Reducing particle accumulation in sewers for mitigation of combined sewer overflow impacts on urban rivers: a critical review of particles in sewer sediments

Abstract

Sewer sediments contain various hazardous compounds, leading to significant pollution risks when combined sewer overflows (CSOs) occur without appropriate controls. This paper presents a comprehensive review of the issues associated with particles in sewers, specifically focusing on the non-negligible contribution of particulate matter to CSOs, which leads to pollution in urban rivers. Therefore, the sources of particulate matter in sewers, their contributions to the overflow particles, and the specific areas of concern when it comes to managing particulate matter during particle transportation are outlined. Overall, carefully considering the goal of avoiding sedimentation during the drainage system design is the most effective prevention and control method for pipeline sediment, where minimum velocity and minimum shear stress are the core parameters. The establishment of a flexible and adaptive particle simulation method in drainage pipelines requires reliable simulation of particle sedimentation and erosion, the development of sediment prevention facilities with strong adaptability, and a comprehensive evaluation of economic and environmental benefits. With the ongoing enhancement of urbanization in developing countries, such studies will have more practical significance.