English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

En production d'eau potable, la nature bactérienne de l'abattement du carboneorganique dissous biodégradable (CODB) observé dans les filtres à charbon actif en grains(CAG) a été démontrée. Les performances de fonctionnement de ce type de contacteurbiologique ont été principalement étudiées sur pilotes. Dans la présente étude, elles sontvérifiées et transposées en condition d'exploitation sur une usine de production d'eaupotable de la. banlieue parisienne. La colonisation bactérienne du CAG a été suivie etmontre que l'équilibre biologique est atteint après filtration d'environ12500m3 d'eau/m3 de CAG. Durant cette phase decolonisation, la biodégradation se substitue progressivement à l'adsorption pour abattre leCOD. Après colonisation, l'efficacité des filtres biologiques, exprimée en termed'abattement de CODB, est fonction du temps de contact quelle que soit la vitesse defiltration (dans la gamme de 2 à 18 m/h). Les résultats de suivis de deux filtres sur deuxans montrent que l'efficacité a été globalement meilleure en 1989 qu'en 1990, cettedifférence s'explique par les fluctuations plus importantes de CODB dans l'influent en 1989.Un modèle mathématique, établi à partir des équations cinétiques des processus bactériensdans les filtres à CAG (modèle CHABROL), développé sur base d'observations antérieures,permet de simuler correctement les observations faites au cours de la présente étude. Avecla mesure du CODB, le modèle CHABROL constitue un outil très bien adapté pour contrôler lesperformances des contacteurs biologiques. Ils permettent, entre autre, de définir le tempsde contact optimal de l'eau dans le filtre en fonction d'une température et d'une qualitéd'eau donnée dans l'influent et d'une qualité d'eau souhaitée dans l'effluent.In drinking water production, filtration on granular activated carton (GAC) isgenerally used in order to remove by adsorption the dissolved organic matter. Nevertheless,the adsorption capacity of GAC is rapidly saturated and it is so necessary to regenerate theGAC. An interesting alternate has been applied in some treatment plants. It consists to useGAC filtration without regeneration taking benefit of the activity of the microbialcommunity which colonize the GAC particles (RITTMAN and HUCK, 1989). In fact, thisbiological filtration offers the advantage to specially remove the biodegradable fraction ofthe dissolved organic carbon (BDOC), which is responsible for the problem of bacterialgrowth into the distribution networks.The bacterial nature of the BDOC removal achieved by the biological filtration on GAChas been now clearly demonstrated (SERVAIS et al., 1991) and some important results of thefunctioning of these filters has been obtained in studies conducted on pilots filters(BOUILLOT et al., 1990; SERVAIS et al., 1992). These studies have for example shown thatonly a very small part of the bacterial biomass produced in the filter is exported with theoutflow.In the present study, biological filtration has been investigated in a full scaletreatment line at Choisy-le-Roi in the Parisian suburbs and the results compared with thosegained on pilot filters.The working conditions of the three GAC filter studied are presented in table 1 andcompared with those of pilot filters used in a previous study conducted al Neuilly-sur-Marne(table 2). The microbial colonization has been followed in two of the liners. If lastedroughly 3 months to reach biological equilibration, it corresponds to a water volumefiltrated of 12 500 m3 per m3 of GAC. Efficiencyof the removal during this period is presented in figure 2. Progressively, biologicalprocesses take turn with adsorption (fig.1).As already demonstrated by SERVAIS et al. (1992), the efficiency of biologicalfiltration, calculated in percentage of BDOC removal, increases with increasing contact timewhatever the filtration velocity could be in the range 2 m/h to 18 m/h (fig. 3). However, the percentage of BDOC, at similartemperature, is higher in the GAC filters at Choisy-le-Roi than at Neuilly-sur-Marne. Thefixed bacterial biomass is also higher at Choisy-le-Roi (average 7.5µgC/cm3) than at Neuilly-sur-Marne (average 2µC/cm3).Following during two years the functioning of the n° 56 and 38 filters (tables 3, 4 and fig. 5, 7), it seems that the globalefficiency of filtration is better in 1990 than in 1989. This can be linked to the greaterfluctuations in BDOC in the influent water in 1989 than in 1990, as shown on figure 8.Fluctuations in the quality of the influent water requires a period to reach the equilibriumduring which the effluent is charchacterized by a lower quality (fig. 8). This period is longer at low temperature. The mathematical modal based on the kinetics of the basic microbiological processesinvolved in biological filtration (the CHABROL model) has been previously developed (BILLENet al., 1992) in order la simulate the performances of the filtration. It can be used tosimulate the vertical profiles of BDOC and bacterial biomass in the filters of theChoisy-le-Roi treatment plant, with modifying only one parameter in the model, the averagebacterial mortality “kd” (fig. 4). BDOC decreasesversus empty bed contact time (EBCT) calculated by the modal are presented on figure 6 forthe Choisy-le-Roi and Neuilly-sur-Marne treatment plants and for two temperatures.From a management point of view, the minimum BDOC is reached for contact time between15 and 20 minutes at Neuilly-sur-Marne, while at Choisy-le-Roi it is rather between 10 and15 minutes.In conclusion, BDOC measurements and CHABROL modal constitute powerful tools formanagement and design of biological GAC filters

Biodegradable dissolved organic carbon removal during biological filtration on granular actived carbon