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RO/NF Service Bulletin – Cleaning Procedure

RO Membrane Element Cleaning and Flushing Procedures

  1. Low-Pressure Flush
    • Perform a low-pressure flush at 60 psi (4 bar) or less with clean water from the cleaning tank for several minutes to displace feed/brine solution from RO membranes. Use clean water of RO permeate or DI quality, free of hardness, transition metals, and chlorine. Flushing flow rates should normally be half of the cleaning flow rates.
  2. Mix Cleaning Solution
    • Mix a fresh batch of the selected cleaning solution in the cleaning tank using clean water of RO permeate or DI quality, free of hardness, transition metals, and chlorine. Adjust temperature and pH to target levels. Record conductivity, turbidity, and iron concentration of the freshly prepared solution.
  3. Circulate Cleaning Solution
    • Circulate the solution through the pressure tubes. Start by sending displaced water to drain to avoid diluting the cleaning chemical, then divert up to 20% of the fouled cleaning solution to drain before returning it to the cleaning tank. Gradually increase the flow rate: first to 1/3, then to 2/3, and finally to the maximum design flow rate. Maintain temperature and adjust pH if needed. Drain and replace the solution if conductivity, turbidity, and iron content increase significantly.
  4. Soak and Recirculation
    • Optionally, use a soak and recirculation sequence: 30 minutes of circulation followed by 30 minutes of soaking. Maintain proper temperature and pH during the cycle.
  5. Chemical Cleaning Steps
    • Perform a low-pressure cleaning rinse with clean water to remove all traces of chemicals from the cleaning skid and RO skid. Drain and flush the cleaning tank, then refill with clean water for the rinse. Rinse the pressure tubes by pumping all rinse water through them to drain. Repeat the cleaning if necessary.
  6. Final Low-Pressure Flush
    • Use pretreated feed water for a final flush, keeping the permeate line open to drain. Feed pressure should be less than 60 psi (4 bar). Continue until flush water flows clean and free of residues. Check for detergent removal and absence of foaming using a clear flask and conductivity meter.
  7. Service Rinse
    • Once stages are cleaned and chemicals flushed out, restart the RO system and perform a service rinse. Divert RO permeate to drain until it meets quality requirements. Stabilization may take from a few hours to a few days.

By following these procedures, the RO membranes can be effectively cleaned and maintained, ensuring optimal performance and longevity.

Cleaner for Mineral Scale – Non-hazmat formulation

Cleaner for Organic foulants and Bio-Films – Non-hazmat formulation

Cleaner for Silica mineral fouling