Release of infectious human enteric viruses by full-scale wastewater utilities

Effect of Human Adenovirus Type 35 Concentration on Its Inactivation and Sorption on Titanium Dioxide Nanoparticles

Removal of pathogenic viruses from water resources is critically important for sanitation and public health. Nanotechnology is a promising technology for virus inactivation. In this paper, the effects of titanium dioxide (TiO2) anatase nanoparticles (NPs) on human adenovirus type 35 (HAdV-35) removal under static and dynamic (with agitation) batch conditions were comprehensively studied. Batch experiments were performed at room temperature (25 °C) with and without ambient light using three different initial virus concentrations. The virus inactivation experimental data were satisfactorily fitted with a pseudo-first-order expression with a time-dependent rate coefficient. The experimental results demonstrated that HAdV-35 sorption onto TiO2 NPs was favored with agitation under both ambient light and dark conditions. However, no distinct relationships between virus initial concentration and removal efficiency could be established from the experimental data.

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.

Evaluation of virus removal in membrane bioreactor (MBR) and conventional activated sludge (CAS) processes based on long-term monitoring at two wastewater treatment plants

The membrane bioreactor (MBR) process always offers better wastewater treatment than conventional activated sludge (CAS) treatment. However, the difference in their efficacy of virus reduction remains unknown. To investigate this, we monitored virus concentrations before and after MBR and CAS processes over 2 years. Concentrations of norovirus genotypes I and II (NoV GI and GII), aichivirus (AiV), F-specific RNA phage genotypes I, II, and III (GI-, GII-, and GIII-FRNAPHs), and pepper mild mottle virus (PMMoV) were measured by a quantitative polymerase chain reaction (qPCR) method at two municipal wastewater treatment plants (WWTPs A and B) in Japan. Virus concentration datasets containing left-censored data were estimated by using both maximum likelihood estimation (MLE) and robust regression on order statistics (rROS) approaches. PMMoV was the most prevalent at both WWTPs, with median concentrations of 7.5 to 8.8 log10 copies/L before treatment. Log10 removal values (LRVs) of all viruses based on means and standard deviations of concentrations before and after treatment were consistently higher following MBR than following CAS. We used NoV GII as a model pathogen in a quantitative microbial risk assessment of the treated water, and we estimated the additional reductions required following MBR and CAS processes to meet the guideline of 10-6 DALYs pppy for safe wastewater reuse.

Portable, single nucleotide polymorphism-specific duplex assay for virus surveillance in wastewater

The Argonaute protein from the archaeon Pyrococcus furiosus (PfAgo) is a DNA-guided nuclease that targets DNA with any sequence. We designed a virus detection assay in which the PfAgo enzyme cleaves the reporter probe, thus generating fluorescent signals when amplicons from a reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assay contain target sequences. We confirmed that the RT-LAMP-PfAgo assay for the SARS-CoV-2 Delta variant produced significantly higher fluorescent signals (p < 0.001) when a single nucleotide polymorphism (SNP), exclusive to the Delta variant, was present, compared to the samples without the SNP. Additionally, the duplex assay for Pepper mild mottle virus (PMMOV) and SARS-CoV-2 detection produced specific fluorescent signals (FAM or ROX) only when the corresponding sequences were present. Furthermore, the RT-LAMP-PfAgo assay does not require dilution to reduce the impact of environmental inhibitors. The limit of detection of the PMMOV assay, determined with 30 wastewater samples, was 28 gc/μL, with a 95 % confidence interval of [11,103]. Finally, using a point-of-use device, the RT-LAMP-PfAgo assay successfully detected PMMOV in wastewater samples. Based on our findings, we conclude that the RT-LAMP-PfAgo assay can be used as a portable, SNP-specific duplex assay, which will significantly improve virus surveillance in wastewater.

Novel multiplexed alkali enzyme lysis coupled with EDTA pretreatment for RNA virus extraction from wastewater sludge: Optimization, recovery, and detection

RNA viruses are readily enriched in wastewater sludge owing to adsorption by extracellular polymeric substances (EPS) during wastewater treatment, causing pathogenicity. However, conventional wastewater extraction methods often fail to fully extract these viruses from sludge. In this study, three methods: enzymatic (ENP), alkaline (ALP), and ethylenediaminetetraacetic acid (EDTA) pretreatments were applied to sludges and promote the RNA virus extraction from sludge. Our results show that the total recovery rate of RNA viruses increased by 87.73% after ENP pretreatment, whereas ALP pretreatment inhibited virus extraction. The highest recovery rate of viruses from sludge, reaching 296.80%, was achieved with EDTA pretreatment (EDP) coupled with ENP. Notably, the most significant increase was observed in the abundance of Astroviruses, which increased from 7.60 × 107 to 7.86 × 108 copies/g TSS after EDP + ENP treatment. Our investigations revealed that virus extraction was affected by a class of short-wavelength protein substances, as opposed to tryptophan or tyrosine, which were eluted by proteins with beef paste buffer by substitution after EDP + ENP treatment. The results of this study provide essential insights for sludge-based epidemiology with the required sensitivity for managing the extraction of RNA epidemic viruses to control viral transmission.

SARS-CoV-2 removal in municipal wastewater treatment plants: Focus on conventional activated sludge, membrane bioreactor and anaerobic digestion

This work focuses on the removal of SARS-CoV-2 RNA in the various stages of a full-scale municipal WWTP characterised by two biological processes in parallel: (i) conventional activated sludge (CAS) and (ii) membrane bioreactor (MBR). The monitoring was carried out during the Omicron wave in 2022, a period characterised by a high concentration of SARS-CoV-2 in influent wastewater. The average concentration of SARS-CoV-2 in influent wastewater was 3.7 × 104 GU/L. In the primary sedimentation, the removal of SARS-CoV-2 was not appreciable. The largest log removal value of SARs-CoV-2 occurred in the biological stages, with 1.8 ± 0.9 and 2.2 ± 0.7 logs in CAS and MBR systems. The mean concentrations of SARS-CoV-2 in the CAS and MBR effluents were 6.8 × 102 GU/L and 6.4 × 102 GU/L, respectively. The MBR effluent showed more negative samples, because small particles are retained by membrane and cake layer. The analysis of the different types of sludge confirmed the accumulation of SARS-CoV-2 in primary (5.2 × 104 GU/L) and secondary sludge (3.5 × 104 GU/L), due to the affinity of enveloped viruses towards biosolids. A SARS-CoV-2 concentration in the digested sludge equal to 4.8 × 104 GU/L denotes a negligible reduction in the mesophilic anaerobic digester at temperature of 31-33 °C.

Reduction of SARS-CoV-2 by biological nutrient removal and disinfection processes in full-scale wastewater treatment plants

Detection of SARS-CoV-2 RNA in wastewater poses people's concerns regarding the potential risk in water bodies receiving wastewater treatment effluent, despite the infectious risk of SARS-CoV-2 in wastewater being speculated to be low. Unlike well-studied nonenveloped viruses, SARS-CoV-2 in wastewater is present abundantly in both solid and liquid fractions of wastewater. Reduction of SARS-CoV-2 in past studies were likely underestimated, as SARS-CoV-2 in influent wastewater were quantified in either solid or liquid fraction only. The objectives of this study were (i) to clarify the reduction in SARS-CoV-2 RNA during biological nutrient removal and disinfection processes in full-scale WWTPs, considering the SARS-CoV-2 present in both solid and liquid fractions of wastewater, and (ii) to evaluate applicability of pepper mild mottle virus (PMMoV) as a performance indicator for reduction of SARS-CoV-2 in WWTPs. Accordingly, large amount of SARS-CoV-2 RNA were partitioned in the solid fraction of influent wastewater for composite sampling than grab sampling. When SARS-CoV-2 RNA in the both solid and liquid fractions were considered, log reduction values (LRVs) of SARS-CoV-2 during step-feed multistage biological nitrogen removal (SM-BNR) and enhanced biological phosphorus removal (EBPR) processes ranged between>2.1-4.4 log and did not differ significantly from those in conventional activated sludge (CAS). The LRVs of SARS-CoV-2 RNA in disinfection processes by ozonation and chlorination did not differ significantly. PMMoV is a promising performance indicator to secure reduction of SARS-CoV-2 in WWTPs, because of its higher persistence in wastewater treatment processes and abundance at a detectable concentration even in the final effluent after disinfection.

SARS-CoV-2 in the environment: Contamination routes, detection methods, persistence and removal in wastewater treatment plants

The present study reviewed the occurrence of SARS-CoV-2 RNA and the evaluation of virus infectivity in feces and environmental matrices. The detection of SARS-CoV-2 RNA in feces and wastewater samples, reported in several studies, has generated interest and concern regarding the possible fecal-oral route of SARS-CoV-2 transmission. To date, the presence of viable SARS-CoV-2 in feces of COVID-19 infected people is not clearly confirmed although its isolation from feces of six different patients. Further, there is no documented evidence on the infectivity of SARS-CoV-2 in wastewater, sludge and environmental water samples, although the viral genome has been detected in these matrices. Decay data revealed that SARS-CoV-2 RNA persisted longer than infectious particle in all aquatic environment, indicating that genome quantification of SARS-CoV-2 does not imply the presence of infective viral particles. In addition, this review also outlined the fate of SARS-CoV-2 RNA during the different steps in the wastewater treatment plant and focusing on the virus elimination along the sludge treatment line. Studies showed complete removal of SARS-CoV-2 during the tertiary treatment. Moreover, thermophilic sludge treatments present high efficiency in SARS-CoV-2 inactivation. Further studies are required to provide more evidence with respect to the inactivation behavior of infectious SARS-CoV-2 in different environmental matrices and to examine factors affecting SARS-CoV-2 persistence.

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.

Boronic acid-modified bacterial cellulose microspheres as packing materials for enveloped virus removal

Viruses are the most abundant microorganisms on the earth, their existence in contaminated waters possesses a significant threat to humans. Waterborne viral infections could be fatal to sensitive population including young child, the elderly, and the immune-compromised. It is imperative to remove viruses during water treatment to better protect public health, especially in the light of evidence of detection of coronaviruses genetic fragments in raw sewage. We reported bench-scale experiments evaluating the extent and mechanisms of removal of a model virus (spring viremia of carp virus, SVCV) in water by adsorption. Microspheres made by boronic acid-modified bacterial cellulose with excellent mechanical strength were successfully fabricated as packing materials for the column to remove glycoproteins and enveloped viruses from water. The synthesized adsorbent was characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Brunauer Emmett Teller (BET) measurement. The adsorption efficiency of glycoproteins was investigated by SDS-PAGE and the Broadford protein assay, while the binding capacity with the virus (spring viremia of carp virus) was monitored by cell culture to calculate the viral cytopathic effect and viral titer caused by the virus. The data obtained from the above experiments showed that ∼3-log removal of SVCV in 3 h, which significantly reduced the virus concentration from microspheres packed column. The present study provides substantial evidence to prove beyond doubt that material based on bacterial cellulose seems to have the potential for virus removal from water which can be extended to systems of significant importance.

Occurrence of Hepatitis A Virus in Water Matrices: A Systematic Review and Meta-Analysis

Hepatitis A is a common form of viral hepatitis. It is usually transmitted through the ingestion of contaminated food and water. This systematic review was carried out to summarise the overall prevalence of Hepatitis A virus (HAV) in different water matrices: untreated and treated wastewater, surface water, groundwater, drinking water, and others (e.g., irrigation water and floodwater). The literature search was performed in four databases: PubMed, Web of Science, Global Index Medicus, and Excerpta Medica Database. Heterogeneity (I2) was assessed using the χ2 test on the Cochran Q statistic and H parameters. A total of 200 prevalence data from 144 articles were included in this meta-analysis. The overall prevalence of HAV in water matrices was 16.7% (95% CI: 13.4−20.3). The prevalence for individual matrix was as follows: 31.4% (95% CI: 23.0−40.4) untreated wastewater, 18.0% (95% CI: 9.5−28.2) treated wastewater, 15.0% (95% CI: 10.1−20.5) surface water, 2.3% (95% CI: 0.1−6.0) in groundwater, 0.3% (95% CI: 0.0−1.7) in drinking water, and 8.5% (95% CI: 3.1−15.6) in other matrices. The prevalence was higher in low-income economies (29.0%). Africa and Eastern Mediterranean were the regions with higher HAV prevalence values. This study showed a high heterogeneity (I2 > 75%) with a significant publication bias (p value Egger test < 0.001). The results of this review suggest that water matrices could be an important route of HAV transmission even in industrialized countries, despite the lower prevalence compared to less industrialized countries, and the availability of advanced water management systems. More effective water/wastewater treatment strategies are needed in developing countries to limit the environmental circulation of HAV.

Binding, recovery, and infectiousness of enveloped and non-enveloped viruses associated with plastic pollution in surface water

Microplastics in wastewater and surface water rapidly become colonised by microbial biofilm. Such 'plastisphere' communities are hypothesised to persist longer and be disseminated further in the environment and may act as a vector for human pathogens, particularly as microplastics entering wastewater treatment plants are exposed to high concentrations of pathogenic bacteria. However, the potential for human viral pathogens to become associated with the plastisphere has never before been quantified. Here, we have used rotavirus (RV) SA11 (a non-enveloped enteric virus) and the enveloped bacteriophage Phi6 as model viruses to quantify binding and recovery from biofilm-colonised microplastic pellets in three different water treatments (filtered and non-filtered surface water, and surface water with added nutrients). Viruses associated with biofilm-colonised pellets were more stable compared to those remaining in the water. While infectious particles and genome copies of RV remained stable over the 48 h sampling period, Phi6 stability was highly impacted, with a reduction ranging from 2.18 to 3.94 log₁₀. Virus particles were protected against inactivation factors when associated with the biofilm on microplastic surfaces, and when there was a high concentration of particulate matter in the liquid phase. Although our results suggest that the presence of an envelope may limit virus interaction with the plastisphere, the ability to recover both enveloped and non-enveloped infectious viruses from colonised microplastic pellets highlights an additional potential public health risk of surface waters becoming contaminated with microplastics, and subsequent human exposure to microplastics in the environment.

Disinfection of corona and myriad viruses in water by non-thermal plasma: a review

Nowadays, in parallel to the appearance of the COVID-19 virus, the risk of viruses in water increases leading to the necessity of developing novel disinfection methods. This review focuses on the route of virus contamination in water and introduces non-thermal plasma technology as a promising method for the inactivation of viruses. Effects of essential parameters affecting the non-thermal discharge for viral inactivation have been exposed. The review has also illustrated a critical discussion of this technology with other advanced oxidation processes. Additionally, the inactivation mechanisms have also been detailed based on reactive oxygen and nitrogen species.

Occurrence of SARS-CoV-2 in excreta, sewage, and environment: epidemiological significance and potential risks

The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patients' excreta raises the issue of its occurrence and fate in sewage. This review has focused on the presence of the SARS-CoV-2 in human excreta, wastewater, sewage sludge, and river waters. It explored the potential use of the wastewater-based epidemiology approach to report on the situation of current and eventual future SARS-CoV-2 outbreaks. The main concern of the occurrence of SARS-CoV-2 in the environment is the public health risks at sites of sewage products disposal and reuse, especially in low-income countries with inadequate sanitation, where direct discharge and reuse of raw sewage are common practices. The review also addressed the role sewage-irrigated agriculture can have in SARS-CoV-2 spread in the environmental compartments reached through sewage products application. An overview was made on the interest of sewage management, water safety, and hygienic practices for controlling the environmental dissemination of SARS-CoV-2.

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.

Coronaviruses and SARS-CoV-2 in sewerage and their removal: Step by step in wastewater treatment plants

The fate of Coronaviruses (CoVs) and in particular SARS-CoV-2 in wastewater treatment plants (WWTPs) has not been completely understood yet, but an adequate knowledge on the removal performances in WWTPs could help to prevent waterborne transmission of the virus that is still under debate. CoVs and SARS-CoV-2 are discharged from faeces into the sewer network and reach WWTPs within a few hours. This review presents the fate of SARS-CoV-2 and other CoVs in the primary, secondary and tertiary treatments of WWTPs as well as in sludge treatments. The viral loads decrease progressively along with the treatments from 20 to 3.0E+06 GU/L (Genomic Units/L) in the influent wastewater to concentrations below 2.50E+05 GU/L after secondary biological treatments and finally to negative concentrations (below detection limit) in disinfected effluents. Reduction of CoVs is due to (i) natural decay under unfavourable conditions (solids, microorganisms, temperature) for relatively long hydraulic retention times and (ii) processes of sedimentation, filtration, predation, adsorption, disinfection. In primary and secondary settling, due to the hydrophobic properties, a partial accumulation of CoVs may occur in the separated sludge. In secondary treatment (i.e. activated sludge) CoVs and SARS-CoV-2 loads can be reduced only by about one logarithm (∼90%). To enhance this removal, tertiary treatment with ultrafiltration (Membrane Bioreactors) and chemical disinfection or UV light is needed. CoVs and SARS-CoV-2 in the sludge (1.2E+04-4.6E+08 GU/L) can be inactivated significantly in the thermophilic digestion (55 °C), while mesophilic temperatures (33-37 °C) are not efficient. Additional studies are required to investigate the infectivity of SARS-CoV-2 in WWTPs, especially in view of increasing interest in wastewater reclamation and reuse.

Microbial characteristics of municipal solid waste compost: Occupational and public health risks from surface applied compost

Land application of MSW compost promotes the soil fertility and productivity, but there is concern about its chemical and microbial quality. Although, current microbial indicators of MSW compost are generally considered to be protective of human health, the use of these indicators doesn't adequately represent the presence of pathogens that might be more resistant to inactivation during composting process. This work aims evaluation of the microbial characteristics of MSW compost and estimation of the health risks associated with exposure to pathogens of potential concern in MSW compost. Although the recommended standards for fecal coliforms and Salmonella were met in a relatively high percentage of samples, there were detectable levels of microbial pathogens. The highest daily infection risk was estimated for Cryptosporidium (1.25 × 10^-3 per person) followed by Salmonella and Campylobacter, while the lowest related to adenovirus. Infection risks were low for both farmers and children in one-time exposure and all pathogen risks were decreased with increasing waiting time to near insignificant levels. However, the median annual risk of cryptosporidiosis or gastroenteritis was above the recommended value of 10^-3 per person per year. Because of potential presence of pathogens in MSW compost, some level of pathogen monitoring beyond conventional indicators may be required to estimate potential risks. The findings of this study could provide information to governments and local authorities in making decisions on measures to reduce risk from application of MSW compost. Further research is needed to obtain the reliable information about the inactivation of microorganisms in environment.

Distributions of waterborne pathogens in raw wastewater based on a 14-month, multi-site monitoring campaign

The California State Water Resources Control Board is the first regulatory body in the United States to develop statewide regulations for direct potable reuse (DPR). To support this effort, a pathogen monitoring campaign was undertaken to develop and implement an optimized standard operating protocol to better characterize the concentration of human pathogens in raw wastewater. Methods to detect relevant viral and protozoan pathogens in raw wastewater were optimized and implemented during a 14-month monitoring campaign. Over 120 samples were collected from five wastewater treatment plants treating a quarter of California's population. Samples were analyzed for two protozoa (Cryptosporidium and Giardia) using microscopy methods, three enteric viruses (enterovirus, adenovirus, and norovirus) using culture and/or molecular methods, and male-specific coliphage using culture methods. The method recovery efficiency was measured in every protozoa sample and every other virus sample to confirm minimum recovery efficiencies were achieved and to correct the concentrations for pathogen losses during sample processing. The results from this study provide the industry with a large, high-quality dataset as demonstrated by the high degree of method sensitivity, method recovery, and QA/QC steps. Such high-quality data on pathogen concentrations in raw wastewater are critical for confirming the level of treatment needed to reduce pathogen concentrations down to acceptable levels for potable water in DPR projects.

Monitoring Human Viral Pathogens Reveals Potential Hazard for Treated Wastewater Discharge or Reuse

Wastewater discharge to the environment or its reuse after sanitization poses a concern for public health given the risk of transmission of human viral diseases. However, estimating the viral infectivity along the wastewater cycle presents technical challenges and still remains underexplored. Recently, human-associated crAssphage has been investigated to serve as viral pathogen indicator to monitor fecal impacted water bodies, even though its assessment as biomarker for infectious enteric viruses has not been explored yet. To this end, the occurrence of potentially infectious norovirus genogroup I (GI), norovirus GII, hepatitis A virus (HAV), rotavirus A (RV), and human astrovirus (HAstV) along with crAssphage was investigated in influent and effluent water sampled in four wastewater treatment plants (WWTPs) over 1 year by a PMAxx-based capsid integrity RT-qPCR assay. Moreover, influent and effluent samples of a selected WWTP were additionally assayed by an in situ capture RT-qPCR assay (ISC-RT-qPCR) as estimate for viral infectivity in alternative to PMAxx-RT-qPCR. Overall, our results showed lower viral occurrence and concentration assessed by ISC-RT-qPCR than PMAxx-RT-qPCR. Occurrence of potentially infectious enteric virus was estimated by PMAxx-RT-qPCR as 88–94% in influent and 46–67% in effluent wastewaters with mean titers ranging from 4.77 to 5.89, and from 3.86 to 4.97 log₁₀ GC/L, with the exception of HAV that was sporadically detected. All samples tested positive for crAssphage at concentration ranging from 7.41 to 9.99 log₁₀ GC/L in influent and from 4.56 to 6.96 log₁₀ GC/L in effluent wastewater, showing higher mean concentration than targeted enteric viruses. Data obtained by PMAxx-RT-qPCR showed that crAssphage strongly correlated with norovirus GII (ρ = 0.67, p < 0.05) and weakly with HAstV and RV (ρ = 0.25–0.30, p < 0.05) in influent samples. In effluent wastewater, weak (ρ = 0.27–0.38, p < 0.05) to moderate (ρ = 0.47–0.48, p < 0.05) correlations between crAssphage and targeted viruses were observed. Overall, these results corroborate crAssphage as an indicator for fecal contamination in wastewater but a poor marker for either viral occurrence and viral integrity/infectivity. Despite the viral load reductions detected in effluent compared to influent wastewaters, the estimates of viral infectivity based on viability molecular methods might pose a concern for (re)-using of treated water.

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.

Decreased levels and ecological risks of disinfection by-product chloroform in a field-scale artificial groundwater recharge project by colloid supplement

To bolster freshwater supply, artificial groundwater recharge with recycled water has increasingly attracted research attentions and interests. However, artificial groundwater recharge has potential risks to groundwater quality, as recharge water disinfection is frequently used for pathogen inactivation and causes the concerns of disinfection by-products (DBPs). Colloid supplement is a good approach solving this problem, but its roles in mitigating DBPs remains unclear. In this study, we collected 20 groundwater and soil samples from a field-scale groundwater recharge project, and explored the impacts of silica colloids on chloroform migration and groundwater bacterial communities during the recharge process. Water physicochemical variables changed along the recharge time, and colloid supplement significantly reduced chloroform formation and slowed its migration in groundwater. Bacterial communities in groundwater, river water and recharge water were significantly different. Gammaproteobacteria in recharge water (71.7%) was more abundant than in river water (30.5%) and groundwater (33.5%), while Actinobacteria dominated groundwater (40.6%). After recharge, Gammaproteobacteria increased more with colloid supplement (75.7%) than without (52.6%), attributing to its dominance in soils (74.6%). Our results suggested more bacterial lineages released from soils into aquifer by silica colloid supplement, owing to the competitive adsorption encouraging microbial transfer, especially Gram-negative bacteria. Our findings unraveled the effects of colloid supplement on chloroform formation and migration during artificial groundwater recharge, which consequently altered groundwater bacterial communities, and offered valuable suggestions for the safety management of DBPs in aquifer recharge.

Inactivation and risk control of pathogenic microorganisms in municipal sludge treatment: A review

The rapid global spread of coronavirus disease 2019 (COVID-19) has promoted concern over human pathogens and their significant threats to public health security. The monitoring and control of human pathogens in public sanitation and health facilities are of great importance. Excessive sludge is an inevitable byproduct of sewage that contains human and animal feces in wastewater treatment plants (WWTPs). It is an important sink of different pollutants and pathogens, and the proper treatment and disposal of sludge are important to minimize potential risks to the environment and public health. However, there is a lack of comprehensive analysis of the diversity, exposure risks, assessment methods and inactivation techniques of pathogenic microorganisms in sludge. Based on this consideration, this review summarizes the control performance of pathogenic microorganisms such as enterovirus, Salmonella spp., and Escherichia coli by different sludge treatment technologies, including composting, anaerobic digestion, aerobic digestion, and microwave irradiation, and the mechanisms of pathogenic microorganism inactivation in sludge treatment processes are discussed. Additionally, this study reviews the diversity, detection methods, and exposure risks of pathogenic microorganisms in sludge. This review advances the quantitative assessment of pathogenic microorganism risks involved in sludge reuse and is practically valuable to optimize the treatment and disposal of sludge for pathogenic microorganism control.

Comparative effectiveness of membrane technologies and disinfection methods for virus elimination in water: A review

The pandemic of the 2019 novel coronavirus disease (COVID-19) has brought viruses into the public horizon. Since viruses can pose a threat to human health in a low concentration range, seeking efficient virus removal methods has been the research hotspots in the past few years. Herein, a total of 1060 research papers were collected from the Web of Science database to identify technological trends as well as the research status. Based on the analysis results, this review elaborates on the state-of-the-art of membrane filtration and disinfection technologies for the treatment of virus-containing wastewater and drinking water. The results evince that membrane and disinfection methods achieve a broad range of virus removal efficiency (0.5-7 log reduction values (LRVs) and 0.09-8 LRVs, respectively) that is attributable to the various interactions between membranes or disinfectants and viruses having different susceptibility in viral capsid protein and nucleic acid. Moreover, this review discusses the related challenges and potential of membrane and disinfection technologies for customized virus removal in order to prevent the dissemination of the waterborne diseases.

Capacity of existing wastewater treatment plants to treat SARS-CoV-2. A review

Water is one of many viral transmission routes, and the presence of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) in wastewater has brought attention to its treatment. SARS CoV-2 primarily transmits in the air but the persistence of the virus in the water possibly can serve as a secondary source even though current studies do not show this. In this paper, an evaluation of the current literature with regards to the treatment of SARS-CoV-2 in wastewater treatment plant (WWTP) effluents and biosolids is presented. Treatment efficiencies of WWTPs are compared for viral load reduction on the basis of publicly available data. The results of this evaluation indicate that existing WWTPs are effectively removing 1-6 log10 viable SARS-CoV-2. However, sludge and biosolids provide an umbrella of protection from treatment and inactivation to the virus. Hence, sludge treatment factors like high temperature, pH changes, and predatory microorganisms can effectively inactivate SARS-CoV-2.

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.

Coliphages as a Complementary Tool to Improve the Management of Urban Wastewater Treatments and Minimize Health Risks in Receiving Waters

Even in countries with extensive sanitation systems, outbreaks of waterborne infectious diseases are being reported. Current tendencies, such as the growing concentration of populations in large urban conurbations, climate change, aging of existing infrastructures, and emerging pathogens, indicate that the management of water resources will become increasingly challenging in the near future. In this context, there is an urgent need to control the fate of fecal microorganisms in wastewater to avoid the negative health consequences of releasing treated effluents into surface waters (rivers, lakes, etc.) or marine coastal water. On the other hand, the measurement of bacterial indicators yields insufficient information to gauge the human health risk associated with viral infections. It would therefore seem advisable to include a viral indicator—for example, somatic coliphages—to monitor the functioning of wastewater treatments. As indicated in the studies reviewed herein, the concentrations of somatic coliphages in raw sewage remain consistently high throughout the year worldwide, as occurs with bacterial indicators. The removal process for bacterial indicators and coliphages in traditional sewage treatments is similar, the concentrations in secondary effluents remaining sufficiently high for enumeration, without the need for cumbersome and costly concentration procedures. Additionally, according to the available data on indicator behavior, which is still limited for sewers but abundant for surface waters, coliphages persist longer than bacterial indicators once outside the gut. Based on these data, coliphages can be recommended as indicators to assess the efficiency of wastewater management procedures with the aim of minimizing the health impact of urban wastewater release in surface waters.

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.

Bidirectional association between COVID-19 and the environment: A systematic review

The global crisis caused by SARS-CoV-2 (COVID-19) affected economics, social affairs, and the environment, not to mention public health. It is estimated that near 82% of the SARS-CoV-2 genome is similar to the severe acute respiratory syndrome. The purpose of the review is to highlight how the virus is impacted by the environment and how the virus has impacted the environment. This review was based on an electronic search of the literature in the Scopus, Science Direct, and PubMed database published from December 2019 to July 2020 using combinations of the following keywords: SARS-CoV-2 transmission, COVID-19 transmission, coronavirus transmission, waterborne, wastewater, airborne, solid waste, fomites, and fecal-oral transmission. Studies suggest the thermal properties of ambient air, as well as relative humidity, may affect the transmissibility and viability of the virus. Samples taken from the wastewater collection network were detected contaminated with the novel coronavirus; consequently, there is a concern of its transmission via an urban sewer system. There are concerns about the efficacy of the wastewater treatment plant disinfection process as the last chance to inactivate the virus. Handling solid waste also requires an utmost caution as it may contain infectious masks, etc. Following the PRISMA approach, among all reviewed studies, more than 36% of them were directly or indirectly related to the indoor and outdoor environment, 16% to meteorological factors, 11% to wastewater, 14% to fomites, 8% to water, 9% to solid waste, and 6% to the secondary environment. The still growing body of literature on COVID-19 and air, suggests the importance of SARS-CoV-2 transmission via air and indoor air quality, especially during lockdown interventions. Environmental conditions are found to be a factor in transmitting the virus beyond geographical borders. Accordingly, countries need to pay extra attention to sustainable development themes and goals.

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.

Levels of human Rotaviruses and Noroviruses GII in urban rivers running through the city mirror their infection prevalence in populations

Enteric viruses exposed to water pose a huge threat to global public health and can lead to waterborne disease outbreaks. A sudden increase in enteric viruses in some water matrices also underpins the prevalence of corresponding waterborne diseases in communities over the same time period. However, few efforts have been focused on water matrices whose viral pollution may best reflect the clinical prevalence in communities. Here, a one-year surveillance of human enteric viruses including Enteroviruses (EnVs), Rotaviruses (HRVs), Astroviruses (AstVs), Noroviruses GII (HuNoVsGII) and Mastadenoviruses (HAdVs) in four representative water matrices: an urban river (UR) running through city, effluent from Wastewater Treatment Plant (EW), raw water for Urban Water Treatment Plant (RW), and tap water (TW) were performed by qPCR. The relationship between the virus detection frequency at each site and their prevalence in clinical PCR assay was further analyzed. We found that the detection frequencies of HRVs, HuNoVsGII, and AstVs in stools peaked in winter, while EnVs peaked in autumn. No EnVs occurred in EW, RW, or TW, but HuNoVsGII and AstVs occurred intensively in winter. For UR, all types of enteric viruses could be detected and the levels of acute gastroenteritis viruses (HRVs, HuNoVsGII, AstVs, and HAdVs) were highest in autumn or winter, whereas EnVs peaked in summer. In terms of correlation analyses, only HRVs and HuNoVsGII levels in UR showed a strong positive correlation with their prevalence in clinical stool samples. This study indicated that HRVs and HuNoVsGII levels in URs may mirror the local virus prevalence, thereby implying the possibility of revealing their local epidemiology by monitoring them in the URs.

Occurrence, fate and removal of SARS-CoV-2 in wastewater: Current knowledge and future perspectives

The coronavirus disease 2019 (COVID-19), a pandemic of global concern, is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Recently, many studies have documented the detection of SARS-CoV-2 in human excreta and wastewater. The presence of SARS-CoV-2 in human excreta and wastewater poses serious implications for wastewater treatment. Thus, this review aims to understand the fate of SARS-CoV-2 in the urban water cycle and its inactivation in different stages of treatment in wastewater treatment plants (WWTPs) for effective control to prevent any recurrence of the outbreak. The viral load of SARS-CoV-2 in feces of individuals tested positive has been reported to be in the range of 104-108 copies/L depending on the infection stages. In the wastewater, dilution of feces results in the decrease of the viral load in the range of 102-106.5 copies/L. Monitoring of SARS-CoV-2 in WWTP samples following the wastewater-based epidemiology (WBE) can complement real epidemiological data from clinical testing to help to monitor disease outbreaks in a community. Though promising, high uncertainty involved with the WBE technique warrants further research for reliable and quantitative information. Inactivation of SARS-CoV-2 in WWTPs depends on the operational parameters and is generally enhanced by the tertiary treatment and disinfection techniques with a higher dosage. However, the risk of SARS-CoV-2 dissemination by the treated effluent intended to be disposed of or reused in the urban water cycle needs to be assessed with respect to the extent of viral infectivity.

Tracking COVID-19 via sewage

PURPOSE OF REVIEW

We discuss the potential role of the faecal chain in COVID-19 and highlight recent studies using waste water-based epidemiology (WBE) to track severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

RECENT FINDINGS

WBE has been suggested as an adjunct to improve disease surveillance and aid early detection of circulating disease. SARS-CoV-2, the aetiological agent of COVID-19, is an enveloped virus, and as such, typically not associated with the waste water environment, given high susceptibility to degradation in aqueous conditions. A review of the current literature supports the ability to detect of SARS-CoV-2 in waste water and suggests methods to predict community prevalence based on viral quantification.

SUMMARY

The summary of current practices shows that while the isolation of SARS-CoV-2 is possible from waste water, issues remain regarding the efficacy of virial concentration and subsequent quantification and alignment with epidemiological data.

Variations among Viruses in Influent Water and Effluent Water at a Wastewater Plant over One Year as Assessed by Quantitative PCR and Metagenomics

Influent wastewater and effluent wastewater at the Rya treatment plant in Gothenburg, Sweden, were continuously monitored for enteric viruses by quantitative PCR (qPCR) during 1 year. Viruses in effluent wastewater were also identified by next-generation sequencing (NGS) in samples collected during spring, early summer, and winter. Samples of incoming wastewater were collected every second week. Seasonal variations in viral concentrations in incoming wastewater were found for noroviruses GII, sapovirus, rotavirus, parechovirus, and astrovirus. Norovirus GI and GIV and Aichi virus were present in various amounts during most weeks throughout the year, while hepatitis A virus, enterovirus, and adenovirus were identified less frequently. Fluctuations in viral concentrations in incoming wastewater were related to the number of diagnosed patients. The viruses were also detected in treated wastewater, however, with a 3- to 6-log₁₀ reduction in concentration. Seven different hepatitis E virus (HEV) strains were identified in the effluents. Five of these strains belonged to genotype 3 and have been isolated in Sweden from swine, wild boars, and humans and in drinking water. The other two strains were divergent and had not been identified previously. They were similar to strains infecting rats and humans. Surveillance of enteric viruses in wastewater is a tool for early detection and follow-up of gastroenteritis outbreaks in society and for the identification of new viruses that can cause infection in humans.IMPORTANCE Both influent wastewater and treated wastewater at a wastewater treatment plant (WWTP) contain a high variety of human viral pathogens with seasonal variability when followed for 1 year. The peak of the amount of 11 different viruses in the inlet wastewater preceded the peak of the number of diagnosed patients by 2 to 4 weeks. The treatment of wastewater reduced viral concentrations by 3 to 6 log₁₀ Despite the treatment of wastewater, up to 5 log₁₀ virus particles per liter were released from into the surrounding river. Hepatitis E virus (HEV) strains previously identified in drinking water and two new strains, similar to those infecting rats and humans, were identified in the treated wastewater released from the WWTP.

SARS-CoV-2 from faeces to wastewater treatment: What do we know? A review

SARS-CoV-2, the virus that causes COVID-19, has been found in the faeces of infected patients in numerous studies. Stool may remain positive for SARS-CoV-2, even when the respiratory tract becomes negative, and the interaction with the gastrointestinal tract poses a series of questions about wastewater and its treatments. This review aims to understand the viral load of SARS-CoV-2 in faeces and sewage and its fate in wastewater treatment plants (WWTPs). The viral load in the faeces of persons testing positive for SARS-CoV-2 was estimated at between 5·103 to 107.6 copies/mL, depending on the infection course. In the sewerage, faeces undergo dilution and viral load decreases considerably in the wastewater entering a WWTP with a range from 2 copies/100 mL to 3·103 copies/mL, depending on the level of the epidemic. Monitoring of SARS-CoV-2 in sewage, although no evidence of COVID-19 transmission has been found via this route, could be advantageously exploited as an early warning of outbreaks. Preliminary studies on WBE seem promising; but high uncertainty of viral loads in wastewater and faeces remains, and further research is needed. The detection of SARS-CoV-2 in sewage, based on RNA sequences and RT-PCR, requires a shared approach on sample pre-treatment and on-site collection to ensure comparable results. The finding of viral RNA in stools does not imply that the virus is viable and infectious. Viability of CoVs such as SARS-CoV-2 decreases in wastewater - due to temperature, pH, solids, micropollutants - but high inactivation in WWTPs can be obtained only by using disinfection (free chlorine, UVC light). A reduction in the quantity of disinfectants can be obtained by implementing Membrane-Bioreactors with ultrafiltration to separate SARS-CoV-2 virions with a size of 60-140 nm. In sludge treatment, thermophilic digestion is effective, based on the general consensus that CoVs are highly sensitive to increased temperatures.

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.

Spillover of SARS-CoV-2 into novel wild hosts in North America: A conceptual model for perpetuation of the pathogen

There is evidence that the current outbreak of the novel coronavirus SARS-CoV-2, which causes COVID-19, is of animal origin. As with a number of zoonotic pathogens, there is a risk of spillover into novel hosts. Here, we propose a hypothesized conceptual model that illustrates the mechanism whereby the SARS-CoV-2 could spillover from infected humans to naive wildlife hosts in North America. This proposed model is premised on transmission of SARS-CoV-2 from human feces through municipal waste water treatment plants into the natural aquatic environment where potential wildlife hosts become infected. We use the existing literature on human coronaviruses, including SARS CoV, to support the potential pathways and mechanisms in the conceptual model. Although we focus on North America, our conceptual model could apply to other parts of the globe as well.

Profile of the Spatial Distribution Patterns of the Human and Bacteriophage Virome in a Wastewater Treatment Plant Located in the South of Spain

In wastewater treatment plants, most microbial characterization has focused on bacterial, archaeal, and fungal populations. Due to the difficult isolation, quantification, and identification of viruses, only a limited number of virome studies associated with wastewater treatment plants have been carried out. However, the virus populations play an important role in the microbial dynamics in wastewater treatment systems and the biosafety of effluents. In this work, the viral members present in influent wastewater, mixed liquor (aerobic bioreactor), excess sludge, and effluent water of a conventional activated sludge system for the treatment of urban wastewater were identified. Viral members were observed by transmission electron microscopy and studied through next-generation sequencing studies. The results showed the dominance of bacteriophages in the viral community in all samples, with the dominant viral phylotype classified as Escherichia coli O157 typing phage 7. Moreover, different human viruses, such as Cynomolgus cytomegalovirus and Gammaherpesvirus, were also detected.

Interlaboratory Comparative Study to Detect Potentially Infectious Human Enteric Viruses in Influent and Effluent Waters

Wastewater represents the main reusable water source after being adequately sanitized by wastewater treatment plants (WWTPs). In this sense, only bacterial quality indicators are usually checked to this end, and human pathogenic viruses usually escape from both sanitization procedures and controls, posing a health risk on the use of effluent waters. In this study, we evaluated a protocol based on aluminum adsorption-precipitation to concentrate several human enteric viruses, including norovirus genogroup I (NoV GI), NoV GII, hepatitis A virus (HAV), astrovirus (HAstV), and rotavirus (RV), with limits of detection of 4.08, 4.64, 5.46 log genomic copies (gc)/L, 3.31, and 5.41 log PCR units (PCRU)/L, respectively. Furthermore, the method was applied in two independent laboratories to monitor the presence of NoV GI, NoV GII, and HAV in effluent and influent waters collected from five WWTPs at two different sampling dates. Concomitantly, a viability PMAxx-RT-qPCR was applied to all the samples to get information on the potential infectivity of both influent and effluent waters. The ranges of the titers in influent waters for NoV GI, NoV GII, RV, and HAstV were 4.80-7.56, 5.19-7.31 log gc/L, 5.41-6.52, and 4.59-7.33 log PCRU/L, respectively. In effluent waters, the titers ranged between 4.08 and 6.27, 4.64 and 6.08 log gc/L, < 5.51, and between 3.31 and 5.58 log PCRU/L. Moreover, the viral titers detected by viability RT-qPCR showed statistical differences with RT-qPCR alone, suggesting the potential viral infectivity of the samples despite some observed reductions. The proposed method could be applied in ill-equipped laboratories, due to the lack of a requirement for a specific apparatus (i.e., ultracentrifuge).

Understanding temporal and spatial variations of viral disease in the US: The need for a one-health-based data collection and analysis approach

Viral diseases exhibit spatial and temporal variation, and there are many factors that can affect their occurrence. The identification of these factors is critical in the efforts to predict and lessen viral disease burden. Because viral infection is able to spread to humans from the environment, animals, and other humans, the One-Health framework can be used to investigate the critical pathways through which viruses are transported and transmitted. A holistic approach, incorporating publicly available clinical data for human, livestock, and wildlife disease occurrence, together with environmental data reported in federal and state databases such as parameters related to land use, environmental quality, and weather, can enhance the understanding of variations in disease patterns, leading to the design and implementation of surveillance systems. An example analysis approach is presented for Michigan, United States, which is a state with large urban centers as well as a sizeable rural and agricultural population. Analysis of publicly available data from 2017 indicates that gastrointestinal (GI) and influenza-associated illnesses in Michigan may have been related with agricultural land use to a higher extent than with developed land use during that year. Meanwhile, hepatitis A virus appears to be most closely related with developed land use in dense population areas. GI illnesses may be related to precipitation, and this relationship is strongest in the springtime, although GI illnesses are most common in the winter months. Integration of human-related clinical data, animal disease data, and environmental data can ultimately be used for prioritization of the most critical locations and times for viral outbreaks in both urban and rural environments.

Enteric viruses in municipal wastewater effluent before and after disinfection with chlorine and ultraviolet light

In Ontario, Canada, information is lacking on chlorine and ultraviolet (UV) light disinfection performance against enteric viruses in wastewater. We enumerated enteroviruses and noroviruses, coliphages, and Escherichia coli per USEPA methods 1615, 1602, and membrane filtration, respectively, in pre- and post-disinfection effluent at five wastewater treatment plants (WWTPs), with full-year monthly sampling, and calculated log₁₀ reductions (LRs) while WWTPs complied with their monthly geometric mean limit of 200 E. coli/100 mL. Modeling of densities by left-censored estimation and Bayesian inference gave very similar results. Polymerase chain reaction (PCR)-detected enteroviruses and noroviruses were abundant in post-disinfection effluent (mean concentrations of 2.1 × 10⁺⁴-7.2 × 10⁺⁵ and 2.7 × 10⁺⁴-3.6 × 10⁺⁵ gene copies (GC)/L, respectively). Chlorine or UV disinfection produced modest LRs for culture- (0.3-0.9) and PCR-detected enteroviruses (0.3-1.3), as well as noroviruses GI + GII (0.5-0.8). Coliphages and E. coli were more susceptible, with LRs of 0.8-3.0 and 2.5, respectively. Sand-filtered effluent produced significantly higher enteric virus LRs (except cultured enteroviruses). Coliphage and human enteric virus densities gave significantly positive correlations using Kendall's Tau test. Enteric viruses are abundant in wastewater effluent following routine chlorine or UV disinfection processes that target E. coli. Coliphages appear to be good indicators for evaluating wastewater disinfection of enteric viruses.

Constructed wetland for wastewater reuse: Role and efficiency in removing enteric pathogens

Water stress has become a perennial concern in most of the developing countries due to rapid urbanization and population growth. As the growing population requires more fresh water and better ways for wastewater disposal, the demand for wastewater reclamation has increased drastically in recent years. Wastewater, either raw or treated, is being widely used for agricultural irrigation in developing countries, which cause a serious threat to human health mainly because of its pathogenic content. One of the alternative methods to treat wastewater and make it reusable for agricultural irrigation is to implement constructed wetland (CW); a sustainable and cost-effective technology that is applicable for the elimination of both pollutants and pathogens from wastewater. Despite its wide application, the role of macrophytes that form an integral part of CW and specific mechanisms involved in pathogen removal by them is still barely understood due to complexities involved and influencing factors. This has, therefore, attracted various scientific studies to reveal further functional mechanisms involved in vegetated CW to increase its proficiencies. This review paper illustrates the comparative studies of different CW and their pathogen removal efficiencies with major emphasis on macrophytes involved and factors influencing related mechanism. Further, the paper also covers detailed information on the enteric pathogens present in wastewater and the associated health risks involved in its reuse. The ultimate objective is to further clarify the role of CW in enteric pathogen removal and its efficiency for wastewater purification in perspective with safe reuse in agriculture.

Potable Water Reuse: What Are the Microbiological Risks?

PURPOSE OF REVIEW

With the increasing interest in recycling water for potable reuse purposes, it is important to understand the microbial risks associated with potable reuse. This review focuses on potable reuse systems that use high-level treatment and de facto reuse scenarios that include a quantifiable wastewater effluent component.

RECENT FINDINGS

In this article, we summarize the published human health studies related to potable reuse, including both epidemiology studies and quantitative microbial risk assessments (QMRA). Overall, there have been relatively few health-based studies evaluating the microbial risks associated with potable reuse. Several microbial risk assessments focused on risks associated with unplanned (or de facto) reuse, while others evaluated planned potable reuse, such as indirect potable reuse (IPR) or direct potable reuse (DPR). The reported QMRA-based risks for planned potable reuse varied substantially, indicating there is a need for risk assessors to use consistent input parameters and transparent assumptions, so that risk results are easily translated across studies. However, the current results overall indicate that predicted risks associated with planned potable reuse scenarios may be lower than those for de facto reuse scenarios. Overall, there is a clear need to carefully consider water treatment train choices when wastewater is a component of the drinking water supply (whether de facto, IPR, or DPR). More data from full-scale water treatment facilities would be helpful to quantify levels of viruses in raw sewage and reductions across unit treatment processes for both culturable and molecular detection methods.

A water-focused one-health approach for early detection and prevention of viral outbreaks

Despite consistent efforts to protect public health there is still a heavy burden of viral disease, both in the United States and abroad. In addition to conventional medical treatment, there is a need for a holistic approach for early detection and prevention of viral outbreaks at a population level. One-Health is a relatively new integrative approach to the solving of global health challenges. A key component to the One-Health approach is the notion that human health, animal health, and environmental health are all innately interrelated. One-Health interventions, initiated by veterinary doctors, have proven to be effective in controlling outbreaks, but thus far the applications focus on zoonotic viruses transmitted from animals to humans. Environmental engineers and environmental scientists hold a critical role in the further development of One-Health approaches that include water-related transport and transmission of human, animal, and zoonotic viruses. In addition to waterborne viruses, the proposed approach is applicable to a wide range of viruses that are found in human excrement since contaminated water-based surveillance systems may be used for early detection of viral disease. This paper proposes a greater One-Health based framework that involves water-related pathways. The first step in the proposed framework is the identification of critical exposure pathways of viruses in the water environment. Identification of critical pathways informs the second and third steps, which include water-based surveillance systems for early detection at a population level and implementation of intervention approaches to block the critical pathways of exposure.

Evaluation of a Male-Specific DNA Coliphage Persistence Within Eastern Oysters (Crassostrea virginica)

Male-specific coliphages (MSCs) are currently used to assess the virologic quality of shellfish-growing waters and to assess the impact of sewage release or adverse weather events on bivalve shellfish. Since MSC can have either DNA or RNA genomes, and most research has been performed exclusively on RNA MSCs, persistence of M13, a DNA MSC, was evaluated for its persistence as a function of time and temperature within Eastern oysters (Crassostrea virginica). Oysters were individually exposed to seawater containing a total of 10¹⁰ to 10¹² pfu of M13 for 24 h at 15 °C followed by maintenance in tanks with as many as 21 oysters in continuously UV-sterilized water for up to 6 weeks at either 7, 15, or 22 °C. Two trials for each temperature were performed combining three shucked oysters per time point which were assayed by tenfold serial dilution in triplicate. Initial contamination levels averaged 10^6.9 and ranged from 10^6.0 to 10^7.0 of M13. For oysters held for 3 weeks, log₁₀ reductions were 1.7, 3.8, and 4.2 log₁₀ at 7, 15, and 22 °C, respectively. Oysters held at 7 and 15 °C for 6 weeks showed average reductions of 3.6 and 5.1 log₁₀, respectively, but still retained infectious M13. In total, this work shows that DNA MSC may decline within shellfish in a manner analogous to RNA MSCs.

Occurrence of coliphage in raw wastewater and in ambient water: A meta-analysis

Coliphage have been proposed as indicators of fecal contamination in recreational waters because they better reflect the persistence of pathogenic viruses in the environment and through wastewater treatment than traditional fecal indicator bacteria. Herein, we conducted a systematic literature search of peer-reviewed publications to identify coliphage density data (somatic and male-specific, or MSC) in raw wastewater and ambient waters. The literature review inclusion criteria included scope, study quality, and data availability. A non-parametric two-stage bootstrap analysis was used to estimate the coliphage distributions in raw wastewater and account for geographic region and season. Additionally, two statistical methodologies were explored for developing coliphage density distributions in ambient waters, to account for the nondetects in the datasets. In raw wastewater, the analysis resulted in seasonal density distributions of somatic coliphage (SC) (mean 6.5 log₁₀ plaque forming units (PFU)/L; 95% confidence interval (CI): 6.2-6.8) and MSC (mean 5.9 log₁₀ PFU/L; 95% CI: 5.5-6.1). In ambient waters, 49% of MSC samples were nondetects, compared with less than 5% for SC. Overall distributional estimates of ambient densities of coliphage were statistically higher for SC than for MSC (mean 3.4 and 1.0 log₁₀ PFU/L, respectively). Distributions of coliphage in raw wastewater and ambient water will be useful for future microbial risk assessments.

Inactivation and Loss of Infectivity of Enterovirus 70 by Solar Irradiation

Enterovirus 70 (EV70) is an emerging viral pathogen that remains viable in final treated effluent. Solar irradiation is, therefore, explored as a low-cost natural disinfection strategy to mitigate potential concerns. EV70 was exposed to simulated sunlight for 24 h at a fluence rate of 28.67 J/cm2/h in three different water matrices, namely, phosphate-buffered saline (PBS), treated wastewater effluent, and chlorinated effluent. In the presence of sunlight, EV70 decreased in infectivity by 1.7 log, 1.0 log, and 1.3 log in PBS, effluent, and chlorinated effluent, respectively. Irradiated EV70 was further introduced to host cell lines and was unable to infect the cell lines. In contrast, EV70 in dark microcosms replicated to titers 13.5, 3.3, and 4.2 times the initial inoculum. The reduction in EV70 infectivity was accompanied by a reduction in viral binding capacity to Vero cells. In addition, genome sequencing analysis revealed five nonsynonymous nucleotide substitutions in irradiated viruses after 10 days of infection in Vero cells, resulting in amino acid substitutions: Lys14Glu in the VP4 protein, Ala201Val in VP2, Gly71Ser in VP3, Glu50Gln in VP1, and Ile47Leu in 3Cpro. Overall, solar irradiation resulted in EV70 inactivation and an inhibition of viral activity in all parameters studied.

Poliovirus and Other Enteroviruses from Environmental Surveillance in Italy, 2009-2015

Within the initiatives for poliomyelitis eradication by WHO, Italy activated an environmental surveillance (ES) in 2005. ES complements clinical Acute Flaccid Paralysis (AFP) surveillance for possible polio cases, detects poliovirus circulation in environmental sewage, and is used to monitor transmission in communities. In addition to polioviruses, the analyses comprised: (i) the monitoring of the presence of non-polio enteroviruses in sewage samples and (ii) the temporal and geographical distribution of the detected viruses. From 2009 to 2015, 2880 sewage samples were collected from eight cities participating in the surveillance. Overall, 1479 samples resulted positive for enteroviruses. No wild-type polioviruses were found, although four Sabin-like polioviruses were detected. The low degree of mutation found in the genomes of these four isolates suggests that these viruses have had a limited circulation in the population. All non-polio enteroviruses belonged to species B and the most frequent serotype was CV-B5, followed by CV-B4, E-11, E-6, E-7, CV-B3, and CV-B2. Variations in the frequency of different serotypes were also observed in different seasons and/or Italian areas. Environmental surveillance in Italy, as part of the 'WHO global polio eradication program', is a powerful tool to augment the polio surveillance and to investigate the silent circulation or the re-emergence of enteroviruses in the population.