The current design of integrated wastewater treatment equipment features a smooth deflector plate that, while capable of guiding water flow to some degree, suffers from significant flow disturbances at its junctions. This leads to localized low flow rates, the development of circulating vortices, and an uneven flow distribution, which can result in sludge reflux and deposition—conditions detrimental to the efficient circulation of mixed liquids. To mitigate these issues, we propose a biomimetic approach inspired by the convex knot structure found at the leading edge of the humpback whale’s pectoral fin. By constructing a three-dimensional computational fluid dynamics (CFD) model incorporating this biomimetic structure, we conducted comparative analyses that revealed a more stable internal flow field and enhanced uniformity in liquid mixing. The biomimetic model demonstrated superior vortex suppression capabilities, effectively minimizing sludge reflux and deposition. These findings underscore the potential for practical application in optimizing the operational efficacy of integrated wastewater treatment systems through advanced numerical simulations.