Inactivation Of MS2 Bacteriophage Research Articles

Photo-Fenton inactivation of MS2 bacteriophage at alkaline pH by Fe salts or nm to μm-sized oxides, and the Janus-faced effects of natural organic matter in surface waters

In this study, MS2 bacteriophage was inactivated by homogeneous and heterogeneous photo-Fenton processes in an alkaline matrix (pH 8) using low concentrations of H2O2 and iron forms (1 mg/L), including Fe(II), Fe(III), and Fe (hydr)oxides. As a reference, it has been demonstrated that excellent efficiency towards MS2 inactivation was achieved within 2 min with Fe(II) and 10 min with Fe(III) in the homogeneous photo-Fenton process. Mined iron and five naturally occurring iron (hydr)oxides, including wüstite, goethite, hematite, magnetite, and maghemite, were used to assess the virus removal in the heterogeneous photo-Fenton process. Total (5-logU) inactivation of the MS2 bacteriophage was observed within 15–40 min by iron (hydr)oxides in the presence of light and H2O2. Photosensitization of natural organic matter had a significant impact on virus inactivation in both homogeneous and heterogeneous photo-Fenton processes, but dually; it enhanced the formation of complexes between organic matter and iron species, facilitating the homogeneous process at alkaline pH, but hindering the heterogeneous photo-Fenton reaction. Nevertheless, the heterogeneous photo-Fenton process may serve as an efficient method for the inactivation of enteric viruses in water, even at a slightly basic pH, despite the scavenging action of natural organic matter. The low-concentration requirements of this process and the availability of iron oxides in nature contribute to the sustainability of the process, which can be suitable for use in resource-poor environments.

Microplastics as potential barriers to ultraviolet light emitting diode inactivation of MS2 bacteriophage: Influence of water-quality parameters

Microplastics have emerged as a concerning contaminant in drinking water sources, potentially interacting with pathogenic microorganisms and affecting the disinfection processes. In this study, MS2 was selected as an alternative for the human enteric virus. The influence of microplastics polyvinylchloride (MPs-PVC) on ultraviolet light emitting diode (UV-LED) inactivation of MS2 was investigated under various water chemistry conditions, such as MPs-PVC concentration, pH, salinity, and humic acid concentration. The results revealed that higher concentrations of MPs-PVC led to the reduced inactivation of MS2 by decreased UV transmittance, hindering the disinfection process. Additionally, the inactivation efficiency of MS2 in the presence of MPs-PVC was influenced by pH, and acidic solution (pH at 4, 5, and 6) exhibited higher efficiency compared to alkaline solution (pH at 8 and 9) and neutral solution (pH at 7). The low Na+ concentrations (0–50 mM) had a noticeable effect on MS2 inaction efficiency in the presence of MPs-PVC, while the addition of Ca2+ posed an insignificant effect due to the preferential interaction with MPs-PVC. Furthermore, the inactivation rate of MS2 initially increased and then decreased with increasing the concentration of humic acid, which was significantly different without MPs-PVC. These findings shed light on the complex interactions between MPs-PVC and MS2 in the UV-LED disinfection process under various water-quality parameters, contributing to drinking water safety and treatment.

Interfacial mechanism and inactivation efficiency of bacteriophage MS2 by ozone in high turbidity and algal-laden water resource

With the onset of the COVID-19 epidemic and the measures implemented to curb the spread of the SARS-CoV-2 virus, there has been increasing attention on safe drinking water and waterborne viruses during water treatment processes. In this study, we investigate the impact of solution chemistry, including ionic strength (Na+ or Ca2+) pH, and natural organic matter (NOM), on the efficiency of MS2 bacteriophage inactivation by ozone in the presence of inorganic and organic particles (kaolinite (KAO) and microcystis aeruginosa (MA), respectively). The study results demonstrate that KAO has been found to adsorb MS2, but it does not significantly affect the inactivation of MS2 by ozone. In contrast, the inactivation of MS2 increased at low MA concentrations ranging from 105 to 106 cells/L due to MS2 dispersion, but decreased at higher concentrations ranging from 107 to 108 cells/L. The monovalent Na+ ion solutions (~200 mmol/L) maintain MS2 stability and dispersion irrespective of the presence of particles, and did not affect inactivation. Additionally, MS2 aggregates in divalent Ca2+ solutions, resulting in reduced inactivation with or without particles present. Increasing the solution's pH had a negative impact on inactivation, leading to ozone reduction and weakening of the inactivation. However, the presence of NOM poses a significant risk to the safety of drinking water by reducing MS2 inactivation.

Inactivation of MS2 bacteriophage on copper film deployed in high touch areas of a public transport system.

Although SARS-CoV-2 is primarily an airborne risk, the COVID-19 pandemic also highlighted the need for self-disinfection surfaces that could withstand the demand of high occupant densities characteristic of public transportation systems. The aim of this study was to evaluate the durability and antiviral activity of a copper film deployed for 90 days in two high touch locations within an active metropolitan bus and railcar. The antiviral efficacy of this copper film after being deployed in transit vehicles for 90 days (deployed copper film) was then compared to new (unused) copper film to determine if frequent touches and cleaning protocols could decrease the efficacy of the copper films. Deployed copper film, new copper film, and aluminium foil (positive control) coupons were inoculated with ~1 × 106 MS2 virus particles, allowed a contact time of either 5- or 10-min, and analysed for residual viral infectiousness. On both new and deployed copper films, MS2 was completely inactivated (≥5 log reduction) at both time points. These results suggest that the copper film may provide the durability demanded by high touch public spaces while maintaining the antiviral activity necessary to reduce exposure risk and viral transmission via surfaces in public transportation settings.

Control of sulfides and coliphage MS2 using hydrogen peroxide and UV disinfection for non-potable reuse of pilot-scale anaerobic membrane bioreactor effluent

Anaerobic membrane bioreactors reduce the energy cost of wastewater treatment and meet filtration requirements for non-potable reuse. However, sulfides (H2S/HS−) formed during anaerobic treatment exert a high chlorine demand and inhibit UV disinfection by photon shielding at 254 nm. This study evaluated the feasibility of hydrogen peroxide (H2O2) for sulfide oxidation, UV disinfection for inactivation of MS2 bacteriophage, and chlorine to provide a residual for distribution. H2O2 treatment at pH ≥ 8 favored sulfide oxidation to sulfate in 30 min at a 4:1 H2O2:sulfide stoichiometry. Compared to a 6:1 H2O2:sulfide molar ratio, treatment of anaerobic effluent with 0.5 mM sulfides with a 4:1 H2O2:sulfide molar ratio would increase the applied UV fluence needed for 5-log MS2 inactivation from 180 mJ cm−2 to 225 mJ cm−2. However, the lower H2O2 dose reduced the dose of chlorine needed to quench residual H2O2 and provide a residual for distribution. Treatment at the 4:1 H2O2:sulfide molar ratio was favored, because the cost savings in H2O2 and chlorine reagents outweighed the energy savings associated with UV treatment. However, H2O2/UV/chlorine treatment of anaerobic effluent was cost-competitive with conventional treatment of aerobic effluent for non-potable reuse only for < 285 µM sulfides.

Evaluating the Environmental Persistence and Inactivation of MS2 Bacteriophage and the Presumed Ebola Virus Surrogate Phi6 Using Low Concentration Hydrogen Peroxide Vapor.

Ebola virus (EBOV) disease outbreaks, as well as the ability of EBOV to persist in the environment under certain conditions, highlight the need to develop effective decontamination techniques against the virus. We evaluated the efficacy of hydrogen peroxide vapor (HPV) to inactivate MS2 and Phi6 bacteriophages, the latter a recommended surrogate for EBOV. The phages were inoculated onto six material types with and without the presence of whole human blood. The inoculated materials were then exposed to either a high or low concentration of HPV for various elapsed times. The phages were also recovered from positive controls at these same elapsed times, to assess environmental persistence and decontamination efficacy. Low concentration hydrogen peroxide vapor (LCHP; 25 ppm) was effective against both phages on all materials without the presence of blood at 2 h. LCHP was ineffective against the phages in the presence of blood, on all materials, even with a 3-day contact time. Higher concentrations of HPV (>400 ppm) with contact times of 24-32 h achieved approximately 2-6 log reduction of the phages in the presence of blood.

Inactivation of MS2 Bacteriophage and Adenovirus with Silver and Copper in Solution and Embedded in Ceramic Water Filters

This study investigates the inactivation of adenovirus by silver and copper in aqueous solution, compares silver and copper disinfection of adenovirus to the MS2 phage, and quantifies MS2 transport through porous ceramic filters fabricated with silver nitrate and copper nitrate added prior to firing the clay-sawdust-water mixture. The MS2 phage is commonly used as a model virus for testing the efficacy of point-of-use water treatment technologies. However, results show that MS2 phage is not a representative virus, specifically as a surrogate for silver ion inactivation of viruses. At safe drinking water concentrations, after 8 h of exposure, silver and copper resulted in a 0.91- and 1.61-log10 reduction of viable adenovirus, respectively. Under the same conditions, silver and copper resulted in a 0.42- and 1.46-log10 reduction of viable MS-2 phage, respectively. Transmission electron microscopy (TEM) images suggest the mechanism of adenovirus inactivation may be related to damage/removal of the viral fibers. Removal of MS2 phage by ceramic water filters is modest, 71.95% and 75.98% by silver- and copper-embedded filters, respectively. These results indicate that ionic silver is a better viral disinfectant than previously known based on data for the MS2 phage alone and that copper, both alone and in combination with silver, may further improve viral disinfection.

Influence of algal organic matter of Microcystis aeruginosa on ferrate decay and MS2 bacteriophage inactivation

Surface water contaminated with algae and with enteric viruses is a global problem. When surface water is used as a drinking water source, it is important to know the influence of algal organic matter on the disinfection of viruses. In this work, we studied the disinfection efficacy of ferrate and the influence of algal organic matter on the disinfection. We determined the MS2 inactivation kinetics by ferrate under three pH conditions (7, 8, and 8.7). The experimental results and pH-dependent calculation suggest that H2FeO4 and HFeO4− are 1935 and 8 times as effective as FeO42− in MS2 inactivation. We also found that intracellular algal organic matter (IAOM) had a stronger effect on MS2 inactivation kinetics than extracellular algal organic matter (EAOM) suggesting that IAOM led to higher consumption of Fe(VI) compared to EAOM. At pH 8.7, while significant consumption of FeO42− by as low as 8 mg C/L of EAOM and 2 mg C/L of IAOM was detected, MS2 inactivation was negatively influenced only when 13 mg C/L of IAOM present. This study showed that it is important to control pH and to determine the concentration of algal organic matter if ferrate is used for disinfection of surface water contaminated with algae.

UV LED water disinfection: Validation and small system demonstration study

AbstractDisinfection by ultraviolet (UV) light via non‐mercury light‐emitting diodes (LEDs) may be a sustainable solution for drinking water disinfection in small systems. The world's first commercial UVC LED water disinfection reactor (the PearlAqua by Aquisense) was studied over a year‐long demonstration test, and performance was compared side by side with an existing chlorination system at a small water treatment plant in Colorado. The UVC LED disinfection system was validated using MS2 bacteriophage inactivation over a range of flow rates and water UV transmittances. The reactor was also challenge‐tested with MS2 periodically during the year‐long demonstration. During lab tests and the field study in challenging conditions without any maintenance, the reactor demonstrated viral and bacterial disinfection efficacy and resilience equivalent to the chlorination system, providing proof of concept for application of UVC LEDs for municipal water treatment.

Influence of algal organic matter on MS2 bacteriophage inactivation by ultraviolet irradiation at 220 nm and 254 nm

We determined the potential interference of extracellular algal organic matter (EAOM) and intracellular algal organic matter (IAOM) extracted from Microcystis aeruginosa on MS2 bacteriophage inactivation under UV irradiation at two wavelengths (220 and 254 nm). UV irradiation at 220 nm doubled the inactivation rate of MS2 in water containing EAOM than in organic-free phosphate buffered solution. In contrast, EAOM did not change MS2 inactivation by exposure to UV 254 nm. The presence of IAOM did not significantly influence MS2 inactivation by exposure to either UV 254 or UV 220 nm. To achieve 3 log10 inactivation of MS2, UV254 nm required more than double the dose of UV220 nm (45 mJ/cm2 vs. 20 mJ/cm2). Linear correlations between the reduction in infectivity and the reduction in genome copies detected by reverse transcription quantitative polymerase chain reaction suggested that genomic damage is the main mechanism responsible for MS2 inactivation in water containing algal organic matter (AOM) by exposure to UV irradiation. These findings suggest that the presence of AOM did not negatively influence MS2 inactivation by either 220 or 254 nm irradiation, and that a lower UV dose of 220 nm irradiation can be used to achieve the same level of inactivation in water containing AOM.

Free Chlorine Disinfection of Full-Scale MBR Effluent to Achieve 5-Log Virus Inactivation.

A series of full-scale testing was performed at the City of Lathrop Consolidated Treatment Facility to determine the "concentration times time" (Ct) value for free chlorine disinfection of nitrified membrane bioreactor (MBR) effluent to achieve more than 5-log virus inactivation. The full-scale testing consisted of tracer study, chlorine decay study, and virus seeding study. The virus seeding study was performed at a flow rate of 1 million gal/d (3800 m3/min), which corresponded to a theoretical contact time of 117 minutes in the chlorine contact basin. It was found that Ct values as small as 3 mg·min/L were sufficient to achieve 5-log inactivation of MS2 bacteriophage in this study, which is comparable to the results of previous bench- and pilot-scale free chlorine disinfection studies on nitrified MBR effluent (3 to 40 mg·min/L), as well as those of pilot- and full-scale studies on granular media-filtered nitrified effluent (2 to 22 mg·min/L).

Tradeoffs between pathogen inactivation and disinfection byproduct formation during sequential chlorine and chloramine disinfection for wastewater reuse

Treatment of fully nitrified municipal wastewater effluents with chlorine followed by chloramines (i.e., sequential chlorine disinfection) upstream of advanced treatment trains can contribute pathogen inactivation credits for potable reuse while leaving a chloramine residual to control biofouling on membrane units in the advanced treatment train. However, free chlorine exposures must be optimized to maximize pathogen inactivation while minimizing the formation of disinfection byproducts (DBPs) that are challenging to remove in the advanced treatment train. Using a pilot-scale disinfection contactor receiving fully-nitrified, tertiary municipal wastewater effluent, this study found that a 3 mg × min/L free chlorine CT (i.e., the product of the chlorine residual “C” and the contact time “T”) followed by a 140 mg × min/L chloramine CT could reliably achieve 5-log inactivation of MS2 bacteriophage and reduce median total coliform concentrations below 2.2 MPN/100 mL. Free chlorine disinfection was equally effective when chlorine was dosed to exceed the breakpoint for 1 mg/L of ammonia as N. At this free chlorine exposure, regulated trihalomethane (THM) and haloacetic acid (HAA) formation remained below their Maximum Contaminant Levels (MCLs), but NDMA concentrations of ∼30 ng/L were above the 10 ng/L California Notification Level. Increasing the free chlorine exposure to ∼30 mg × min/L increased THM and HAA formation, with regulated THMs approaching or exceeding the MCL. Although this free chlorine exposure prevented NDMA formation during chloramination, the ∼10 ng/L background NDMA formation in the tertiary effluent remained. Increasing the free chlorine exposure also increased the formation of unregulated halogenated DBP classes that may be significant contributors to the DBP-associated toxicity of the disinfected wastewater. The results indicate that sequential chlorination can be used to optimize the benefits of free chlorine (virus and NDMA control) and chloramine disinfection (THM, HAA, and coliform control).

Effect of Post-Treatment Conditions on the Inactivation of MS2 Bacteriophage as Indicator for Pathogenic Viruses after the Composting Process

A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting toilet by setting post-treatment conditions. The kinetics inactivation of MS2 bacteriophage, selected as indicator for pathogenic viruses were determined during post-treatment at different temperatures (30°C, 40°C and 50°C) with varying moisture contents (50%, 60% and 70%). As a result, the inactivation rates during the post-treatment were 0.093 - 0.020 h-1, 0.025 - 0.088 h1, 0.447 - 0.100 h-1 at 30°C, 40°C and 50°C respectively. The inactivation rate coefficient (k) values of MS2 bacteriophage depended on higher temperature but not on moisture content.

Thermal inactivation of MS2 bacteriophage as a surrogate of enteric viruses in cow milk

This study examined the effect of 4 thermal processing methods on inactivation of male-specific bacteriophage MS2 in cow milk. MS2 was used as a viral surrogate of enteric viruses in this inactivation study. Milk samples were spiked at 10, 103, 105, and 107 PFU/ml with a milk fat content of 1.5, 2.5 and 3% weight per volume. We found that with higher milk fat content, survival of MS2 increased in the samples spiked with 105 or 107 PFU/ml, indicating that increasing the milk fat content had a significant effect on the survival of MS2 (p < 0.05) in the thermally processed samples. The inactivation results suggest that the most effective thermal processing for viral inactivation in cow milk was having a high temperature long time (HTLT: 85 °C for 30 min) followed by boiling for 2 min. The least effective thermal processing was low temperature for a long time. Therefore, inactivation of enteric viruses in dairy products with a high level of contamination can be effectively achieved under severe thermal processing such as HTLT, or boiling.

Inactivation of MS2 bacteriophage by titanium dioxide nanoparticles in the presence of quartz sand with and without ambient light

Virus inactivation by nanoparticles (NPs) is hypothesized to affect virus fate and transport in the subsurface. This study examines the interactions of viruses with titanium dioxide (TiO2) anatase NPs, which is a good disinfectant with unique physiochemical properties. The bacteriophage MS2 was used as a model virus. A series of batch experiments of MS2 inactivation by TiO2 NPs were conducted at room temperature (25°C), in the presence and absence of quartz sand, with and without ambient light. Three sets of experiments were performed in phosphate buffered saline solution (PBS) and one in distilled deionized water (ddH2O). The virus inactivation experimental data were satisfactorily fitted with a pseudo-first order expression with a time dependent rate coefficient. Quartz sand was shown to affect MS2 inactivation by TiO2 NPs both in the presence and absence of ambient light, because, under the experimental conditions of this study, the quartz sand offers a protection to the attached MS2 against inactivation. Moreover, it was shown that low TiO2 concentration (10mg/L) affected only slightly MS2 inactivation with and without ambient light. Furthermore, PBS hindered MS2 inactivation by TiO2 NPs.

Visible-light-induced activation of periodate that mimics dye-sensitization of TiO2: Simultaneous decolorization of dyes and production of oxidizing radicals

Inspired by the mechanism behind self-sensitized destruction of dyes on semiconductor photocatalysts, we herein present the first instance of visible-light-induced activation of periodate (IO4−) into reactive iodine radicals via sensitized electron transfer from an organic dye, Rhodamine B (RhB). The IO4− reduction not only leads to oxidative decolorization of RhB but also formation of reactive intermediates that degrade organic compounds. Electron transfer from the excited dye to IO4− was confirmed by detecting RhB radical cation (RhB+) and measuring its lifetime. The efficiency of organic compound degradation was found to significantly vary depending on the target substrate, i.e., phenol, bisphenol A, and 4-chlorophenol were rapidly decomposed, whereas benzoic acid, carbamazepine, 4-nitrophenol, and sulfamethoxazole exhibited moderate decomposition rate. Lines of evidence in addition to the substrate specificity, such as insignificant hydroxylation, non-stoichiometric dechlorination, and marginal quenching effects of organic/inorganic compounds (e.g., methanol, natural organic matters, and chloride ion), points toward the involvement of iodate radical (IO3). The dye-sensitized IO4− activation process was also found to be highly effective in inactivation of MS2 bacteriophage.

Optimization of resource and water recovery from urine

This study deals with the feasibility and practicality to recover water and nutrients from fresh urine by means of evaporation/condensation. The evaporation process generated two distinct fractions: a condensate and a concentrate. The optimal percentage of evaporation (in volume) was found to be 80%, resulting in optimal condensate quality. Higher percentages of evaporation resulted in a deterioration of water quality, as urea decomposed into ammonia, followed by volatilization of the ammonia which ended up in the condensate. Following evaporation, struvite was recovered from the concentrate at an optimal Mg/N ratio of 1/1. The condensate was purified by filtration into two layers of soil and sand, followed by zeolites. Complete removal of N-NH3 and 91% removal of chemical oxygen demand (COD) could be achieved throughout this process. Finally, the condensate was disinfected by sodium hypochlorite, achieving over 6-log inactivation of MS2 bacteriophage at a dose of 1,200 mg min/L. In conclusion, this study shows that there exist some potential benefits to the production of high-quality water and fertilizer from urine. The value of struvite recovered from the concentrate was found to be equivalent to that of the water from the condensate, showing that both streams deserve equal attention.

Cationic Fullerene Aggregates with Unprecedented Virus Photoinactivation Efficiencies in Water

Of the many fullerene derivatives that have been examined, cationic functionalization has proven to be most promising for aqueous or biological applications. Until recently, however, no cationic colloidal fullerene aggregates in the nanosize regime have been characterized in the aqueous phase. The results presented here represent the most rapid and efficient, to the best of our knowledge, viral inactivation reported for any colloidal fullerene aggregates. Tris-adducted fulleropyrrolidinium aggregates are prepared and analyzed for concentration-dependent singlet oxygen (1O2) production and MS2 bacteriophage inactivation. Experiments are performed under visible, UVA, and sunlight irradiation with the addition of natural organic matter (NOM) to simulate environmental conditions. Viral inactivation was observed at sensitizer concentrations in the nanomolar range. A 5-log inactivation of MS2 was observed after 4 or 1 min of sunlight exposure with 250 nM fullerenes with or without NOM, respectively. The environmental implications of these results are discussed in the context of previously reported 1O2-mediated MS2 inactivation.

C60 aminofullerene-magnetite nanocomposite designed for efficient visible light photocatalysis and magnetic recovery

A magnetically recyclable photosensitizing system for harnessing solar energy for water treatment and disinfection is reported. This system comprises C60 aminofullerene as a sensitizer for singlet oxygenation and functionalized mesoporous silica (msu-f SiO2) encapsulating magnetite nanoparticles (msu-SiO2/mag) as a magnetically separable host. Rapid degradation of furfuryl alcohol (FFA) (a singlet oxygen (1O2) probe) under visible-light irradiation along with the kinetic retardation of FFA decomposition in the presence of 1O2 quenchers suggests that the visible-light activity of C60 aminofullerene-derivatized msu-SiO2/mag (C60/msu-SiO2/mag) is related to the photosensitization of 1O2. On the other hand, the use of SiO2 gel and fumed SiO2 as magnetic supports drastically reduced the photosensitized generation of 1O2, which is ascribed to the absence of an ordered pore structure in the alternative silica support, resulting in an uncontrolled growth of Fe3O4 and an aggregation of the fullerenes on the SiO2 gel and fumed SiO2. Significant 1O2 production using C60/msu-SiO2/mag led to the effective oxidation of emerging pharmaceutical contaminants and inactivation of MS-2 bacteriophage under visible-light irradiation. Magnetic recovery and the subsequent reuse of the composite did not cause any significant loss in the photosensitizing activity of C60/msu-SiO2/mag, demonstrating its potential for catalytic applications.

Atmospheric pressure, nonthermal plasma inactivation of MS2 bacteriophage: effect of oxygen concentration on virucidal activity

The main aim of this study was to determine the virucidal inactivation efficacy of an in-house-designed atmospheric pressure, nonthermal plasma jet operated at varying helium/oxygen feed gas concentrations against MS2 bacteriophage, widely employed as a convenient surrogate for human norovirus. The effect of variation of percentage oxygen concentration in the helium (He) carrier gas was studied and found to positively correlate with MS2 inactivation rate, indicating a role for reactive oxygen species (ROS) in viral inactivation. The inactivation rate constant increased with increasing oxygen concentrations up to 0·75% O2 . 3 log10 (99·9%) reductions in MS2 viability were achieved after 3min of exposure to the plasma source operated in a helium/oxygen (99·25%:0·75%) gas mixture, with >7 log10 reduction after 9min exposure. Atmospheric pressure, nonthermal plasmas may have utility in the rapid disinfection of virally contaminated surfaces for infection control applications. The atmospheric pressure, nonthermal plasma jet employed in this study exhibits rapid virucidal activity against a norovirus surrogate virus, the MS2 bacteriophage, which is superior to previously published inactivation rates for chemical disinfectants.