Analysis of the Hydrodynamic Characteristics in a Rectangular Clarifier under Earthquake-Induced Sloshing

Wastewater treatment plants, which play a crucial role in protecting the hydrosphere, are earthquake-prone infrastructures with large tanks and sensitive equipment. Damage to the structures in such facilities during seismic activity on the lithosphere can cause environmental pollution and threaten public health. Since the units/tanks in the treatment plants are not of different geometries and sizes, they may exceed the freeboard of the wave height due to the sloshing event. In this study, the sloshing dynamics of a rectangular type of clarifier were investigated. First, numerical parameters, boundaries, and initial conditions were validated using the results of an experimental campaign. Secondly, model conditions were kept constant, and geometry was enlarged (i.e., scaled-up) to investigate the variation of hydrodynamic forces near vulnerable equipment (such as scrapers and weirs) in clarifier. The numerical model was run for characteristics of two different earthquakes (i.e., Chi Chi -1999 and Kocaeli-1999). The results showed that dynamic pressure values near vulnerable equipment increased up to 120 times higher than the operating conditions. The maximum sloshing wave heights were calculated as 1.2 m and 1.45 m for Chi Chi (1999) and Kocaeli (1999) earthquakes, respectively.