Separation of organic matter and grit in sludge is essential for effective sludge recycling. However, the high viscosity and fine particles of sludge cause organic matter to adhere to grit surfaces, making separation challenging. To address this issue, we propose a novel prismatic hydrocyclone that generates intense turbulent flows, under strong turbulence, the prism boundary layer's "elutriation" enhances particle separation, increasing particle looseness and improving grit removal efficiency in sludge. This study compares the separation performance of the prismatic hydrocyclone with that of a conventional hydrocyclone using numerical simulations. We also investigate how the number of prism edges affects flow field characteristics and separation performance. The results show that, unlike conventional hydrocyclone, prismatic hydrocyclones generally maintain lower static pressure, pressure drop, and the diameter of the air core, indicating lower energy consumption and higher processing capacity. When the number of edges is 6, the pressure drop is the most reduced compared to the conventional hydrocyclone, which is 22.17%. Under similar feed velocity, the centrifugal intensity in prismatic hydrocyclones is reduced compared to conventional hydrocyclone, lower centrifugal forces mitigate the risk of fine particles moving toward the wall under high-speed conditions. Meanwhile, turbulence intensity beneath the vortex finder decreases, which signifies the flow field is more stable, and grit removal efficiency in sludge is improved.