COMPUTATIONAL FLUID DYNAMICS (CFD) MODELING USED TO ASSESS THE FATE OF FLUSHABLE SOLID CONSUMER PRODUCTS IN SEPTIC TANKS

The major objective of this study was to develop a simulation model that could be used to predict the fate of flushable consumer products in septic tanks. As part of this study we wanted to obtain an understanding of flow patterns that develop within septic tanks during normal operation, determine the settling properties of materials most likely to enter septic tanks, and identify additional data required to improve our understanding of the behavior of solids transport within septic tanks. These goals were accomplished by developing a Computational Fluid Dynamics (CFD) model that simulates flow patterns and solids transport within septic tanks. The model was then validated via a field study. Results from this study showed that: (1) the CFD modeling techniques can be successfully used to replicate the main characteristics of the studied flows and product settling properties, (2) the flushable products being tested settle mostly in the first 1/3 of the septic tanks, and (3) the three-dimensional modeling techniques were successful in determining the fate of the products (i.e., the model results predict settling of materials in the first 1/3 of the septic tanks).