Three Indications of Fouling
- Permeate Rate
- Final pressure
Knowing the nature of the membrane foulants is necessary to select cleaners. Foulants are typically mixtures of two or more of the following: scale, organic debris, metal hydroxides, bacteria, colloids, and chemical properties.
Determining When to Clean
Cleaning is recommended when: there is a 10%-15% decrease in normalized permeate flow, a 10% increase in salt passage, or a 10% to 15% increase in differential pressure across all or part of the RO system
Heat cleaning solutions to the maximum temperature allowed by the membrane manufacturers cleaning guideline. Always use recommended flow rates per vessel; even if it means cleaning fewer vessels at a time. Make sure to use at least a 10 micron pre or post filter on the cleaning system. Higher pressure will cause increased permeate flow and hold foulant to the surface of the membrane.