Salt water Salinity changes in membrane technology desalination

I am working for a company who makes in membrane desalination module. When I use salt water which salinity is 35000 ppm to test the module every time, permeate salinity keep changes. I tried to back flush with distilled water in order to clean the module to remove salt deposits to the module but still I can see the variation in salinity.

Can someone suggest for me an effective way to maintain a constant permeate salinity? and also why does salinity change dramatically even after back flush with distilled water?

Much appreciated

Taxonomy

• Membranes
• Polymeric Membranes
• Membrane Technology
• Membrane Filtration
• Sea Water Desalinisation
• UF membranes/cassettes for waste water treatment MBR
• Membrane distillation

2 Answers

1. You should check if The temp of the water is always the same on each test.

   If you are using more than one membrane per vessel you should check the connectors in between or the joins/ oring in the beginning and the end of the pressure vessel

2. The salt passage is due to defects in the membrane. The salt passage depends on Feed temperature, Feed TDS, and Recovery %. Normally membranes are not back flushed and only it is flushed with permeate water.