par Servais, Pierre 
;Laurent, Patrick ;Randon, Guy
Référence Revue des sciences de l'eau, 5, 4, page (473-488)
Publication Publié, 1992
;Laurent, Patrick ;Randon, GuyRéférence Revue des sciences de l'eau, 5, 4, page (473-488)
Publication Publié, 1992
Article révisé par les pairs
| Résumé : | Bacterial regrowth in distribution systems is an important problem for drinking water producers. It is linked to the more and more frequent utilization of low quality surface waters, containing high concentration of organic matter, as raw water, and also to the increase in size and complexity of the distribution networks with high residence time of the water between its production and utilization. At the present time chlorination of treated water, with sometimes rechlorination in the network, is the usual way to limit growth in distribution systems. This solution however presents disadvantages, the major one is the formation of unpleasant organochlorine compounds which are responsible for tastes and odours of water. An alternative strategy consists of developing treatment lines in which biodegradable dissolved organic carbon is removed. It allows through a reduction of the chlorine demand of the water to increase the stability of the chlorine residual of the water. In this context, it is important to get a good knowledge of the factors controlling bacterial development in distribution networks. Up to now, studies on this subject have met some methodological problems linked to the fact that classical bacteriological methods are inadequate to study this kind of systems. In this paper, various methods have been investigated to estimate bacterial biomass and activity in tap water. For this study, the analyzed water samples have been collected in the distribution system of the Parisian suburts. Three methods have been tested for the determination of bacterial biomass: plate count, measurement of DNA associated with particles with a size higher than 0.2 nm and direct mircroscopic enumeration. Heterotrophic plate counts have been performed following the French standard and results are expressed in CFU (Colony Forming Units) per ml; the DNA collected after filtration of 500 ml to 1500 ml of water on a 0.2 |
