Transport of MS2 Phage, Escherichia coli, Clostridium perfringens, Cryptosporidium parvum and Giardia intestinalis in a Gravel and a Sandy Soil •
15 Oct 2005-Environmental Science & Technology (American Chemical Society)-Vol. 39, Iss: 20, pp 7860-7868
TL;DR: In this paper, column experiments were conducted using natural soil and water from an infiltration site with fine sandy soil and a river bank infiltrate site with gravel soil to determine the removal of phages, bacteria, bacterial spores, and protozoan (oo)-cysts.
Abstract: To define protection zones around groundwater abstraction wells and safe setback distances for artificial recharge systems in watertreatment, quantitative information is needed about the removal of microorganisms during soil passage. Column experiments were conducted using natural soil and water from an infiltration site with fine sandy soil and a river bank infiltration site with gravel soil. The removal of phages, bacteria, bacterial spores, and protozoan (oo)-cysts was determined at two velocities and compared with field data from the same sites. The microbial elimination rate (MER) in both soils was generally >2 log, but MER in the gravel soil was higher than that in the fine sandy soil. This was attributed to enhanced attachment, related to higher metal-hydroxides content. From the high sticking efficiencies (>1) and the low influence of flow rate on MER it was deduced that straining played a significant role in the removal of Escherichia coli and Cryptosporidium parvum oocysts in the gravel soil. Lower removal of oocysts than the 4-5 times smaller E. coli and spores in the fine sand indicates that the contribution of straining is variable and needs further attention in transport models. Thus, simple extrapolation of grain size and particle size to the extent of microbial transport underground is inappropriate. Finally, the low MER of indigenous E. coli and Clostridium perfringens observed in the soil columns as well as under field conditions and the second breakthrough peak found for Cryptosporidium and spores in the fine sandy soil upon a change in the feedwater pH indicate a significant role of detachment and retardation to microbial transport and the difficulty of extrapolation of quantitative column test results to field conditions.
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TL;DR: In this article, a number of transport pathways, processes, factors, and mathematical models often are needed to describe pathogen fate in agricultural settings, and the level of complexity is dramatically enhanced by soil heterogeneity, as well as by temporal variability in temperature, water inputs, and pathogen sources.
Abstract: An understanding of the transport and survival of microbial pathogens (pathogens hereafter) in agricultural settings is needed to assess the risk of pathogen contamination to water and food resources, and to develop control strategies and treatment options. However, many knowledge gaps still remain in predicting the fate and transport of pathogens in runoff water, and then through the shallow vadose zone and groundwater. A number of transport pathways, processes, factors, and mathematical models often are needed to describe pathogen fate in agricultural settings. The level of complexity is dramatically enhanced by soil heterogeneity, as well as by temporal variability in temperature, water inputs, and pathogen sources. There is substantial variability in pathogen migration pathways, leading to changes in the dominant processes that control pathogen transport over different spatial and temporal scales. For example, intense rainfall events can generate runoff and preferential flow that can rapidly transport...
197 citations
TL;DR: The results of this yearlong study suggest that adenoviruses have the most stable persistence profile and an ability to survive for a long time in groundwater.
Abstract: Detection of specific genetic markers can rapidly identify the presence of enteric viruses in groundwater. However, comparison of stability characteristics between genetic and infectivity markers is necessary to better interpret molecular data. Human adenovirus serotype 2 (HAdV2), in conjunction with MS2 phages or GA phages, was spiked into raw groundwater microcosms. Viral stability was periodically assessed by both infectivity and real-time PCR methods. The results of this yearlong study suggest that adenoviruses have the most stable persistence profile and an ability to survive for a long time in groundwater. According to a linear regression model, infectivity reductions of HAdV2 ranged from 0.0076 log(10)/day (4°C) to 0.0279 log(10)/day (20°C) and were significantly lower than those observed for phages. No adenoviral genome degradation was observed at 4°C, and the reduction was estimated at 0.0036 log(10)/day at 20°C. Occurrence study showed that DNA of human adenoviruses could be observed in groundwater from a confined aquifer (7 of the 60 samples were positive by real-time PCR), while no fecal indicators were detected. In agreement with the persistence of genetic markers, the presence of adenoviral DNA in groundwater may be misleading in term of health risk, especially in the absence of information on the infective status.
130 citations
TL;DR: The purpose of the study was to compare methods for extraction of faecal bacteria from sands and recommend a standardized extraction technique.
Abstract: Aims: The absence of standardized methods for quantifying faecal indicator bacteria (FIB) in sand hinders comparison of results across studies. The purpose of the study was to compare methods for extraction of faecal bacteria from sands and recommend a standardized extraction technique. Methods and Results: Twenty-two methods of extracting enterococci and Escherichia coli from sand were evaluated, including multiple permutations of hand shaking, mechanical shaking, blending, sonication, number of rinses, settling time, eluant-to-sand ratio, eluant composition, prefiltration and type of decantation. Tests were performed on sands from California, Florida and Lake Michigan. Most extraction parameters did not significantly affect bacterial enumeration. anova revealed significant effects of eluant composition and blending; with both sodium metaphosphate buffer and blending producing reduced counts. Conclusions: The simplest extraction method that produced the highest FIB recoveries consisted of 2 min of hand shaking in phosphate-buffered saline or deionized water, a 30-s settling time, one-rinse step and a 10 : 1 eluant volume to sand weight ratio. This result was consistent across the sand compositions tested in this study but could vary for other sand types. Significance and Impact of the Study: Method standardization will improve the understanding of how sands affect surface water quality.
128 citations
Cites background from "Transport of MS2 Phage, Escherichia..."
...The strength of physicochemical interactions between bacterial and sand surfaces, such as electrostatic, hydrophobic and Van der Waals forces, are modulated by pH and ionic strength, which varied across eluants (Derjaguin and Landau 1941; Verwey and Overbeek 1948; Hijnen et al. 2005)....
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TL;DR: Analysis of published data from field experiments and large intact soil cores established an extensive database of microbial removal rates for a wide range of subsurface media, finding high and low removal rates in volcanic soils, pumice sand, fine sand, and highly weathered aquifer rocks.
Abstract: Information about the microbial removal efficiencies of subsurface media is essential for assessing the risk of water contamination, estimating setback distances between disposal fields and receiving waters, and selecting suitable sites for wastewater reclamation. By analyzing published data from field experiments and large intact soil cores, an extensive database of microbial removal rates was established for a wide range of subsurface media. High microbial removal rates were found in volcanic soils, pumice sand, fine sand, and highly weathered aquifer rocks. Low removal rates were found in structured clayey soils, stony soils, coarse gravel aquifers, fractured rocks, and karst limestones. Removal rates were lower for enteroviruses than for other human viruses; for MS2 phage than for other phage species; for waste-associated microbes than for those cultivated in the laboratory; and for contaminated media than for uncontaminated media. Microbial removal rates are inversely correlated with infiltration rates and transport velocity. The assumption of first-order law, or a constant removal rate (when the transport scale reaches a representative elementary volume), is appropriate for most of field data analyzed. However 30% of the datasets (26 out of 87 pairs) are better described with the power law, implying reduced removal rates with transport distance. The latter is most prominent for organically contaminated media, especially in relatively fine aquifer media. The presence of organic matter, heterogeneity in microbial properties, change in solution chemistry, detachment, and physical straining, may have caused the discrepancies from the first-order law traditionally used in transport models for describing microbial removal.
121 citations
TL;DR: The main objective of this study was to evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three waterborne fecal indicator organisms in laboratory-scale columns packed with clean quartz sand.
119 citations
Cites background from "Transport of MS2 Phage, Escherichia..."
...However, for certain experimental conditions greater removal of bacteria than viruses has been reported in the literature (Hijnen et al., 2005; van der Wielen et al., 2008)....
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References
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TL;DR: This massive outbreak of watery diarrhea among the residents of Milwaukee was caused by cryptosporidium oocysts that passed through the filtration system of one of the city's water-treatment plants, and water-quality standards and the testing of patients for cryptOSporidium were not adequate to detect this outbreak.
Abstract: Background Early in the spring of 1993 there was a widespread outbreak of acute watery diarrhea among the residents of Milwaukee. Methods We investigated the two Milwaukee water-treatment plants, gathered data from clinical laboratories on the results of tests for enteric pathogens, and examined ice made during the time of the outbreak for cryptosporidium oocysts. We surveyed residents with confirmed cryptosporidium infection and a sample of those with acute watery diarrhea consistent with cryptosporidium infection. To estimate the magnitude of the outbreak, we also conducted a survey using randomly selected telephone numbers in Milwaukee and four surrounding counties. Results There were marked increases in the turbidity of treated water at the city's southern water-treatment plant from March 23 until April 9, when the plant was shut down. Cryptosporidium oocysts were identified in water from ice made in southern Milwaukee during these weeks. The rates of isolation of other enteric pathogens remained stab...
2,040 citations
"Transport of MS2 Phage, Escherichia..." refers background in this paper
...In the past decades, however, viruses, and more recently protozoa like Cryptosporidium and Giardia, have been recognized as pathogens of major concern in the water industry (Craun et al., 1997; MacKenzie et al., 1994; Gerba et al., 1990)....
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Book•
26 Apr 1999
TL;DR: This paper presents a meta-analysis of 120 databases relating to Microbial Agents and Their Transmission and their Transmission and the Dose-Response Assessment that were generated during the preparation of this study.
Abstract: Scope of Coverage. Microbial Agents and Their Transmission. Risk Assessment Paradigms. Conducting the Hazard Identification. Analytical Methods for Developing Occurrence and Exposure Databases. Exposure Assessment. Conducting the Dose-Response Assessment. Conducting the Risk Characterization. Compendium of Data. Index.
1,236 citations
"Transport of MS2 Phage, Escherichia..." refers background in this paper
...How effective it is, however, is not known and is a question of growing interest since the introduction of quantitative microbial risk assessment for drinking water safety (Haas et al., 1999)....
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TL;DR: In this paper, the authors present theories describing colloid mobilization, deposition, and transport, laboratory experiments in model systems designed to test these theories, and applications of these theories to colloid-facilitated transport experiments in natural groundwater systems.
1,145 citations
"Transport of MS2 Phage, Escherichia..." refers background in this paper
...___________________________________________________________________ - 214 Adsorption of micro-organisms to solid surfaces is governed by electrostatic forces when surfaces are charged, and by intermolecular forces governed by the hydrophobic or hydrophilic composition of both surfaces (Ryan and Elimelech, 1996)....
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TL;DR: In this paper, the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method, based on the Stokes sedimentation rates, for the fine fractions.
Abstract: Classically, the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method, based on the ‘Stokes’ sedimentation rates, for the fine fractions. Results from the two methods are compared with results from laser diffraction size analysis, which is based on the forward scattering of monochromatic coherent light. From a point of view of laboratory efficiency, the laser sizing technique is far superior. Accuracy and reproducibility are shown by measurements on certified materials. It appears that laser grain size measurements of certified materials correspond very well with the certificated measurements. Tests were also done on a set of randomly selected sediments of fluvial, aeolian and lacustrine origin. Except for the (<2 μm) clay fraction, there is a coarsening of the mean diameter of one to two size classes (0.25 ɛ), caused by the non-sphericity of the particles. The platy form of the clay particles induces considerable differences (eight size classes) between pipette and laser measurements: the <2 μm grain size, defined by the pipette method corresponds with a grain size of 8 μm defined by the Laser Particle Sizer for the studied sediments. Using a higher grain size level for the clay fraction, when laser analysis is applied, enables workers in the geological and environmental field to compare classical pipette analysis with a laser sizing technique.
990 citations
"Transport of MS2 Phage, Escherichia..." refers methods in this paper
...The clay and silt fractions were converted to the traditional grain size analysis with pipet and sieve analysis (Konert and Vandenberghe, 1997). Total organic material and carbonate were determined using the methods of Stuyfzand and van der Jagt (1997). Soil pH and the electrical conductivity (EC) were determined after shaking 20 g for 2 h with 50 mL of ultrapure water in the decanted fluid at 20°C....
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...The clay and silt fractions were converted to the traditional grain size analysis with pipet and sieve analysis (Konert and Vandenberghe, 1997)....
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810 citations
"Transport of MS2 Phage, Escherichia..." refers background or methods in this paper
...It is described in the literature that straining becomes important when this ratio is >5% (Herzig et al., 1970),...
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...perfringens D10 and the enumeration method were described by Hijnen et al. (2002). C....
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...perfringens spores, delayed breakthrough (retardation), and as a consequence a low elimination rate, have been described for slow sand filters (Hijnen et al. 2004). Clostridial spores are persistent and survive longer than E. coli (Medema et al., 1997), which might explain why indigenous C. perfringens showed the lowest MER values in three of the four columns. The results of a column study (1.4 m of length; 1.5 m.day-1) by Schijven et al. (2003), using the same soil and C....
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