Fouling is an inevitable phenomenon when using nanofiltration (NF) membranes in water
treatment applications which necessitates periodic chemical cleaning to restore the permeate
flux. However, harsh cleaning chemicals and conditions (i.e. high cleaning temperature) may
accelerate membrane ageing, and cause variation in membrane surface properties and
separation efficiency. Indeed, some evidence has emerged that chemical cleaning may lead to
considerable variation in the retention of inorganic salts as well as some trace organic
contaminants of concern (Simon et al. 2009; Simon et al. 2012).