How to protect the reverse osmosis membrane during system operation?
Preprocessing is done; operational details during operation are more critical—many membrane damages result from "human errors," such as sudden pressure increases or excessively high recovery rates. Remember these four key points:
- Slow pressure rise: The rate should be ≤0.07 MPa/min. When starting the system, avoid suddenly opening the valve! A rapid pressure increase can cause shock to the membrane elements, leading to misalignment of the membrane fibers and cracking of the sealing adhesive. The correct approach is to gradually open the feed water valve, allowing the pressure to rise slowly to the set value.
- Control Recovery Rate: For single module ≤15%, system ≤85%. The higher the recovery rate, the higher the pollutant concentration on the concentrated side, increasing the likelihood of scaling. For example, if the single module recovery rate exceeds 15%, the salt concentration on the concentrated side will double, quickly forming scale that blocks the membrane pores. Adjust the system recovery rate based on water quality; for high-salinity water, it is recommended to reduce it appropriately.
- Timely Cleaning: If three warning signs appear, it's time to clean. The membrane is not "maintenance-free." Once contamination reaches a certain level, cleaning is necessary to avoid a vicious cycle
The production water volume decreases by more than 10% from the initial value
The TDS of the produced water increased by more than 15% compared to the initial value
The pressure differential across the membrane increases by more than 15% compared to the initial value. Cleaning must be performed in sequence: first alkaline cleaning (to remove organic matter and colloids), followed by acid cleaning (to remove calcium-magnesium scale and metal oxides). Use specialized cleaning agents and avoid strong acids or alkalis to prevent residual damage to the membrane.
- Real-time Monitoring: Closely track three key data points—daily recording of feed water pressure, product water TDS, and concentrate flow rate. If any abnormalities arise (such as a sudden TDS spike), promptly investigate the cause to prevent minor issues from escalating into major malfunctions.