Desalination Rate
Desalination Rate = (1 – Permeate Salt Content / Feed Salt Content) × 100% The desalination rate of a membrane element is determined during its manufacturing process. The level of desalination rate depends on the density of the ultra-thin desalination layer on the membrane element surface; the denser the desalination layer, the higher the desalination rate, but the lower the permeate flow. The desalination rate of reverse osmosis for different substances is mainly determined by the structure and molecular weight of the substance. The desalination rate for high-valence ions and complex monovalent ions can exceed 99%. The desalination rate for monovalent ions such as sodium, potassium, and chloride ions is slightly lower, but can still exceed 98% (the longer the membrane is used and the more chemical cleaning is performed, the lower the desalination rate of the reverse osmosis membrane). The removal rate for organic matter with a molecular weight greater than 100 can also exceed 98%, but the removal rate for organic matter with a molecular weight less than 100 is lower.
Permeation Rate
Water Flux – refers to the permeate flow capacity of a reverse osmosis system, that is, the amount of water permeating through the membrane per unit time, usually expressed in tons/hour or gallons/day.
Salt permeation rate – The amount of salt that permeates per unit time and per unit membrane area; also called salt flux or salt permeability.
Recovery rate
Recovery rate – The percentage of feed water converted into product water or permeate in a membrane system. It depends on the quality of the pretreated feed water and water usage requirements. The recovery rate of the membrane system is determined during the design phase.
Recovery rate = (Product water flow rate / Feed water flow rate) × 100%