How to calculate the desalination rate and salt permeability of zero-emission DTRO disc-tube reverse osmosis membrane elements?

Zero-emission DTRO is a form of reverse osmosis. It is a membrane component specially used to treat high-concentration sewage. Its core technology is disc-tube membrane column. The reverse osmosis membrane and hydraulic guide plate are stacked together, fixed with a central tie rod and end plate, and then placed in a pressure-resistant casing to form a membrane column. DTRO overcomes the disadvantage that general reverse osmosis systems are prone to clogging when treating leachate, making the system more stable and lower operating costs.

The application of zero-emission DTRO disc-tube reverse osmosis membrane treatment technology in water treatment in power plants in my country has entered the stage of gradual promotion. It has the advantages of high raw water treatment quality, wide application range, economic and environmental protection, and easy maintenance and management. The application of DTRO disc-tube reverse osmosis technology can better solve various water resource problems through efficient purification of unconventional water sources. In water-scarce areas with high energy demand, DTRO disc-tube reverse osmosis technology is a general technology for solving the "water problem". It has the advantages of clean production with low land use and no other pollution, which helps to break through the ecological and environmental bottleneck for the further development of the local economy.

Desalination rate and salt permeability of zero-emission DTRO disc-tube reverse osmosis membrane elements
The principle of desalination rate is to remove the percentage of soluble impurities from the system influent through the DTRO reverse osmosis membrane. The salt permeability refers to the percentage of soluble impurities in the influent that pass through the membrane. The relationship between them is explained by the following expression:
Desalination rate = (1-salinity content of produced water/salinity content of influent) × 100%
Salt permeability = 100%-desalination rate

The desalination rate of the membrane element is determined when the membrane is manufactured. The desalination rate depends on the density of the ultra-thin desalination layer on the surface of the membrane element. The denser the desalination layer, the higher the desalination rate, and the lower the water production. The removal rate of reverse osmosis for different substances is mainly determined by the structure and molecular weight of the substances. The removal rate of high-valent ions and complex monovalent ions can exceed 98%. The removal rate of monovalent ions such as sodium ions, potassium ions, and chloride ions is lower, but it also exceeds 95%. The removal rate of organic matter with a molecular weight greater than 100 can also reach more than 98%, but the removal rate of organic matter with a molecular weight less than 100 is lower.

Storage of zero-emission DTRO disc-tube reverse osmosis membrane elements:
(1) The membrane elements are tested for water flow before leaving the factory, and are stored with 1% sodium sulfite solution, and then vacuum-packed in oxygen-isolating bags.
(2) The membrane elements must always be kept moist. Even when they need to be temporarily opened to confirm the quantity of the same package, they must be opened without damaging the plastic bag, and this state should be kept until use.
(3) The membrane elements are best stored at a low temperature of 5~10℃. When storing in an environment with a temperature exceeding 10℃, choose a well-ventilated place and avoid direct sunlight. The storage temperature should not exceed 35℃.