Elution Is a Critical Step for Recovering Human Adenovirus 40 from Tap Water and Surface Water by Cross-Flow Ultrafiltration.

UNLABELLED: This paper examines the recovery of the enteric adenovirus human adenovirus 40 (HAdV 40) by cross-flow ultrafiltration and interprets recovery values in terms of physicochemical interactions of virions during sample concentration. Prior to ultrafiltration, membranes were either blocked by exposure to calf serum (CS) or coated with a polyelectrolyte multilayer (PEM). HAdV 40 is a hydrophobic virus with a point of zero charge between pH 4.0 and pH 4.3. In accordance with predictions from the extended Derjaguin-Landau-Verwey-Overbeek theory, the preelution recovery of HAdV (rpre) from deionized water was higher with PEM-coated membranes (rpre (PEM) = 74.8% ± 9.7%) than with CS-blocked membranes (rpre (CS) = 54.1% ± 6.2%). With either membrane type, the total virion recovery after elution (rpost) was high for both deionized water (rpost (PEM) = 99.5% ± 6.6% and rpost (CS) = 98.8% ± 7.7%) and tap water (rpost (PEM) = 89% ± 15% and rpost (CS) = 93.7% ± 6.9%). The nearly 100% recoveries suggest that the polyanion (sodium polyphosphate) and surfactant (Tween 80) in the eluent disrupt electrostatic and hydrophobic interactions between the virion and the membrane. Addition of EDTA to the eluent greatly improved the elution efficacy (rpost (CS) = 88.6% ± 4.3% and rpost (PEM) = 87.0% ± 6.9%) with surface water, even when the organic carbon concentration in the water was high (9.4 ± 0.1 mg/liter). EDTA likely disrupts cation bridging between virions and particles in the feed water matrix or the fouling layer on the membrane surface. For complex water matrices, the eluent composition is the most important factor for achieving high virion recovery. IMPORTANCE: Herein we present the results of a comprehensive physicochemical characterization of HAdV 40, an important human pathogen. The data on HAdV 40 surface properties enabled rigorous modeling to gain an understanding of the energetics of virion-virion and virion-filter interactions. Cross-flow filtration for concentration and recovery of HAdV 40 was evaluated, with postelution recoveries from ultrapure water (99%), tap water (∼91%), and high-carbon-content surface water (∼84%) being demonstrated. These results are significant because of the very low adenovirus recoveries that have been reported, to date, for other methods. The recovery data were interpreted in terms of specific interactions, and the eluent composition was designed accordingly to maximize HAdV 40 recovery.

Diversity of DNA viruses in effluents of membrane bioreactors in Traverse City, MI (USA) and La Grande Motte (France).

This study assesses diversity of DNA viruses in the effluents of two membrane bioreactor (MBR) wastewater treatment plants (WWTPs): an MBR in the United States and an MBR in France. Viral diversity of these effluents is compared to that of a conventional activated sludge WWTP in the U.S. Diversity analysis indicates Herpesvirales to be the most abundant order of potentially pathogenic human DNA viruses in wastewater treated effluent in all utilities. Other potentially pathogenic human viruses detected include Adenoviridae, Parvoviridae, and Polyomaviridae. Bacteriophage order Caudovirales comprises the majority of DNA virus sequences in the effluent of all utilities. The choice of treatment process (MBR versus activated sludge reactor) utilized had no impact on effluent DNA viral diversity. In contrast, the type of disinfection applied had an impact on the viral diversity present in the effluent.

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.

Removal of human enteric viruses by a full-scale membrane bioreactor during municipal wastewater processing.

In the US, human enteric viruses are the main etiologic agents of childhood gastroenteritis, resulting in several hospitalizations and deaths each year. These viruses have been linked to several waterborne diseases, such as acute gastroenteritis, conjunctivitis and respiratory illness. The removal of human enterovirus (EV) and norovirus genogroup II (NoV GGII) was studied in a full-scale membrane bioreactor (MBR) wastewater treatment plant (WWTP) and compared with the removal of human adenovirus (HAdV). In total, 32 samples were quantified using real-time reverse transcription-PCR (RT-PCR) from four separate locations throughout the treatment process; influent, primary settling effluent, membrane influent (which includes the MLSS) and membrane effluent. EV was detected in all 32 samples (100%) with an average concentration of 1.1 × 10(7) and 7.8 × 10(1) viruses/L for the membrane influent and membrane effluent, respectively. NoV GGII was detected in 20 of 32 samples (63%) with an average membrane influent and membrane effluent concentration of 2.8 × 10(5) and 1.2 × 10(1) viruses/L, respectively. HAdV was detected in all 32 samples with an average membrane influent concentration of 5.2 × 10(8) and 2.7 × 10(3) viruses/L in the membrane effluent. Our findings indicate that this particular full-scale MBR treatment was able to reduce the viral loads by approximately 5.1 and 3.9 log units for EV and NoV GGII as compared to 5.5 log units for HAdV. This full-scale MBR system outperformed the removal observed in previous pilot and bench scale studies by 1 to 2 log units. To the best of our knowledge, this is the first study focusing on the removal of EV in a full-scale MBR WWTP using real-time RT-PCR, and on the solid-liquid distribution of EV and NoV GII in secondary biological treatment.

Assessment of human adenovirus removal in a full-scale membrane bioreactor treating municipal wastewater.

Human adenoviruses (HAdVs) in wastewater samples taken from four different treatment stages of a full-scale municipal wastewater treatment plant (i.e., incoming raw sewage, primary sedimentation effluent, membrane bioreactor (MBR) influent, and MBR effluent) were quantified by real-time PCR assays to further estimate removal efficiency of the HAdVs. Based on hexon gene sequence comparisons, HAdV species A, C, and F were consistently found in the wastewater samples. In general, all three identified HAdV species were detected in most of the wastewater samples using the real-time PCR assays. Overall HAdV concentrations were rather stable over the entire 8-month study period (January-August, 2008) (approximately 10(6)-10(7)viral particles/L of wastewater for the raw sewage and primary effluent; 10(8)-10(9)viral particles/L for the MBR influent; and, 10(3)-10(4)viral particles/L for the MBR effluent). No significant seasonal differences were noticed for the HAdV abundances. Removal efficiencies of the viral particles in the full-scale MBR process were assessed and showed an average HAdV removal of 5.0+/-0.6logs over the study period. The removal efficiencies for F species (average log removal of 6.5+/-1.3logs) were typically higher (p-value <0.05) than those of the other two species (average of 4.1+/-0.9 and 4.6+/-0.5logs for species A and C, respectively). These results demonstrate that the full-scale MBR system efficiently removed most HAdV from the wastewater leaving about 10(3)viral particles/L in the MBR effluent.