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Simple deterministic model of the hydraulic buffer effect in septic tanks
Author(s) -
Forquet Nicolas,
Dufresne Matthieu
Publication year - 2015
Publication title -
water and environment journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 37
eISSN - 1747-6593
pISSN - 1747-6585
DOI - 10.1111/wej.12114
Subject(s) - outflow , hydrograph , septic tank , flow (mathematics) , environmental science , simple (philosophy) , mechanics , geology , environmental engineering , drainage basin , geography , oceanography , physics , cartography , philosophy , epistemology
Septic tanks are widely used in on‐site wastewater treatment systems. In addition to anaerobic pretreatment, 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 computational fluid dynamics (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 input hydrographs are smoother. In those cases, there is an observable lag between the input hydrograph and outflow hydrograph.