1. Return the retentate and filtrate line back to the feed reservoir
2. Open the retentate and filtrate screw clamps.
3. Increase the pump speed to deliver 50-80 mL/min
through retentate.
4. Adjust retentate clamp to generate a retentate pressure
of about 2 bar (30 psi).
5. Run for about 2-3 minutes to flood the membrane with
cleaning solution
6. Open the retentate clamp and close the filtrate clamp.
7. Adjust pump speed give a retentate flow rate of 50-80
mL/min
8. Run for 45 - 60 minutes for cleaning.
Note: If the cleaning solution gets “dirty” after only a
few minutes, flush it out from the system using the
following procedure and then immediately add fresh
cleaning solution and repeat the cleaning cycle. Do
not continue to circulate dirty cleaning solution as it
will reduce the effectiveness of the cleaning process.
Flushing the Cleaning Agent from capsule
1. Direct retentate and filtrate lines to drain.
2. Open retentate and filtrate clamps.
3. Remove feed tubing from cleaning solution.
4. Start pump and run until all solution has been purged
from capsule.
5. Drain reservoir and add water for flushing, 0.2 um filtered
deionized water or WFI.
6. Close the filtrate clamp.
7. Turn on the pump and adjust to 50-80 mL/min. Run at
least 250mL through retentate to drain.
8. Stop the pump. Open filtrate clamp and then close
retentate clamp. Refill reservoir with water if necessary.
9. Start pump and increase flow until the feed pressure is
about 2 bar (30 psi). Run until a minimum of 250 mL is
flushed through the filtrate to drain.
Determining the Membrane Recovery for the cleaned
Minimate
™
TFF Capsule
Membrane recovery is a calculation that defines the efficiency
of the cleaning process performed on the membrane capsule.
It compares the normalized water permeability (NWP) after
cleaning to the "original" NWP. The original NWP was meas-
ured when the membrane was first installed and precondi-
tioned (described on page 5)
Water should be wateWFI or at a minimum, 0.2 µm filtered
DI water.
All water permeability rates are normalized to a temperature
of 20 °C by using a temperature correction factor (TCF 20 °C)
in Table 3.
Determining the water permeability after cleaning
1. Add water to the reservoir.
2. Return the retentate and filtrate line back to the feed
reservoir
3. Open the retentate and filtrate screw clamps.
4. Increase the pump speed to deliver 80 -100 mL/min
through retentate. Stop and restart the pump several
times. Observe whether any air is expelled from the
retentate line when the pump is restarted. If no air is
observed, turn off pump and proceed to the next step.
5. Close the retentate clamp. Adjust the pump flow rate to
develop an transmembrane pressure of approximately
10 psig (0.7 bar).
TMP = ( P
feed
+ P
retentate
)/2– P
filtrate
6. Measure the filtrate flow rate
7. Calculate the filtrate flux rate in mL/min/cm2 and LMH.
8. Calculate the water permeability at the recorded
transmembrane pressure.
Water Permeability = Filtrate Flux Rate (LMH)/TMP
9. Calculate the Normalized Water Permeability using the
temperature correction factor (TCF 20°C) in Table 3,
page 8.
NWP = Water Permeability x TCF
20°C
10.Calculate the membrane recovery.
Membrane Recovery = (NWP after cleaning /“original”
NWP) x 100%
If the membrane recovery is less than 75 - 80%, perform
another cleaning cycle starting from the step, “Adding and
circulating cleaning agent”.
If after the second cleaning the NWP has increased but
acceptable recovery has not been achieved, perform
another cleaning cycle. If after the second cleaning the NWP
has not increased, the cleaning agent or parameters (time,
temperature, etc.) may have to be altered.
NOTE: Between uses, the capsule is stored in a
caustic solution (typically 0.05N - 0.1 NaOH).
During this time, remaining foulants on the membrane
may be released and removed from the capsule when
it is flushed prior to the next use. Therefore, it is not
unusual to find membrane recoveries increase after
storage versus values obtained immediately after
cleaning.
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13
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