Air Flow Modeling in a Prototype Sanitary Sewer System

Abstract

Modeling air movement in sewer systems is important because of its importance in addressing sewer odor issues and pipe corrosion. In this study, a steady-state model was developed for simulating the air pressure and movement in a prototype sewer pipe network with dropshafts and a pump station. It was found that the model was able to simulate the air pressure distribution along the trunk line with reasonable assumptions and simplifications. The lateral leakage model presented in this study suggested that the air leakage at lateral connections is a function of lateral pipe properties and the number of pipes. Increasing the pipe number has limited influence on the leakage air flow. The air pressure force, wastewater drag, and the friction force by pipe wall are dominant factors affecting the air flow in sewer pipes. The operation of the pump station affects the air pressure in the system significantly as a result of the alternate partially full and full-pipe flow condition near the pump station. The dropshafts were regarded as the key contribution for downstream pressurization of the sewer headspace.