Backwashing is a critical step in the maintenance of water treatment equipment,wahich can effectively remove pollutants
from the membrane surface and filter media, prevent blockages and performance degradation, and thus extend equipment life. The following are specific methods and precautions:
1. The function of backwashing
Removing pollutants: Reverse water flow washes away particles, colloids, organic matter, and microorganisms accumulated on the membrane or filter material.
Restore flux: alleviate membrane fouling and scaling, and maintain stable water production efficiency.
Reduce the frequency of chemical cleaning: Reduce the chemical damage to the membrane caused by strong acid-base cleaning.
2. Applicable equipment types
Reverse osmosis (RO) system: Regular cleaning is required, but RO membranes are usually cleaned chemically (CIP), and backwashing is more commonly used in pre-treatment processes (such as multi-media filters, ultrafiltration UF).
Ultrafiltration (UF)/Microfiltration (MF) systems: often equipped with automatic backwash function.
Sand filter/activated carbon filter: The filter bed is expanded by reverse water flow to remove trapped impurities.
4. Techniques for optimizing the backwash effect
Air Scouring: Injecting compressed air during backwashing to enhance pollutant stripping efficiency (applicable to MBR and UF systems).
Chemical Enhanced Backwash (CEB): Regularly add low concentration agents (such as sodium hypochlorite, citric acid) to the backwash water.
Monitoring pressure difference (Δ P): When the inlet and outlet pressure difference of the filter or membrane component increases by 10% to 15%, backwashing needs to be triggered.
5. Precautions
Avoid excessive backwashing: High frequency or high-pressure backwashing may damage the membrane fibers or filter material structure.
Pre treatment guarantee: Ensure that the influent SDI (pollution index) is less than 5, reducing the risk of membrane fouling.
Record data: track flow and pressure changes before and after backwashing, optimize cycle settings.
6. Other maintenance suggestions
Regular Chemical Cleaning (CIP): When backwashing fails to restore performance, use specialized cleaning agents (such as pH2 acid cleaning to remove scale, pH12 alkali cleaning to remove organic matter).
Replace consumables: Security filter cartridges, activated carbon, etc. need to be replaced periodically.
Through scientific backwashing and comprehensive maintenance, the lifespan of RO/UF and other equipment can be extended by 30% to 50%, reducing operating costs.
Post time: Apr-12-2025