Dispersion and Travel Time of Dissolved and Floating Tracers in Urban Sewers

Abstract

Environmental impacts of oil spills affecting urban sewage networks can be eliminated if timely intervention is taken. The design of such actions requires knowledge of the transport of surface pollutants in open channels. In this study we investigated the travel time and dispersion of pollutants by means of tracer experiments in sewage networks and a creek. The travel time of surface tracers has been found to be significantly shorter than that of a bulk flow tracer. The ratio of the travel times of a bulk flow tracer and surface tracers agreed with the known correlations obtained for rivers. An increasing tendency in the ratio of travel times has been observed for increasing bulk flow velocity.A segment-wise dispersion model was implemented in the existing hydraulic model of a sewer system. The simulation results were compared with the experimental observations. The dispersion rate of the bulk flow tracer has been found to obey Taylor's mixing theory for long channels and was more intensive than that of surface tracers in community sewage channels.

Quantifying Mixing in Sewer Networks for Source Localization

“…Fluorescent dye tracing has a wide variety of applications (Swarnkar et al 2022), including model validation (e.g., Garsdal et al 1995;Magnusson et al 1998), and particularly is often used in determining D x (e.g., Guymer and O'Brien 2000;Boxall et al 2003;Istók and Kristóf 2014). Most fluorescent dyes are largely conservative, have low limits of detection, and can be continuously monitored (Wilson et al 1984).…”