ExcellPureRO™ High Silica Rejection RO Elements
High Silica Rejection Membrane Elements
Many potable waters from surface sources contain naturally low levels of silica (4-8 ppm), but volcanic areas like Japan and Mexico and groundwater sources in the Middle East normally contain 20-100 ppm. This causes problems when purifying water. Hence, membranes with high rejection of soluble silica (SiO2) are valuable for producing ultrapure water.
Standard (BW) and low energy (LE and XLE) reverse osmosis (RO) membranes do not reject silica well, often only 97-98%. Special membranes (ExcellPureRO™) have been developed to reject silica over 99.2%.
SnowPure’s ExcellPureRO™ membranes produce a high rejection of silica. Low silica permeate from RO is important for many applications, including providing feedwater for electrodeionization (EDI) systems. We have matched our SXR™ RO membrane elements to specific Electropure™ EDI modules.
An article is published here on successfully operating RO-EDI in a high-silica environment.
Key properties to be successful rejecting silica:
- flat sheet membrane must be designed for silica removal (SnowPure’s is)
- the correct flux must be used (SnowPure has an element for each EDI model)
Avoiding silica scale:
When silica in the RO feedwater is high, silica scale is likely unless the right anti-scalant is used.
SnowPure recommends using AWC‘s Pureflux Si with ExcellPureRO™ membranes to prevent silica scaling. With Pureflux Si, you can achieve up to 400 ppm SiO2 in the RO concentrate. With proper control of the other water chemistry ions, you can achieve over 600 ppm SiO2 in the RO concentrate. When operating at 300 ppm in RO concentrate, CIP cleaning frequency will be significantly reduced.