How to judge the contamination of membrane elements? How to solve the heavy pollution of membrane elements?

1. The concept of heavy pollution of reverse osmosis membrane elements

Suspended solids, colloids, organic matter, microorganisms and other particles contained in the inlet water of the reverse osmosis system attach to the RO membrane surface, deposit pollution, or the ion accumulation of chemical ion components on the membrane surface due to concentration polarization and other factors. Phenomenon such as the formation of chemical scales after the solubility product is larger. Severe pollution means that the single-stage pressure difference after pollution is more than 2 times the single-stage pressure difference value at the initial stage of system operation, the water production of the reverse osmosis system has dropped by more than 30%, or the weight of a single reverse osmosis membrane element exceeds the normal value by more than 3 kg. Happening.

2. Causes and characteristics of heavy pollution of reverse osmosis membrane elements

Although the design of the reverse osmosis system will have a certain degree of surplus to ensure that in an emergency, the water production or desalination rate of the reverse osmosis system will not be reduced, and the pressure difference of the reverse osmosis system will increase, resulting in insufficient water supply and causing safety in production. Threats, but in fact, it is precisely because of the existence of these surpluses that sometimes hidden faults cannot be manifested in time, which may eventually evolve into heavy pollution of reverse osmosis membrane elements.

3. Offline cleaning methods and steps of reverse osmosis membrane elements

  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 to ensure the continuous stability of the entire production process.
  2. Performance test of reverse osmosis membrane elements:
    Test each membrane element individually for its performance indicators, including: desalination rate, water production, pressure difference, weight, etc., and record the desalination rate, water production and pressure difference before testing. Test conditions: meet different types of membrane manufacturers Provided standards.
  3. Know the current operating status of the system before cleaning the system;
  4. Collect each parameter index of the reverse osmosis system and make original records;
  5. Judging the cleaning process based on the user’s raw water analysis report, performance test results, and system information learned;
  6. Identification of pollutants. First, make a preliminary judgment based on the analysis result of 3.5, and then use special equipment and appliances for
  7. According to the analysis results of 3.5 and 3.6, determine the required cleaning formula. When the contaminants on the RO membrane are determined, we can choose a series of formulas provided by the membrane manufacturer, and choose one or two more suitable formulas; or select a special formula (when the RO membrane is contaminated by special contaminants, use ordinary The effect of the formula is not good, or from an economic point of view, the special formula is more economical). At present, there are many special agents for cleaning reverse osmosis membrane elements at home and abroad.
  8. Use the above cleaning agents combined with physical treatment cleaning methods on the reverse osmosis special cleaning equipment to conduct experimental cleaning to select the appropriate cleaning formula and cleaning procedure;
  9. Determine the cleaning method and process all the above membrane elements;
  10. The cleaned membrane elements will enter the test platform for testing and record. Those that do not meet the requirements will be sent back to the cleaning equipment for processing;
  11. Organize cleaning data and write a cleaning summary report.

In the pollution control of reverse osmosis, the most fundamental measures are the control of the design, manufacturing and installation process of the water treatment system with reverse osmosis as the core, the selection of various consumables of the reverse osmosis system, and the control of operation management level. A good grasp of these aspects plays a vital role in the safe and healthy operation of the reverse osmosis system.

Of course, when the reverse osmosis system is seriously polluted, the first measure to be taken must be to analyze the cause of the pollution, find a solution to the pollution, and clean the reverse osmosis system in the shortest possible time through appropriate means, because with time The extension means that the difficulty of cleaning is reduced.

As a deep filtration means, reverse osmosis membrane elements will inevitably leave colloids, microorganisms, impurity particles and insoluble salts on the surface. Therefore, reverse osmosis devices used in various fields will inevitably be put into use. , In the end all need to be cleaned, but the length of the cleaning cycle is different. However, as a means of reverse osmosis system cleaning and maintenance, impact sterilization and regular protection, on-line cleaning is powerless when faced with heavy pollution of reverse osmosis membrane elements. At this time, off-line cleaning of reverse osmosis membrane elements is required.

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