An intermediate process between Ultrafiltration (UF) and RO, often called "membrane softening". It operates at lower pressures, allowing some monovalent ions (e.g., sodium, chloride) to pass while effectively removing multivalent ions (e.g., calcium, magnesium) and larger organic molecules. Key Performance Factors
Fouling, or the accumulation of contaminants on the membrane surface, is the "Achilles' heel" of these systems, requiring robust pre-treatment (e.g., UF, chlorination, pH adjustment). Reverse Osmosis and Nanofiltration
Uses dense, high-pressure membranes to reject almost all dissolved salts (monovalent/divalent), organic compounds, and microorganisms (>99% rejection). It is the standard for seawater/brackish water desalination. An intermediate process between Ultrafiltration (UF) and RO,
Recent advancements focus on lowering operating pressures and improving pressure recovery devices (PRDs) to reduce energy consumption. allowing some monovalent ions (e.g.
