Removal of Rotavirus and Bacteriophages by Membrane Bioreactor Technology from Sewage

Surface modification of PVDF ultrafiltration membranes using spacer arms and synthetic receptors for virus capturing and separation

Although membrane technology has demonstrated outstanding pathogen removal capabilities, current commercial membranes are insufficient for removing small viruses at trace levels due to certain limitations. The theoretical and practical significance of developing a new form of hydrophilic, anti-fouling, and virus-specific ultra-purification membrane with high capturing and separation efficiency, stability, and throughput for water treatment is of the utmost importance. In this study, molecularly imprinted membranes (MIMs) were fabricated from polyvinylidene fluoride (PVDF) membranes utilizing novel surface hydrophilic modification techniques, followed by the immobilization of virus-specific molecularly imprinted nanoparticles (nanoMIPs) as synthetic receptors. Three distinct membrane functionalization strategies were established and optimized for the first time: membrane functionalization with (i) polyethyleneimine (PEI) and dopamine (DOP), (ii) PEI and 3-(chloropropyl)-trimethoxysilane (CTS), and (iii) chitosan (CS). Hydrophilicity was enhanced significantly as a result of these modification strategies. Additionally, the modifications enabled spacer arms between the membrane surface and the nanoMIPs to decrease steric hindrance. The surface chemistry, morphology, and membrane performance results from the characterization analysis of the MIMs demonstrated excellent hydrophilicity (e.g., the functionalized membrane presented 37.84° while the unmodified bare membrane exhibited 128.94° of water contact angle), higher permeation flux (145.96 L m-2 h-1 for the functionalized membrane), excellent uptake capacity (up to 99.99 % for PEI-DOP-MIM and CS-MIM), and recovery (more than 80 % for PEI-DOP-MIM). As proof of concept, the cutting-edge MIMs were able to eliminate the model adenoviruses up to 99.99 % from water. The findings indicate that the novel functionalized PVDF membranes hold promise for implementation in practical applications for virus capture and separation.

Relative abundance and the fate of human rotavirus in wastewater during treatment processes: identification of potential infectious rotavirus in the final effluents and receiving aquatic milieu in Durban area, South Africa

The occurrence and persistence of rotaviruses in raw and treated wastewater and their discharge into rivers represent a significant health risk for humans and animals, worldwide. In this study, samples were collected monthly from each of the four Durban wastewater treatment plants (DWWTPs) and receiving rivers for a period of 3 months. Rotavirus was quantified by real-time quantitative PCR (RT-qPCR), and viability was assessed using integrated cell culture (ICC)-qPCR. Rotavirus was detected consistently in 100% of influent wastewaters (mean concentration range, 4.36-4.46 log10 genome equivalent (GE) copies/L) and final effluent samples of three DWWTPs (range, 3.35-3.61 log10 GE copies/L). Overall, 94% (45/48) of the wastewater analyzed and 95% (20/21) of the associated river water samples were positive for rotavirus (range, 2.04-6.77 log10 GE copies/L). The activated sludge process with 0.10-0.43 log10 reduction values (LRV) only moderately reduced the viral loads. Similarly, one of the DWWTPs that operated the biofilter modality produced 0.20 LRV. Though the additional treatment with chlorine produced higher LRV (range, 0.31-0.53) than the corresponding activated sludge or biofilter process, the difference in viral removals was not significant (p > 0.05). The equivalent treatment efficiencies of the four DWWTPs varied from 19 to 43% decay in the population of rotavirus. Further, infectious rotavirus ranging from 66.67 to 100%, 50 to 100%, and 66.67 to 100% were detected in the post-activated sludge, final effluents, and river water samples, respectively. In conclusion, the findings of infectious rotavirus in both the final effluents and associated rivers represent an infection risk for humans or animals during contact. Thus, close monitoring for rotavirus and risk assessment studies under distinct exposure scenarios may further shed light on the health-related risks associated with water recovery and reuse in urban settings.

Detection of Enteroviruses and SARS-CoV-2 in Tunisian Wastewater

Monitoring the circulation of enteric viruses in environmental wastewater is a valuable tool for preventing the emergence of waterborne and food-borne diseases in humans. The detection of viruses was performed in five Tunisian wastewater treatment plants, three located in the Grand Tunis City (WWTP 1, WWTP 2, WWTP 3) and two in the Sahel of Tunisia (WWTP 4, WWTP 4), known as very developed and crowded zones, to assess the effectiveness of three biological wastewater treatment procedures namely natural oxidizing lagoons, rotating biodisks procedure, activated sludge procedure, and one tertiary sewage treatment using UV-C254 reactor for this enteric viruses' removal. Thus, 242 sewage samples were collected between June 2019 and May 2020 from different lines of wastewater treatment procedures implemented in the five wastewater treatment plants investigated. SARS-CoV-2 was analyzed using real-time multiplex reverse-transcription polymerase chain reaction (multiplex real-time RT-PCR) and enteroviruses using reverse-transcription polymerase chain reaction (RT-PCR). The enteroviruses detection showed 93% and 73% respective high frequencies only in the two WWTPs of the Grand Tunis (WWTP 1 and WWTP 2). SARS-CoV-2 was detected in 58% of the all wastewater samples collected from the five studied WWTPs with a respective dominance of N gene (47%), S gene (42%), RdRp gene (42%) and at last E gene (20%). These enteroviruses and SARS-CoV-2 detection were revealed in all steps of the wastewater treatment procedures, so poor virological quality is found at the exit of each biological and tertiary step of treatment investigated. For the first time in Tunisia, these results highlighted the enterovirus and SARS-CoV-2 detection with high rates, and the ineffectiveness of the biological and UV-C254 treatment implemented to remove these viruses. The preliminary results of SARS-CoV-2 circulation in Tunisian wastewater confirmed the wide positivity rate underlined by other works worldwide and allowed showing a move towards integrating wastewater as a way for this virus to spread in different areas and environments. So, this last result about SARS-CoV-2 circulation allowed us to caution about the strong probability of diffusion of this hazardous virus through water and sewage; despite its enveloped character and nature, as a labile and sensitive virus in these environments. Thus, establishing a national surveillance strategy is needed to improve the sanitary quality of treated wastewater and prevent public health problems related to these viruses in treated wastewater.

Bioselective PES Membranes Based on Chitosan Functionalization and Virus-Imprinted NanoMIPs for Highly Efficient Separation of Human Pathogenic Viruses from Water

Waterborne viruses are a public health concern due to relatively small infection doses. Particularly, adenoviruses (AdVs) are more resistant than RNA viruses to water purification treatments in terms of ultraviolet (UV) irradiation, pH, and chlorination tolerance. Moreover, AdVs are one of the most predominant waterborne viruses. Membrane separations have proven superior removal capabilities of waterborne pathogens over other separation methods. However, virus removal at ultratrace levels is still a significant challenge for current membrane technology. This study successfully addressed this challenge by developing a bioselective polyethersulfone (PES) membrane by a joint strategy involving chitosan hydrophilic surface modification and the immobilization of adenovirus-specific molecularly imprinted nanoparticles (nanoMIPs). The topological and chemical changes taking place on the membrane surface were characterized by using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Furthermore, hydrophilicity and membrane performance were investigated in terms of swelling behavior, permeation flux, and surface fouling studies. The membrane efficacy was evaluated by filtration experiments, where the virus concentration of the loading solution before filtration and the permeates after filtration was quantified. The novel bioselective membrane showed excellent virus removal capabilities by separating 99.99% of the viruses from the water samples.

Epidemiological significance of the occurrence and persistence of rotaviruses in water and sewage: a critical review and proposal for routine microbiological monitoring

Globally, waterborne gastroenteritis attributable to rotaviruses is on the increase due to the rapid increase in population growth, poor socioeconomic conditions, and drastic changes in climatic conditions. The burden of diarrhea is quite alarming in developing nations where the majority of the populations still rely on untreated surface water that is usually polluted for their immediate water needs. Humans and animals of all ages are affected by rotaviruses. In humans, the preponderance of cases occurs in children under 5 years. Global efforts in advancing water/wastewater treatment technologies have not yet realized the objective of complete viral removal from wastewater. Most times, surface waters are impacted heavily by inadequately treated wastewater run-offs thereby exposing people or animals to preventable health risks. The relative stability of rotaviruses in aquatic matrices during wastewater treatment, poor correlation of bacteriological indicators with the presence of rotaviruses, and their infectiousness at a low dose informed the proposal for inclusion in the routine microbiological water screening panel. Environmental monitoring data have been shown to provide early warnings that can complement clinical data used to monitor the impact of current rotavirus vaccination in a community. This review was therefore undertaken to critically appraise rotavirus excretion and emission pathways, and the existence, viability and persistence in the receiving aquatic milieu. The efficiency of the current wastewater treatment modality for rotavirus removal, correlation of the current bacteriological water quality assessment strategy, public health risks and current laboratory methods for an epidemiological study were also discussed.

Inactivation of Hepatovirus A in wastewater by 254 nm ultraviolet-C irradiation

Hepatovirus A is known as a waterborne and foodborne virus that can be transmitted from one person to another through contaminated water and raw food. Therefore, it is necessary to survey the circulation of this type of enteric virus in the wastewater to prevent prospective outbreaks. Wastewater samples collected from WWTP El Menzeh I and Charguia I have been the subject for physicochemical, bacteriological (MPN) and virological analyses. Hepatovirus A (HAV) detection was carried out using the standard reverse transcription-polymerase chain reaction (RT-PCR). Hepatovirus A was detected respectively in 62% (63/102) and 66% (92/140) of the collected wastewater samples at El Menzeh I and Charguia I WWTPs. The treated effluent by natural oxidizing lagoon procedure was characterized by a poor physical-chemical and virological qualities but with excellent bacteriological quality. Consequently, this effluent is not suitable to be recycled and reused in agriculture or even dismissed in the environment. The treated sewage by activated sludge and rotating biodisk procedures turned out to be of a very good physical-chemical quality but with a poor bacteriological and virological quality. After tertiary UV-C₂₅₄ nm irradiation, the faecal indicator bacteria concentration was mostly reduced and removed. These findings confirmed the need for improvement and upgrade of the treatment processes used in these two studied sewage purification plants and the necessity of implementation and establishment of a proper national virological standard to control the circulation rates of enteric viruses in Tunisian municipal wastewater.

Nutritional, Energy and Sanitary Aspects of Swine Manure and Carcass Co-digestion

Renewable energy can assist the management of the effects of population growth and rapid economic development on the sustainability of animal husbandry. The primary aim of renewable energy is to minimize the use of fossil fuels via the creation of environmentally friendly energy products from depleted fossil fuels. Digesters that treat swine manure are extensively used in treatment systems; and inclusion of swine carcasses can increase the organic loading rate (OLR) thereby improving biogas yield and productivity on farms. However, the characteristics of the components including animal residues, proteins, lipids, remains of undigested feed items, antimicrobial drug residues, pathogenic microorganisms and nutrient contents, are complex and diverse. It is therefore necessary to manage the anaerobic process stability and digestate purification for subsequent use as fertilizer. Efficient methane recovery from residues rich in lipids is difficult because such residues are only slowly biodegradable. Pretreatment can promote solubilization of lipids and accelerate anaerobic digestion, and pretreatments can process the swine carcass before its introduction onto biodigesters. This review presents an overview of the anaerobic digestion of swine manure and carcasses. We analyze the characteristics of these residues, and we identify strategies to enhance biogas yield and process stability. We consider energy potential, co-digestion of swine manure and carcasses, physical, chemical, and biological pretreatment of biomass, sanitary aspects of swine manure and co-digestates and their recycling as fertilizers.

Occurrence of Staphylococcus spp. and investigation of fecal and animal viral contaminations in livestock, river water, and sewage from Tunisia and Romania

The objective of this study was to determine the occurrence of Staphylococcus spp., Escherichia coli, somatic coliphages, F-specific RNA bacteriophages, hepatitis E virus (HEV), and bovine enterovirus (BEV) in fecal and water samples. The occurrence of Staphylococcus spp. was investigated in treated wastewater samples collected from slaughterhouse of Tunisia. Results showed that Staphylococcus spp. were detected in the totality of collected samples with an average mean of 5.44 Log₁₀ (CFU/100 ml). Regarding fecal indicator bacteria, E. coli was detected in the totality of water samples and was more abundant in Tunisian samples than in samples collected from Romania (P < 0.05). Concerning somatic coliphages and F-specific RNA bacteriophages used as viral indicators, they were detected in all raw and treated wastewaters. Bovine enterovirus (BEV) was detected in 20.1% and 28% of bovine stool samples collected from Tunisia and Romania, respectively. BEV was also detected in 60% of porcine stool samples from Romania. BEV was absent in all treated sewage samples. HEV was detected in raw sewage and bovine fecal sample from Romania with low occurrence and none sample from Tunisia was positive. This study may give us an insight into the monitoring of water quality in Tunisia and Romania.

Performance of wastewater reclamation systems in enteric virus removal

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

Transmission of hepatitis E virus by water: An issue still pending in industrialized countries

Hepatitis E virus (HEV) is an enteric virus divided into eight genotypes. Genotype 1 (G1) and G2 are specific to humans; G3, G4 and G7 are zoonotic genotypes infecting humans and animals. Transmission to humans through water has been demonstrated for G1 and G2, mainly in developing countries, but is only suspected for the zoonotic genotypes. Thus, the water-related HEV hazard may be due to human and animal faeces. The high HEV genetic variability allows considering the presence in wastewater of not only different genotypes, but also quasispecies adding even greater diversity. Moreover, recent studies have demonstrated that HEV particles may be either quasi-enveloped or non-enveloped, potentially implying differential viral behaviours in the environment. The presence of HEV has been demonstrated at the different stages of the water cycle all over the world, especially for HEV G3 in Europe and the USA. Concerning HEV survival in water, the virus does not have higher resistance to inactivating factors (heat, UV, chlorine, physical removal), compared to viral indicators (MS2 phage) or other highly resistant enteric viruses (Hepatitis A virus). But the studies did not take into account genetic (genogroups, quasispecies) or structural (quasi- or non-enveloped forms) HEV variability. Viral variability could indeed modify HEV persistence in water by influencing its interaction with the environment, its infectivity and its pathogenicity, and subsequently its transmission by water. The cell culture methods used to study HEV survival still have drawbacks (challenging virus cultivation, time consuming, lack of sensitivity). As explained in the present review, the issue of HEV transmission to humans through water is similar to that of other enteric viruses because of their similar or lower survival. HEV transmission to animals through water and how the virus variability affects its survival and transmission remain to be investigated.

Characterization of Natural Organic Substances Potentially Hindering RT-PCR-Based Virus Detection in Large Volumes of Environmental Water

Quantitative detection of pathogenic viruses in the environmental water is essential for the assessment of water safety. It is known that some of natural organic substances interfere with virus detection processes, i.e., nucleic acid extraction and reverse transcription-PCR. Such substances are carried over into a sample after virus concentration. In this study, inhibitory substances in coastal water samples were characterized in view of their effects on efficiency of virus detection and property as organic matters. Among 81 samples tested, 77 (95%) showed low recoveries (<10%) of spiked murine norovirus. These recovery rates were correlated with the levels of organic matter present in virus concentrates as measured by ultraviolet absorbance at 254 nm (r = -0.70 - -0.71, p < 0.01). High-performance gel chromatography and fluorescence excitation-emission matrix spectroscopy revealed that organic fractions in the 10-100 kDa size range, which were not dominant in the original samples, and those possessing humic acid-like fluorescence properties were dominant in virus concentrates. The inhibitory effect was more pronounced during summer. Substances originating from seawater seemed to cause a more pronounced effect than those originating from wastewater. Our data highlight the previously unknown characteristics of natural inhibitory substances and are helpful in establishing an effective sample purification technique.

Real-Time qPCR as a Method for Detection of Antibody-Neutralized Phage Particles

The most common method for phage quantitation is the plaque assay, which relies on phage ability to infect bacteria. However, non-infective phage particles may preserve other biological properties; specifically, they may enter interactions with the immune system of animals and humans. Here, we demonstrate real-time quantitative polymerase chain reaction (qPCR) detection of bacteriophages as an alternative to the plaque assay. The closely related staphylococcal bacteriophages A3R and 676Z and the coliphage T4 were used as model phages. They were tested in vivo in mice, ex vivo in human sera, and on plastic surfaces designed for ELISAs. T4 phage was injected intravenously into pre-immunized mice. The phage was completely neutralized by specific antibodies within 5 h (0 pfu/ml of serum, as determined by the plaque assay), but it was still detected by qPCR in the amount of approximately 10⁷ pfu/ml of serum. This demonstrates a substantial timelapse between "microbiological disappearance" and true clearance of phage particles from the circulation. In human sera ex vivo, qPCR was also able to detect neutralized phage particles that were not detected by the standard plaque assay. The investigated bacteriophages differed considerably in their ability to immobilize on plastic surfaces: this difference was greater than one order of magnitude, as shown by qPCR of phage recovered from plastic plates. The ELISA did not detect differences in phage binding to plates. Major limitations of qPCR are possible inhibitors of the PCR reaction or free phage DNA, which need to be considered in procedures of phage sample preparation for qPCR testing. We propose that phage pharmacokinetic and pharmacodynamic studies should not rely merely on detection of antibacterial activity of a phage. Real-time qPCR can be an alternative for phage detection, especially in immunological studies of bacteriophages. It can also be useful for studies of phage-based drug nanocarriers or biosensors.

Public health risks associated with hepatitis E virus (HEV) as a food-borne pathogen

Hepatitis E virus (HEV) is an important infection in humans in EU/EEA countries, and over the last 10 years more than 21,000 acute clinical cases with 28 fatalities have been notified with an overall 10-fold increase in reported HEV cases; the majority (80%) of cases were reported from France, Germany and the UK. However, as infection in humans is not notifiable in all Member States, and surveillance differs between countries, the number of reported cases is not comparable and the true number of cases would probably be higher. Food-borne transmission of HEV appears to be a major route in Europe; pigs and wild boars are the main source of HEV. Outbreaks and sporadic cases have been identified in immune-competent persons as well as in recognised risk groups such as those with pre-existing liver damage, immunosuppressive illness or receiving immunosuppressive treatments. The opinion reviews current methods for the detection, identification, characterisation and tracing of HEV in food-producing animals and foods, reviews literature on HEV reservoirs and food-borne pathways, examines information on the epidemiology of HEV and its occurrence and persistence in foods, and investigates possible control measures along the food chain. Presently, the only efficient control option for HEV infection from consumption of meat, liver and products derived from animal reservoirs is sufficient heat treatment. The development of validated quantitative and qualitative detection methods, including infectivity assays and consensus molecular typing protocols, is required for the development of quantitative microbial risk assessments and efficient control measures. More research on the epidemiology and control of HEV in pig herds is required in order to minimise the proportion of pigs that remain viraemic or carry high levels of virus in intestinal contents at the time of slaughter. Consumption of raw pig, wild boar and deer meat products should be avoided.

Effect of pressure relaxation and membrane backwash on adenovirus removal in a membrane bioreactor

Pressure relaxation and permeate backwash are two commonly used physical methods for membrane fouling mitigation in membrane bioreactor (MBR) systems. In order to assess the impact of these methods on virus removal by MBRs, experiments were conducted in a bench-scale submerged MBR treating synthetic wastewater. The membranes employed were hollow fibers with the nominal pore size of 0.45 μm. The experimental variables included durations of the filtration (tTMP>0), pressure relaxation (tTMP=0) and backwash (tTMP<0) steps. Both pressure relaxation and permeate backwash led to significant reductions in removal of human adenovirus (HAdV). For the same value of tTMP>0/tTMP=0, longer filtration/relaxation cycles (i.e. larger tTMP+tTMP=0) led to higher transmembrane pressure (TMP) but did not have a significant impact on HAdV removal. A shorter backwash (tTMP<0 = 10 min) at a higher flow rate (Q = 40 mL/min) resulted in more substantial decreases in TMP and HAdV removal than a longer backwash (tTMP<0 = 20 min) at a lower flow rate (Q = 20 mL/min) even though the backwash volume (QtTMP<0) was the same. HAdV removal returned to pre-cleaning levels within 16 h after backwash was applied. Moderate to strong correlations (R(2) = 0.63 to 0.94) were found between TMP and HAdV removal.