The Fennoscandian Shield deep terrestrial virosphere suggests slow motion 'boom and burst' cycles.

The deep biosphere contains members from all three domains of life along with viruses. Here we investigate the deep terrestrial virosphere by sequencing community nucleic acids from three groundwaters of contrasting chemistries, origins, and ages. These viromes constitute a highly unique community compared to other environmental viromes and sequenced viral isolates. Viral host prediction suggests that many of the viruses are associated with Firmicutes and Patescibacteria, a superphylum lacking previously described active viruses. RNA transcript-based activity implies viral predation in the shallower marine water-fed groundwater, while the deeper and more oligotrophic waters appear to be in 'metabolic standby'. Viral encoded antibiotic production and resistance systems suggest competition and antagonistic interactions. The data demonstrate a viral community with a wide range of predicted hosts that mediates nutrient recycling to support a higher microbial turnover than previously anticipated. This suggests the presence of 'kill-the-winner' oscillations creating slow motion 'boom and burst' cycles.

Pepper Mild Mottle Virus as Indicator of Pollution: Assessment of Prevalence and Concentration in Different Water Environments in Italy.

Pepper mild mottle virus (PMMoV), a plant pathogenic virus belonging to the family Virgoviridae, has been proposed as a potential viral indicator for human faecal pollution in aquatic environments. The present study investigated the occurrence, amount and diversity of PMMoV in water environments in Italy. A total of 254 water samples, collected between 2017 and 2019 from different types of water, were analysed. In detail, 92 raw sewage, 32 treated sewage, 16 river samples, 9 estuarine waters, 20 bathing waters, 67 groundwater samples and 18 drinking waters were tested. PMMoV was detected in 79% and 75% of untreated and treated sewage samples, respectively, 75% of river samples, 67% and 25% of estuarine and bathing waters and 13% of groundwater samples. No positive was detected in drinking water. The geometric mean of viral concentrations (genome copies/L) was ranked as follows: raw sewage (2.2 × 106) > treated sewage (2.9 × 105) > river waters (6.1 × 102) > estuarine waters (4.8 × 102) > bathing waters (8.5 × 101) > groundwater (5.9 × 101). A statistically significant variation of viral loads could be observed between raw and treated sewage and between these and all the other water matrices. PMMoV occurrence and viral loads did not display seasonal variation in raw sewage nor correlation with faecal indicator bacteria in marine waters and groundwater. This study represents the first report on the occurrence and quantification PMMoV in different water environments in Italy. Further studies are required to evaluate the suitability of PMMoV as a viral indicator for human faecal pollution and for viral pathogens in waters.

Identifying septic pollution exposure routes during a waterborne norovirus outbreak - A new application for human-associated microbial source tracking qPCR.

In June 2017, the Pennsylvania Department of Health (PADOH) was notified of multiple norovirus outbreaks associated with 179 ill individuals who attended separate events held at an outdoor venue and campground over a month period. Epidemiologic investigations were unable to identify a single exposure route and therefore unable to determine whether there was a persistent contamination source to target for exposure mitigation. Norovirus was detected in a fresh recreational water designated swimming area and a drinking water well. A hydrogeological site evaluation suggested a nearby septic leach field as a potential contamination source via ground water infiltration. Geological characterization revealed a steep dip of the bedrock beneath the septic leach field toward the well, providing a viral transport pathway in a geologic medium not previously documented as high risk for viral ground water contamination. The human-associated microbial source tracking (MST) genetic marker, HF183, was used as a microbial tracer to demonstrate the hydrogeological connection between the malfunctioning septic system, drinking water well, and recreational water area. Based on environmental investigation findings, venue management and local public health officials implemented a series of outbreak prevention strategies including discontinuing the use of the contaminated well, issuing a permit for a new drinking water well, increasing portable toilet and handwashing station availability, and promoting proper hand hygiene. Despite the outbreaks at the venue and evidence of ground water contamination impacting nearby recreational water and the drinking water well, no new norovirus cases were reported during a large event one week after implementing prevention practices. This investigation highlights a new application for human-associated MST methods to trace hydrological connections between multiple fecal pollutant exposure routes in an outbreak scenario. In turn, pollutant source information can be used to develop effective intervention practices to mitigate exposure and prevent future outbreaks associated with human fecal contaminated waters.

Inclusion of Oxford Nanopore long reads improves all microbial and viral metagenome-assembled genomes from a complex aquifer system.

Assembling microbial and viral genomes from metagenomes is a powerful and appealing method to understand structure-function relationships in complex environments. To compare the recovery of genomes from microorganisms and their viruses from groundwater, we generated shotgun metagenomes with Illumina sequencing accompanied by long reads derived from the Oxford Nanopore Technologies (ONT) sequencing platform. Assembly and metagenome-assembled genome (MAG) metrics for both microbes and viruses were determined from an Illumina-only assembly, ONT-only assembly, and a hybrid assembly approach. The hybrid approach recovered 2× more mid to high-quality MAGs compared to the Illumina-only approach and 4× more than the ONT-only approach. A similar number of viral genomes were reconstructed using the hybrid and ONT methods, and both recovered nearly fourfold more viral genomes than the Illumina-only approach. While yielding fewer MAGs, the ONT-only approach generated MAGs with a high probability of containing rRNA genes, 3× higher than either of the other methods. Of the shared MAGs recovered from each method, the ONT-only approach generated the longest and least fragmented MAGs, while the hybrid approach yielded the most complete. This work provides quantitative data to inform a cost-benefit analysis of the decision to supplement shotgun metagenomic projects with long reads towards the goal of recovering genomes from environmentally abundant groups.

Virus inactivation in groundwater in a postglacial lava field in arctic climate.

Outbreaks of viral gastroenteritis are often connected to contaminated drinking water. The assessment of the water quality relies on the cultivation of indicator bacteria, and little is known of the fate of viruses in groundwater, especially in arctic regions. In Iceland, the groundwater temperature is between 3 and 6°C. The aim of this study was to determine virus inactivation at low temperature in a groundwater microcosm and in a borehole in a postglacial lava field. Two phage species that are commonly used as surrogates for norovirus were used, MS2 and PhiX174. Dialysis bags were used for the samples, and a device was constructed to hold many samples at a time and protect the samples in the borehole. No significant decrease of infective PhiX174 phages in the borehole or of the MS2 phages in the microcosm was observed. A slightly significant decrease of PhiX174 in the microcosm was noticed, with one log reduction time of 476 days. On the other hand, a significant reduction in MS2 was found in the field test, where the time needed for 90% reduction was 12·5 days. The results showed that an infective virus can exist in groundwater for months or years in arctic regions and a great difference may exist between results from microcosm and field tests. SIGNIFICANCE AND IMPACT OF THE STUDY: This study reveals that arctic regions are highly sensitive to virus contamination as an infective virus may exist in groundwater for years at low temperature. The results also show that the virus inactivation observed in field tests may differ considerably from the inactivation observed in laboratory microcosms. The results emphasize the importance of large protection zones around drinking water intakes as well as good wastewater treatment so that the likelihood of faecal contamination of groundwater is reduced.

Norovirus and human adenovirus occurrence and diversity in recreational water in a karst aquifer in the Yucatan Peninsula, Mexico.

AIMS: To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico. METHODS AND RESULTS: Hollow fibre ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real-time quantitative polymerase chain reaction assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1600 genome copies per litre (GC l-1 ). The NoV genogroup II (GII) was detected in 30 and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l-1 . During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l-1 . Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16 and GII.P17, and HAdV F serotypes 40 and 41. CONCLUSIONS: These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations and diversity of NoVs and HadVs in these particular environments.

Evaluation of Sequencing Library Preparation Protocols for Viral Metagenomic Analysis from Pristine Aquifer Groundwaters.

Viral ecology of terrestrial habitats is yet-to be extensively explored, in particular the terrestrial subsurface. One problem in obtaining viral sequences from groundwater aquifer samples is the relatively low amount of virus particles. As a result, the amount of extracted DNA may not be sufficient for direct sequencing of such samples. Here we compared three DNA amplification methods to enrich viral DNA from three pristine limestone aquifer assemblages of the Hainich Critical Zone Exploratory to evaluate potential bias created by the different amplification methods as determined by viral metagenomics. Linker amplification shotgun libraries resulted in lowest redundancy among the sequencing reads and showed the highest diversity, while multiple displacement amplification produced the highest number of contigs with the longest average contig size, suggesting a combination of these two methods is suitable for the successful enrichment of viral DNA from pristine groundwater samples. In total, we identified 27,173, 5,886 and 32,613 viral contigs from the three samples from which 11.92 to 18.65% could be assigned to taxonomy using blast. Among these, members of the Caudovirales order were the most abundant group (52.20 to 69.12%) dominated by Myoviridae and Siphoviridae. Those, and the high number of unknown viral sequences, substantially expand the known virosphere.

Human health risk assessment for the occurrence of enteric viruses in drinking water from wells: Role of flood runoff injections.

We demonstrated that floods can induce severe microbiological contamination of drinking water from wells and suggest strategies to better address water safety plans for groundwater drinking supplies. Since 2002, the Italian Water Research Institute (IRSA) has detected hepatitis A virus, adenovirus, rotavirus, norovirus, and enterovirus in water samples from wells in the Salento peninsula, southern Italy. Perturbations in the ionic strength in water flow can initiate strong virus detachments from terra rossa sediments in karst fractures. This study therefore explored the potential health impacts of prolonged runoff injections in Salento groundwater caused by severe flooding during October 2018. A mathematical model for virus fate and transport in fractures was applied to determine the impact of floodwater injection on groundwater quality by incorporating mechanisms that affect virus attachment/detachment and survival in flowing water at microscale. This model predicted target concentrations of enteric viruses that can occur unexpectedly in wells at considerable distances (5-8 km) from the runoff injection site (sinkhole). Subsequently, the health impact of viruses in drinking water supplied from contaminated wells was estimated during the summer on the Salento coast. Specific unpublished dose-response model coefficients were proposed to determine the infection probabilities for Echo-11 and Polio 1 enteroviruses through ingestion. The median (50%) risk of infection was estimated at 6.3 ·â€¯10-3 with an uncertainty of 23%. The predicted burden of diseases was 4.89 disability adjusted life years per year, i.e., twice the maximum tolerable disease burden. The results highlight the requirement for additional water disinfection treatments in Salento prior to the distribution of drinking water. Moreover, monthly controls of enteric virus occurrence in water from wells should be imposed by a new water framework directive in semiarid regions because of the vulnerability of karst carbonate aquifers to prolonged floodwater injections and enteric virus contamination.

Analysis of viral and bacterial communities in groundwater associated with contaminated land.

This work aimed at the comprehensive analysis of total microbial communities inhabiting a typical hydrocarbon-polluted site, where chemical characteristics of the groundwater were readily available. To achieve this, a joint metagenomic characterization of bacteria and viruses surrounding a contaminant plume was performed over a one-year period. The results presented demonstrated that both potential hydrocarbon degraders and their bacteriophages were dominant around the plume, and that the viral and bacterial diversities found at the site were probably influenced by the pH of the groundwater. Niche-specific and dispersed associations between phages and bacteria were identified. The niche phage-host associations were found at the edge of the site and at the core of the plume where pH was the highest (9.52). The identified host populations included several classes of bacteria (e.g. Clostridia and Proteobacteria). Thirty-six viral generalists were also discovered, with BGW-G9 having the broadest host range across 23 taxa, including Pseudomonas, Polycyclovorans, Methylocaldum and Candidatus Magnetobacterium species. The phages with broad host ranges are presumed to have significant effects on prokaryotic production and horizontal gene transfer, and therefore impact the biodegradation processes conducted by various bacteria of the environment studied. This study for the first time characterized the phages and their bacterial hosts associated with a contaminant plume.

Prevalence of human Norovirus by genotype in contaminated groundwater in Korea over the last decade (2007-2016).

This study investigated the occurrence of human Norovirus (HuNoV) by genotype in 1,486 groundwater samples collected from 843 groundwater wells suspected of contamination during 2007-2016, in South Korea. We identified and genotyped 186 HuNoV sequences in 178 HuNoV-positive samples using the RIVM-NoroNet norovirus genotyping tool (NGT) and phylogenetic tree analysis based on RIVM-NoroNet reference sequences. HuNoV GII was more prevalent than GI. The major genotypes detected were HuNoV GII.4 (43.0%), GII.22 (15.6%), GI.5 (10.2%), and GI.1 (8.6%); several genotypes accounted for < 5.0% of all HuNoVs, including GII.17, GI.6, GI.4, GII.6, GI.8, GII.3, GII.13, GI.3, GI.7, GI.2, GI.9, GII.1, GII.8, and GII.10. The prevalence of HuNoVs and number of genotypes detected has drastically decreased over the last decade. HuNoV GII.17, the emerging genotype worldwide including Europe and Asia, appeared in Korean groundwater from 2010, dominated in 2013-2014, and continued to be observed. HuNoV GII.4, the major type occurred last decade from Korean groundwater except 2013-2014, continued to be detected and prevalent similar to HuNoV GII.17 in 2016.

Overview of Trends in the Application of Metagenomic Techniques in the Analysis of Human Enteric Viral Diversity in Africa's Environmental Regimes.

There has been an increase in the quest for metagenomics as an approach for the identification and study of the diversity of human viruses found in aquatic systems, both for their role as waterborne pathogens and as water quality indicators. In the last few years, environmental viral metagenomics has grown significantly and has enabled the identification, diversity and entire genome sequencing of viruses in environmental and clinical samples extensively. Prior to the arrival of metagenomics, traditional molecular procedures such as the polymerase chain reaction (PCR) and sequencing, were mostly used to identify and classify enteric viral species in different environmental milieu. After the advent of metagenomics, more detailed reports have emerged about the important waterborne viruses identified in wastewater treatment plant effluents and surface water. This paper provides a review of methods that have been used for the concentration, detection and identification of viral species from different environmental matrices. The review also takes into consideration where metagenomics has been explored in different African countries, as well as the limitations and challenges facing the approach. Procedures including sample processing, experimental design, sequencing technology, and bioinformatics analysis are discussed. The review concludes by summarising the current thinking and practices in the field and lays bare key issues that those venturing into this field need to consider and address.

Research on the contamination levels of norovirus in food facilities using groundwater in South Korea, 2015-2016.

Norovirus (NoV) is a major pathogenic virus that is responsible for foodborne and waterborne gastroenteritis outbreaks. Groundwater is an important source of drinking water and is used in agriculture and food manufacturing processes. This study investigated norovirus contamination of groundwater treatment systems at 1360 sites in seven metropolitan areas and nine provinces in 2015-2016. Temperature, pH, residual chlorine, and turbidity content were assessed to analyze the water quality. In 2015, six sites were positive for the presence of NoV (0.88%) and in 2016, two sites were positive (0.29%); in total, NoV was detected in 8 of the 1360 sample sites (0.59%) investigated. Identified genotypes of NoV in groundwater included GI.5, 9 and GII.4, 6, 13, 17, and 21. GII.17 was the most prevalent genotype in treated groundwater used in the food industry. This dominance of GII.17 was corroborated by NoV infection outbreak cases and the results of a survey of coastal waters in South Korea in 2014-2015. Although a low detection rate was observed in this study, NoV is a pathogen that can spread extensively. Therefore, it is necessary to periodically monitor levels of norovirus which is responsible for food poisoning in groundwater. This is a first report to reveal epidemic genotype shift of norovirus in groundwater treatment system of food facilities in South Korea. Our results may contribute to the enhancement of public health and sanitary conditions by providing molecular epidemiological information on groundwater NoV.

Evaluation of Bacterial Contamination as an Indicator of Viral Contamination in a Sedimentary Aquifer in Uruguay.

In Uruguay, groundwater is frequently used for agricultural activities, as well as for human consumption in urban and rural areas. As in many countries worldwide, drinking water microbiological quality is evaluated only according to bacteriological standards and virological analyses are not mentioned in the legislation. In this work, the incidence of human viral (Rotavirus A, Norovirus GII, and human Adenovirus) and bacterial (total and thermotolerant coliform and Pseudomonas aeruginosa) contamination in groundwater in the Salto district, Uruguay, as well as the possible correlation between these groups of microorganisms, was studied. From a total of 134 groundwater samples, 42 (32.1%) were positive for Rotavirus, only 1 (0.7%) for both Rotavirus and Adenovirus, and 96 (72.6%) samples were positive for bacterial indicators. Results also show that Rotavirus presence was not associated with changes in chemical composition of the aquifer water. Bacteriological indicators were not adequate to predict the presence of viruses in individual groundwater samples (well scale), but a deeper spatial-temporal analysis showed that they are promising candidates to assess the viral contamination degree at aquifer scale, since from the number of wells with bacterial contamination the number of wells with viral contamination could be estimated.

Transport of Escherichia coli phage through saturated porous media considering managed aquifer recharge.

Virus is one of the most potentially harmful microorganisms in groundwater. In this paper, the effects of hydrodynamic and hydrogeochemical conditions on the transportation of the colloidal virus considering managed aquifer recharge were systematically investigated. Escherichia coli phage, vB_EcoM-ep3, has a broad host range and was able to lyse pathogenic Escherichia coli. Bacteriophage with low risk to infect human has been found extensively in the groundwater environment, so it is considered as a representative model of groundwater viruses. Laboratory studies were carried out to analyze the transport of the Escherichia coli phage under varying conditions of pH, ionic strength, cation valence, flow rate, porous media, and phosphate buffer concentration. The results indicated that decreasing the pH will increase the adsorption of Escherichia coli phage. Increasing the ionic strength, either Na+ or Ca2+, will form negative condition for the migration of Escherichia coli phage. A comparison of different cation valence tests indicated that changes in transport and deposition were more pronounced with divalent Ca2+ than monovalent Na+. As the flow rate increases, the release of Escherichia coli phage increases and the retention of Escherichia coli phage in the aquifer medium reduces. Changes in porous media had a significant effect on Escherichia coli phage migration. With increase of phosphate buffer concentration, the suspension stability and migration ability of Escherichia coli phage are both increased. Based on laboratory-scale column experiments, a one-dimensional transport model was established to quantitatively describe the virus transport in saturated porous medium.

Persistent Norovirus Contamination of Groundwater Supplies in Two Waterborne Outbreaks.

Microbiological contamination of groundwater supplies causes waterborne outbreaks worldwide. In this study, two waterborne outbreaks related to microbiological contamination of groundwater supplies are described. Analyses of pathogenic human enteric viruses (noroviruses and adenoviruses), fecal bacteria (Campylobacter spp. and Salmonella spp.), and indicator microbes (E. coli, coliform bacteria, intestinal enterococci, Clostridium perfringens, heterotrophic plate count, somatic and F-specific coliphages) were conducted in order to reveal the cause of the outbreaks and to examine the effectiveness of the implemented management measures. Moreover, the long-term persistence of noro- and adenovirus genomes was investigated. Noroviruses were detected in water samples from both outbreaks after the intrusion of wastewater into the drinking water sources. In the outbreak I, the removal efficiency of norovirus genome (3.0 log10 removal) in the sand filter of onsite wastewater treatment system (OWTS) and during the transport through the soil into the groundwater well was lower than the removal efficiencies of E. coli, coliform bacteria, intestinal enterococci, and spores of C. perfringens (6.2, 6.0, > 5.9, and > 4.8 log10 removals, respectively). In the outbreak II, cleaning of massively contaminated groundwater well and drinking water distribution network proved challenging, and noro- and adenovirus genomes were detected up to 3 months (108 days). The long-term persistence study showed that noro- and adenovirus genomes can remain detectable in the contaminated water samples up to 1277 and 1343 days, respectively. This study highlights the transport and survival properties of enteric viruses in the environment explaining their potency to cause waterborne outbreaks.

Strong release of viruses in fracture flow in response to a perturbation in ionic strength: Filtration/retention tests and modeling.

Effluents derived from a municipal wastewater treatment plant were used for virus filtration/retention experiments by using a horizontal laboratory filter. Filtration tests were performed to examine how soil geochemical heterogeneity and fracture patterns affected the transport of viruses in groundwater in order to model the influence of reductive perturbations in ionic strength (IS) during wastewater filtration. Although perturbations of IS and velocity are known to result in resuspension of colloids, we found that the effect of soil geochemical heterogeneity can produce strong and instantaneous virus releases in fractured aquifers, likely an internal additional source of viruses. Sixteen limestone slabs were packed in a PVC box filter at the Bari Laboratory (South Italy) to replicate wastewater filtration throughout a fractured medium similar to the Bari carbonate aquifer. Terra rossa, which is an aggregate of sand, silt and clay, was unevenly spread on the surface of each limestone slab within the filter. Since the mineralogical composition of terra rossa includes iron (hematite, magnetite, and goethite) oxides, the soil exhibited localized unfavorable colloid/collector interactions for attachment. In contrast, soil-free parts of the fracture surfaces maintained favorable colloid/collector interactions. We found in our experiments that the lowering of IS due to the reduction of water salt content, which could occur during runoff injections after rainfall, might be sufficient to cause strong detachment of viruses from fracture surfaces, allowing further migration into the groundwater. The model in this work can predict the count and pathways of released viruses in groundwater fractures under soil geochemical heterogeneity and originated by reductions of IS, by using analytical solutions.

Occurrence of Pepper Mild Mottle Virus (PMMoV) in Groundwater from a Karst Aquifer System in the Yucatan Peninsula, Mexico.

The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons. Total coliform bacteria were detected at all sites, whereas Escherichia coli were found at relatively low levels <40 MPN/100 ml. The highest average concentrations of somatic and male F+ specific coliphages were 920 and 330 plaque forming units per 100 ml, respectively, detected in freshwater during the rainy season. PMMoV RNA was detected in 85% of the samples with gene sequences sharing 99-100% of nucleotide identity with PMMoV sequences available in GenBank. Quantification of PMMoV genome copies (GC) by quantitative real-time PCR indicated concentrations ranging from 1.7 × 101 to 1.0 × 104 GC/L, with the highest number of GC detected during the rainy season. No significant correlation was observed between PMMoV occurrence by season or water type (p > 0.05). Physicochemical and indicator bacteria were not correlated with PMMoV concentrations. The abundance and prevalence of PMMoV in the karst aquifer may reflect its environmental persistence and its potential as a fecal indicator in this karst aquifer system.

Quantification and Genotyping of Aichi Virus 1 in Water Samples in the Kathmandu Valley, Nepal.

Aichi virus 1 genomes were detected by quantitative PCR in groundwater from shallow dug (10/22) and tube wells (1/15), river water (14/14), and sewage (1/1), with the maximum concentration of 4.0 × 109 copies/l. Nucleotide sequencing analysis demonstrated the prevalence of genotype B in the virus positive samples.

Temperature dependency of virus and nanoparticle transport and retention in saturated porous media.

The influence of temperature on virus (PRD1 and ΦX174) and carboxyl-modified latex nanoparticle (50 and 100nm) attachment was examined in sand-packed columns under various physiochemical conditions. When the solution ionic strength (IS) equaled 10 and 30mM, the attachment rate coefficient (katt) increased up to 109% (p<0.0002) and the percentage of the sand surface area that contributed to attachment (Sf) increased up to 160% (p<0.002) when the temperature was increased from 4 to 20°C. Temperature effects at IS=10 and 30mM were also dependent on the system hydrodynamics; i.e., enhanced retention at a lower pore water velocity (0.1m/day). Conversely, this same temperature increase had a negligible influence on katt and Sf values when IS was 1mM or >50mM. An explanation for these observations was obtained from extended interaction energy calculations that considered nanoscale roughness and chemical heterogeneity on the sand surface. Interaction energy calculations demonstrated that the energy barrier to attachment in the primary minimum (∆Φa) decreased with increasing IS, chemical heterogeneity, and temperature, especially in the presence of small amounts of nanoscale roughness (e.g., roughness fraction of 0.05 and height of 20nm in the zone of influence). Temperature had a negligible effect on katt and Sf when the IS=1mM because of the large energy barrier, and at IS=50mM because of the absence of an energy barrier. Conversely, temperature had a large influence on katt and Sf when the IS was 10 and 30mM because of the presence of a small ∆Φa on sand with nanoscale roughness and a chemical (positive zeta potential) heterogeneity. This has large implications for setting parameters for the accurate modeling and transport prediction of virus and nanoparticle contaminants in ground water systems.

Simultaneous removal of rotavirus and adenovirus from artificial ground water using hydrochar derived from swine feces.

Hydrothermal carbonization technology can convert fecal waste into a valuable carbonaceous product referred to as hydrochar. We investigated the potential of fecal waste-derived hydrochar as an adsorbent for virus removal in water treatment. Swine feces was hydrothermally treated under two conditions: at 180 °C for 2 h and 230 °C for 7 h. The resulting solid products (hydrochar) were evaluated as virus adsorbents in water treatment. Simultaneous removal of pathogenic rotavirus (RV) and human adenovirus (HAdV) was investigated using a sand column set-up of 10 cm bed height with and without hydrochar supplement (1.5%, w/w). The removal efficiency of both viruses in a hydrochar-amended column was >3 log (complete removal). The amount of virus released in deionized water when flushed into the virus-retaining columns indicated that the secondary energy minimum played a more important role in RV retention than that of HAdV. Zeta-potential and hydrophobicity measurements on hydrochar materials indicated that the improved virus removal performance of hydrochar-amended columns was induced by the provision of extra hydrophobic surfaces. This study provides evidence that fecal waste-derived hydrochar can be used as a competent virus adsorbent.