Reverse Osmosis Pretreatment
|Why a pre treatment? |
Reverse Osmosis Thin Film Composite membranes are subject to fouling by many substances:
NOM, particles and colloids can be removed by so-called "conventional treatment" consisting of coagulation followed by media filtration for low turbidity water . Additional steps such as flocculation and sedimentation are added in case of very turbid shallow seawater.
The non-conventional pretreatment for NOM , particles and colloids is Ultrafiltration.
An antiscalant solution should be dosed before the reverse osmosis membranes to disperse calcium carbonate and sulfates precipitates in order to avoid scaling.
Fine filtration (5-micron) is required as a last step before the RO membranes to prevent any debris, sand particles or piping material to damage the membranes.
--> See also ULTRAFILTRATION as a reverse osmosis pretreatment <--