A UF filter system is a membrane-based separation system. The membrane has a pore size generally in the range of 1-100 nanometers (nominal molecular weight cut-off ~1-100 kDa). This size range allows water, salts, and small dissolved molecules to pass through (the filtrate or permeate), while retaining larger particles like bacteria, viruses, protozoa, and macromolecules (the retentate or concen..