Delamination is the lifting of the thin-film membrane from the backing material. As the thin-film membrane is a delicate material, once it has lifted, it can easily become damaged resulting in severe losses in permeate quality. This type of damage is most often caused by a positive pressure on the permeate side of the element, also termed backpressure. Backpressures as low as 5 psi can cause delamination of the membrane.
Damage from delamination is most common closest to the concentrate end glue line but may occur across membrane leaves. Severe delamination at the glue line can result in pouching of the glue line, allowing feedwater bypass into the permeate stream.
Symptoms of delamination include:
- Rapid loss in permeate quality
- Increase in permeate flow