During the entire application process of reverse osmosis devices, it is inevitable that the reverse osmosis membrane will be blocked due to unreasonable actual operation or removal. Below, the editor will take you to understand the reasons and solutions for reverse osmosis membrane blockage.

Reasons and solutions for reverse osmosis membrane blockage

1. The system configuration preparation processing equipment is not suitable for the source water body and total flow rate, or the necessary processing equipment and processing stages are not configured in the system.

2. The operation of the preparatory treatment equipment is abnormal, that is, the original preparatory treatment machine equipment of the system has a low ability to remove SDI components, turbidity, sticky substances, etc. from the source water, and the actual effect of preparatory treatment is not ideal.

3. The system has selected inappropriate machinery or equipment materials (such as pumps, pipelines, and so on).

4. Common malfunctions occur in the introduction of system chemicals into equipment, such as acid, inclined plate sedimentation tanks/coagulants, anti scaling/wetting agents, oxidants, and so on.

5. Failure to take appropriate protective measures after machine equipment interruption or system shutdown.

6. The unscientific operation and application of machinery and equipment by operational managers (utilization rate, water production, liquid extraction volume, pressure difference, cleaning, and so on).

7. Long term insoluble precipitation deposition within the membrane system.

8. The dual component transformation of source water is significant or there is a fundamental change in the characteristics of water resources.

9. The reverse osmosis membrane system has experienced a considerable degree of bacterial environmental pollution.

The main manifestations of fouling and film blockage caused by different pollutants

1. Inorganic salt scale

The main manifestation after scaling is a decrease in the amount of water infiltrated and discharged according to regulations, or a decrease in the desalination rate.

Reason: The channel effect on the surface of the membrane is enhanced. 2. Iron/Manganese

After environmental pollution, the main manifestation is an increase in standard pressure difference (which mainly occurs in the membrane components in front of the equipment), and it is also likely to cause a decrease in water permeability. Usually, manganese and iron are present simultaneously. 3. Potassium thiocyanate scale

If accumulation occurs, it will first harm the membrane components of the system with the highest salt content, mainly manifested as a significant increase in the second stage pressure difference. Special cleaning agents must be used.

4. Silicon

Particle silicon: fouling and blocking the flow safety channel of membrane components, causing an increase in system pressure difference. It is reasonable to choose 0.4% dichloramine for the treatment of heavily polluted silica scale during melting.

Silicone: Similar to particulate silicon.

Dissolved silicon: To produce silicate materials for precipitation, dichloramine should be used for cleaning.

5. Suspended solids/organic compounds

The main manifestation of pollution blockage is a decrease in water permeability and a significant increase in pressure difference in a certain section. If the SDI of water supply and drainage exceeds 4 or the turbidity exceeds 1, the possibility of organic compound environmental pollution is relatively high.

6. Microbial strains

The main manifestation of pollution blockage is an increase in standard pressure difference or a decrease in standard permeability. Non reducing pesticide fungicides can be added with alkali for cleaning.

7. Iron bacteria

The main manifestation of pollution blockage is the increase in standard pressure difference. EDTA acetate and alkali can be used for cleaning.

When the following situations occur, the film should be cleaned

1. The standardized production of machinery and equipment has decreased by 10-15%;

2. The operating pressure of the standardized membrane system has increased by 15%;

3. The salt transmittance of the standardized membrane system has increased by 10-15% compared to the original standard value;

4. The operating pressure difference has increased by 15% compared to the original operation.

Cleaning methods for reverse osmosis membranes

1. Negative pressure cleaning: Negative pressure cleaning can be said to be based on the working pressure generated on the side of the reverse osmosis membrane by the vacuum pump of the machine equipment, which can reasonably remove pollutants on the surface and inside of the membrane;

2. Backwashing force: Backwashing is the use of ultra strong air or liquid to clean the surface of the membrane, in order to remove pollutants inside the membrane and make the membrane repair clean. Backwashing force is currently one of the common methods for cleaning reverse osmosis membranes;

3. Organic chemical cleaning: The method of chemical cleaning is to use organic chemical cleaning agents to clean the reverse osmosis membrane, as purposeful cleaning with organic chemicals can also reasonably clean the membrane. This type of method is also one of the common cleaning methods.

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