1. Decreased water yield

Membrane fouling: Particles deposited in the first section of the membrane, scaling in the last section, or the entire system is clogged. - Low inlet water temperature: For every 3°C decrease in inlet water temperature, water yield decreases by approximately 10%. - Increased inlet water conductivity: High conductivity increases osmotic pressure, leading to a decrease in water yield. - Improper system design: Improper pressure setting on the permeate side or improper piping design can lead to a decrease in net pressure. - Aging or damage to the membrane element: Membrane element flux decreases or mechanical damage requires replacement.

2. Reduced Salt Rejection Rate

Membrane fouling: Microbial and natural organic matter contamination may lead to reduced salt rejection. - Chemical damage: Oxidants damage the membrane, resulting in reduced salt rejection. - Instrument reading errors: Uncalibrated conductivity meters can result in lower calculated salt rejection.

3. Increased Pressure Drop

Improper piping design: This can lead to significant pressure drop. - Pretreatment system issues: These may include insufficient flocculant dosage, excessive loading on the multi-media and activated carbon filters, etc.

4. Other Common Problems

Improper system maintenance: Such as improper shutdown protection, incorrect acid or antiscalant dosage, etc. - Instrument calibration issues: Pressure gauges, flow meters, etc. are out of calibration, resulting in inaccurate readings.