How to Recognize Membrane Foulants

Posted by
John Woodard on August 23, 2018
Pretreating feedwater can lengthen the life of membrane elements, improve the quality of the water produced and reduce the amount of maintenance and cleaning a system requires.

Membrane fouling occurs when materials from the feed stream collect on or near the membrane surface and restrict water permeation. Fouling may occur as layers of deposition on the surface of the membrane (cake fouling), a hardened layer on the membrane surface (scale), particle insertion into the pore channel or entrance (pore blockage), or chemical attachment of particles to the membrane (adsorption).




Inorganic Salts

Reduced permeate flow

Remove hardness via pretreatment and softening

Scale formation on membrane surface

Add antiscalant or dispersant

Increased salt passage

Decrease feed pH

Increased differential pressure

Clean with an acid cleaner


(oils, grease)

Decreased permeate flow

Optimize pretreatment

Increased salt passage

Install an activated carbon filter

Clean with suitable detergent


Stains membrane surface

Remove iron with pretreatment

Rapid reduction in permeate flow

Clean with chelating agent


Decreased permeate flow

Evaluate recovery and pH

Slight increase in salt passage

Optimize pretreatment for colloidal removal


Foul odor or taste

Perform routine sanitizing


Reduced permeate flow

Employ continuous operation

Slime formation

Increased differential pressure

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