Polydisperse

Polydisperse describes a population with a broad particle‑size distribution. In filtration, polydispersity complicates operation: fines invade pore entrances and promote blocking, while coarse fractions may build a permeable skeleton. The result is a steeper ∆p rise and greater variability in clarity compared to near‑monodisperse feeds. Engineering responses include upstream classification or conditioning with coagulation/flocculation to suppress the fines tail, and media selection that balances surface retention with some depth tolerance—for example composite meshes with a fine top layer and a more open support. Control strategies may blend constant‑rate and constant‑pressure phases within a cycle to manage energy and quality. When polydispersity is unavoidable, QA should track not only D50 but also width (D90–D10) and shape metrics, and operators should expect shorter cleaning intervals or higher wash ratios to maintain stable performance.