Comparison of Microbial Removal Between Slow Dead-End Versus Tangential Sand Filtration.

  Both river bank filtration and dead-end sand filtration are becoming increasingly applied in rural areas to improve the quality of fecally contaminated water. To evaluate the capacity of both treatments to remove E. coli, fecal streptococci, and somatic and K13-phages, this study investigates their concentrations in diluted wastewater after short-distance tangential sand filtration and dead-end sand filtration.

Virus removal vs. subsurface water velocity during slow sand filtration.

In an attempt to obtain a conservative estimate of virus removal during slow sand and river bank filtration, a somatic phage was isolated with slow decay and poor adsorption to coarse sand. We continuously fed a phage suspension to a 7-m infiltration path and measured the phage removal. In a second set of experiments, we fed the phage suspension to 1-m long columns run at different pore water velocities.

Removal of indigenous coliphages and enteric viruses during riverbank filtration from highly polluted river water in Delhi (India).

Emerging countries frequently afflicted by waterborne diseases require safe and cost-efficient production of drinking water, a task that is becoming more challenging as many rivers carry a high degree of pollution. A study was conducted on the banks of the Yamuna River, Delhi, India, to ascertain if riverbank filtration (RBF) can significantly improve the quality of the highly polluted surface water in terms of virus removal (coliphages, enteric viruses). Human adenoviruses and noroviruses, both present in the Yamuna River in the range of 10(5) genomes/100 mL, were undetectable after 50 m infiltration and approximately 119 days of underground passage.

Relationships between human adenoviruses and faecal indicator organisms in European recreational waters.

Human adenoviruses (HAdV) may be implicated in some disease outbreaks associated with recreational water exposures, typically in swimming pools. Modern molecular methods can be used to detect HAdV in environmental water samples. During the EU FP6 Project VIROBATHE a database of over 290 HAdV analyses with corresponding faecal indicator organism (FIO) determinations was gathered and used to explore statistical associations between HAdV and FIO results.

Surveillance of adenoviruses and noroviruses in European recreational waters.

Exposure to human pathogenic viruses in recreational waters has been shown to cause disease outbreaks. In the context of Article 14 of the revised European Bathing Waters Directive 2006/7/EC (rBWD, CEU, 2006) a Europe-wide surveillance study was carried out to determine the frequency of occurrence of two human enteric viruses in recreational waters. Adenoviruses were selected based on their near-universal shedding and environmental survival, and noroviruses (NoV) selected as being the most prevalent gastroenteritis agent worldwide.

Removal of bacterial fecal indicators, coliphages and enteric adenoviruses from waters with high fecal pollution by slow sand filtration.

The aim of the present study was to estimate the performance of slow sand filtration (SSF) facilities, including the time needed for reaching stabilization (maturation), operated with surface water bearing high fecal contamination, representing realistic conditions of rivers in many emerging countries. Surface water spiked with wastewater was infiltrated at different pore water velocities (PWV) and samples were collected at different migration distances. The samples were analyzed for phages and to a lesser extent for fecal bacteria and enteric adenoviruses.

[Removal of microorganisms by soil filters for bathing ponds].

"Bathing ponds" are artificial outdoor water pools without disinfection. Whereas in conventional pools, chlorine promptly kills pathogens shed by bathers, such quick inactivation is missing in bathing ponds. We have explored the retention of indicator bacteria and viruses by a vertically operated, reed grown soil filter.

Development and application of a one-step low cost procedure to concentrate viruses from seawater samples.

A novel and simple procedure for concentrating adenoviruses from seawater samples is described. The technique entails the adsorption of viruses to pre-flocculated skimmed milk proteins, allowing the flocs to sediment by gravity, and dissolving the separated sediment in phosphate buffer. Concentrated virus may be detected by PCR techniques following nucleic acid extraction.

A randomized controlled trial assessing infectious disease risks from bathing in fresh recreational waters in relation to the concentration of Escherichia coli, intestinal enterococci, Clostridium perfringens, and somatic coliphages.

We performed epidemiologic studies at public freshwater bathing sites in Germany to provide a better scientific basis for the definition of recreational water quality standards. A total of 2,196 participants were recruited from the local population and randomized into bathers and nonbathers. Bathers were exposed for 10 min and had to immerse their head at least three times.

Quantitative detection of enteroviruses in activated sludge by cell culture and real-time RT-PCR using paramagnetic capturing.

We have compared in extracts of activated sludge the number of enteroviruses detectable with buffalo green monkey (BGM) cell-cultures versus the number of enteroviral genomes determined by reverse-transcription quantitative real-time PCR (RT-qPCR). In order to find conditions adequate for quantifying enteroviral RNA isolated from (waste)water we have investigated affinity capture of RNA with polystyrene beads (Dynabeads). The capture efficiency strongly depended on the genomic region chosen for the affinity binding.

[The EU Bathing Water Directive. Risk assessment and standards].

In an attempt to reduce the risk of infection in natural bathing waters the European Union is in the process of improving the Bathing Water Directive 76/160/EWG, which regulates the safety of such waters. The proposal contains several positive innovations which will improve the protection of the bathers: (1) health-related indicators, (2) harmonized detection methods, (3) requirements for active bathing water management, and (4) stricter standards for coastal waters. One of the most salient features of the current draft is the introduction of bacterial standards that are more stringent for coastal than for fresh waters.

An outbreak of viral meningitis associated with a public swimming pond.

From July to October 2001, 215 cases of aseptic meningitis occurred among the inhabitants of the German city of Kassel and neighbouring counties. A matched case-control study identified bathing in a public, nature-like pond during the beginning of the outbreak as a risk factor for disease [matched odds ratio (mOR) 44.8, 95% confidence interval (CI) 3.

Contribution of the colmation layer to the elimination of coliphages by slow sand filtration.

River bank or slow sand filtration is a major procedure for processing surface water to drinking water in central europe. In order to model the performance of river bank and slow sand filtration plants, we are studying the different mechanisms by which the elimination of pathogens is realized. An important question concerning the mode of action of slow sand filters and river bank filtration units is the role of the colmation layer or "schmutzdecke" on the elimination of human pathogens.

Persistence of heterologous nucleic acids after uptake by mammalian cells.

Plasmids containing the complete genome of poliovirus-1 are transcribed at random in transfected cells and give rise to infectious RNA molecules. These generate viruses which can be detected easily in a plaque assay. Using this system, we analyzed the persistence of the biologically active portion of transfected poliovirus cDNA by determining its infectious activity in mammalian cells.

Wastewater treatment and elimination of pathogens: new prospects for an old problem.

Although the development of wastewater treatment technology is more than one hundred years old, most wastewater treatment plants existing today do not eliminate pathogens satisfactorily. Even in highly developed nations, receiving waters, serving in many cases as drinking water resources, are contaminated with pathogens. Surface waters also contain large concentration of phosphate due to long lasting wastewater discharges.

[Reduction of bacteria and viruses in purification plant discharges using microfiltration in a model plant].

Microfiltration through a membrane matrix of a nominal pore size of 0.2 microns has been applied for advanced treatment of mechanically and biologically treated wastewater. Elimination of bacteria and coliphages as well as the decrease in some chemical constituents were studied at a flow rate of 80 l/h.

Differentiation of vaccine and wild-type polioviruses using polymerase chain reaction and restriction enzyme analysis.

Genomic amplification followed by selective digestion of restriction enzymes was used to differentiate polioviruses. The method was based on conserved and variable components of the 5'-noncoding region. The differences between Sabin vaccine and wild-type viruses made it possible to identify rapidly an isolated poliovirus as vaccine-related or wild-type virus.

[Inactivation of bacteria and coliphages in surface water highly polluted by secondary effluent and purified by flocculation and filtration by means of UV irradiation at a pilot plant scale].

The water of a channel in Berlin which is highly polluted by municipal sewage effluent is treated at the phosphate elimination plant (PEP) Tegel by flocculation and filtration in order to reduce eutrophication in the following Lake Tegel. The elimination of bacteria and coliphages in the effluent of the PEP was investigated in a scale pilot UV irradiation reactor installed at the outlet of the PEP Tegel. The influence of technical parameters such as flow rate and the arrangement of 23 UV lamps in the reactor on the inactivation was tested.

Detection of naturally occurring enteroviruses in waters by reverse transcription, polymerase chain reaction, and hybridization.

Comparison in virus-seeded mineral water of three detection methods for enteroviruses, direct hybridization, cell culture, and reverse transcription into cDNA followed by polymerase chain reaction and hybridization, showed that the last procedure was 10 to 1,000 times more sensitive than detection by cell culture and 10(5) to 10(7) times more sensitive than direct hybridization. The presence of naturally occurring enteroviruses was also demonstrated in activated sludge and in concentrated and non-concentrated surface water samples by reverse transcription-polymerase chain reaction-hybridization. However, in activated sludge and in concentrated surface waters, enzymatic amplification was sometimes inhibited by contaminants.

Lack of evidence for strand-specific inhibition of poliovirus RNA synthesis by 3-methylquercetin.

Buffalo Green Monkey cells were infected with poliovirus-1 in the presence of 3-methylquercetin or guanidine, and the formation of positive- and negative-strand viral RNA was monitored using single-stranded RNA probes. Both 3-methylquercetin and guanidine prevented the formation of plus-strand as well as minus-strand viral RNA, although, due to the high multiplicity of infection used, a high number of genomic viral RNA was always present in the cells.

[Adsorption of selected enteroviruses on sand from a groundwater stratum: effect of pH, grain size, water solutes and organic contamination].

Elimination of human pathogenic viruses during the filtration of contaminated water or during groundwater recharge with surface water relies a great deal on the adsorption and permanent binding of the viruses to the soil or to the aquifer material. In the present study we have investigated the influence of organic contamination, of grain size, and of the presence of several ions and other compounds on the adsorption of four enteroviruses to sand. Results showed an impaired adsorption of viruses in organic contaminated soil.

[The ATP concentration of drinking water compared to the colony count].

During a four months' period we have monitored the drinking water of the city of Berlin for its ATP-content and for its Total Colony Count. After concentrating the drinking water by a factor of 1000 by filtration, we obtained ATP-values which were always significantly above the blanks. The profile of the ATP-values roughly paralleled that of the Colony Counts; however, as we never observed Colony Counts nearly approaching 100 colonies/ml (which is the value not to be exceeded according to current German Law), we are unable to positively assess how the ATP-value would have behaved in samples with Colony Counts above 100 ml.