Further, a common issue with many RO-EDI applications is the mis-match between the two flow-rate and pressure requirements, especially becuase many are mislead and try to sell the catchy-sounding low-engery RO membranes, which just won't reject any ions very well (thoroughly) let alone silica; further, if the RO produces too much permeate, the engineer (or operator) must either send some product water to drain (or recirc) or to the concentrate stream (or recirc), or reduce the inlet flow, which in-turn reduces the pressure, which will lower the rejection, and then again like the first method, send more water to drain or to concentrate stream, and all just to [often only partially] meet the EDI inlet specifications. On the other side, too little flow (and again, pressure) to the RO and it will not reject ions well, resulting in a smaller ratio across the membrane(s).
SnowPure's started our soley as an EDI manufacturer, therefore it's no surprise that pretreatment for EDI be our target applications market for the ExcellPureRO™ Product Line! So why is silica a concern in the RO if there's an EDI (polishing technology) after it?
EDI uses an electric current to draw ions over ion-exchange resins, through ion-exchange membranes, and then trapped in a concentrating chamber. However, CO2/HCO3 (dissolved Carbon Dioxide) and Silica are both weakly charged ions; silica being less charged than the former. Therefore, the CO2/HCO3 will be removed before SiO2, but only after all other trace ions (Ca, Na, Cl, F, ect.). Hence why having good silica (and CO2/HCO3) rejection prior to the EDI whether by the RO or otherwise, is always a good choice in critical UPW applications. How does SnowPure do this? How is your sillica rejection membrane different from ABC Co's?
Aside from the propriety membrane formulation & manufacturing process, SnowPure engineers their ExcellPureROTM with a focus on being used specifically as pretreatment to their ElectropureTM EDI products. As previously mentioned, trying to mix & match the correct RO with any manufacturers EDI can be tricky, if not edging near impossible. This is why SnowPure has engineered each ExcellPureRO model to match the flow rate of a corresponding EDI model, while maintaining a high-pressure RO design. By increasing (or decreasing) the surface area of each RO, with a corresponding EDI model in mind, the desgin operating pressure will be high enough to get about 99.2 to 99.8% silica rejection, while also leaving enough pressure to feed the EDI with the RO pump. Which RO pump should I get?
Well hey now, that's your job isn't it? We don't want to do everything for our OEMs, and if you've been to our training (or in the industry long enough) you know that no two water sources, and thus systems, are the same!
Many potable waters from surface sources contain naturally low levels of silica (4-8 ppm), but groundwater sources in volcanic areas like Japan and Mexico contain 20-100 ppm. This causes problems when purifying water. Hence, membranes with high rejection of silica (SiO2) are valuable for producing ultrapure water.
Standard and low energy (LE) reverse osmosis (RO) membranes do not reject silica well, often only 97%. Special membranes have been developed to reject silica over 99%.
SnowPure's Separation Technologies
- Electropure EDI
- Zapwater Laboratory EDI
- Electropure ED-Electrodialysis
- ExcellMembranes (IX, RO, NF, UF)
- SPUV High Efficiency UV
- GTM-Gas Transfer Membranes
- DC Power Supplies for EDI
- DemandPure EDI Systems
Doing Business with SnowPure
- Electropure'1' EDI technology was born in 1977, before lonpure
- SnowPure is privately held
- SnowPure is your partner, not a competitor
- High quality technology training and OEM support
- Focus on Customer Service, rapid response.
Benefits of ExcellMembranes
- USA Membrane Technology
- Manufactured in USA
- Highly controlled process
- 34 years of broad membrane experience
- Reliable, robust, proprietary membranes
- ISO-9001 compliant quality system
Technology Training and OEM System Design Support
- SnowPure believes strongly in training—this helps ensure field success with our technologies.
- SnowPure assists new OEM customers through their system design phase, both during the OEM training and the design process. Support includes reviews of P&l diagrams and feedwater requirements.
- Combined with ongoing Technical Service, we help ensure success.