Coliforms and other microbial indicators occurrence in water and biofilm in full-scale distribution systems.

Biofilm and microbial water quality were studied in four middle size full-scale distribution systems (DS) in France serving 5,000-30,000 inhabitants (maximum residence time 23-160h) through three sampling campaigns over 1 year. Three of these DSs were chosen because of a quite high occurrence of bacterial indicators (i.e. total coliforms), the last DS was considered as a reference. Biofilm was studied on cast iron coupons incubated for more than 1 month in devices continuously fed with water from the DS in conditions imitating those met in DS. The devices were located at different points (4-6) along each DS. The abundance of bacteria in biofilm was estimated by heterotrophic plate counts (HPC) after detachment of the biofilm from the support by sonication. Microbiological water quality was estimated in parallel; analysis of total coliforms, E. coli, enterococci and anaerobic sulphide-reducing bacteria spores (ASRB spores) was carried out in biofilm and water. Over the period of the study, 171 water samples and 57 biofilm samples were collected. Over these 171 waters, 19 (11%) were positive for at least one of the measured indicators while two biofilm samples were positive (3.5%). Significant differences were observed in the levels of contamination between the DSs. High residence time in the DS, low disinfectant residual and high temperature increased the risk of indicator occurrence in the water phase. Due to the low number of biofilm samples positive for bacterial indicators, the data collected in the present study did not allow observation of a direct association between biofilm and water contaminations, even if the occurrence of indicators in water appeared on DSs with the highest density of biofilm (HPC).

A new analytical tool to assess health risks associated with the virological quality of drinking water (EMIRA study).

This work assessed the risks associated with the virological quality of tapwater using a molecular analytical tool manageable in a field survey. It combined a daily epidemiological follow-up of digestive morbidity among a panel of volunteers and a microbiological surveillance of drinking water. RT-PCR was used for detection of enterovirus, rotavirus and astrovirus. 712 cases of acute digestive conditions occurred in the 544 volunteers. 38% (9/24) raw water and 23% (10/44) tap water samples were positive for at least one virus marker with 9/10 positive tap water samples complying with bacterial criteria. No statistically significant association was found between the presence of viral markers and observed incidence of digestive morbidity. However, when an outbreak occurred, enterovirus and rotavirus RNA was detected in the corresponding stored tap water samples. Sequencing of the amplified fragments showed that the rotavirus detected was of bovine origin. This work demonstrated that enteric virus markers were common in tapwater of the study communities (characterised by a vulnerable raw water) despite absence of bacterial indicators. Tangential ultrafiltration coupled to RT-PCR allowed a simultaneous and fast detection of the study viruses from environmental samples. This process is a promising tool usable for virological water surveillance, in as much the corresponding know-how is transferred to the field professionals.

[Comparative study on methods to recover indigenous viruses from samples of activated sewage sludge]. / Methodenvergleich zur Isolierung von Viren aus Belebtschlammproben.

Samples of activated sewage sludge were investigated for their contents of indigenous enteric viruses. Therefore sewage sludge solids were collected by centrifugation and the embedded viruses eluted by blending (Waring blendor), glycine buffer (0.05 M) treatment at pH 11.5 or Freon1 treatment. Eluted viruses were concentrated on microfiberglass filters ("Balston" filters) at pH 3.5 or by flocculation with beef extract (3%, pH 3.5). Simple blending of the activated sludge was found being not very efficient, while the other two methods gave better results in freeing the viruses from the sewage flocs. Usually highest virus titers were obtained after glycine treatment and concentration with Balston filters. Freon treatment of activated sewage sludge produces aqueous supernatants containing much denaturated floc material which seems to cause a certain number of viruses to remain in the supernatant after flocculation.

Sampling strategy for detecting viruses in a sewage treatment plant.

A study of pollutant flows was carried out at a wastewater treatment plant in Nancy, France, which used activated-sludge treatment. To carry out observation of hourly flow variation, a sampling strategy needs to be defined. A comparison between two methods of sampling was conducted: dip samples every 2 h over a period of 24 h and one 24-h composite sample were taken from raw and treated wastewater and then analyzed for enteroviruses, fecal coliforms, chemical oxygen demand, biochemical oxygen demand, and suspended solids. The results showed that the hourly variations of these pollutants in the effluents are in good agreement with expectations based upon the customers' usage and the characteristics of the wastewater network. Significant correlations were found between all tested parameters and enteroviruses in raw wastewater. After biological treatment, no correlation remained in treated wastewater between viruses and other parameters. As for the two sampling methods, a rather good representation of the daily load was given by the composite mode of sampling as concerns physicochemical and microbiological parameters. Biological treatment removed an average of 83% of viruses.

[Survival of enteric viruses adsorbed on glass microfibers during postal transport]. / Survie de virus entériques adsorbés sur microfibre de verre aucours d'un transport postal.

The survival of enteric viruses (poliovirus type 1, Mahoney strain, and indigenous viruses of waste waters) has been studied after adsorption of the viruses (pH 3.5) on glass microfiber filters. After postal transport, the presence of the viruses was checked on the filters being soaked in a 3% beef extract solution (pH 7.5) either frozen or without protection against heat. Viruses were recovered at a rate of 59 to 65%. For qualitative studies, postal shipment of samples adsorbed on fiberglass may allow extension of a control system for enteroviruses in water.

[Evaluation of the alginat membrane filter method for the Enterovirus concentration in water (author's transl)]. / Alginat-Filter zur Konzentrierung von Enterovirus aus wässerigem Milieu - Grenzen der Methode.

It is bound to use a concentration method for the research of enteroviruses in water. One of the concentration methods, the filtration on alginat membranes, avoids the problem of the virus elution from the filter, then the membrane is soluble in a sodium citrat buffer. This method was studied with different types of water (synthetic water, tap water and wastewater). -The recovery efficiency of Poliovirus I in clear waters (synthetic water and tap water) was poor, unsatisfying reproducible; the results are better for small virus concentrations. This efficiency may be slowly enhanced by the addition to the sample of aluminium chlorid at a final concentration of 5.10(-4) M. -The technical problems (brittleness of the membranes, slow filtrations speed, small sample volume), soon noticeable with clear waters, are more important in the case of trouble waters. Meanwhile the use of this filtration method gives better results for the recovery of Poliovirus I in wastewaters than the direct inoculation to cells cultures.