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

Influence of suspended particles and dissolved organic matters on virus enrichment in reclaimed water by two-step tangential flow ultrafiltration: Phenomena and mechanisms

Enteric virus concentration in large-volume water samples is crucial for detection and essential for assessing water safety. Certain dissolution and suspension components can affect the enrichment process. In this study, tangential flow ultrafiltration (TFUF) was used as an enrichment method for recovering enteric virus in water samples. Interestingly, the bacteriophage MS2 recovery in reclaimed water and the reclaimed water without particles were higher than that in ultrapure water. The simulated reclaimed water experiments showed that humic acid (HA) (92.16% ± 4.32%) and tryptophan (Try) (81.50 ± 7.71%) enhanced MS2 recovery, while the presence of kaolin (Kaolin) inhibited MS2 recovery with an efficiency of 63.13% ± 11.17%. Furthermore, Atomic force microscopy (AFM) revealed that the MS2-HA cluster and the MS2-Try cluster had larger roughness values on the membrane surface, making it difficult to be eluted, whereas MS2-Kaolin cluster had compact surfaces making it difficult to be eluted. Additionally, the MS2-HA cluster is bound to the membrane by single hydrogen bond with SO, whereas both the MS2-Try cluster and the MS2-Kaolin cluster are bound to the membrane by two hydrogen bonds, making eluting MS2 challenging. These findings have potential implications for validating standardized methods for virus enrichment in water samples.

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.

Viral community distribution, assembly mechanism, and associated hosts in an industrial park wastewater treatment plant

Viruses manipulate bacterial community composition and impact wastewater treatment efficiency. Some viruses pose threats to the environment and human populations through infection. Improving the efficiency of wastewater treatment and ensuring the health of the effluent and receptor pools requires an understanding of how viral communities assemble and interact with hosts in wastewater treatment plants (WWTPs). We used metagenomic analysis to study the distribution, assembly mechanism, and sensitive hosts for the viral communities in raw water, anaerobic tanks, and returned activated sludge units of a large-scale industrial park WWTP. Uroviricota (53.42% ± 0.14%) and Nucleocytoviricota (26.1% ± 0.19%) were dominant in all units. Viral community composition significantly differed between units, as measured by β diversity (P = 0.005). Compared to raw water, the relative viral abundance decreased by 29.8% in the anaerobic tank but increased by 9.9% in the activated sludge. Viral community assembly in raw water and anaerobic tanks was predominantly driven by deterministic processes (MST <0.5) versus stochastic processes (MST >0.5) in the activated sludge, indicating that differences in diffusion limits may fundamentally alter the assembly mechanisms of viral communities between the solid and liquid-phase environments. Acidobacteria was identified as the sensitive host contributing to viral abundance, exhibiting strong interactions and a mutual dependence (degree = 59). These results demonstrate the occurrence and prevalence of viruses in WWTPs, their different assembly mechanism, and sensitive hosts. These observations require further study of the mechanisms of viral community succession, ecological function, and roles in the successive wastewater treatment units.

Investigating the Presence of Rotavirus in Wastewater Samples of Bhopal Region, India, by Utilizing Droplet Digital Polymerase Chain Reaction

INTRODUCTION

Rotavirus-induced viral gastroenteritis outbreaks result in over two million hospitalizations globally yearly. Wastewater-based epidemiology (WBE) has emerged as a crucial tool for detecting and monitoring viral outbreaks. The adoption of WBE has been instrumental in the early detection and surveillance of such viral outbreaks, providing a non-invasive method to assess public health.

OBJECTIVE

This study aims to utilize droplet digital polymerase chain reaction (ddPCR) technology to detect and quantify Rotavirus in wastewater samples collected from the Bhopal region of India, thereby contributing to the understanding and management of viral gastroenteritis outbreaks through environmental surveillance.

METHODS

In this study, we used ddPCR to detect and quantify Rotavirus in wastewater samples collected from the Bhopal region of India. We monitored its viral presence in municipal sewage treatment plants bi-weekly using an advanced ddPCR assay. Targeting the rotavirus non-structural protein 3 (NSP-3) region with custom primers and TaqMan probes, we detected virus concentration employing polyethylene glycol (PEG). Following RNA isolation, complementary DNA (cDNA) synthesis, and ddPCR analysis, our novel method eliminated standard curve dependence, propelling virus research and treatment forward.

RESULTS

Out of the 42 samples collected, a 16.60% positivity rate was observed, indicating a moderate presence of Rotavirus in Bhopal. The wastewater treatment plants (WWTP) attached to a hospital exhibited a 42.85% positivity rate, indicating the need for targeted monitoring. Leveraging ddPCR, precise quantification of rotavirus concentrations (ranging from 0.75 to 28.9 copies/µL) facilitated understanding and supported effective remediation.

CONCLUSIONS

 This study emphasizes the importance of vigilant wastewater surveillance, especially in WWTPs with higher rotavirus prevalence. The significance of ddPCR in comparison to conventional and real-time PCR lies in its superior sensitivity and specificity in detecting and quantifying positive samples. Furthermore, it can identify positive samples even in the smallest quantities without the need for a standard curve to evaluate. This makes ddPCR a valuable tool for accurate and precise detection and quantification of samples.

Field-deployable assay based on CRISPR-Cas13a coupled with RT-RPA in one tube for the detection of SARS-CoV-2 in wastewater

CRISPR-based nucleic acid detection is easy to implement, field deployable, and always coupled with isothermal amplification to improve the sensitivity. However, the conventional detection requires two separate steps, which can cause long-lasting amplicon aerosol contaminants, hence leading to false-positive results. To address this problem, we proposed a one-tube assay based on CRISPR-Cas13a coupled with reverse transcription-recombinase polymerase amplification to avoid aerosol pollution. The one-tube assay could be completed within 40 min with a sensitivity of up to 180 copies of RNA per reaction, and exhibited no cross reactivity with two related coronaviruses. Our technology showed reproducibility with relative standard deviation of 4.6% responding to 1 fM nucleic acid for three times. It could be used to detect SARS-CoV-2 nucleic acids in raw wastewater with a limit of detection of 103 copies/mL. We also validated the practicability of this technique for viral detection in environmental water samples by detecting SARS-CoV-2 in wastewater, which were not detectable by RT-qPCR technology, showing resistance of this technology to wastewater matrix. It is anticipated that the robustness and high sensitivity will significantly promote the development of a point-of-care method in environmental virus monitoring.

Inactivation of the enveloped virus phi6 with hydrodynamic cavitation

The COVID -19 pandemic reminded us that we need better contingency plans to prevent the spread of infectious agents and the occurrence of epidemics or pandemics. Although the transmissibility of SARS-CoV-2 in water has not been confirmed, there are studies that have reported on the presence of infectious coronaviruses in water and wastewater samples. Since standard water treatments are not designed to eliminate viruses, it is of utmost importance to explore advanced treatment processes that can improve water treatment and help inactivate viruses when needed. This is the first study to investigate the effects of hydrodynamic cavitation on the inactivation of bacteriophage phi6, an enveloped virus used as a SARS-CoV-2 surrogate in many studies. In two series of experiments with increasing and constant sample temperature, virus reduction of up to 6.3 logs was achieved. Inactivation of phi6 at temperatures of 10 and 20 °C occurs predominantly by the mechanical effect of cavitation and results in a reduction of up to 4.5 logs. At 30 °C, the reduction increases to up to 6 logs, where the temperature-induced increased susceptibility of the viral lipid envelope makes the virus more prone to inactivation. Furthermore, the control experiments without cavitation showed that the increased temperature alone is not sufficient to cause inactivation, but that additional mechanical stress is still required. The RNA degradation results confirmed that virus inactivation was due to the disrupted lipid bilayer and not to RNA damage. Hydrodynamic cavitation, therefore, has the potential to inactivate current and potentially emerging enveloped pathogenic viruses in water at lower, environmentally relevant temperatures.