How to judge the good and bad of reverse osmosis membrane?

How to judge the good and bad of reverse osmosis membrane?

Generally speaking, the main indicators to measure the performance of reverse osmosis membrane recovery rate, water production and flux, desalination rate of three indicators.

Reverse osmosis membrane performance indicators: recovery rate

Recovery rate is an important indicator of reverse osmosis membrane elements or reverse osmosis system energy efficiency, used to indicate how much of the incoming water into the membrane element has become product water, expressed in the formula: Recovery rate = product water flow (purified water out of the water) ÷ incoming water flow

Reverse osmosis membrane performance indicators: water production and its flux

Water production is expressed in a certain pressure conditions of reverse osmosis membrane, how much volume of pure water produced per unit of time indicators. Under certain pressure conditions, the reverse osmosis membrane produces the volume of pure water per unit of time. Measurement unit common to GPD (gallons per day), LPH (liters per hour). Flux refers to the unit area of the reverse osmosis membrane in the unit of time can produce the volume of water how much, usually with gallons / square feet × day (GFD and cubic meters / square meter × day to express. Membrane element water production = flux x effective membrane area.

Reverse Osmosis Membrane Performance Indicator III: Desalination Rate

Desalination rate is an indication of the ability of a reverse osmosis membrane to remove impurities from water. Generally speaking the removal rate of reverse osmosis membrane on the relevant impurities can be expressed as follows: reverse osmosis membrane elements of different substances have different removal rates, in general there are the following laws: 1. the removal rate of multivalent ions is higher than the monovalent ions; the removal rate of complex ions is higher than the simple ions; the molecular weight of 100 or less of the removal rate of the organic matter is lower; the nitrogen group of elements and their compounds have a lower rate of removal. 2. the desalination rate performance Apparent desalination rate and actual desalination rate. Apparent desalination rate = 1 - produced water salinity / influent salinity actual desalination rate = 1-2 × produced water salinity / (influent salinity + wastewater salinity) ÷ 2 × A, where A represents the concentration polarization coefficient (generally between 1.1-1.2).