Reverse osmosis membrane as a deep filtration means, its surface will inevitably residual colloids, microorganisms, impurity particles and insoluble salts on its surface precipitation. Therefore, once the reverse osmosis device is put into use, it eventually needs to be cleaned, but the length of the cleaning cycle is different. The cleaning of reverse osmosis membrane elements can be divided into two ways: online cleaning and offline cleaning. Online cleaning is a conventional cleaning method, mainly for the reverse osmosis system maintenance and maintenance. The biggest problem with online cleaning is that the concentration of the cleaning solution at the end of the cleaning direction will gradually decrease. When the reverse osmosis system runs for more than a certain period or the reverse osmosis membrane is seriously polluted, online cleaning is powerless, and it is necessary to clean the reverse osmosis membrane components offline.
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Conditions for off-line cleaning of reverse osmosis membrane:
1. When the single-stage pressure difference of the reverse osmosis system is more than 2 times of the single-stage pressure difference in the initial stage of the system operation.
2, reverse osmosis system water production decreased by more than 30%.
3, the weight of a single reverse osmosis membrane element exceeds the normal value of more than 3 kg.
4, the reverse osmosis system through online cleaning performance can not be restored.
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Features of Offline cleaning When cleaning online, the pertinency of the film in different positions is poor. Because a membrane shell is usually not a membrane element, so the pollution of these membrane elements is also different, when using the same concentration of cleaning liquid to clean the membrane of different pollution situations, it is inevitable that some membrane cleaning is excessive, and some membrane cleaning is insufficient, so the cleaning effect is poor, but also easy to form cross-contamination.
After the above reasons, I put forward the off-line cleaning method, its main characteristics are: use the spare membrane to replace the field use of reverse osmosis membrane, does not affect the user's normal production. The use of a special cleaning device for single reverse osmosis membrane cleaning, the device can be targeted to deal with different pollution conditions of the membrane, and can conveniently achieve reverse osmosis membrane positive and negative washing, with sufficient cleaning flow for a single membrane. During the cleaning process, the cleaning condition of the RO film can be monitored at any time, and the cleaning degree can be determined according to the actual situation. By analyzing the main components of the pollutants in the cleaning solution, the pollutants of the system are determined, and the corresponding system adjustment suggestions are put forward in order to extend the service life of the customer system.
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Off-line cleaning steps for reverse osmosis membranes
1. First, replace the membrane elements to be cleaned on the reverse osmosis system with spare membrane elements with excellent performance to ensure that the reverse osmosis system does not stop running and ensure the continuous stability of the entire production process.
2. Test the performance of reverse osmosis membrane components:
3. Understand the current operating status of the system before system cleaning; Collect the parameters and indexes of the reverse osmosis system and make the original records.
4. Judge the cleaning process according to the user's raw water full analysis report, performance test results and system information.
5. Identification of pollutants. First of all, according to the analysis results of 3.4, the preliminary judgment is made, and then the special equipment and appliances are further verified to determine the specific pollutant types.
6. According to the analysis results, determine the required cleaning formula and concentration.
7, in the reverse osmosis special cleaning equipment with the above cleaning agent combination treatment cleaning means for experimental cleaning, in order to choose the appropriate cleaning formula and cleaning procedures.
8, determine the cleaning method, and process all the above membrane elements.
9, the cleaned membrane elements into the test platform for testing and record, do not meet the requirements will be re-sent to the cleaning equipment for processing.
