Full Description

Whatever the treatment is, drinking water always contains biodegradable organic matter and microorganisms at the outlet of a water treatment plant. Such a situation invariably leads to the formation of a complex microbiological ecosystem (biofilm) which can cause water quality deterioration in the network. The Soci¿t¿ Anonyme de Gestion des Eaux de Paris (SAGEP) is the only potable water producer for the city of Paris, France. Each day, this society supplies 750,000 m 3 of potable water for which the origin can be groundwater (54%) or treated surface water from the Seine River and the Marne River. In order to supply high water quality, one of SAGEP's main concerns is to assess bacterial regrowth phenomenon in the distribution system. That is why an experimental procedure has been optimized and tested to assess the biofilm formation potential of a given water in collaboration with the University Paris XI. Based on interlaboratories European works, incubators have been designed which allow biofilm formation and quantification in terms of fixed total organic carbon, fixed culturable bacteria and fixed total bacteria. Such incubators have been connected to a surface water during treatment (slow sand filtered water), a treated water at the outlet of a treatment plant, and a drinking water in the distribution system. The results obtained show that the biofilm formation potential decreases from slow sand filtration to treated water in terms of extracted fixed culturable bacteria and extracted fixed total organic carbon. No difference is observed between slow sand filtered water and treated water for the biofilm density in terms of extracted fixed total bacteria. On the other hand, at the equilibrium state, the number of extracted fixed culturable bacteria in the biofilm formed on the distribution system is higher than those observed on the treated water, but still lower than those of the slow sand filtered water. More generally, the results obtained validate the use of this type of incubators as a monitoring system which could be a suitable tool for all potable water producers. Includes 19 references, tables, figures.

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Edition: Vol. - No. Published: 01/01/2001 Number of Pages: 15File Size: 1 file , 340 KB