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

Wastewater invariably accumulates soluble and insoluble waste and requires treatment at a wastewater treatment plant (WTP) to become reusable. The preliminary screening of insoluble waste occurs through a wastewater screening mechanism (WSM) before entering the WTP. The present study computationally investigates the impact of a WSM, comprising a main screen, sliding sub-screen, and rake, on channel flow distribution, deformation, and stresses. Various sub-screen configurations, fully and partially lowered, are examined. The fluid-structure interaction between sewage water and the WSM was solved using the arbitrary Lagrangian-Eulerian approach. Unlike similar studies in the past which have been conducted in 2D, the present study considers the 3D design and thus captures a greater complexity of the WSM assembly. The velocity distribution inside the channel, structural deformation, and von Mises stresses of WSM components were analyzed for a range of inlet velocities at different stages of the screening process. The results reveal that a fully lowered sub-screen with an inactive rake ensures a uniform flow through the WSM, while a partially lowered sub-screen induces persistent flow separation. Structural analysis reveals significant deformation in the upper mid-region of the sub-screen and fluctuating deformations in the rake, accompanied by elevated von Mises stresses. The study serves as a design guideline for manufacturing and operating a WSM, ensuring the prevention of unfavorable stress and deformation in the WSM and the WTP.