Jan 01, 2010 · There are four major pressure-driven membrane processes that can be divided by the pore sizes of membranes and the required transmembrane pressure (TMP): MF (0.1–5 μm, 1–10 bar), UF (500–100,000 Da, 1–100 nm, 1–10 bar), NF (100–500 Da, 0.5–10 nm, 10–30 bar), and RO (<0.5 nm, 35–100 bar). Figure 1.2 presents a classification