. Recent efforts are being made to evaluate different viral concentration methodologies to overcome supplier shortages during lockdowns. A set of 22-wastewater samples seeded with murine hepatitis virus (MHV), a member of the Coronaviridae family, and the bacteriophage MS2, were used to characterize and compare two ultrafiltration-based methods: a centrifugal ultrafiltration device (Centricon® Plus-70) and the automated concentrating pipette CP-Select™. Based on the recovery efficiencies, significant differences were observed for MHV, with Centricon® Plus-70 (24%) being the most efficient method. Nevertheless, concentrations of naturally occurring SARS-CoV-2, Human adenoviruses and JC polyomaviruses in these samples did not result in significant differences between methods suggesting that testing naturally occurring viruses may complement the evaluation of viral concentration methodologies. Based on the virus adsorption to solids and the necessity of a pre-centrifugation step to remove larger particles and avoid clogging when using ultrafiltration methods, we assessed the percentage of viruses not quantified after ultrafiltration. Around 23% of the detected SARS-CoV-2 would be discarded during the debris removal step. The CP-Select™ provided the highest concentration factor (up to 333×) and the lowest LoD (6.19 × 103 GC/l) for MHV and proved to be fast, automatic, highly reproducible and suitable to work under BSL-2 measures.

The novel SARS-CoV-2 pandemic: Possible environmental transmission, detection, persistence and fate during wastewater and water treatment

The contagious SARS-CoV-2 virus, responsible for COVID-19 disease, has infected over 27 million people across the globe within a few months. While literature on SARS-CoV-2 indicates that its transmission may occur predominantly via aerosolization of virus-laden droplets, the possibility of alternate routes of transmission and/or reinfection via the environment requires considerable scientific attention. This review aims to collate information on possible transmission routes of this virus, to ascertain its fate in the environment. Concomitant with the presence of SARS-CoV-2 viral RNA in faeces and saliva of infected patients, studies also indicated its occurrence in raw wastewater, primary sludge and river water. Therefore sewerage system could be a possible route of virus outbreak, a possible tool to assess viral community spread and future surveillance technique. Hence, this review looked into detection, occurrence and fate of SARS-CoV-2 during primary, secondary, and tertiary wastewater and water treatment processes based on published literature on SARS-CoV and other enveloped viruses. The review also highlights the need for focused research on occurrence and fate of SARS-CoV-2 in various environmental matrices. Utilization of this information in environmental transmission models developed for other enveloped and enteric viruses can facilitate risk assessment studies. Preliminary research efforts with SARS-CoV-2 and established scientific reports on other coronaviruses indicate that the threat of virus transmission from the aquatic environment may be currently non-existent. However, the presence of viral RNA in wastewater provides an early warning that highlights the need for effective sewage treatment to prevent a future outbreak of SARS-CoV-2.

Assessment of enteric viruses during a hepatitis outbreak in Detroit MI using wastewater surveillance and metagenomic analysis

AIMS

This study investigates enteric viruses in wastewater during an outbreak of acute hepatitis caused by hepatitis A virus (HAV) in a large metropolitan area. Emphasis is given to caliciviruses and HAV.

METHODS AND RESULTS

Metagenomic analysis was performed to characterize enteric viruses excreted by the population of Detroit MI, during a hepatitis A outbreak that occurred in 2017 and 2018. Additionally, HAV, norovirus GII, and sapovirus were quantified, using qPCR, in 54 untreated wastewater samples collected over the course of 4 months. Correlation analysis was performed to identify associations between the number of disease cases and HAV concentrations in wastewater. HAV obtained the highest relative abundance among other enteric viruses detected in wastewater metagenomes. Metagenomic analysis also detected several other enteric viruses including astrovirus, enterovirus and hepatitis E virus. Average sapovirus concentrations of 1·36 × 10⁶  gc l^-1 were significantly greater than norovirus GII concentrations (2·94 × 10⁴  gc l^-1 ). Additionally, norovirus GI and GII along with sapovirus GI.1 were detected using metagenomics. HAV loads in wastewater were significantly correlated with the number of disease cases reported 1 week after wastewater sampling.

CONCLUSIONS

Surveying untreated wastewater is a promising method for detecting early signs of hepatitis A outbreaks and for routine environmental monitoring of enteric viruses circulating in the environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Authors demonstrate the usefulness of metagenomics for genogrouping and enteric viral surveillance.

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa

Enteric viruses are a diverse group of human pathogens which are primarily transmitted by the faecal-oral route and are a major cause of non-bacterial diarrhoeal disease in both developed and developing countries. Because they are shed in high numbers by infected individuals and can persist for a long time in the environment, they pose a serious threat to human health globally. Enteric viruses end up in the environment mainly through discharge or leakage of raw or inadequately treated sewage into water sources such as springs, rivers, dams, or marine estuaries. Human exposure then follows when contaminated water is used for drinking, cooking, or recreation and, importantly, when filter-feeding bivalve shellfish are consumed. The human health hazard posed by enteric viruses is particularly serious in Africa where rapid urbanisation in a relatively short period of time has led to the expansion of informal settlements with poor sanitation and failing or non-existent wastewater treatment infrastructure, and where rural communities with limited or no access to municipal water are dependent on nearby open water sources for their subsistence. The role of sewage-contaminated water and bivalve shellfish as vehicles for transmission of enteric viruses is well documented but, to our knowledge, has not been comprehensively reviewed in the African context. Here we provide an overview of enteric viruses and then review the growing body of research where these viruses have been detected in association with sewage-contaminated water or food in several African countries. These studies highlight the need for more research into the prevalence, molecular epidemiology and circulation of these viruses in Africa, as well as for development and application of innovative wastewater treatment approaches to reduce environmental pollution and its impact on human health on the continent.

SARS-CoV-2 in environmental perspective: Occurrence, persistence, surveillance, inactivation and challenges

The unprecedented global spread of the severe acute respiratory syndrome (SARS) caused by SARS-CoV-2 is depicting the distressing pandemic consequence on human health, economy as well as ecosystem services. So far novel coronavirus (CoV) outbreaks were associated with SARS-CoV-2 (2019), middle east respiratory syndrome coronavirus (MERS-CoV, 2012), and SARS-CoV-1 (2003) events. CoV relates to the enveloped family of Betacoronavirus (βCoV) with positive-sense single-stranded RNA (+ssRNA). Knowing well the persistence, transmission, and spread of SARS-CoV-2 through proximity, the faecal-oral route is now emerging as a major environmental concern to community transmission. The replication and persistence of CoV in the gastrointestinal (GI) tract and shedding through stools is indicating a potential transmission route to the environment settings. Despite of the evidence, based on fewer reports on SARS-CoV-2 occurrence and persistence in wastewater/sewage/water, the transmission of the infective virus to the community is yet to be established. In this realm, this communication attempted to review the possible influx route of the enteric enveloped viral transmission in the environmental settings with reference to its occurrence, persistence, detection, and inactivation based on the published literature so far. The possibilities of airborne transmission through enteric virus-laden aerosols, environmental factors that may influence the viral transmission, and disinfection methods (conventional and emerging) as well as the inactivation mechanism with reference to the enveloped virus were reviewed. The need for wastewater epidemiology (WBE) studies for surveillance as well as for early warning signal was elaborated. This communication will provide a basis to understand the SARS-CoV-2 as well as other viruses in the context of the environmental engineering perspective to design effective strategies to counter the enteric virus transmission and also serves as a working paper for researchers, policy makers and regulators.

Viruses in wastewater: occurrence, abundance and detection methods

This paper presents an updated and comprehensive review on the different methods used for detection and quantification of viruses in wastewater treatment systems. The analysis of viability of viruses in wastewater and sludge is another thrust of this review. Recent studies have mostly focused on determining the abundance and diversity of viruses in wastewater influents, in samples from primary, secondary, and tertiary treatment stages, and in final effluents. A few studies have also examined the occurrence and diversity of viruses in raw and digested sludge samples. Recent efforts to improve efficiency of virus detection and quantification methods in the complex wastewater and sludge matrices are highlighted in this review. A summary and a detailed comparison of the pre-treatment methods that have been utilized for wastewater and sludge samples are also presented. The role of metagenomics or sequencing analysis in monitoring wastewater systems to predict disease outbreaks, to conduct public health surveillance, to assess the efficiency of existing treatment systems in virus removal, and to re-evaluate current regulations regarding pathogenic viruses in wastewater is discussed in this paper. Challenges and future perspectives in the detection of viruses, including emerging and newly emerged viruses such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), in wastewater systems are discussed in this review.

Coronaviruses in wastewater processes: Source, fate and potential risks

The last 17 years have seen three major outbreaks caused by coronaviruses, with the latest outbreak, COVID-19, declared a pandemic by the World Health Organization. The frequency of these outbreaks, their mortality and associated disruption to normal life calls for concerted efforts to understand their occurrence and fate in different environments. There is an increased interest in the occurrence of coronaviruses in wastewater from the perspective of wastewater-based epidemiology. However, there is no comprehensive review of the knowledge on coronavirus occurrence, fate and potential transmission in wastewater. This paper, provides a review of the literature on the occurrence of coronaviruses in wastewater treatment processes. We discuss the presence of viral RNA in feces as a result of diarrhoea caused by gastrointestinal infections. We also reviewed the literature on the presence, survival and potential removal of coronaviruses in common wastewater treatment processes. The detection of infectious viral particles in feces of patients raises questions on the potential risks of infection for people exposed to untreated sewage/wastewater. We, therefore, highlighted the potential risk of infection with coronaviruses for workers in wastewater treatment plants and the public that may be exposed through faulty plumbing or burst sewer networks. The mortalities and morbidities associated with the current COVID-19 pandemic warrants a much more focused research on the role of environments, such as wastewater and surface water, in disease transmission. The current wealth of knowledge on coronaviruses in wastewater based on the reviewed literature is scant and therefore calls for further studies.

Metagenomic Insights into the Sewage RNA Virosphere of a Large City

Sewage-associated viruses can cause several human and animal diseases, such as gastroenteritis, hepatitis, and respiratory infections. Therefore, their detection in wastewater can reflect current infections within the source population. To date, no viral study has been performed using the sewage of any large South American city. In this study, we used viral metagenomics to obtain a single sample snapshot of the RNA virosphere in the wastewater from Santiago de Chile, the seventh largest city in the Americas. Despite the overrepresentation of dsRNA viruses, our results show that Santiago’s sewage RNA virosphere was composed mostly of unknown sequences (88%), while known viral sequences were dominated by viruses that infect bacteria (60%), invertebrates (37%) and humans (2.4%). Interestingly, we discovered three novel genogroups within the Picobirnaviridae family that can fill major gaps in this taxa’s evolutionary history. We also demonstrated the dominance of emerging Rotavirus genotypes, such as G8 and G6, that have displaced other classical genotypes, which is consistent with recent clinical reports. This study supports the usefulness of sewage viral metagenomics for public health surveillance. Moreover, it demonstrates the need to monitor the viral component during the wastewater treatment and recycling process, where this virome can constitute a reservoir of human pathogens.

A Somatic Coliphage Threshold Approach To Improve the Management of Activated Sludge Wastewater Treatment Plant Effluents in Resource-Limited Regions

Effective wastewater management is crucial to ensure the safety of water reuse projects and effluent discharge into surface waters. Multiple studies have demonstrated that municipal wastewater treatment with conventional activated sludge processes is inefficient for the removal of a wide spectrum of viruses in sewage. In this study, a well-accepted statistical approach was used to investigate the relationship between viral indicators and human enteric viruses during wastewater treatment in a resource-limited region. Influent and effluent samples from five urban wastewater treatment plants (WWTPs) in Costa Rica were analyzed for somatic coliphage and human enterovirus, hepatitis A virus, norovirus genotypes I and II, and rotavirus. All WWTPs provide primary treatment followed by conventional activated sludge treatment prior to discharge into surface waters that are indirectly used for agricultural irrigation. The results revealed a statistically significant relationship between the detection of at least one of the five human enteric viruses and somatic coliphage. Multiple logistic regression and receiver operating characteristic curve analysis identified a threshold of 3.0 × 103 (3.5 log10) somatic coliphage PFU per 100 ml, which corresponded to an increased likelihood of encountering enteric viruses above the limit of detection (>1.83 × 102 virus targets/100 ml). Additionally, quantitative microbial risk assessment was executed for farmers indirectly reusing WWTP effluent that met the proposed threshold. The resulting estimated median cumulative annual disease burden complied with World Health Organization recommendations. Future studies are needed to validate the proposed threshold for use in Costa Rica and other regions.IMPORTANCE Effective wastewater management is crucial to ensure safe direct and indirect water reuse; nevertheless, few countries have adopted the virus log reduction value management approach established by the World Health Organization. In this study, we investigated an alternative and/or complementary approach to the virus log reduction value framework for the indirect reuse of activated sludge-treated wastewater effluent. Specifically, we employed a well-accepted statistical approach to identify a statistically sound somatic coliphage threshold value which corresponded to an increased likelihood of human enteric virus detection. This study demonstrates an alternative approach to the virus log reduction value framework which can be applied to improve wastewater reuse practices and effluent management.

Viral indicators for tracking domestic wastewater contamination in the aquatic environment

Waterborne enteric viruses are an emerging cause of disease outbreaks and represent a major threat to global public health. Enteric viruses may originate from human wastewater and can undergo rapid transport through aquatic environments with minimal decay. Surveillance and source apportionment of enteric viruses in environmental waters is therefore essential for accurate risk management. However, individual monitoring of the >100 enteric viral strains that have been identified as aquatic contaminants is unfeasible. Instead, viral indicators are often used for quantitative assessments of wastewater contamination, viral decay and transport in water. An ideal indicator for tracking wastewater contamination should be (i) easy to detect and quantify, (ii) source-specific, (iii) resistant to wastewater treatment processes, and (iv) persistent in the aquatic environment, with similar behaviour to viral pathogens. Here, we conducted a comprehensive review of 127 peer-reviewed publications, to critically evaluate the effectiveness of several viral indicators of wastewater pollution, including common enteric viruses (mastadenoviruses, polyomaviruses, and Aichi viruses), the pepper mild mottle virus (PMMoV), and gut-associated bacteriophages (Type II/III FRNA phages and phages infecting human Bacteroides species, including crAssphage). Our analysis suggests that overall, human mastadenoviruses have the greatest potential to indicate contamination by domestic wastewater due to their easy detection, culturability, and high prevalence in wastewater and in the polluted environment. Aichi virus, crAssphage and PMMoV are also widely detected in wastewater and in the environment, and may be used as molecular markers for human-derived contamination. We conclude that viral indicators are suitable for the long-term monitoring of viral contamination in freshwater and marine environments and that these should be implemented within monitoring programmes to provide a holistic assessment of microbiological water quality and wastewater-based epidemiology, improve current risk management strategies and protect global human health.

Seroprevalence of Torque Teno Virus in hemodialysis and renal transplant patients in Australia: A cross-sectional study

INTRODUCTION

Torque teno virus (TTV) is a non-pathogenic anellovirus commonly found in the blood of human beings. Emerging data suggest that TTV viral load is proportional to the degree of immunosuppression, but its seroprevalence is unknown in Australia. We aimed to determine the seroprevalence of TTV in an Australian population of renal patients.

METHODS

We developed a real-time PCR to measure TTV viral load, using the TaqMan platform and previously published primers and probes. Following ethics approval and informed consent, we collected blood from hemodialysis patients not receiving immunosuppression, and renal transplant patients. All patients were recruited from a single teaching hospital in New South Wales.

RESULTS

We enrolled 50 hemodialysis and 30 renal transplant patients. 56 (70%) were males, and the mean (sd) age was 61 (16) years. TTV was detectable in plasma of 40/50 (80%) of hemodialysis patients and 28/30 (93%) of transplant patients. The mean TTV viral load was higher in transplant patients than in dialysis patients (6.3 log versus 5.0 log copies/ml, P = .001).

CONCLUSIONS

Torque teno virus is prevalent in Australian renal patients and thus may be a useful novel marker to help tailor immunosuppressive therapy in renal transplant patients. Further work is needed to establish TTV seroprevalence in other regions and patient groups, and to investigate whether there is correlation with clinically important events (infection and rejection episodes) in longitudinal studies.

Viral and Bacterial Fecal Indicators in Untreated Wastewater across the Contiguous United States Exhibit Geospatial Trends

Cultivated fecal indicator bacteria such as Escherichia coli and enterococci are typically used to assess the sanitary quality of recreational waters. However, these indicators suffer from several limitations, such as the length of time needed to obtain results and the fact that they are commensal inhabitants of the gastrointestinal tract of many animals and have fate and transport characteristics dissimilar to pathogenic viruses. Numerous emerging technologies that offer same-day water quality results or pollution source information or that more closely mimic persistence patterns of disease-causing pathogens that may improve water quality management are now available, but data detailing geospatial trends in wastewater across the United States are sparse. We report geospatial trends of cultivated bacteriophage (somatic, F⁺, and total coliphages and GB-124 phage), as well as genetic markers targeting polyomavirus, enterococci, E. coli, Bacteroidetes, and human-associated Bacteroides spp. (HF183/BacR287 and HumM2) in 49 primary influent sewage samples collected from facilities across the contiguous United States. Samples were selected from rural and urban facilities spanning broad latitude, longitude, elevation, and air temperature gradients by using a geographic information system stratified random site selection procedure. Most indicators in sewage demonstrated a remarkable similarity in concentration regardless of location. However, some exhibited predictable shifts in concentration based on either facility elevation or local air temperature. Geospatial patterns identified in this study, or the absence of such patterns, may have several impacts on the direction of future water quality management research, as well as the selection of alternative metrics to estimate sewage pollution on a national scale.IMPORTANCE This study provides multiple insights to consider for the application of bacterial and viral indicators in sewage to surface water quality monitoring across the contiguous United States, ranging from method selection considerations to future research directions. Systematic testing of a large collection of sewage samples confirmed that crAssphage genetic markers occur at a higher average concentration than key human-associated Bacteroides spp. on a national scale. Geospatial testing also suggested that some methods may be more suitable than others for widespread implementation. Nationwide characterization of indicator geospatial trends in untreated sewage represents an important step toward the validation of these newer methods for future water quality monitoring applications. In addition, the large paired-measurement data set reported here affords the opportunity to conduct a range of secondary analyses, such as the generation of new or updated quantitative microbial risk assessment models used to estimate public health risk.

Microbiological contamination of conventional and reclaimed irrigation water: Evaluation and management measures

The wide diversity of irrigation water sources (i.e., drinking water, groundwater, reservoir water, river water) includes reclaimed water as a requested measure for increasing water availability, but it is also a challenge as pathogen exposure may increase. This study evaluates the level of microbial contamination in different irrigation waters to improve the knowledge and analyses management measures for safety irrigation. Over a one-year period, the occurrence of a set of viruses, bacteria and protozoa, was quantified and the performance of a wetland system, producing reclaimed water intended for irrigation, was characterized. Human fecal pollution (HAdV) was found in most of the irrigation water types analysed. Hepatitis E virus (HEV), an emerging zoonotic pathogen, was present in groundwater where porcine contamination was identified (PAdV). The skin-carcinoma associated Merkel cell polyomavirus (MCPyV), was found occasionally in river water. Noroviruses were detected, as expected, in winter, in river water and reclaimed water. Groundwater, river water and reservoir water also harboured potential bacterial pathogens, like Helicobacter pylori, Legionella spp. and Aeromonas spp. that could be internalized and viable inside amoebas like Acanthamoeba castellanii, which was also detected. Neither Giardia cysts, nor any Cryptosporidium oocysts were detected. The wetland system removed 3 Log10 of viruses and 5 Log10 of bacteria, which resembled the river water quality. Irrigation waters were prone to variable contamination levels and according to the European guidance documents, the E. coli (EC) levels were not always acceptable. Sporadic detection of viral pathogens as NoV GII and HAdV was identified in water samples presenting lower EC than the established limit (100MNP/100 mL). When dealing with reclaimed water as a source of irrigation the analysis of some viral parameters, like HAdV during the peak irrigation period (summer and spring) or NoV during the coldest months, could complement existing water management tools based on bacterial indicators.

Water reclamation and reuse

Literature published in 2018 pertinent to water reclamation and reuse has been classified into five topics: safe reuse, treatment technologies, management, assessment, and case studies. Researches have been conducted to develop new technologies and improve conventional treatments for achieving sustainable wastewater reclamation, and increasing efforts have been made to facilitate safe water reuse. PRACTITIONER POINTS: The way of publicity greatly influences people's acceptance of water reuse and willingness to purchase produce irrigated with recycled water. Integrated process is the most commonly used treatment technology to reclaim water. There is a lack of local or regional regulatory and policy for sustainable water management.

Performance of wastewater reclamation systems in enteric virus removal

Analysis of virus removal by tertiary or advanced sewage treatment processes is an emerging topic due to importance of reusing water on a global level. This study aimed to monitor important human viral pathogens: the human adenovirus (HAdV), JC polyomavirus (JCV) and Species A rotaviruses (RVA) in urban sewage, secondary effluents and reclaimed water from metropolitan São Paulo (MSP), Brazil. Four large wastewater treatment plants (WWTPs) in MSP were sampled monthly during a one-year period (April 2015 to March 2016). The viruses were quantified by quantitative PCR (qPCR), and HAdV viability was tested by the integrated cell culture (ICC)-qPCR assay. WWTPs are composed of activated sludge processes and different tertiary treatments (coagulation/sedimentation, sand-anthracite filters, membrane bioreactors (MBRs)/reverse osmosis (RO) and disinfection by chlorination). Physicochemical parameters were also evaluated to verify association with density of viruses detected in different treatment stages. HAdV, JCV and RVA were consistently detected (100%) in the sewage influent samples (range: 10⁶-10⁸ genome copies GC/L). In the secondary effluent, HAdV was detected in 100% (48/48) of the analysed samples, JCV in 85.4% and RVA in 97.9% (range: 10⁴-10⁷ GC/L for all viruses tested). HAdV was the most frequently detected virus in the tertiary effluent (62.2%) (28/45), exhibiting a viability between 0 and 44% of the tested samples in the wastewater reclamation systems. The MBR/RO systems demonstrated better virus removal efficiencies (range: 2.3-2.9 log₁₀). Temperature, pH, turbidity and total organic carbon presented association with the viral density in the reclaimed water samples. Presence of viruses in treated effluents can indicates health risks depending on uses of recovery water. Further risk assessment studies should be conducted to better assess health risks under different exposure scenarios for water recovery in urban settings.

Anaerobic submerged membrane bioreactor (AnSMBR) treating municipal wastewater at ambient temperature: Operation and potential use for agricultural irrigation

A 496 L pilot scale anaerobic submerged membrane bioreactor (AnSMBR) for the treatment of municipal wastewater was evaluated during a year of stable operation at ambient (28-10 °C) temperature, and inoculated with mesophilic inoculum. The temperature was the main parameter affecting the process performance. The chemical oxygen demand (COD) of the effluent was around 150 mg O₂/L in the summer period, operating with a volumetric loading rate (VLR) of 5 kg COD/m³ d and hydraulic retention time (HRT) of 8-10 h, with a specific methane production between 0.09 and 0.14 Nm³/kg COD_removed. However, during the winter season, an important increase of effluent COD was observed, and therefore the VLR was decreased to values around 1 kg COD/m³ d in order to recover the quality of the effluent. Biogas production was negligible in this period. The effluent complies with the parameters stipulated by Spanish law regarding the use of treated wastewater for agricultural irrigation.

Critical Evaluation of CrAssphage as a Molecular Marker for Human-Derived Wastewater Contamination in the Aquatic Environment

The discharge of human-derived wastewater represents a major threat to water quality with the potential for waterborne disease outbreaks mainly associated with enteric viruses. To prevent illnesses, indicators associated with fecal contamination are monitored in polluted areas, however, their prevalence often does not correlate well with viral pathogens. In this study, we used crAssphage, a recently discovered human-specific gut-associated bacteriophage, for the surveillance of wastewater-derived viral contamination. Untreated and treated wastewater, surface water, sediment and mussel samples were collected monthly over 1 year from the Conwy River and estuary (UK) and were analyzed for crAssphage marker by quantitative PCR. This is the first long-term catchment-to-coast scale study of environmental crAssphage concentrations. CrAssphage was detected in all sample types and showed no distinct seasonal pattern. CrAssphage concentrations were 2 × 105-109 genome copies (gc)/L in all untreated wastewater influent and 107-108 gc/L in secondary treated effluent samples, 3 × 103 gc/L-3 × 107 gc/L in surface water samples (94% positive) and 2 × 102-104 gc/g sediment (68% positive) and mussel digestive tissue (79% positive). CrAssphage concentrations were 1-5 log10 higher than human enteric virus titers (norovirus, sapovirus, adenovirus, polyomavirus). Our results indicate that crAssphage is well suited to tracking human wastewater contamination and pollution risk assessment in aquatic environments.

Microbial risk assessment in recreational freshwaters from southern Brazil

In this study, total coliforms (TC), Escherichia coli, enterovirus (EV), rotavirus (RV), and human mastadenovirus species C and F (HAdV-C and HAdV-F) were evaluated in water samples from Belo Stream. For HAdV-C and F, the infectivity was assessed by integrated cell culture quantitative real-time polymerase chain reaction (ICC-qPCR). Samples were collected monthly (May/2015 to April/2016) at four sites. Viral analyses were performed for both ultracentrifuge-concentrated and unconcentrated samples. For site P4 (used for recreational purposes), QMRA was applied to estimate health risks associated with exposure to E. coli and HAdV-C and F. TC and E. coli were present throughout the collection period. EV and RV were not detected. HAdV-C were present in 8.51% (1.89E + 06 to 2.28E + 07 GC (Genomic Copies)/L) and 21.27% (2.36E + 05 to 1.29E + 07 GC/L) for unconcentrated and concentrated samples, respectively. For HAdV-F were 12.76% (2.77E + 07 to 3.31E + 08 GC/L) and 48.93% (1.10E + 05 to 4.50E + 08 GC/L) for unconcentrated and concentrated samples, respectively. For unconcentrated samples, infectivity for HAdV-C was detected in 37.20% (1st ICC-qPCR) and 25.58% (2nd ICC-qPCR). For HAdV-F, infectivity was detected in 6.97% (1st ICC-qPCR) and 6.97% (2nd ICC-qPCR). For concentrated samples, HAdV-C infectious was observed in 17.02% (1st ICC-qPCR) and in 8.51% (2nd ICC-qPCR). For HAdV-F, were present in 8.51% for both 1st and 2nd ICC-qPCR. Statistical analyzes showed significant difference between the collection sites when analyzed the molecular data of HAdV-F, data of TC and E. coli. Correlation tests showed direct correlation between HAdV-F with E. coli and TC. E. coli concentrations translated to the lowest estimates of infection risks (8.58E-05 to 2.17E-03). HAdV-F concentrations were associated with the highest infection risks at 9.99E-01 and for group C, 1.29E-01 to 9.99E-01. These results show that commonly used bacterial indicators for water quality may not infer health risks associated with viruses in recreational freshwaters.

Noroviruses in raw sewage, secondary effluents and reclaimed water produced by sand-anthracite filters and membrane bioreactor/reverse osmosis system

The importance of noroviruses (NoVs) in the epidemiology of waterborne diseases has increased globally in the last decades. The present study aimed to monitor genogroup I and II noroviruses in different treatment stages of four wastewater treatment plants (WWTPs) in the metropolitan São Paulo. WWTPs consist of secondary (activated sludge) and tertiary treatments (coagulation, sand-anthracite filters, membrane bioreactor (MBR)/reverse osmosis (RO) and chlorination). Raw sewage (500mL) and treated effluents (1L) were concentrated by celite and reclaimed water (40L) by hollow-fiber ultrafiltration system. Quantitative (qPCR) and nested PCR with nucleotide sequencing were used for quantification and molecular characterization. NoVs were widely distributed in raw wastewater samples (83.3%-100% NoV GI and 91.6%-100% NoV GII) and viral loads varied from 3.8 to 6.66log₁₀gcL^-1 for NoV GI and 3.8 to 7.3log₁₀gcL^-1 for NoV GII. Mean virus removal efficiencies obtained for activated sludge processes ranged from 0.3 to 0.8 log₁₀ for NoV GI and 0.4 to 1.4 log₁₀ for NoV GII. NoVs were not detected in the reuse water produced by MBR/RO system, while sand-anthracite filters resulted in a NoV GI and GII decay of 1.1-1.6 log₁₀ and 0.7-1.6 log₁₀, respectively. A variety of genotypes (GI.2, GI.3a, GI.3b, GI.5, GII.1, GII.4 Sydney 2012, GII.5, GII.6, GII.17) was observed, with a predominance of GI.2 and GII.17 in the different genogroups. These results corroborate with recent data about the entry and dissemination of the emerging genotype GII.P17-GII.17 Kawasaki 2014 in the country, and may indicate a change in the epidemiological patterns of norovirus strains circulation in this region. This is the first large-scale study to evaluate burden and genotypes of noroviruses in WWTPs in Brazil, providing a rapid diagnosis of viruses circulating in the population.

Epidemiological Evidence and Health Risks Associated With Agricultural Reuse of Partially Treated and Untreated Wastewater: A Review

The use of partially treated and untreated wastewater for irrigation is beneficial in agriculture but may be associated with human health risks. Reports from different locations globally have linked microbial outbreaks with agricultural reuse of wastewater. This article reviews the epidemiological evidence and health risks associated with this practice, aiming toward evidence-based conclusions. Exposure pathways that were addressed in this review included those relevant to agricultural workers and their families, consumers of crops, and residents close to areas irrigated with wastewater (partially treated or untreated). A meta-analysis gave an overall odds ratio of 1.65 (95% CI: 1.31, 2.06) for diarrheal disease and 5.49 (95% CI: 2.49, 12.10) for helminth infections for exposed agricultural workers and family members. The risks were higher among children and immunocompromised individuals than in immunocompetent adults. Predominantly skin and intestinal infections were prevalent among individuals infected mainly via occupational exposure and ingestion. Food-borne outbreaks as a result of crops (fruits and vegetables) irrigated with partially or untreated wastewater have been widely reported. Contamination of crops with enteric viruses, fecal coliforms, and bacterial pathogens, parasites including soil-transmitted helminthes (STHs), as well as occurrence of antibiotic residues and antibiotic resistance genes (ARGs) have also been evidenced. The antibiotic residues and ARGs may get internalized in crops along with pathogens and may select for antibiotic resistance, exert ecotoxicity, and lead to bioaccumulation in aquatic organisms with high risk quotient (RQ). Appropriate mitigation lies in adhering to existing guidelines such as the World Health Organization wastewater reuse guidelines and to Sanitation Safety Plans (SSPs). Additionally, improvement in hygiene practices will also provide measures against adverse health impacts.

Seasonal and diurnal surveillance of treated and untreated wastewater for human enteric viruses

Understanding the abundance and fate of human viral pathogens in wastewater is essential when assessing the public health risks associated with wastewater discharge to the environment. Typically, however, the microbiological monitoring of wastewater is undertaken on an infrequent basis and peak discharge events may be missed leading to the misrepresentation of risk levels. To evaluate diurnal patterns in wastewater viral loading, we undertook 3-day sampling campaigns with bi-hourly sample collection over three seasons at three wastewater treatment plants. Untreated influent was collected at Ganol and secondary-treated effluent was sampled at Llanrwst and Betws-y-Coed (North Wales, UK). Our results confirmed the presence of human adenovirus (AdV), norovirus genotypes I and II (NoVGI and NoVGII) in both influent and effluent samples while sapovirus GI (SaVGI) was only detected in influent water. The AdV titre was high and relatively constant in all samples, whereas the NoVGI, NoVGII and SaVGI showed high concentrations during autumn and winter and low counts during the summer. Diurnal patterns were detected in pH and turbidity for some sampling periods; however, no such changes in viral titres were observed apart from slight fluctuations in the influent samples. Our findings suggest that viral particle number in wastewater is not affected by daily chemical fluctuations. Hence, a grab sample taken at any point during the day may be sufficient to enumerate the viral load of wastewater effluent within an order of magnitude while four samples a day are recommended for testing wastewater influent samples.