Model
Digital Document
Publisher
Florida Atlantic University
Description
This study evaluated the technical feasibility o f increasing the typical water
recovery of a pilot scale membrane system (85-90%) to 97% by treatment of
nanofiltration concentrate with low-pressure reverse osmosis. The study used Biscayne
aquifer water (freshwater), and determined that it may be technically feasible to increase
the recovery up to approximately 95% when the RO flux is —10 gfd, the feed water pH is
reduced to -6.1 with H2 SO4 , and antiscalant in the NF process. The tested membranes
showed stable and similar performance under the pilot conditions. However, pilot tests
were sensitive to pH variations (pH>6.2). The main barrier for increasing the water
recovery was fouling caused by iron, carbonate hardness, and iron bacteria. A
preliminary cost analysis showed that there is an apparent econom ic advantage when the
recovery is greater than 90%. Estimated water cost at 95% recovery is $1.99 compared
with $2.69 at the typical 85% recovery.
recovery of a pilot scale membrane system (85-90%) to 97% by treatment of
nanofiltration concentrate with low-pressure reverse osmosis. The study used Biscayne
aquifer water (freshwater), and determined that it may be technically feasible to increase
the recovery up to approximately 95% when the RO flux is —10 gfd, the feed water pH is
reduced to -6.1 with H2 SO4 , and antiscalant in the NF process. The tested membranes
showed stable and similar performance under the pilot conditions. However, pilot tests
were sensitive to pH variations (pH>6.2). The main barrier for increasing the water
recovery was fouling caused by iron, carbonate hardness, and iron bacteria. A
preliminary cost analysis showed that there is an apparent econom ic advantage when the
recovery is greater than 90%. Estimated water cost at 95% recovery is $1.99 compared
with $2.69 at the typical 85% recovery.
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