The membrane system is based on continuous operation as the design basis, but in actual operation, there will always be a certain frequency of startup and shutdown.
When the membrane system is shut down, the permeate water or pretreated water must be used for low-pressure flushing to replace the concentrated water with high concentration but containing scale inhibitor from the membrane element. Measures should also be taken to prevent water from leaking out of the system and introducing air, as there may be an irreversible loss of permeate flux if the element loses water and dries out.
If the downtime is less than 24 hours, no measures to prevent microbial growth are required. However, if the downtime exceeds the above-mentioned provisions, protective fluid should be used for system preservation or the membrane system should be flushed regularly.
