Numerical modeling of fluid–structure interaction between sewage water flow and bar screen to improve the screening process

Abstract

A self‐cleaning bar screen is often used in the first filtration level of a wastewater treatment plant to screen out solid debris from sewage water. The screening process of the bar screen was numerically investigated using the arbitrary Lagrangian–Eulerian method to model the fluid–structure interaction between the sewage water and bar screen. The bar screen design is improved by installing a rotating subscreen under the bar screen to prevent solid waste from passing through. The effects of bar screen on the water flow were examined using hydrodynamic properties. The structural properties were estimated to observe the effects of water flow on the parts of the bar screen. Various inlet flow rates and positions of subscreen and rake were used to examine their effects on velocity, pressure coefficient, structural deformation and von Mises stress. The screening process decreased with the increase in sewage flow rates. The water flow significantly affected the bar screen when the subscreen and rake are not in contact.

Sizing and Structural Analysis of Mechanical Bar Screen

“…Similarly, Schalko & Weitbrecht (2022) used mathematical modelling for optimal design of bar screen used for removing sediments as well as large pieces of wood during floods. Ali et al (2019) carried out a detailed study for the removal of residues in wastewater and provided a mathematical model which illustrates the relationship between water and solids. This study addressed the design of bar screens by obtaining hydrodynamic solutions for water flow, and structural analysis of the rake system used for solids drainage according to Von-mises yield criteria.…”

Hydrostructural Phenomena in a Wastewater Screening Channel with an Ascendable Sub-Screen Using the Arbitrary Lagrangian–Eulerian Approach

“…Such solid waste may be discarded or submitted to a sedimentation process at the beginning of the WTP [4][5][6]. A rake system may also be used to remove the solid waste that has accumulated on the bar screen [7]. A front screen, which is commonly known as sub-screen, is occasionally designed to catch large chunks of debris to avoid overloading the main screen.…”

“…Ali et al used the ALE approach to model and solve fluid flow due to the screening mechanism. The authors considered a 2D model comprising a novel rotating sub-screen and the rake [7]. The main screen was ignored due to computational limitations.…”

“…It is noted that the study of Ali et al [7] possesses certain limitations, mainly due to its focus on 2D analysis. Since their analysis is 2D, the flow impingement in their study is considered on a single bar within the sub-screen and a single rake pin within the rake assembly.…”

“…The collective contribution of the multiple sub-screen bars or the rake pins pertaining to the 3D geometry could not be considered in their study. Moreover, the study by Ali et al [7] presumed plane stress conditions due to its 2D nature. In contrast, a 3D analysis would account for the full geometric complexity of the structure, particularly in regions with significant stress gradients.…”