Do RO Membranes Need to Be Preserved When Taken Off Line

16 Do RO Membranes Need to be Preserved When Taken Off Line  

when membranes come off line, they should be flushed with either permeate water or low-pressure feed water (see Chapter 13.1.1). This will reduce the concentration of ions and any suspended solids on the feed side of the membrane, thereby minimizing the potential for fouling or scaling the membrane while idle. The next step(s) depends on how long the membranes will be off line. 

All air should be vented from the system while flushing. This can be accomplished by overflowing the flushing solution through the utmost point of the highest pressure vessel, o Once the vessels are filled, all valves should be closed to prevent air from entering the membranes. 

These steps should be repeated every 5 days. (2) 

0 Circulate a 1 to 1.5% solution of sodium metabisulfite through the membranes, completely filling the pressure vessels. To ensure that the vessel are completely filled, the solution should be allowed to overflow through an opening located at the utmost point of the highest pressure vessel being filled. 

During long-term in situ storage, the following precautions should be taken  

Short-term idhng Short-term idhng includes membranes that are off line for no more than 48 hotus. An automatic flush event should occur at least once every 24 hours (more frequently in warm weather). No other steps need to be taken to preserve the membranes. 

This can be accomplished by overflowing the flushing solution through the utmost point of the highest pressure vessel. 

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