Propagation of Waves and Dissolved Compounds in Sewer

The phenomenon of the surface wave propagating faster than the fluid that induced it is studied experimentally and numerically. The study focuses on the importance of the wave phenomenon for the urban hydrology system, where it can determine the impact of combined sewer overflows on the environment and the operation of a novel urine (anthropogenic nutrient solution) separation system. Urine would be stored decentrally and released during the night hours so that a wave would form in the sewer. The fullscale experiments were carried out in a 2-km section of a main sewer. The wave was induced with the aid of fire hydrant water traced by salt. Five measurements and sampling stations were operated downstream through which the transport of both fluid and compounds were analyzed. Numerical simulations of the results are discussed focusing on the reliability of friction approaches and dispersion prediction. Although difficult to model with commercial tools, it was shown that the wave phenomenon has no adverse effects on the practicability of the urine separation system, but can lead to the release of undiluted wastewater during a rain event.