Simple deterministic model of the hydraulic buffer effect in septic tanks
Modèle déterministe simple de l'effet tampon hydraulique des fosses toutes eaux
Forquet, N. ; Dufresne, M.
Type de document
Article de revue scientifique à comité de lecture
Affiliation de l'auteur
IRSTEA LYON UR MALY FRA ; ENGEES STRASBOURG FRA
Résumé / Abstract
Septic tanks are widely used in on-site wastewater treatment systems. In addition to anaerobic pre-treatment, hydraulic buffering is one of the roles attributed to septic tanks. However there is still no tool for assessing it, especially in dynamic conditions. For gravity fed system, it could help both researchers and system designers. This technical note reports a simple mechanistic model based on the assumption of flow transition between the septic tank and the outflow pipe. The only parameter of this model was calibrated using CFD modeling for a wide range of discharge rates. The resulting model highlights that a septic tank plays a hydraulic buffer role when faced with sudden and large discharge flow but this role tends to disappear when hydrographs are smoother. In those cases there is an observable lag between the input hydrograph and outflow hydrograph.
Water and Environment Journal, vol. 29, num. 3, p. 360 - 364