Estimation of health risks caused by exposure to enteroviruses from agricultural application of wastewater effluents

A Metagenomic Investigation of Potential Health Risks and Element Cycling Functions of Bacteria and Viruses in Wastewater Treatment Plants

The concentration of viruses in sewage sludge is significantly higher (10-1000-fold) than that found in natural environments, posing a potential risk for human and animal health. However, the composition of these viruses and their role in the transfer of pathogenic factors, as well as their role in the carbon, nitrogen, and phosphorus cycles remain poorly understood. In this study, we employed a shotgun metagenomic approach to investigate the pathogenic bacteria and viral composition and function in two wastewater treatment plants located on a campus. Our analysis revealed the presence of 1334 amplicon sequence variants (ASVs) across six sludge samples, with 242 ASVs (41.22% of total reads) identified as pathogenic bacteria. Arcobacter was found to be the most dominant pathogen accounting for 6.79% of total reads. The virome analysis identified 613 viral genera with Aorunvirus being the most abundant genus at 41.85%. Approximately 0.66% of these viruses were associated with human and animal diseases. More than 60% of the virome consisted of lytic phages. Host prediction analysis revealed that the phages primarily infected Lactobacillus (37.11%), Streptococcus (21.11%), and Staphylococcus (7.11%). Furthermore, our investigation revealed an abundance of auxiliary metabolic genes (AMGs) involved in carbon, nitrogen, and phosphorus cycling within the virome. We also detected a total of 113 antibiotic resistance genes (ARGs), covering major classes of antibiotics across all samples analyzed. Additionally, our findings indicated the presence of virulence factors including the clpP gene accounting for approximately 4.78%, along with toxin genes such as the RecT gene representing approximately 73.48% of all detected virulence factors and toxin genes among all samples analyzed. This study expands our understanding regarding both pathogenic bacteria and viruses present within sewage sludge while providing valuable insights into their ecological functions.

Human viral pathogens in the wastewater-source water-drinking water continuum: Evidence, health risks, and lessons for future outbreaks in low-income settings

Human viral pathogens, including SARS-CoV-2 continue to attract public and research attention due to their disruption of society, global health, and the economy. Several earlier reviews have investigated the occurrence and fate of SARS-CoV-2 in wastewater, and the potential to use such data in wastewater-based epidemiology. However, comprehensive reviews tracking SARS-CoV-2 and other viral pathogens in the wastewater-water-drinking water continuum and the associated risk assessment are still lacking. Therefore, to address this gap, the present paper makes the following contributions: (1) critically examines the early empirical results to highlight the occurrence and stability of SARS-CoV-2 in the wastewater-source water-drinking water continuum, (2) discusses the anthropogenic and hydro(geo)logical processes controlling the circulation of SARS-CoV-2 in the wastewater-source water-drinking water continuum, (3) discusses the risky behaviour, drivers and high-risk settings in the wastewater-source water-drinking water continuum, (4) uses the available empirical data on SARS-CoV-2 occurrence in the wastewater-source water-drinking water continuum to discuss human health risks from multiple exposure pathways, gendered aspects of SARS-CoV-2 transmission via shared on-site sanitation systems, and (5) develops and risk mitigation strategy based on the available empirical evidence and quantitative human risk assessment data. Finally, it presents a comprehensive research agenda on SARS-CoV-2/COVID-19 to guide the mitigation of future similar outbreaks in low-income settings.

Wastewater-based epidemiology of Campylobacter spp.: A systematic review and meta-analysis of influent, effluent, and removal of wastewater treatment plants

Campylobacter spp. is one of the four leading causes of diarrhoeal diseases worldwide, which are generally mild but can be fatal in children, the elderly, and immunosuppressed persons. The existing disease surveillance for Campylobacter infections is usually based on untimely clinical reports. Wastewater surveillance or wastewater-based epidemiology (WBE) has been developed for the early warning of disease outbreaks and the detection of the emerging new variants of human pathogens, especially after the global pandemic of COVID-19. However, the WBE monitoring of Campylobacter infections in communities is rare due to a few large data gaps. This study is a meta-analysis and systematic review of the prevalence of Campylobacter spp. in various wastewater samples, primarily the influent of wastewater treatment plants. The results showed that the overall prevalence of Campylobacter spp. was 53.26 % in influent wastewater and 52.97 % in all types of wastewater samples. The mean concentration in the influent was 3.31 ± 0.39 log10 gene copies or most probable number (MPN) per 100 mL. The detection method combining culture and PCR yielded the highest positive rate of 90.86 %, while RT-qPCR and qPCR were the two most frequently used quantification methods. In addition, the Campylobacter concentration in influent wastewater showed a seasonal fluctuation, with the highest concentration in the autumn at 3.46 ± 0.41 log10 gene copies or MPN per 100 mL. Based on the isolates of all positive samples, Campylobacter jejuni (62.34 %) was identified as the most prevalent species in wastewater, followed by Campylobacter coli (30.85 %) and Campylobacter lari (4.4 %). These findings provided significant data to further develop and optimize the wastewater surveillance of Campylobacter spp. infections. In addition, large data gaps were found in the decay of Campylobacter spp. in wastewater, indicating insufficient research on the persistence of Campylobacter spp. in wastewater.

Non-potable water reuse and the public health risks from protozoa and helminths: a case study from a city with a semi-arid climate

The study estimated the risk due to Cryptosporidium, Giardia, and Ascaris, associated with non-potable water reuse in the city of Jaipur, India. The study first determined the exposure dose of Cryptosporidium, Giardia, and Ascaris based on various wastewater treatment technologies for various scenarios of reuse for six wastewater treatment plants (WWTPs) in the city. The exposure scenarios considered were (1) garden irrigation; (2) working and lounging in the garden; and (3) consumption of crops irrigated with recycled water. The estimated annual risk of infection varied between 8.57 × 10-7 and 1.0 for protozoa and helminths, respectively. The order of treatment processes, in decreasing order of annual risk of infection, was found to be: moving-bed bioreactor (MBBR) technology > activated sludge process (ASP) technology > sequencing batch reactor (SBR) technology. The estimated annual risk was found to be in this order: Ascaris > Giardia > Cryptosporidium. The study also estimated the maximum allowable concentration (Cmax) of pathogen in the effluent for a benchmark value of annual infection of risk equal to 1:10,000, the acceptable level of risk used for drinking water. The estimated Cmax values were found to be 6.54 × 10-5, 1.37 × 10-5, and 2.89 × 10-6 (oo) cysts/mL for Cryptosporidium, Giardia, and Ascaris, respectively.

Exploration of optimal disinfection model based on groundwater risk assessment in disinfection process

Under the influence of different types of disinfectants and disinfection environments, the removal level of pathogens and the formation potential of disinfection by-products (DBPs) will have a dual impact on the groundwater environment. The key points for sustainable groundwater safety management are how to balance the positive and negative relationship and formulate a scientific disinfection model in combination with risk assessment. In this study, the effects of sodium hypochlorite (NaClO) and peracetic acid (PAA) concentrations on pathogenic E. coli and DBPs were investigated using static-batch and dynamic-column experiments, as well as the optimal disinfection model for groundwater risk assessment was explored using quantitative microbial risk assessment and disability-adjusted life years (DALYs) models. Compared to static disinfection, deposition and adsorption were the dominant factors causing E. coli migration at lower NaClO levels of 0-0.25 mg/L under dynamic state, while disinfection was its migration factor at higher NaClO levels of 0.5-6.5 mg/L. In contrast, E. coli removed by PAA was the result of the combined action of deposition, adsorption, and disinfection. The disinfection effects of NaClO and PAA on E. coli differed under dynamic and static conditions. At the same NaClO level, the health risk associated with E. coli in groundwater was higher, whereas, under the same PAA conditions, the health risk was lower. Under dynamic conditions, the optimal disinfectant dosage required for NaClO and PAA to reach the same acceptable risk level was 2 and 0.85 times (irrigation) or 0.92 times (drinking) of static disinfection, respectively. The results may help prevent the misuse of disinfectants and provide theoretical support for managing twin health risks posed by pathogens and DBPs in water treatment.

Health risks of Cryptosporidium and Giardia in the application of surface water and septic tank effluent in Chinese agriculture: Impact on cancer patients identified by quantitative microbial risk assessment

The protozoa Cryptosporidium and Giardia are major causes of diarrhea and are commonly found on vegetables in China. They pose a health risk, particularly to immunocompromised individuals, including cancer patients. A quantitative microbial risk assessment of Chinese data evaluated the risks of Cryptosporidium and Giardia exposure arising from the application of surface water and septic tank effluent to agricultural land. Exposure via agricultural produce consumption (consumers) and agricultural practices (farmers) was considered for subpopulations of cancer patients and immunocompetent people in urban and rural areas, and risk mitigation scenarios were modelled. The cumulative disease burdens attributable to cryptosporidiosis and giardiasis were, respectively, 9.68×10^-6 and 5.57×10^-5 disability-adjusted life years per person per year (DALYs pppy) for immunocompetent people, and 3.14×10^-5 and 1.51×10^-4 DALYs pppy for cancer patients. Cancer patients were approximately three times more likely to have an individual disease burden than immunocompetent people. The disease burden was higher for consumers than farmers, and higher in rural areas than urban areas (all exceeding the maximum recommended by the World Health Organization). The highest burdens were in provinces of high population, such as Henan, Guangdong, and Sichuan, while the burden associated with human and livestock fecal effluent application was higher than with surface water irrigation. Of the three vegetables studied, lettuce posed the greatest risk, followed by bok choy, while cucumber posed the least risk. Risk mitigation scenario analysis showed that pre-treatment of surface water and feces, and appropriate post-harvest handling of vegetables, including disinfection, cooking, and adequate surface heat treatment (75 °C for 60 s), should be considered when attempting to reduce disease burdens. The methodology and findings of this study are useful for evaluating and reducing the burden of Cryptosporidium and Giardia infections associated with agricultural irrigation and fertilization practices, particularly on cancer patients.

Quantitative microbial risk assessment of enteroviruses in raw-eatable vegetables irrigated by wastewater: examining different scenarios of washing

Due to the increasing water crisis, the reuse of wastewater deserves attention as a method to reduce the pressure of the water crisis, especially in developing countries. The application of health risk assessment models is a way to estimate disease burdens associated with crop irrigation by wastewater effluents. In this study, a quantitative microbial risk assessment (QMRA) with probabilistic Monte-Carlo simulation was used to estimate the annual risk of enteroviruses (EVs) infection and disease burden for consumers of effluent-irrigated raw vegetables in Tehran, the capital of Iran. Wastewater effluent samples were collected over two seasons: summer and winter. EVs were analyzed in three stages, concentration and separation, cell culture, and real-time PCR (RT-PCR). A questionnaire was used to determine the dominant patterns of vegetable washing by consumers. There were 4 vegetable washing steps: wiping away mud (A), rinsing (B), using detergents (C), using disinfectants (D). 5 patterns of washing were examined in the laboratory and the concentration of enteroviruses was measured in every pattern. pattern 1: just wiping away mud (A), pattern 2: wiping away mud and rinsing (AB), pattern 3: wiping away mud by using detergents and rinsing (ABCB), pattern 4: wiping away mud by using disinfectants and rinsing (ABDB), and pattern 5: wiping away mud by using detergents and disinfectants and rinsing (ABCBDB). For washing pattern 1, pattern 2, and pattern 3, the estimated annual infection risk of EVs was estimated to be 5.6 × 10^-1, 3.6 × 10^-1, 1.7 × 10^-1 (risk/per.day), and burden of disease was calculated as 3 × 10^-2, 2 × 10^-2, and 9 × 10^-3 (burden/year), respectively. The results showed that if vegetables are washed according to method 5, the microbial risk will be minimized and the excess prevalence of viral infections will be eliminated.

Assessment of rotavirus and norovirus emitted from water spray park: QMRA, diseases burden and sensitivity analysis

A quantitative model on exposure to pathogenic viruses in air of recreational area and their corresponding health effects is necessary to provide mitigation actions in content of emergency response plans (ERP). Here, the health risk associated with exposure to two pathogenic viruses of concern: Rotavirus (RoV) and Norovirus (NoV) in air of water spray park were estimated using a quantitative microbial risk assessment (QMRA) model. To this end, real-time Reverse Transcriptase polymerase chain reaction (real-time RT-PCR) was employed to measure the concentration levels of RoV and NoV over a twelve-month period. The probability of infection, illness and diseases burden of gastrointestinal illness (GI) caused by RoV and NoV for both workers and visitors were estimated using QMRA and Monto-Carlo simulation technique. The annual mean concentration for RoV and NoV in sampling air of water spray park were 20and 1754, respectively. The %95 confidence interval (CI) calculated annual DALY indicator for RoV (Workers: 2.62 × 10⁻⁴–2.62 × 10⁻¹, Visitors: 1.50 × 10⁻⁵–2.42 × 10⁻¹) and NoV (Workers: 5.54 × 10⁻³–2.53 × 10⁻¹; Visitors: 5.18 × 10⁻⁴–2.54 × 10⁻¹) were significantly higher the recommended values by WHO and US EPA (10⁻⁶–10⁻⁴ DALY pppy). According to sensitivity analysis, exposure dose and disease burden per case (DBPC) were found as the most influencing factors on disease burden as a consequences of exposure to RoV and NoV, respectively. The comprehensive information on DALY and QMRA can aid authorities involved in risk assessment and recreational actions to adopt proper approach and mitigation actions to minimize the health risk.

Global public health implications of human exposure to viral contaminated water

Enteric viruses are common waterborne pathogens found in environmental water bodies contaminated with either raw or partially treated sewage discharge. Examples of these viruses include adenovirus, rotavirus, noroviruses, and other caliciviruses and enteroviruses like coxsackievirus and polioviruses. They have been linked with gastroenteritis, while some enteric viruses have also been implicated in more severe infections such as encephalitis, meningitis, hepatitis (hepatitis A and E viruses), cancer (polyomavirus), and myocarditis (enteroviruses). Therefore, this review presents information on the occurrence of enteric viruses of public health importance, diseases associated with human exposure to enteric viruses, assessment of their presence in contaminated water, and their removal in water and wastewater sources. In order to prevent illnesses associated with human exposure to viral contaminated water, we suggest the regular viral monitoring of treated wastewater before discharging it into the environment. Furthermore, we highlight the need for more research to focus on the development of more holistic disinfection methods that will inactivate waterborne viruses in municipal wastewater discharges, as this is highly needed to curtail the public health effects of human exposure to contaminated water. Moreover, such a method must be devoid of disinfection by-products that have mutagenic and carcinogenic potential.

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.

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.

Microbial contamination in surface water and potential health risks for peri-urban farmers of the Bengal delta

Ensuring safe irrigation practices is vital to sustaining food production in water-scarce delta areas. Bangladesh and many other developing countries discharge untreated wastewater into their surrounding surface water bodies, serving as the primary irrigation source. This indirect irrigation of wastewater is believed to pose threats to the farmers, consumers and market vendors and may also affect crop and soil quality. To assess the risk, peri-urban farmers who use surrounding water bodies of Khulna city, Bangladesh, for crop irrigation were selected for the study. The microbial and heavy metal concentrations were measured in water samples collected from various locations over different seasons. For heavy metals As, Co, Ni, Cd, Cr, Cu and Pb, concentrations were below the detection limit, whereas Al, Fe, Mn, Ti and Zn were present but below the FAO recommendation limit for safe irrigation. The mean concentrations of microbial parameters were above the thresholds of WHO guidelines for crop irrigation intended for human consumption. Significant temporal variations in Faecal Coliform, E. coli and Enterococcus concentrations in the water samples were observed. The annual risk of infection for farmers was determined using the screening-level Quantitative Microbial Risk Assessment (QMRA). The results indicated that the annual probability of infection with pathogenic E. coli in different seasons ranges between 5 × 10^-3 to 5 × 10^-2, above the WHO's acceptable threshold for annual risk of infection for safe water reuse in agriculture. During the farmers' survey, around 45% reported health-related issues and more than 26% reported suffering from water-borne diseases after getting in contact with polluted surface water. This illustrates the actuality of the risks in practice. To ensure safe irrigation, the health risks need to be reduced below the acceptable limits. Suggested technical measures include adequate treatment of wastewater before disposal into rivers and access to protective equipment for farmers. This should be complemented by raising awareness through education programs among farmers to reduce accidental ingestion.

Occurrence of viruses in sewage sludge: A systematic review

Enteric viruses are of great importance in wastewater due to their high excretion from infected individuals, low removal in wastewater treatment processes, long-time survival in the environment, and low infectious dose. Among the other viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surveillance in wastewater systems has received particular attention as a result of the current COVID-19 epidemic. Viruses adhering to solid particles in wastewater treatment processes will end up as sewage sludge, and therefore insufficient sludge treatment may result in viral particles dissemination into the environment. Here, we review data on viruses' presence in sewage sludge, their detection and concentration methods, and information on human health issues associated with sewage sludge land application. We used combinations of the following keywords in the Scopus, Web of Science (WOS), and PubMed databases, which were published between 2010 and January 21th, 2022: sludge (sewage sludge, biosolids, sewage solids, wastewater solids) and virus (enteric virus, viral particles, viral contamination, SARS-CoV-2, coronavirus). The sources were searched twice, once with and then without the common enteric virus names (adenovirus, rotavirus, norovirus, enterovirus, hepatitis A virus). Studies suggest adenovirus and norovirus as the most prevalent enteric viruses in sewage sludge. Indeed, other viruses include rotavirus, hepatitis A virus, and enterovirus were frequently found in sewage sludge samples. Untreated biological sludge and thickened sludge showed more viral contamination level than digested sludge and the lowest prevalence of viruses was reported in lime stabilized sludge. The review reveals that land application of sewage sludge may pose viral infection risks to people due to accidently ingestion of sludge or intake of crops grown in biosolids amended soil. Moreover, contamination of groundwater and/or surface water may occur due to land application of sewage sludge.

Extended-spectrum-beta-lactamases and carbapenemase-producing Klebsiella pneumoniae isolated from fresh produce farms in different governorates of Egypt

Background and Aim: Fresh produce farms represents a major source of concern since they are becoming increasingly antibiotic resistant. This study aimed to investigate t he occurrence of carbapenemase and extended-spectrum-beta-lactamases (ESBL) - producing genes in Klebsiella pneumoniae isolated from fresh produce farms in Egypt, irrigation water, and people working in these fields. Materials and Methods: One hundred tomatoes from typical farms were collected in plastic bags. The study also included 20 surface-water samples from different irrigation watersheds in fresh produce farms, as well as 50 feces samples from farmworkers. Suspected K. pneumoniae was grown on Eosin Methylene Blue agar for 24 h before being biochemically identified using the RapID ONE test. PCR was used to detect carbapenemase (blaKPC, blaOXA-48, and blaNDM) and ESBL (blaSHV, blaTEM, and blaCTX) expressing genes on isolates. Results: K. pneumoniae was identified in 30% of water and 10% of worker samples, while only one isolate was found in tomato samples. One of the six irrigation water isolates tested positive for carbapenem-resistant NDM. In contrast, two isolates tested positive for ESBL determinants, one of which was blaSHV and the other having both blaSHV and blaTEM genes. Two of the five K. pneumoniae isolates from farmworkers were positive for blaNDM, with one isolate also testing positive for blaSHV and blaTEM. The blaOXA-48 gene was also discovered in the carbapenem-resistant K. pneumoniae tomato isolate used in this study. Conclusion: Carbapenemase- and ESBL-producing K. pneumoniae were found in fresh produce farms, implying that these resistance genes were being passed down to Egyptian consumers.

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.

The effects of reclaimed water irrigation on the soil characteristics and microbial populations of plant rhizosphere

In this paper, the effects of irrigation with different water qualities on the soil characteristics of 8 kinds of garden plants were analyzed. The results showed that soil pH (ranging at 7.76-8.73) had no significant difference in different soils compared with the contrast treatment. Under the reclaimed water irrigation, the content of soil total salinity, chloride ions, and water soluble sodium in soil of most plants was averagely 160.3%, 83.3%, and 67.5% higher than that of tap water, respectively. The influences of reclaimed water irrigation on soil nutrients were changed with the types of plants. The content of soil organic matter and the available potassium showed no significant differences in most plants. Compared with the tap water irrigation, the content of alkaline nitrogen in 5 plants increased (averagely 25.8%) after 5-year irrigation with reclaimed water. In terms of soil microorganism, the increase of soil microbial population, including bacteria, fungus and actinomycetes, has been promoted by different levels of reclaimed water irrigation, which is closely related with soil nutrients.

Transmission risk of SARS-CoV-2 in the watershed triggered by domestic wastewater discharge

The outbreak of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has already become an unprecedented global pandemic. However, the transmission of SARS-CoV-2, especially the protected SARS-CoV-2 RNA (pRNA) with infectious particles in waterways, is still largely unexplored. In this study, we developed a model to estimate SARS-CoV-2 transmission from the risk source in the excretion of patients to the final exposure in surface water. The model simulated the spatial and temporal distribution of the viral pRNA concentrations in the surface water of the Elbe watershed from March 2020 to January 2021. The results show that the WWTPs with the maximum capacity of >10,000 population equivalents were responsible for 95% of the viral load discharged into the surface water. We estimated the pRNA concentrations in surface water to be 1.33 × 10^-2 copies·L^-1 on average in the watershed based on the model simulation on viral transmission. It had considerable variations in spatial and temporal scales, which are dominantly controlled by epidemic situations and virus transport with decay in water, respectively. A quantitative microbial risk assessment was conducted to estimate the viral infection probability from surface water ingestion with consideration of the influence of toilet usage frequency and gender/age population groups. All the infection probabilities in the study period were lower than the reference risk levels of 10^-4 and 10^-5. The individuals aged 15-34 years had the highest infection probability of 4.86 × 10^-9 on average from surface water ingestion during swimming activities. The data provided herein suggest that the low pRNA concentrations and infection probability reflected that the waterways were unlikely to be a significant transmission route for SARS-CoV-2.

Short-Term Impact of Two Kinds of Vegetables to Exogenous Total Nitrate and Nitrite Intake: Is Antibacterial Mouthwash Influential?

Background:

Nitrate is a compound with adverse effects on human health that can exist also in vegetables. This study aimed to determine the intake of total nitrate/nitrite from lettuce and carrot as high and low nitrate content, respectively. Moreover, the effect of chlorhexidine mouthwash on the elimination of the nitrite level in saliva and urine was surveyed.

Methods:

This study was designed as a crossover based on the randomized selection method. Thirty-nine participants were divided into two groups; the lettuce and carrot juice consumers (control group). The case group was consumed these two vegetables, while they used antibacterial mouthwash. The background of nitrate/nitrite of the participants was determined before exposure. The intake of total nitrate and nitrite via lettuce and carrot juice consumption was investigated. The Griess colorimetric reaction was used for nitrate and nitrite determination in samples.

Results:

Total nitrate concentrations in case and control groups were detected 0.79 and 0.78 mM in saliva and 1.78 and 1.38 mM in urine after lettuce consumption, respectively. However, it was determined 1.55 and 2.43 mM in saliva and 2.92 and 3.04 mM in urine after carrot ingestion. Salivary nitrite concentration 0.53 mM was decreased to 0.45 mM after antibacterial mouthwash application (P-value <0.05).

Conclusions:

This study indicated that the intake of total nitrate/nitrite via leafy vegetables was higher than rooty ones. The chlorhexidine mouthwash is an appropriate recommendation to reduce the nitrite concentration in the human body for preventing the probable side effects of nitrate metabolites such as N-nitrosamines forming.

SARS-CoV-2 detection in wastewater using multiplex quantitative PCR

A multiplex reverse transcription quantitative PCR (RT-qPCR)-based method was designed for the simultaneous detection of different SARS-CoV-2 genes. In this study, we used three target genes encoding for the nucleocapsid 1 and 3 (N1, N3), and the spike (S) proteins, all commonly used in the detection of SARS-CoV-2 in human and environmental samples. The performance of the multiplex assay, compared to the single assay was assessed for the standard calibration curve, required for absolute quantification, and then, for the real environmental samples to detect SARS-CoV-2. For this latter, four environmental samples were collected at a local wastewater treatment plant (WWTP). The results showed that the cycle threshold (Ct) values of the multiplex were comparable to the values obtained by the singleplex PCR. The amplification of the three target genes indicated the presence of SARS-CoV-2 in the four water samples with an increasing trend in February and these results were confirmed in the multiplex approach, showing the robustness of this method and its applicability for the relative abundance analysis among the samples. Overall, both the laboratory and field work results demonstrated that the multiplex PCR assay developed in this study could provide a method for SARS-CoV-2 detection as robust as the single qPCR, but faster and cost-effective, reducing by three times the number of reactions, and consequently the handling time and reagents.

Constructed Wetlands to Face Water Scarcity and Water Pollution Risks: Learning from Farmers’ Perception in Alicante, Spain

Treated wastewater is constantly produced and relatively unaffected by climatic conditions, while Constructed Wetlands (CWs) are recognized as green technology and a cost-effective alternative to improve treated wastewater quality standards. This paper analyses how farmers consider (1) treated wastewater to face water scarcity risk and (2) CW as mechanisms to face agricultural water pollution in a climate change adaptation context. A survey about climate change perception and adaptation measures was answered by 177 farmers from two irrigation communities near El Hondo coastal wetland and the Santa Pola saltmarshes, both perceived as natural-constructed systems in Alicante, southern Spain. Results highlighted how, even with poor-quality standards, treated wastewater is considered a non-riskier measure and more reliable option when addressing climate change impacts. Overall, physical water harvesting (such as CWs) is the favorite choice when investing in water technologies, being perceived as the best option for users of treated wastewater and those concerned about water quality standards. Consequently, CWs were recognized as mechanisms to increase water supply and reduce water pollution. Policy-makers and water managers can use these learnings from farmers’ experience to identify the main barriers and benefits of using treated wastewater and CWs to address water scarcity and water pollution risks.

Occurrence of various viruses and recent evidence of SARS-CoV-2 in wastewater systems

Viruses are omnipresent and persistent in wastewater, which poses a risk to human health. In this review, we summarise the different qualitative and quantitative methods for virus analysis in wastewater and systematically discuss the spatial distribution and temporal patterns of various viruses (i.e., enteric viruses, Caliciviridae (Noroviruses (NoVs)), Picornaviridae (Enteroviruses (EVs)), Hepatitis A virus (HAV)), and Adenoviridae (Adenoviruses (AdVs))) in wastewater systems. Then we critically review recent SARS-CoV-2 studies to understand the ongoing COVID-19 pandemic through wastewater surveillance. SARS-CoV-2 genetic material has been detected in wastewater from France, the Netherlands, Australia, Italy, Japan, Spain, Turkey, India, Pakistan, China, and the USA. We then discuss the utility of wastewater-based epidemiology (WBE) to estimate the occurrence, distribution, and genetic diversity of these viruses and generate human health risk assessment. Finally, we not only promote the prevention of viral infectious disease transmission through wastewater but also highlight the potential use of WBE as an early warning system for public health assessment.

Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries - case studies from Cochabamba, Bolivia

Wastewater irrigation is a common practice in developing countries due to water scarcity and increasing demand for food production. However, there are health risks and ecological risks associated with this practice. Small-scale wastewater treatment plants (WWTPs) intend to decrease these risks but still face management challenges. This study assessed how the management status of five small-scale WWTPs in Cochabamba, Bolivia affects health risks associated with consumption of lettuce and ecological risks due to the accumulation of nutrients in the soil for lettuce and maize crops. Risk simulations for three wastewater irrigation scenarios were: raw wastewater, actual effluent and expected effluent. Results showed that weak O&M practices can increase risk outcomes to higher levels than irrigating with raw wastewater. Improving O&M to achieve optimal functioning of small-scale WWTPs can reduce human health risks and ecological risks up to 2 log₁₀ DALY person^-1 year^-1 and to 2 log₁₀ kg nitrogen ha^-1 accumulated in soil, respectively.

COVID-19 infection risk from exposure to aerosols of wastewater treatment plants

Fecal shedding of SARS-CoV-2 from COVID-19 patients and presence of the viral RNA in wastewater have extensively been reported. Some wastewater treatment plant (WWTP) processes generate aerosols which have the potential to transmit pathogenic microorganisms and present a health risk for exposed individuals. We analyzed the presence of viral RNA of SARS-CoV-2 in raw wastewater and air samples of WWTPs. The risk that may arise from exposure to virus-contaminated aerosols of wastewater was estimated by developing a quantitative microbial risk analysis (QMRA) method. SARS-CoV-2 was detected in 9 of 24 (37.5%) wastewater samples with a concentration about 10⁴ genomic copies L^-1. The viral RNA was also detected in 40% (6/15) of air samples. QMRA analysis showed a relatively high risk of SARS-CoV-2 infection for wastewater workers via exposure to the viral aerosols. The estimated annual infection risk ranged from 1.1 × 10^-2 to 2.3 × 10^-2 per person per year (PPPY) for wastewater workers which was higher than the reference level recommended by WHO (10^-3 pppy). However, due to the lack of data on survival of SARS-CoV-2 in wastewater and its fate in aerosolized state, more research is needed to determine the importance of wastewater in transmission of COVID-19.

A state-of-the-art review on WWTP associated bioaerosols: Microbial diversity, potential emission stages, dispersion factors, and control strategies

Wastewater treatment plants (WWTPs) associated bioaerosols have emerged as one of the critical sustainability indicators, ensuring health and well-being of societies and cities. In this context, this review summarizes the various wastewater treatment technologies which have been studied with a focus of bioaerosols emissions, potential emission stages, available sampling strategies, survival and dispersion factors, dominant microbial species in bioaerosols, and possible control approaches. Literature review revealed that most of the studies were devoted to sampling, enumerating and identifying cultivable microbial species of bioaerosols, as well as measuring their concentrations. However, the role of treatment technologies and their operational factors are investigated in limited studies only. Moreover, few studies have been reported to investigate the presence and concentrations of air borne virus and fungi in WWTP, as compared to bacterial species. The common environmental factors, affecting the survival and dispersion of bioaerosols, are observed as relative humidity, temperature, wind speed, and solar illumination. Further, research studies on recent episodes of COVID-19 (SARS-CoV-2 virus) pandemic also revealed that continuous and effective surveillance on WWTPs associated bioaerosols may led to early sign for future pandemics. The evaluation of reported data is bit complicated, due to the variation in sampling approaches, ambient conditions, and site activities of each study. Therefore, such studies need a standardized methodology and improved guidance to help informed future policies, contextual research, and support a robust health-based risk assessment process. Based on this review, an integrated sampling and analysis framework is suggested for future WWTPs to ensure their sustainability at social and/or health associated aspects.

Quantification and Comparison of Risks Associated with Wastewater Use in Spray Irrigation

In the U.S., spray irrigation is the most common method used in agriculture and supplementing with animal wastewater has the potential to reduce water demands. However, this could expose individuals to respiratory pathogens such as Legionella pneumophila and nontuberculosis Mycobacteria (NTM). Disinfection with methods like anaerobic digestion is an option but can increase concentrations of cytotoxic ammonia (personal communication). Our study aimed to model the annual risks of infection from these bacterial pathogens and the air concentrations of ammonia and determine if anaerobically digesting this wastewater is a safe option. Air dispersion modeling, conducted in AERMOD, generated air concentrations of water during the irrigation season (May-September) for the years 2013-2018. These values fed into the quantitative microbial risk assessments for the bacteria and allowed calculation of ammonia air concentrations. The outputs of these models were compared to the safety thresholds of 10^-4 infections/year and 0.5 mg/m³ , respectively, to determine their potential for negative health outcomes. It was determined that infection from NTM was not a concern for individuals near active spray irrigators, but that infection with L. pneumophila could be a concern, with a maximum predicted annual risk of infection of 3.5 × 10^-3 infections/year and 25.2% of parameter combinations exceeding the established threshold. Ammonia posed a minor risk, with 1.5% of parameter combinations surpassing the risk threshold of 0.5 mg/m³ . These findings suggest that animal wastewater should be anaerobically digested prior to use in irrigation to remove harmful pathogens.

Quantitative microbial risk assessment for occupational health of temporary entrants and staffs equipped with various grade PPE and exposed to microbial bioaerosols in two WWTPs

Purpose

This study was to evaluate the occupational health risks of infection from Gram-negative bacteria and Staphylococcus aureus bioaerosols to temporary entrants and staffs equipped with various grade personal protection equipment (PPE) related to wastewater treatment plants (WWTPs).

Methods

This study determined the emission concentrations of Gram-negative bacteria and Staphylococcus aureus bioaerosols from two WWTPs under various aeration modes. Then, a strict quantitative microbial risk assessment (QMRA) was performed on several exposure scenarios associated with occupational health risks of temporary entrants (researchers, visitors, and inspectors) and staffs (field engineer and laboratory technician).

Results

Although the bioaerosol concentrations were generally regarded as safe according to existing standards, these bioaerosols’ health risks were still unacceptable. The microbial bioaerosols posed considerable infection health risks in WWTPs. These risks were generally above the WHO and US EPA benchmarks. The health risks of females were always smaller than those of male of grown-up age group. Staffs that had been exposed to bioaerosols for a long time were found to have higher health risks compared with temporary entrants. In addition, field engineers equipped with PPE rendered low health risks, thus revealing that wearing PPE could effectively reduce the occupational health risks.

Conclusion

This study provided novel data and enriched the knowledge of microbial bioaerosol emission’s health risks from various aeration modes in WWTPs. Management decisions could be executed by authorities on the basis of the results of QMRA for field engineers equipped with PPE to reduce the related occupational health risks.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-021-01663-5.

Virus removal by membrane bioreactors: A review of mechanism investigation and modeling efforts

The increasing pressure on the global water supply calls for more advanced solutions with higher efficiency and better sustainability, leading to the promptly developing water reclamation and reuse schemes including treatment technologies and risk management strategies where microbial safety is becoming a crucial aspect in the interest of public health. Backed up by the development of membrane technology, membrane bioreactors (MBR) have received substantial attention for their superiority over conventional treatment methods in many ways and are considered promising in the water reclamation realm. This review paper provides an overview of the efforts made to manage and control the potential waterborne viral disease risks raised by the use of effluent from MBR treatment processes, including the mechanisms involved in the virus removal process and the attempts to model the dynamics of the removal process. In principle, generalized and integrated virus removal models that provide insight into real-time monitoring are urgently needed for advanced real-time control purpose. Future studies of approaches that can well handle the inherent uncertainty and nonlinearity of the complex removal process are crucial to the development and promotion of related technologies.

The bioaerosols emitted from toilet and wastewater treatment plant: a literature review

The aerosols harboring microorganisms and viruses released from the wastewater system into the air have greatly threatened the health and safety of human beings. The wastewater systems, including toilet and wastewater treatment plant (WWTP), are the major locations of epidemic infections due to the extensive sources of aerosols, as well as multifarious germs and microorganisms. Viruses and microorganisms may transport from both toilet and hospital into municipal pipes and subsequently into WWTP, which accounts for the main source of bioaerosols dispersed in the air of the wastewater system. This review aims to elaborate the generation, transmission, and diffusion processes of bioaerosols at toilet and WWTP. Moreover, the main factors affecting bioaerosol transmission and the corresponding prevention strategies for the airborne and inhaled bioaerosols are also discussed. Collectively, this review highlights the importance of managing bioaerosol occurrence in the wastewater system, which has aroused increasing concern from the public.

Bacteriophages in water pollution control: Advantages and limitations

Wastewater is a breeding ground for many pathogens, which may pose a threat to human health through various water transmission pathways. Therefore, a simple and effective method is urgently required to monitor and treat wastewater. As bacterial viruses, bacteriophages (phages) are the most widely distributed and abundant organisms in the biosphere. Owing to their capacity to specifically infect bacterial hosts, they have recently been used as novel tools in water pollution control. The purpose of this review is to summarize and evaluate the roles of phages in monitoring pathogens, tracking pollution sources, treating pathogenic bacteria, infecting bloom-forming cyanobacteria, and controlling bulking sludge and biofilm pollution in wastewater treatment systems. We also discuss the limitations of phage usage in water pollution control, including phage-mediated horizontal gene transfer, the evolution of bacterial resistance, and phage concentration decrease. This review provides an integrated outlook on the use of phages in water pollution control.

Adaptation of Human Enterovirus to Warm Environments Leads to Resistance against Chlorine Disinfection

Sunlight, temperature, and microbial grazing are among the environmental factors promoting the inactivation of viral pathogens in surface waters. Globally, these factors vary across time and space. The persistence of viral pathogens, and ultimately their ecology and dispersion, hinges on their ability to withstand the environmental conditions encountered. To understand how virus populations evolve under changing environmental conditions, we experimentally adapted echovirus 11 (E11) to four climate regimes. Specifically, we incubated E11 in lake water at 10 and 30 °C and in the presence and absence of sunlight. Temperature was the main driver of adaptation, resulting in an increased thermotolerance of the 30 °C adapted populations, whereas the 10 °C adapted strains were rapidly inactivated at higher temperatures. This finding is consistent with a source-sink model in which strains emerging in warm climates can persist in temperate regions, but not vice versa. A microbial risk assessment revealed that the enhanced thermotolerance increases the length of time in which there is an elevated probability of illness associated with swimming in contaminated water. Notably, 30 °C-adapted viruses also exhibited an increased tolerance toward disinfection by free chlorine. Viruses adapting to warm environments may thus become harder to eliminate by common disinfection strategies.

Impact of sludge bulking on receiving environment using quantitative microbial risk assessment (QMRA)-based management for full-scale wastewater treatment plants

During sludge bulking in wastewater treatment plants (WWTPs), high amounts of potentially pathogenic bacteria would release into the environment, causing various human-health risks. This is the first study attempting to assess the microbial infections associated with the reuse of WWTP effluents under various bulking conditions. Three common waterborne pathogens, viz., E. coli O157:H7, Salmonella, and Mycobacterium, were quantified from full-scale WWTPs using DNA extraction and qPCR at different sludge volume indices (SVIs). The detected pathogens were incorporated into a quantitative microbial risk assessment (QMRA) model to determine the applicability of WWTP discharge for recreational (bathing) activities and agricultural practices. The QMRA exposures were children, women, and men during swimming, and farmers and vegetable consumers during irrigation. Bacterial abundance in the treated wastewater increased in response to SVIs, and the QMRA values at all bulking events exceeded the tolerable risk of one case of infection per 10,000 people per year. Hence, various disinfection scenarios (chlorination, ultraviolet, and ozonation) were hypothetically tested to control the risks associated with pathogenic bacteria, allowing for safe disposal and reuse of the treated effluent. The ultraviolet application provided the highest ability to inactivate the pathogenic bacteria, except for the case of children exposed to Salmonella infection during swimming. The reduction of Mycobacterium infection risks with either chlorination or ozonation showed inefficient results. This study would be helpful for the management of human health risks associated with effluent wastewater containing pathogens, i.e., particularly concerning the case of sludge bulking.

Campylobacter risk for the consumers of wastewater-irrigated vegetables based on field experiments

Water scarcity is emerging as a major problem in water stressed regions such as Middle East countries which highlights the importance of agricultural reuse of wastewater as a valid alternative source. However, consumption of wastewater-irrigated crops has been implicated as a vehicle for transmission of bacterial infections such as campylobacteriosis. Understanding and minimizing public health threats associated with agricultural reuse of treated wastewater (TWW) are crucial elements in sustainable water resource management. To address this need, the present study was carried out to determine Campylobacter risk for the consumers of TWW-irrigated vegetables by field experiments as well as quantitative microbial risk assessment (QMRA) model. Campylobacter was monitored in secondary treated wastewater, TWW-irrigated soil and harvested vegetables by nested real-time PCR assay. Campylobacter was detected in 64% (16/25) of TWW samples, whereas analysis of TWW-irrigated soil and vegetable samples yielded no positive result for Campylobacter. The estimated mean annual Campylobacter disease burden ranged from 2.37 × 10^-5 to 6.6 × 10^-5 disability-adjusted life years (DALYs) per person per year (pppy) for vegetable consumers which was lower than the less stringent reference level of 10^-4 DALYs pppy has been recommended by world health organization (WHO). Our results in regard to the QMRA estimates and field experiments suggest that the reuse of TWW for irrigation of vegetables doesn't pose a considerable risk to human health from the viewpoint of Campylobacter infections in a semi-arid area.

Responsible Water Reuse Needs an Interdisciplinary Approach to Balance Risks and Benefits

Freshwater is a precious resource, and shortages can lead to water stress, impacting agriculture, industry, and other sectors. Wastewater reuse is increasingly considered as an opportunity to meet the freshwater demand. Legislative frameworks are under development to support the responsible reuse of wastewater, i.e., to balance benefits and risks. In an evaluation of the proposed European regulation for water reuse, we concluded that the proposed regulation is not practically feasible, as the water provider alone is responsible for the risk assessment and management, even beyond their span of control. The required knowledge and resources are extensive. Therefore, without clear guidance for implementation, the regulation would hinder implementation of reuse programs. As a consequence, the current practice of uncontrolled, unintentional, and indirect reuse continues, including related risks and inefficiency. Therefore, we provide an outline of the interdisciplinary approach required to design and achieve safe, responsible water reuse. Responsible water reuse requires knowledge of water demand and availability, quality and health, technology, and governance for the various types of application. Through this paper we want to provide a starting point for an interdisciplinary agenda to compile and generate knowledge (databases), approaches, guidelines, case examples, codes of practice, and legislation to help bring responsible water reuse into practice.

Megacity Wastewater Poured into A Nearby Basin: Looking for Sustainable Scenarios in A Case Study

Megacity sewage creates socioeconomic dependence related to water availability in nearby areas, especially in countries with hydric stress. The present article studies the past, current, and future water balance progression of realistic scenarios from 2005 to 2050 in the Mezquital Valley, the receptor of Mexico City untreated sewage since 1886, allowing for agriculture irrigation under unsustainable conditions. The Water Evaluation and Planning System (WEAP) was used to estimate water demand and supply, and validation was performed by comparing results with outflow data from the Tula River. Simulated scenarios were (1st) steady-state based on inertial growth rates (2nd) transient scenario concerning the influence of forecasted climate change perturbations in surface water and hydric stress for 2050; and (3rd) the previous scenario appending scheduled actions, such as 36% reduction in imported wastewater and the startup of a massive Wastewater Treatment Plant, allowing for drip and sprinkler irrigation from the year 2030. The main results are as follows: (a) in the period 2005–2017, 59% of the agriculture depended on flood irrigation with megacity sewage; (b) the outcomes of water balance scenarios up to 2050 are presented, with disaggregated sectorial supply of ground and superficial water; (c) drip irrigation would reduce agriculture demands by 42% but still does not guarantee the downflow hydroelectric requirements, aggravated by the lack of wastewater supply from 2030. This research highlights how present policies compromise future Valley demands.

Characterization of implementation limits and identification of optimization strategies for sustainable water resource recovery through life cycle impact analysis

How we manage alternative freshwater resources to close the gap between water supply and demand is pivotal to the future of the environment and human well-being. Increased scarcity of water for agricultural irrigation in semi-arid and arid regions has resulted in a growing interest in water reuse practices. However, insight into the life cycle impacts and potential trade-offs of these emerging practices are still limited by the paucity of systematic evaluations of different water reuse implementations. In this study, a host of environmental and human health impacts at three implementation levels of allowing water reclamation for crop irrigation was comparatively evaluated across the operational landscape via a combination of scenario modelling, life-cycle impact analyses and Monte Carlo simulations. Net harvesting of reclaimed water for irrigation was found to be dependent upon the sophistication of the treatment processes, since multistage and complex configurations can cause greater direct water consumption during processing. Further, the direct benefits of water resource recovery can be essentially offset by indirect adverse impacts, such as mineral depletion, global warming, ozone depletion, ecotoxicity, and human health risks, which are associated with increased usage of energy and chemicals for rigorous removal of contaminants, such as heavy metals and contaminants of emerging concern. Nonetheless, expanded simulations suggest the significance of concurrently implementing energy recovery, nutrient recycling, and/or nature-based, chemical-free water technologies to reduce the magnitude of negative impacts from engineered water reclamation processes.

Assessment of airborne enteric viruses emitted from wastewater treatment plant: Atmospheric dispersion model, quantitative microbial risk assessment, disease burden

From a health prospective, it is critical to provide a comprehensive model which integrates all the parameters involved in virus transmission and its consequences on human body. In order to estimate the health risks, for workers and residents, associated with an exposure airborne viruses emitted from a wastewater treatment (WWTP), the concentration levels of viruses in emitted bioaerosols over a twelve-month period were measured by real-time polymerase chain reaction (RT-PCR). A combined Gaussian plum dispersion model and quantitative microbial risk assessment (QMRA) with Monte-Carlo simulation served as suitable explanatory tools to estimate the risk of acquiring gastrointestinal illness (GI) due to exposure to air containing Rotavirus (RoV) and Norovirus (NoV) bioaerosols. Additionally, DALY metric was applied to quantify the disability and mortality for workers and residents. RoV and NoV were detected above aeration tank with annual mean concentration 27 and 3099 (Viruses/m³.h), respectively. The medium calculated DALY indicator based on viral loads in contaminant source (RoV:5.76 × 10^-2 and NoV:1.23 × 10^-1) and estimated in different distances away (300-1000 m) (RoV:2.87 × 10^-2- 2.75 × 10^-2 and NoV:1.14 × 10^-1-1.13 × 10^-1) were markedly higher than the threshold values recommended by US EPA (10^-4 DALY pppy) and WHO (10^-6 DALY pppy). The sensitivity analysis highlighted dose exposure and disease burden per case (DBPC) as two most influential factors for both workers and residents following exposure to two pathogens of concern. Due to high resistance and high concentration in the environment, the presence of RoV and NoV can intensify the consequences of diarrhea especially for children under five years of age; A comprehensible and transparent presentation of DALYs and QMRA can help decision makers and responsibilities to justify the priorities of exposure to wastewater in comparison with other risks of daily life.

Cold Atmospheric Plasma as a Novel Method for Inactivation of Potato Virus Y in Water Samples

While one of the biggest problems we are facing today is water scarcity, enormous quantities of water are still being used in irrigation. If contaminated, this water can act as an effective pathway for the spread of disease-causing agents, like viruses. Here, we present a novel, environmentally friendly method known as cold atmospheric plasma for inactivation of viruses in water used in closed irrigation systems. We measured the plasma-mediated viral RNA degradation as well as the plasma-induced loss of viral infectivity using potato virus Y as a model virus due to its confirmed water transmissibility and economic as well as biological importance. We showed that only 1 min of plasma treatment is sufficient for successful inactivation of viruses in water samples with either high or low organic background. The plasma-mediated inactivation was efficient even at markedly higher virus concentrations than those expected in irrigation waters. Obtained results point to reactive oxygen species as the main mode of viral inactivation. Our laboratory-scale experiments confirm for the first time that plasma has an excellent potential as the eukaryotic virus inactivation tool for water sources and could thus provide a cost-effective solution for irrigation mediated plant virus transmission. The outstanding inactivation efficiency demonstrated by plasma treatments in water samples offers further expansions of its application to other water sources such as reused wastewater or contaminated drinking waters, as well as other plant, animal, and human waterborne viruses, ultimately leading to the prevention of water scarcity and numerous human, animal, and plant infections worldwide.

Risk-Yuck Factor Nexus in Reclaimed Wastewater for Irrigation: Comparing Farmers’ Attitudes and Public Perception

The successes and failures of water reuse schemes are shaped by complex interrelationships between technological, economic, and socio-political factors. However, it has long been recognized that the main challenges to more effective water management are largely social rather than technical. This article reviews the recent literature (2007–2017) to analyze driving factors associated with farmers’ concerns and public perception of reclaimed wastewater for irrigation. The aim of the paper is to synthetize how both environmental and health risks and the yuck factor could be addressed in order to promote mutual understanding between farmers and the public. Results show: (1) how farmers and the public perceive environmental and health risks in a similar way, (2) how the yuck factor is more noticeable for the public than farmers, and (3) how constructed wetlands, reclaimed water exchange consortiums, product certification, and direct site visits to water reuse infrastructure could be promoted in order to foster understanding between farmers and the public. The article concludes by providing key research questions for managers and public authorities relating to how to focus on the study of technical and social issues related to water reuse.

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.

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.

Effects of irrigation with secondary treated wastewater on physicochemical and microbial properties of soil and produce safety in a semi-arid area

Water scarcity is becoming one of the largest problems worldwide. Agricultural reuse of wastewater has been considered a valuable and reliable alternative, alleviating the pressure on freshwater resources in arid and semi-arid regions such as the Middle East. Inadequate microbial quality of treated wastewater is a challenge for developing countries, which limits agricultural reuse of wastewater. This study assessed the impact of irrigation with secondary treated wastewater (STWW) on soil properties as well as the safety of various types of crops as compared with tap water (TW) irrigation through a furrow system. Total and fecal coliforms and Escherichia coli were monitored as indicator bacteria in STWW, irrigated soil and harvested crops. The presence of pathogenic E. coli O157, Salmonella and Shigella was also monitored in all samples using a combination of culture and molecular methods. The microbial quality of wastewater in terms of E. coli concentration (4.18 Log MPN/100 ml) failed to meet the world health organization (WHO) recommendation for irrigation of root and leafy crops (≤103 and ≤ 104E. coli per 100 ml for root and leafy crops, respectively). No significant effects on physicochemical properties of the soil irrigated with STWW was found in comparison with control plots, except for electrical conductivity (EC) and sodium adsorption ratio (SAR), which were slightly higher in STWW soil samples. Although the microbial quality of soil was affected by STWW irrigation, a relatively low concentration of E. coli was detected in soil. No microbial contamination in terms of E. coli was found on harvested maize and onion. E. coli contamination of lettuce and spring onion was found for both irrigation schemes. No STWW, soil or crop samples were found positive for pathogenic bacteria. According to the analyzed parameters, STWW could be safely used as an alternative source for irrigation of root and leafy crops.

Particle size distribution mathematical models and properties of suspended solids in a typical freshwater pond

Many countries, such as China, today are facing the scarcity and pollution issues of freshwater resources. Suspended solids, as wastewater contaminants, may contain components such as nitrogen, phosphorus, heavy metals and pathogens that are harmful to the environment and human health, it is essential to know the size distribution regularity of the solids with a view to guiding the management of freshwater resources for sustainability. Particle size distribution (PSD) mathematical models and properties of suspended solids in a typical freshwater pond were investigated in this study. Particle size was measured using a laser particle size analyzer (measurement range: 0.01-3500 μm). The power law model and the variable-β model were tested for their ability to fit the numeric distribution of suspended solids; Gaussian (i.e., normal) distribution and log-normal distribution models were used to evaluate the volumetric distribution of suspended solids. The results showed that: by number, about 80% of the particles contributed to only 10% of total particle volume, while the remaining 20% contributed about 90% of the total volume. For numeric distribution, the variable-β model (R² = 0.975 ± 0.011) was better than the power law model (R² = 0.899 ± 0.033); for the volumetric distribution, the log-normal distribution model (R² = 0.968 ± 0.020) clearly outperformed the Gaussian distribution model (R² = 0.655 ± 0.093). Overall, the variable-β model and log-normal distribution were shown to accurately describe the numerical and volumetric distribution of pond water suspended solids, respectively. PSD model parameters can be related to some compositions in the wastewater and can provide guidance for suspended solids further treatment, be it physical, biological, chemical or synthetic methods.

Impacts of exogenous pollutant bisphenol A on characteristics of soybeans

Bisphenol A (BPA) is an endocrine disruptor that is ubiquitous in the environment. Previous studies have focused on the effects of BPA on plants to assess the ecological risk of BPA in the environment. To evaluate the effects of BPA on plant biological characters more systematically, we investigated the biological characters of above-ground and under-ground organs of soybean plants exposed to BPA. Meanwhile, the mechanisms for the observed changes were also analyzed from the view of hormone levels and photosynthesis. The results showed that after exposure to 0.8 mg L-1 BPA for three days, indole-3-acetic acid (IAA) and gibberellic acid levels in roots increased significantly, and the IAA level increased in leaves, so the character indices of roots and leaves both increased. The IAA and ethylene levels in stems increased, but the character indices of stems did not increased. With higher BPA concentrations, especially exposure to 17.2 mg L-1 BPA, the levels of IAA, gibberellic acid, and zeatin decreased (except for the increased zeatin in leaves), and abscisic acid and ethylene levels increased; thus, all of the character indices significantly decreased. By comparing the changes in various biological characters, we found that leaf area, root surface area, and root length changed most significantly. In addition, changes in photosynthetic parameters provided initial causes for plant growth changes, and impacted biological characters. The changes of character indices were stronger when the BPA exposure time was prolonged, and after the removal of BPA, the character indices showed some recovery. Therefore, BPA exposure can regulate the changes in plant characters by influencing hormone levels and photosynthesis, and root surface area, root length, and leaf area were the most sensitive to BPA.

Selected Viruses Detected on and in our Food

PURPOSE OF REVIEW

The purpose of this review is to provide an update on recent literature and findings concerning selected foodborne viruses. Two groups of viruses were selected: (a) the most important viruses contaminating food, based on numbers of publications in the last 5 years and (b) viruses infecting sources of food that might have an impact on human health.

RECENT FINDINGS

Important foodborne viruses such as norovirus, hepatitis A and rotavirus are usually "only" contaminating food and are detected on the surface of foodstuffs. However, they are threats to human public health and make up for the majority of cases. In contrast, the meaning of viruses born from within the food such as natural animal and plant viruses is still in many cases unknown. An exception is Hepatitis E virus that is endemic in pigs, transmitted via pork meat and is recognised as an emerging zoonosis in industrialised countries.

SUMMARY

Even though the clinical meaning of "new" foodborne viruses, often detected by next generation sequencing, still needs clarification, the method has great potential to enhance surveillance and detection particularly in view of an increasingly globalised food trade.