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Hydranautics RO membrane element

Reverse osmosis membrane pollution and Special tips for reverse osmosis membrane cleaning

1. Reverse osmosis membrane membrane pollution

The reverse osmosis membrane may get contaminated by various pollutants, including suspended solids and insoluble salts such as calcium carbonate, calcium sulfate, barium sulfate, and metal oxide precipitation, among others. Contaminants could also be in the form of silicon deposits, organic and inorganic deposition mixtures, natural or synthetic organic substances like scale inhibitors/dispersants and cationic polyelectrolytes, as well as microorganisms like algae, molds, and fungi.

Pollution’s severity and development depend on factors like water quality and system recovery rate. Delayed control will damage membrane elements quickly. Cleaning them is recommended during contamination, long-term shutdowns, or routine maintenance.

When the following problems occur in the reverse osmosis system (or device), chemical cleaning or physical flushing is required:

  • Under normal water supply pressure conditions, the water production after temperature correction is 10-15% lower than the normal value;
  • In order to maintain the normal water production, the feed water pressure after temperature correction has increased by 10-15%;
  • The quality of produced water is reduced by 10-15%, and the salt permeability is increased by 10-15%;
  • Water supply pressure increased by 10-15%;
  • The pressure difference between the various sections of the system has increased significantly (there may be no instrument to monitor this parameter).

The cleaning principles can be applied even if the operating data is not standardized, as long as key parameters are not changed. Regular monitoring is important to confirm if the membrane element has been contaminated. The cleaning cycle of a contaminated membrane depends on the actual situation but is usually done once every 3-12 months. Reverse osmosis product water can be used to flush the contaminants and reduce the frequency of cleaning, and soaking membrane elements with product water can help dissolve and fall off dirt. Chemical cleaning and physical cleaning are two methods that can cooperate with each other. When it is difficult to remove contaminants by flushing, stop the device and use chemical cleaning. Before cleaning, analyze the pollution situation to determine the type of pollution and choose the right cleaning chemicals for successful cleaning.

2. Special tips for reverse osmosis membrane cleaning

This message is vitally important for anyone working with composite polyamide reverse osmosis and nanofiltration membrane elements. These filtration devices have diameters of 4, 6, 8 and 8.5 inches, making them a popular choice in many industries.

When it comes to polyamide reverse osmosis membrane elements, it is absolutely crucial to understand that these elements must never come into contact with free chlorine under any circumstances. This is because free chlorine has the potential to oxidize membrane elements, which in turn can cause irreparable damage that cannot be reversed.

Therefore, it is incredibly important to handle these membrane elements with the utmost care and attention to detail. Professionals who are responsible for maintaining and operating these devices must exercise extreme caution and always follow the manufacturer’s guidelines to ensure that the membranes remain in optimal condition, and are able to provide reliable and effective filtration results for years to come.

Check for free chlorine in the feed water of the membrane system after sterilization, cleaning and storage protection. Test if unsure and reduce free chlorine with sodium bisulfite (SBS). Add 1.8-3.0ppm SBS when free chlorine=1.0PPm. Consult Hyde Energy before cleaning reverse osmosis membranes and avoid using cationic and amphoteric surfactants as they may reduce water production irreversibly.

Xi’an CHIWATEC Water Treatment Technology provide the RO membrane to clients both inland and oversea with more than 10years experience. We manufacture our own brand Daltonen RO membrane and we are also the official distributor of Dupont, Toray, CSM, Nitto, LG and Vontron RO membrane. Whatever product you need, we cold meet your requirement.

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