Targeted Cleaning and Maintenance Strategies for Power Plant RO Membranes Based on Water Quality Analysis

Power plants typically use surface water, groundwater, or reclaimed water - each with unique characteristics:

• Surface water: High in suspended solids, organics, and microbes.
• Groundwater: Stable but high in hardness, prone to scaling.
• Reclaimed water: Rich in ammonia nitrogen and biodegradable matter.

Key parameters include turbidity, SDI, pH, conductivity, hardness, and microbial count. For optimal performance, turbidity < 1 NTU and SDI < 5 are recommended.

1.Inorganic Scaling
Caused by calcium, magnesium, and iron ions forming CaCO₃ or CaSO₄.
→ Use acidic cleaners (citric acid or dilute HCl), maintain pH 2–4 for 1–2 hours.

2.Organic Fouling
Results from proteins, oils, and polysaccharides.
→ Use alkaline cleaners (NaOH) with surfactants at pH 10–12, 15°C for 2–3 hours.

3.Biofouling
Formed by microbial growth on membrane surfaces.
→ Disinfect with 50–200 mg/L NaOCl, followed by biological cleaners to remove residues.

Cleaning should be performed when:

• Permeate flow drops by 10–15%;
• Salt rejection decreases by over 5%;
• Pressure differential increases by 15–20%;
• SDI or turbidity shows a sharp rise.

A power plant using surface water experienced reduced output and high pressure drop after months of operation. Combined inorganic and organic fouling was diagnosed.
Cleaning method: Acid cleaning with citric acid followed by alkaline cleaning with NaOH and surfactant mixture.

Results:

Performance fully recovered, demonstrating the effectiveness of targeted cleaning.

Optimize pretreatment: Replace cartridge filters, add coagulants and biocides properly.

Control operation parameters: Maintain stable pressure and flow; flush membranes regularly.

Storage protection: Use 1–2% sodium bisulfite solution during shutdowns to prevent microbial growth.