Characteristics of Severe Pollution of Reverse Osmosis Membrane and Offline Cleaning

In the design of reverse osmosis systems, there is a certain degree of redundancy to ensure that in emergency situations, water supply is not insufficient due to a decrease in water production or desalination rate of the reverse osmosis system, or an increase in pressure difference of the reverse osmosis system, which poses a threat to safety production. However, in reality, it is precisely the existence of these redundancy that sometimes hidden faults cannot be displayed in a timely manner, This may eventually evolve into severe contamination of reverse osmosis membrane components.

1. The concept of severe pollution in reverse osmosis membrane components

The suspended solids, colloids, organic matter, microorganisms, and other particles contained in the influent of the reverse osmosis system can cause surface adhesion, deposition pollution to the RO membrane, or the chemical ion components in the water can cause ion accumulation on the membrane surface due to concentration polarization, which is greater than the formation of chemical scale after solubility accumulation. Severe pollution refers to situations where the pressure difference in a single section after pollution is greater than twice the pressure difference in the initial stage of system operation, the water production of the reverse osmosis system decreases by more than 30%, or the weight of a single reverse osmosis membrane element exceeds the normal value by more than 3 kilograms.

2. Offline cleaning requirements for heavily polluted RO membranes

When the following situations occur, it is necessary to perform offline cleaning of heavily contaminated RO membrane components:

(1) The pollution of reverse osmosis membrane components meets the "severe pollution" standard;

(2) The reverse osmosis system cannot meet the rated standard of the system through online cleaning;

(3) The reverse osmosis water treatment system is unable to perform online cleaning or lacks online cleaning equipment due to tight water supply;

(4) The types of reverse osmosis pollution are relatively complex, and online cleaning can easily cause cross contamination; (Cross contamination refers to the possibility that pollutants in the front section of the reverse osmosis system may be introduced into the back section of the system through online cleaning, causing contamination of the membrane components in the back section.);

(5) The reverse osmosis system has been repeatedly contaminated after multiple cleaning cycles.

3. Offline cleaning methods and steps for reverse osmosis membrane components

1) Firstly, replace the membrane components to be cleaned on the reverse osmosis system with high-performance backup membrane components to ensure that the reverse osmosis system does not stop running and the continuous stability of the entire production process.

2) Performance testing of reverse osmosis membrane components (this step is particularly important):

Test each membrane component separately for its various performance indicators, including desalination rate, water yield, pressure difference, weight, etc., and keep records before testing.

Desalination rate, water yield, and pressure difference test conditions: meet the standards provided by different types of membrane manufacturers.

3) Understand the current operating status of the system before cleaning;

4) Collect various parameter indicators of the reverse osmosis system and make original records;

5) Determine the cleaning process based on the complete analysis report of the user's raw water, performance test results, and the known system information;

6) Identification of pollutants. Firstly, based on the analysis results of 5), a preliminary judgment is made, and then further verification is conducted using special equipment and tools to determine the specific type of pollutant.

7) Based on the analysis results of 5) and 6), determine the required cleaning formula. After determining the pollutants on the RO membrane, we can choose a series of formulas provided by the membrane manufacturer and choose one or two more suitable formulas; Alternatively, choose a special formula (when the RO membrane is contaminated with special pollutants, using a regular formula may not be effective, or when compared from an economic perspective, a special formula may be more economical). At present, there are many special cleaning agents for reverse osmosis membrane elements at home and abroad, such as KY series cleaning agents and bactericides of Kaiyuan Hengye. According to the author's experience, the use effect is good, and compared with traditional agents, the economy is also good.

8) Conduct experimental cleaning using the above cleaning agents combined with physical treatment cleaning methods on reverse osmosis dedicated cleaning equipment to select appropriate cleaning formulas and procedures;

9) Determine the cleaning method and treat all membrane components mentioned above;

10) Enter the cleaned membrane components into the testing platform for testing and record them. If they do not meet the requirements, they will be sent back to the cleaning equipment for processing;

11) Organize cleaning data and write a cleaning summary report.

The importance of offline cleaning of membrane components in reverse osmosis pure water equipment

In the current cleaning of reverse osmosis membrane components, offline cleaning has been accepted by a large number of reverse osmosis users as an effective means to completely eliminate the pollution of reverse osmosis membrane components, and is becoming an increasingly important cleaning method for reverse osmosis membrane components.

But more and more homeowners are also adding some confusion:

1. During the off-line cleaning of reverse osmosis membrane elements, the water treatment system must stop or operate intermittently, which is often difficult for industrial enterprises to do, and even if it is done, it is also done under the condition of affecting normal production, which brings considerable hidden dangers to enterprise profits and safety production;

2. Due to the lack of backup membrane components and the need to accelerate cleaning progress, the cleaning effect of membrane components cannot fully meet the requirements, and the potential pollution hazard still exists;

3. The system after offline cleaning had good operating parameters during the initial installation stage, but the pollution causes and solutions found during the cleaning process were not fully verified, and pollution often followed. Even after signing the relevant content on the warranty period, the reverse osmosis system soon entered the cycle of pollution - cleaning - pollution, which led to a shorter service life of membrane components. However, due to various other reasons, the interests of the owner may not be guaranteed.

Membrane components for reverse osmosis pure water equipment have emerged in the early stages of offline cleaning, and their excellent performance has enabled backup membrane components to have the same ability as new membranes. During the use of backup membranes:

1. Effectively take measures to address and verify the problems found during the cleaning process;

2. Some measures used for RO pre-treatment may not be appropriate and may cause damage to membrane components. However, as it is a backup membrane component (old membrane), the potential losses may be relatively small, which is beneficial for both Party A and Party B;

3. After taking effective measures to solve the problem, it needs a period of observation of operating parameters to prove whether the measures taken for the problems found by the expedition are appropriate and can ensure the long-term stable operation of the system. With first-hand data, the pollution problem after cleaning is not a problem, nor is it comparable to a text on paper.

In the pollution control of reverse osmosis, the fundamental measures lie in the design, manufacturing and installation process of the water treatment system centered on reverse osmosis, the selection of various consumables for the reverse osmosis system, and the control of operational management level. A good grasp of these aspects plays a crucial role in the safe and healthy operation of the reverse osmosis system.

Of course, when serious pollution occurs in the reverse osmosis system, the first measure to be taken must be to analyze the causes of pollution, find solutions to pollution, and clean the reverse osmosis system in a short period of time through appropriate channels, because as time goes on, it means that the difficulty of cleaning increases.

Introduction to RO reverse osmosis membrane products

Reverse osmosis membrane is a fine membrane separation product that can intercept substances greater than 0.0001 microns. It can effectively intercept all dissolved salts and organic matter with a molecular weight greater than 100, while allowing water molecules to pass through. Reverse osmosis membrane material: polyamide, unique composite membrane.

The above is what Hongjie Water brings to everyone about the characteristics of severe pollution of reverse osmosis membranes and offline cleaning. We hope it can help you!