Effective cleaning of ultrafiltration(UF) membrane modules is crucial for maintaining their performance and extending their service life.

I. When to Clean?
Cleaning should be initiated immediately when the transmembrane pressure (TMP) of the ultrafiltration (UF) membrane module consistently exceeds 0.1 MPa, or when the normalized water production capacity declines by 50-60%. Cleaning is also essential during planned maintenance or before a prolonged system shutdown to protect the ultrafiltration (UF)  membrane module.

II. How to Clean?
Step 1: Routine Physical Cleaning
1.Backwash: Perform automatically every 30-60 minutes. Use ultrafiltration permeate to backflush the ultrafiltration (UF)  membrane module for 30-60 seconds.
2.Forward Flush: Conduct after backwashing and before/after chemical cleaning. Flush the membrane module in the forward direction at twice the operational feed flow rate for 1-2 minutes.
3.Air-Scour Wash: For severe fouling, introduce oil-free compressed air into the ultrafiltration (UF)  membrane module for combined air-water scrubbing.
Step 2: Restorative Chemical Cleaning
1.Alkaline Cleaning (for organic/biofouling removal):
Solution: 0.1-0.5% NaOH + 0.05-0.2% NaClO (based on active chlorine), pH=11-12.
Conditions: 25-40°C. Perform recirculation + soaking for 2-4 hours.
2.Acidic Cleaning (for inorganic scale/metal oxide removal):
Solution: 1-2% Citric Acid or 0.1-0.4% HCl, pH=2-3.
Conditions: 25-35°C. Recirculate for 1-2 hours.

III. Key Points
Sequence: Always perform physical cleaning before chemical cleaning. For complex fouling, typically apply alkaline cleaning first, followed by acidic cleaning.
Rinsing: The membrane module must be thoroughly rinsed to neutral pH (influent vs. effluent) before and after any chemical cleaning.
Safety: Wear appropriate personal protective equipment (PPE). Always add acid to water slowly when preparing cleaning solutions.
Documentation: Record all cleaning parameters and results to optimize future cleaning protocols.

IV. Enhanced Methods
For severe or specific fouling, consider adding the following to the main cleaning agent:

Surfactants (e.g., SDS) to enhance oil removal and wettability.

Chelating Agents (e.g., EDTA) to address colloidal silica or hardness scales.

Enzymatic Cleaners to break down biological macromolecules like proteins and polysaccharides.