Membrane Scaling
Prevention and removal
All reverse osmosis (RO) feed waters are different in ionic composition. As a result, different types of scale may deposit on the membranes if the correct antiscalant is not used. Selecting the right antiscalant and cleaning chemicals will optimise operating efficiency and help to prevent plant failure.
Below we list some of the most common types of scales that we have identified on RO membranes during autopsy procedures and the appropriate chemicals to use.
We always recommend a membrane autopsy to ensure deposits are correctly identified. Read more about our autopsy services.
Scale Species
Information
Antiscalant
Cleaners
Calcium Carbonate is the most common scale found in membranes. Appears as an off white powder. Easily cleaned with a strong acid product.
Genesys LF
Genesol 37 and 38
Silica - can be present on a membrane as colloids, aluminosilicates on the lead membrane elements, or as scale on the final elements. Both forms are difficult to remove, being dependent on pH and temperature.
Genesys SI
Genesol 40 or 703, depending on colloidal or silica scale
Calcium sulphate (gypsum) - crystalline structure with very sharp blade-like features, which cut the membrane surface. Common occurrence in areas where there is a natural sulphate content in the underlying geology. This makes it very difficult to clean.
Genesys CAS
Genesol 50, 34 and 703Difficult to clean - ask us for advice on cleaning protocol design
Calcium phosphate - appears in many forms. Commonly found in RO membrane systems fed with waste water or agricultural leachate, due to the high phosphate loading.
Genesys PHO
Genesol 37 and 38
Magnesium hydroxide (brucite) - precipitates at high pH, above 9.5, in membrane systems. Can be found in second pass elevated pH brackish water boron rejection plants, where pH levels are increased above 9.5 with sodium hydroxide to aid boron rejection. Relatively rare.
Genesys MG
Genesol 37 and 38
Barium sulphate (barite) - appears as white crystals, which can take on-blade like formations. Very difficult to clean effectively.
Genesys BS
Genesol 50 and 34Difficult to clean - ask us for advice on cleaning protocol design
Strontium sulphate (celestine) - appears as crystals or as needles, which can damage the membrane surface. Very difficult to remove.
Genesys CAS
Genesol 50 and 34Difficult to clean - ask us for advice on cleaning protocol design
