Coliphage MS2 Research Articles

Real-time monitoring of changes of the pathogens concentration in water under influence of nanosilver particles by resonance laser spectroscopy techniques

We investigated the nonlinear scattering in solutions of water containing E. coli and the mixture of E. coli and silver nanoparticles. As a result of these investigations, we developed a method of controlling the concentration of pathogenic organisms in the water and the concentration of the nanoparticles influences these organisms. For the study we selected pathogens – goldish staphylococcus, E-coli and coliphage MS-2. Standard biological method is qualitatively in agreement with our results.

Principal parameters affecting virus inactivation by the solar photo-Fenton process at neutral pH and μM concentrations of H2O2 and Fe2+/3+

The inactivation of the coliphage MS2 (a human virus indicator) by solar photo-Fenton at near neutral pH in carbonate buffer solution matrix was evaluated. The effects of reactant concentration (H2O2, Fe2+, Fe3+) and solar irradiance on the photo-Fenton process were studied. Specifically, the solar exposure/Fe3+ treatment showed a strong dependence on the iron concentration and solar irradiance intensity leading to complete inactivation (from 106 PFU mL−1 to the detection limit) with 1mgL−1 of Fe3+ and 60min of solar irradiance (45Wm−2). The MS2 inactivation observed with the photo-Fenton process (solar exposure/H2O2/Fe2+/3+) carried out with Fe3+, was faster than with Fe2+ (detection limit achieved at 20min and 50min, respectively). Moreover, virus inactivation by photo-Fenton under different solar irradiance values (15, 30 and 45Wm−2), H2O2 and Fe3+ concentrations (0.1, 0.5 and 1mgL−1) and different pH values (6, 7 and 8) were evaluated. In order to validate the efficiency of the photo-Fenton process at near neutral pH on virus inactivation, the photocatalytic treatment was carried out in natural water (Lake Geneva, Switzerland) and with a human virus (Echovirus). Finally, a conceptual mechanistic interpretation was proposed regarding how solar photo-Fenton acts on viruses in water, involving the key species Fe2+, Fe3+, H2O2, solar irradiance, organic matter, and their possible reactions and interactions.

Removal and inactivation of virus by drinking water treatment in the presence of bromide or iodide

The inactivation of virus in raw water was conducted in a continuous flow pilot scale system. Coliphage MS2 was used as model organism for human enteric virus. The effect of disinfection technologies (single or combined process of ozonation and chlorination) and interfering substances (bromide or iodide) on inactivation of virus, and the removal performance of virus in raw water by the pilot scale system (Train A and B) were investigated. The results indicated that bromide or iodide in water was detrimental to ozonation but beneficial to chlorination for virus inactivation. After bromide or iodide was added, the removal of MS2 by ozonation unit was much lower than before (p < 0.01), the removal of MS2 by chlorination unit was significantly higher than before (p < 0.05). Both Train A and B could remove and inactivate MS2 in raw water completely even at high concentration of bromide (675.24 μg/dm3) and iodide (52.33 μg/dm3). The processes of Train A and B can effectively guarantee the virological safety of drinking water.

Interaction of human adenoviruses and coliphages with kaolinite and bentonite

Human adenoviruses (hAdVs) are pathogenic viruses responsible for public health problems worldwide. They have also been used as viral indicators in environmental systems. Coliphages (e.g., MS2, ΦX174) have also been studied as indicators of viral pollution in fecally contaminated water. Our objective was to evaluate the distribution of three viral fecal indicators (hAdVs, MS2, and ΦΧ174), between two different phyllosilicate clays (kaolinite and bentonite) and the aqueous phase. A series of static and dynamic experiments were conducted under two different temperatures (4, 25°C) for a time period of seven days. HAdV adsorption was examined in DNase I reaction buffer (pH=7.6, and ionic strength (IS)=1.4mM), whereas coliphage adsorption in phosphate buffered saline solution (pH=7, IS=2mM). Moreover, the effect of IS on hAdV adsorption under static conditions was evaluated. The adsorption of hAdV was assessed by real-time PCR and its infectivity was tested by cultivation methods. The coliphages MS2 and ΦΧ174 were assayed by the double-layer overlay method. The experimental results have shown that coliphage adsorption onto both kaolinite and bentonite was higher for the dynamic than the static experiments; whereas hAdV adsorption was lower under dynamic conditions. The adsorption of hAdV increased with decreasing temperature, contrary to the results obtained for the coliphages. This study examines the combined effect of temperature, agitation, clay type, and IS on hAdV adsorption onto clays. The results provide useful new information on the effective removal of viral fecal indicators (MS2, ΦX174 and hAdV) from dilute aqueous solutions by adsorption onto kaolinite and bentonite. Factors enabling enteric viruses to penetrate soils, groundwater and travel long distances within aquifers are important public health issues. Because the observed adsorption behavior of surrogate coliphages MS2 and ΦΧ174 is substantially different to that of hAdV, neither MS2 nor ΦΧ174 is recommended as a suitable model for adenovirus.

Effect of sodium alginate on UVC inactivation of coliphage MS2

Enhancement of UVC inactivation of coliphage MS2 by sodium alginate and its mechanisms through reactive oxygen species (ROS) generation.

Factors affecting decay of Salmonella Birkenhead and coliphage MS2 during mesophilic anaerobic digestion and air drying of sewage sludge.

Factors affecting the decay of Salmonella Birkenhead and coliphage, as representatives of bacterial and viral pathogens, respectively, during mesophilic anaerobic digestion (MAD) and air drying treatment of anaerobically digested sewage sludge were investigated. Controlled concentrations of S. Birkenhead were inoculated into non-sterile, autoclaved, γ-irradiated and nutrient-supplemented sludge and cultures were incubated at 37 °C (MAD sludge treatment temperature) or 20 °C (summer air drying sludge treatment temperature). Nutrient limitation caused by microbial competition was the principal mechanism responsible for the decay of S. Birkenhead by MAD and during air drying of digested sludge. The effects of protease activity in sludge on MS2 coliphage decay in digested and air dried sludge were also investigated. MS2 coliphage showed a 3.0-3.5 log10 reduction during incubation with sludge-protease extracts at 37 °C for 25 h. Proteases produced by indigenous microbes in sludge potentially increase coliphage inactivation and may therefore have a significant role in the decay of enteric viruses in sewage sludge. The results help to explain the loss of viability of enteric bacteria and viral pathogens with treatment process time and contribute to fundamental understanding of the various biotic inactivation mechanisms operating in sludge treatment processes at mesophilic and ambient temperatures.

Action spectra for validation of pathogen disinfection in medium-pressure ultraviolet (UV) systems

Ultraviolet (UV) reactors used for disinfecting water and wastewater must be validated and monitored over time. The validation process requires understanding the photochemical properties of the pathogens of concern and the challenge microorganisms used to represent them. Specifically for polychromatic UV systems, the organisms' dose responses to UV light and their sensitivity across the UV spectrum must be known. This research measured the UV spectral sensitivity, called action spectra, of Cryptosporidium parvum, and MS2, T1UV, Q Beta, T7, and T7m Coliphages, as well as Bacillus pumilus spores. A tunable laser from the National Institute of Standards and Technology was used to isolate single UV wavelengths at 10 nm intervals between 210 and 290 nm. Above 240 nm, all bacteria and viruses tested exhibited a relative peak sensitivity between 260 and 270 nm. Of the coliphage, MS2 exhibited the highest relative sensitivity below 240 nm, relative to its sensitivity at 254 nm, followed by Q Beta, T1UV, T7m and T7 coliphage. B. pumilus spores were more sensitive to UV light at 220 nm than any of the coliphage. These spectra are required for calculating action spectra correction factors for medium pressure UV system validation, for matching appropriate challenge microorganisms to pathogens, and for improving UV dose monitoring. Additionally, understanding the dose response of these organisms at multiple wavelengths can improve polychromatic UV dose calculations and enable prediction of pathogen inactivation from wavelength-specific disinfection technologies such as UV light emitting diodes (LEDs).

Survival of Porcine teschovirus as a surrogate virus on pork chops during storage at 2 °C

Due to the lack of an efficient cultivation system, little is known about the stability and inactivation of hepatitis E virus (HEV). In addition, there is a lack of information on which cultivable virus(es) are suitable as model or surrogate viruses for HEV. Murine norovirus (MNV) and F-RNA coliphage MS2 are potential surrogates and F-RNA coliphages are a potential indicator for enteric viruses. However, the numbers of F-RNA coliphages excreted by swine are relatively low. In contrast, Porcine teschovirus (PTV) is cultivable and is excreted abundantly. PTV is readily detected on swine carcasses and the potential of PTV as a viral indicator of fecal contamination on hog carcasses is currently being explored, however, there is no information on the environmental stability of PTV. The survival of PTV was determined on vacuum packaged pork chops during storage at 2°C using cultivation and molecular techniques and compared to published data on the survival of MNV and MS2 under similar conditions. Viable PTV was reduced by ≥1.8log units compared to a reduction of 0.6 log genomic copies after 7weeks. The viability data indicates that PTV is less stable than MS2 and MNV during storage at 2°C whereas similar reductions in genomic copies were observed for all 3 viruses. This study provides data on the survival of PTV on pork and insight on the potential of PTV as a surrogate for HEV in the pork processing chain.

Aerosolization of respirable droplets from a domestic spa pool and the use of MS-2 coliphage and Pseudomonas aeruginosa as markers for Legionella pneumophila.

Legionnaires' disease can result when droplets or aerosols containing legionella bacteria are inhaled and deposited in the lungs. A number of outbreaks have been associated with the use of a spa pool where aeration, a high water temperature, and a large and variable organic load make disinfectant levels difficult to maintain. Spa pool ownership is increasing, and the aim of this study, using two surrogate organisms (MS-2 coliphage and Pseudomonas aeruginosa [a natural contaminant]), was to assess the potential risk to domestic users when disinfection fails. A representative "entry level" domestic spa pool was installed in an outdoor courtyard. The manufacturer's instructions for spa pool maintenance were not followed. A cyclone sampler was used to sample the aerosols released from the spa pool with and without activation of the air injection system. Samples were taken at increasing heights and distances from the pool. An aerodynamic particle sizer was used to measure the water droplet size distribution at each sample point. When the air injection system was inactivated, neither surrogate organism was recovered from the air. On activation of the air injection system, the mean mass of droplets within the respirable range (10 cm above the water line) was 36.8 μg cm(-3). This corresponded to a mean air concentration of P. aeruginosa of 350 CFU m(-3). From extrapolation from animal data, the estimated risk of infection from aerosols contaminated with similar concentrations of Legionella pneumophila was 0.76 (males) and 0.65 (females). At 1 m above and/or beyond the pool, the mean aerosol mass decreased to 0.04 μg cm(-3) and corresponded to a 100-fold reduction in mean microbial air concentration. The estimated risk of infection at this distance was negligible.

Inactivation of MS2 coliphage in sewage by solar photocatalysis using metal-doped TiO2

The beneficial properties of metal-doped titania nanoparticles with respect to wastewater disinfection under solar irradiation were investigated. Mn-, Co- and binary Mn/Co-doped TiO2 catalysts were prepared by means of a co-precipitation method and were subsequently assessed in terms of their potential to inactivate MS2 bacteriophage in slurry reactor under simulated and natural solar irradiation. Disinfection effectiveness was evaluated in relation to influential operating parameters, like catalyst type (Mn-, Co- and Mn/Co), dopant concentration (0.02–1molwt%), artificial and natural solar light, wavelength (i.e. >420nm) and photon flux (4.93–5.8×10−7E/(Ls)). Metal doping led to considerable narrowing of the band gap and the spectral response of the catalysts extended well into the visible region. MS2 phage was readily inactivated in sewage samples under simulated solar irradiation in the presence of the prepared metal-doped catalysts. The latter proved to be superior to the commercial P25, under the current experimental conditions, resulting in an approximately 60% phage population decrease in almost 60min of simulated solar irradiation when initial MS2 concentration was 105PFU/mL. Catalysts with the binary dopant exhibited the best photocatalytic activity in all cases, as almost 99% of MS2 population was eliminated in less than 20min of irradiation highlighting the fact that composite dopants induce a synergistic effect. The effect of different dopants concentration was apparent up to a certain limit. Disinfection follows a pseudo-first order kinetic rate. Retardation of the process by a factor 1.6–3.8 was recorded under natural solar light, based on the kinetic rate constants of inactivation curves which were within the range of 0.032–0.057min−1. The corresponding range for inactivation under simulated solar irradiation was 0.053–0.221min−1. Moreover, testing the Mn-, Co-, and binary Mn/Co doped TiO2 in the absence of UV light, they were considerably sensitized making clear that they can be activated in the visible part of the spectrum.

Removal of norovirus from water by coagulation, flocculation and sedimentation processes

In this study, we determined the removal of a prototype human norovirus (Norwalk virus, NV) by bench-scale alum coagulation, flocculation and sedimentation processes using reverse transcriptase polymerase chain reaction (RT-PCR) for norovirus assays. After determining optimum conditions for the coagulation, flocculation and sedimentation processes in terms of turbidity reduction, jar tests were performed using the same waters seeded with test viruses. For comparison, two other important health-related viruses, poliovirus 1 (PV1) and coliphage MS2, were included in this study. The removal of NV by coagulation, flocculation and sedimentation processes based on RT-PCR assay in this study was 1.5 log10, which was similar to that of PV1 and a little lower than that of coliphage MS2 (2 log10) based on the same RT-PCR assay. The removal of NV in this study (1.5 log10) is considerably higher than the one in a recent study using recombinant norovirus virus-like particles (∼0.7 log10). Overall, the results of this study suggest that human noroviruses can be appreciably reduced by a properly-operated coagulation, flocculation and sedimentation processes and the contamination of drinking water by noroviruses should be controlled by conventional water treatment processes with conventional physico-chemical processes and disinfection.

Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

Segmented mesocosms (n = 3) packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE)-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE) and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 105 cfu/mL STE and 105–106 pfu/mL STE, respectively. In all soils, removal rates were &gt;99.99% at 25 cm. The transport simulation compared (1) optimization; and (2) trial-and-error modeling approaches. Only slight differences between the transport parameters were observed between these approaches. Treating both the die-off rates and attachment/detachment rates as variables resulted in an overall better model fit, particularly for the tailing phase of the experiments. Independent of the fitting procedure, attachment rates computed by the model were higher in sandy and sandy loam soils than clay, which was attributed to unsaturated flow conditions at lower water content in the coarser-textured soils. Early breakthrough of the bacteria and virus indicated the presence of preferential flow in the system in the structured clay loam soil, resulting in faster movement of water and microbes through the soil relative to a conservative tracer (bromide).

Sunlight Inactivation of MS2 Coliphage in the Absence of Photosensitizers: Modeling the Endogenous Inactivation Rate Using a Photoaction Spectrum

The endogenous sunlight inactivation rates of MS2 coliphage in photosensitizer-free water were measured (kobs) under different light conditions and compared to modeled inactivation rates (kmod) computed using a previously published action spectrum. Experiments were conducted under simulated and natural sunlight. There was generally good agreement between modeled and observed MS2 sunlight inactivation rates in the summer and winter, suggesting that the action spectrum can be used to predict changes in the inactivation rate caused by diurnal and seasonal changes in natural sunlight irradiance. However, we show that a major source of uncertainty in the predictions is the ability to accurately measure or model the comparatively weak and highly variable solar irradiance between 280 and 300 nm, a range to which the inactivation rate is very sensitive. The action spectrum was also used to predict the endogenous inactivation rates of MS2 at different depths in a column of strongly humic-colored [i.e., solar ultraviolet (UV)-attenuating] wetland water under simulated sunlight; we observed fairly good agreement between kobs and kmod, suggesting that the action spectrum can be used to estimate the decrease in the endogenous inactivation rate caused by spectrally selective sunlight attenuation in the water column.

In situ airborne virus inactivation by microwave irradiation.

Infectious diseases cause tremendous costs of both human and economy annually. Previously, we have studied the bacterial, fungal, and allergen aerosol inactivation by direct microwave irradiation. Here, we further investigated its effects on airborne viruses. MS2 coliphage used as a human model virus was aerosolized and exposed to the direct microwave irradiation for ~2 min at three different power levels (700, 385, and 119 W). In addition to the survival rate, the viral genes before and after the microwave treatments were also examined using PCR and gel electrophoresis. Direct exposure of airborne MS2 viruses to the microwave irradiation at 700 W for less than 2 min was shown to result in more than 90 % inactivation efficiency, about 65 % at medium power level (385 W), and 50 % at the lowest level (119 W). The aerosol inactivation rate followed a linear relationship with the microwave exposure time (R 2 = 0.9889). Scanning electron images revealed visible damages to the viral surface after the exposure. Damages were also observed to the viral RNA genes coding for coat proteins, among which the A protein gene was completely destroyed. This study demonstrated that even without the filtration the direct microwave irradiation could also achieve rapid inactivation of viral aerosols. The information obtained can provide useful guidance on the development of microwave-based viral threat mitigation solutions in a closed or semi-closed space.

Effect of handling and storage conditions and stabilizing agent on the recovery of viral RNA from oral fluid of pigs

There is an increasing interest in using oral fluid to determine herd health and documenting the circulation of viruses in commercial swine populations but little is known about the stability of viruses in oral fluid. Hepatitis E virus (HEV) is a zoonotic virus which is widespread in swine herds. Information on optimal handling methods such as heat treatments, freezing and RNA stabilization agents is needed to prevent or minimize degradation of viral RNA by degradative enzymes. The objectives of the study were to determine optimum handling conditions of the oral fluid before RNA extraction and to compare the performance of the RNeasy Protect Saliva Mini kit, which contains a stabilizing agent, with that of the QIAamp Viral RNA Mini kit, which does not contain a stabilizing agent. Preliminary studies with oral fluid inoculated with HEV indicated that a heat treatment of 60°C for 15min was detrimental to HEV RNA. HEV was recovered from 25/25 and 24/25 samples of oral fluid when samples were incubated for ≤24h at 4°C and 30days at −20°C, respectively, without a stabilizing agent and extracted with the QiaAMP kit. In contrast, HEV RNA was detected in 16/25 and 11/25 samples when samples were incubated with a stabilizing agent for 24h at 37°C and 30days at −20°C, respectively, and extracted with the RNeasy Protect Saliva kit. Moreover, the mean number of genome copies/ml of HEV recovered from oral fluid stored at −20°C without the stabilizing agent was 2.9 log units higher than oral fluid stored at −20°C in the presence of the stabilizing agent. The recovery of RNA from HEV, F-RNA coliphage MS2 and murine norovirus (MNV), which are surrogates for norovirus, was significantly greater when oral fluid was incubated for 24h at 4°C than when oral fluid was stabilized with RNAprotect Saliva Reagent for 24h at 37°C, where the relative differences between the two processes were 1.4, 1.8, and 2.7 log genome copies/ml for MS2, MNV, and HEV, respectively. The findings suggest that it is unnecessary to stabilize oral fluid from swine for the detection of viral RNA, provided the samples are stored at 4°C or frozen at −20°C, and that the RNeasy Protect Saliva Mini kit did not perform well for the detection of viral RNA.

Inactivation of MS2 coliphage by UV and hydrogen peroxide: Comparison by cultural and molecular methodologies

The use of advanced oxidation processes (AOP) are expected to increase for removal of emerging contaminants and pathogens from drinking water. In this study, the performance of a small community ultraviolet light reactor in combination with hydrogen peroxide (H2O2) for MS2 coliphage inactivation with two different flow rate conditions of 1 gal/min (gpm) and 2 gpm was evaluated. Following UV radiation, MS2 showed a reduction of 5.3–5.8 log10 when quantified with cultural plaque counts, whereas corresponding quantitative polymerase chain reaction (qPCR) data showed only a 1.7–2.8 log10 reduction in viral RNA copy number. When H2O2 was added at either 2.5 or 5 ppm with UV at both flow rate conditions, enhanced MS2 inactivation occurred with a more than 7 log10 reduction observed via plaque counts, indicating that all added MS2 had been inactivated, since no plaques were formed after incubation at 37°C for 24 h. In contrast, qPCR only showed a corresponding 3–4 log10 reduction in viral RNA copy number. This research also sheds light on the inactivation of MS2 with ultraviolet light and in the presence of hydroxyl radicals and provides a practical use of qPCR to detect MS2 concentration following advanced oxidation relative to traditional plaque methodology; however qPCR detection overestimates the true number of infective virus.

Microbial Inactivation by Cupric Ion in Combination with H2O2: Role of Reactive Oxidants

The cupric ion mediated inactivation of Escherichia coli was enhanced by the presence of hydrogen peroxide (H2O2), with increasing inactivation efficacy observed in response to increasing concentrations of H2O2. The biocidal activity of the Cu(II)/H2O2 system is believed to result from the oxidative stress caused by reactive oxidants such as the hydroxyl radical ((•)OH), cupryl species (Cu(III)), and the superoxide radical (O2(•-)), which are produced via the catalytic decomposition of H2O2. In E. coli cells treated with Cu(II) and H2O2, the intracellular level of (•)OH and Cu(III) increased significantly, leading to complete disruption of cell membranes. On the basis of experimental observations made using an (•)OH scavenger, copper-chelating agents, and superoxide dismutase, it is concluded that Cu(III) is the predominant species responsible for the death of E. coli cells. It was also found that the production of Cu(III) was promoted by the reactions of copper with intracellular O2(•-). MS2 coliphage was found to be even more susceptible than E. coli to the oxidative stress induced by the Cu(II)/H2O2 system.

High-throughput assay for temporal kinetic analysis of lytic coliphage activity

Plaque analysis allows the determination of phage titer and multiplicity of infection. Yet, this overnight assay provides only endpoint results, ignoring kinetic aspects. We introduce an alternative high-throughput and rapid method for kinetic analysis of lytic coliphage activity. Escherichia coli was infected with serial dilutions of MS2 coliphage, and bacterial growth was monitored using a multi-well plate reader providing within hours the equivalent data as obtained overnight. Additional information is yielded, including phage replication rate, progeny size per cycle, and viral propagation during bacterial growth. This method offers further insights into physicochemical mechanisms of lytic coliphage infection and temporal control. It also provides a virus–host interaction acumen.

Disinfection performance of nanosilver and impacts of environmental conditions on viral inactivation by nanosilver

Three types of nanosilver materials, which were commercial, chemically-synthesized and biologically-synthesized, respectively, were compared in terms of the disinfection efficiencies against Escherichia coli and MS2 coliphage in order to pinpoint promising material with the best performance. Disinfection results showed biologically-synthesized silver nanoparticles (referred to hereafter as ‘bio-AgNPs’) had the best disinfection performance, 10 mg/L of which was able to inactivate all the E. coli in 1 min (&amp;gt;6 log removals) and achieved 4 log removals of MS2 coliphage. Bio-AgNPs were therefore selected for further study in terms of effects of the concentration and contact time as well as the impacts of environmental conditions on the viral inactivation. Given the viral inactivation profile of bio-AgNPs shown in this study, it could be concluded that viral inactivation by bio-AgNPs could be inhibited by total organic carbon (TOC) (10 mg/L as humic acid) and chloride ion (5 mg/L) to a large extent while Ca2+/Mg2+/ionic strength only had minor effects on the viral inactivation at high concentrations (188 mg/L as CaCO3 of hardness or 5.6 mM of ionic strength, respectively). This part of the study may help enlighten further mechanism studies on viral inactivation by nanosilver.

Virus removal and inactivation by iron (hydr)oxide-mediated Fenton-like processes under sunlight and in the dark

Advanced oxidation processes (AOPs) have emerged as a promising alternative to conventional disinfection methods to control microbial water quality, yet little is known about the fate of viruses in AOPs. In this study, we investigated the fate of MS2 coliphage in AOPs that rely on heterogeneous Fenton-like processes catalyzed by iron (hydr)oxide particles. Both physical removal of viruses from solution via adsorption onto particles as well as true inactivation were considered. Virus fate was studied in batch reactors at circumneutral pH, containing 200 mg L(-1) of four different commercial iron (hydr)oxide particles of similar mesh sizes: hematite (α-Fe2O3), goethite (α-FeOOH), magnetite (Fe3O4) and amorphous iron(iii) hydroxide (Fe(OH)3). The effect of adsorption and sunlight exposure on the survival of MS2 was considered. On a mass basis, all particles exhibited a similar virus adsorption capacity, whereas the rate of adsorption followed the order FeOOH > Fe2O3 > Fe3O4 ≈ Fe(OH)3. This adsorption behavior could not be explained by electrostatic considerations; instead, adsorption must be governed by other factors, such as hydrophobic interactions or van der Waals forces. Adsorption to three of the particles investigated (α-FeOOH, Fe3O4, Fe(OH)3) caused virus inactivation of 7%, 22%, and 14%, respectively. Exposure of particle-adsorbed viruses to sunlight and H2O2 resulted in efficient additional inactivation, whereas inactivation was negligible for suspended viruses. The observed first-order inactivation rate constants were 6.6 × 10(-2), 8.7 × 10(-2), 0.55 and 1.5 min(-1) for α-FeOOH, α-Fe2O3, Fe3O4 and Fe(OH)3 respectively. In the absence of sunlight or H2O2, no inactivation was observed beyond that caused by adsorption alone, except for Fe3O4, which caused virus inactivation via a dark Fenton-like process. Overall our results demonstrate that heterogeneous Fenton-like processes can both physically remove viruses from water as well as inactivate them via adsorption and via a particle-mediated (photo-)Fenton-like process.