Page 17 - Opportunities in the Treatment of Water and Other Wast Streams

Osmosis
Application:
Why: Water recycling and brackish groundwater treatment.
Where: Containerized systems on-site, maybe near well heads and off-site facilities
where technologies are preceded by significant pretreatment processes. Target Contaminants:
Divalent salts (e.g., calcium sulfate, calcium carbonate) (nanofiltration may be used in tandem with
reverse osmosis or a second stage of nanofiltration membranes to increase constituent rejection)
Ions, including sodium, nitrate, and chloride.
Nanofiltration and reverse osmosis are cross- flow membrane filtration processes. Nanofitration membranes have a higher rate of salt transport and preferentially retain higher charged ions such as calcium and sulfate than reverse osmosis membranes. Depending on the specific membrane properties, the rejection of monovalent ions, such as nitrate, sodium, and chloride will be as low as 45 percent. Reverse osmosis
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