Reasons for the rapid decline in desalination rate of reverse osmosis membrane-Hezhong Environment (Beijing) Co., Ltd. was established in 2003

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Reasons for the rapid decline in desalination rate of reverse osmosis membrane

Published Time:

2023-08-29

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Reverse osmosis membranes currently have very small pore sizes, effectively removing dissolved salts, colloids, microorganisms, and organic matter from water. They offer advantages such as high water quality, low energy consumption, no pollution, simple processes, and easy operation, making them widely used in industrial production and other fields. However, many users encounter problems during use, such as a rapid decrease in desalination rate.

No.1

High Pressure Difference Leading to Desalination Rate Decrease

An increase in pressure difference is often accompanied by a rapid decrease in desalination rate. Under normal flow rates, a rise in pressure difference is usually caused by impurities, pollutants, and scale entering the water flow channels of the membrane elements, leading to a decrease in water production. Excessive pressure difference can also occur when the feed water flow rate exceeds the set value, or when the feed water pressure increases too quickly at startup, causing a large water hammer pressure difference. If the membrane is already polluted, especially by microorganisms, the pressure difference will also increase. The pressure difference between feed water and concentrate represents hydraulic resistance and is related to the flow rate and temperature of the feed water. A certain flow rate for both product water and concentrate should be maintained.

No.2

Unreasonable Online Chemical Cleaning Leading to Desalination Rate Decrease

Pretreatment and the addition of various chemicals can only minimize the possibility of reverse osmosis membrane pollution, but cannot completely eliminate it. Therefore, after a certain period of operation, a long-term running reverse osmosis system requires thorough investigation and confirmation of the type of pollutant.

No.3

Poor Control of Residual Chlorine Leading to Desalination Rate Decrease

To prevent microbial contamination of reverse osmosis, chlorination treatment is required for the feed water. Residual chlorine is measured using a colorimeter. The mass concentration of residual chlorine is generally controlled at 0.5 mg/L at the inlet of the sand filter, not less than 0.3 mg/L, and should be less than 0.1 mg/L at the pre-reverse osmosis security filter. A prominent issue with polyamide membranes is preventing oxidation. Feed water residual chlorine and strong oxidants have adverse effects and must be strictly controlled. Therefore, regular testing of the residual chlorine in the reverse osmosis feed water is crucial.