L'équipartition et la régulation des débits dans les installations de traitement des eaux

Equal division and regulation of treatment plant flows

Ingénieur en Chef à la Compagnie Générale des Eaux.

Résumé

Satisfactory quantitative and qualitative filtering plant efficiency requires that the same quantities of water should be delivered to all its filter basins at any time and that the inflow rate to each basin should remain constant throughout its filtering cycle. At plants belonging to the "Syndicat des Communes de la Banlieue de Paris" and run by the "Compagnie Générale des Eaux", this double problem has been solved by installing a "Polhydra" regulator at the delivery from each filler basin. Basically, the "Polhydra" regulator comprises a watertight hood with a filtered water spill operating under depression. A float controls the depression under the hood according to the spill head for which it is set, so that any increase in the loss of head through the filter is compensated for by an equivalent increase in hood depression ; the head of filtered water on the spill and filler basin discharge thus both remain constant until the head loss reaches its maximum constructional limit, i.e. throughout the filter basin filtration cycle. Where all the regulator floats in a given installation are set for the same spill head, all the filler basins deliver the same discharge. As any variation in overall discharge into the filtering plant results in a change in water level in the canal supplying all the filter basins, the head of water on the spill of each regulator is made to depend on this canal level by making the latter control the ballasting of the floats governing the respective spill heads.