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Details about the permeate rate
| The permeate rate is measured as a direct function of the available square footage of
membrane. The permeate rate is referred to as the "flux rate" and is measured as
gallons per square foot of available membrane area per day. This is typically abbreviated
as GSFD. Flux rates are between 20 and 40 GSFD. The more concentrated the feed solution,
the slower the flux rate. The remaining rejected spent metal removal solution, the
difference between the feed rate and the permeate rate, is returned to the process tank
for recirculation, retreatment, and concentration. |
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| The success of operating a very tight membrane, 0.005 micron pore size, in a
relatively dirty environment (spent metal removal fluids) is due to a very high feed rate
as a function of permeate rate. This ratio is in the range of 30 gallons feed to one
gallon permeate. The remaining 29 gallons are used as a high flow across the membrane
surface. This high cross flow rate essentially allows the membrane to be self-cleaning. |
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| The recirculated fluids continue to concentrate until the flux rate drops to an
unacceptable level. This unacceptable flux rate is typically between 5 and 8 GSFD. At this
point, the concentrated recirculated fluid is transferred to a separate tank for contract
disposal. The spent metal removal solutions can be concentrated from 30% to 50%
(volume/volume) oil. |
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Contact Chris Roman, 