Research and Prevention of Harmful Gases in Special Structures of Urban Deep Drainage Systems

Wastewater remaining in pipes for extended periods can create anaerobic environments, fostering the growth of anaerobic bacteria and producing harmful gases such as methane and hydrogen sulfide. Additionally, certain structures within drainage systems, such as drop shafts and vertical shafts, induce turbulent flow, causing the release of dissolved harmful gases, which pose significant risks to public health and urban infrastructure. This study focused on the investigation and analysis of vertical shafts with helical tray structures in drainage systems. Using ANSYS 2021 R2 software, simulations of the shafts were conducted by employing the standard k-ε turbulence model and Eulerian multiphase flow method to simulate the shaft’s operation and obtain various parameters of hydrogen sulfide release. Concurrently, a scale model constructed in the laboratory was used to study and analyze the release of hydrogen sulfide gas dissolved in water from this type of structure. Combining the simulation and laboratory experiments, the hydrogen sulfide gas release rate from water in this structure was 0.05–0.4%. This research provides a reference for the study and control of hydrogen sulfide gas release.