Optimization Of Submarine Outfalls With A Multiport Diffuser Design

Immission of civil sewage into sea is realized to complete the onshore depurative process or to take out the already purified wastewater from the bathing area, ensuring a good perceived seawater quality. Anyhow the compliance of the pollutant concentrations limits is necessary to ensure safe bathing. The design of submarine pipes is usually completed contemplating a diffuser with a series of ports for the repartition of the wastewater discharge. The real process of pollutants diffusion into the sea, simulated with complex diffusion-dispersion models in a motion-field dependent from environmental conditions and drift speeds, affect the submarine pipe design. A design optimization procedure has been realized for the marine outfall pipe-diffuser system using a simplified zone model, subjected to a sensitivity analysis on the characteristic parameter. The method is shown using an example project for the submarine outfall at service for the sewage treatment plant of Belvedere Marittimo, on the southern Tyrrhenian Sea in Italy.