AQUADYN® FZ50 Series Hollow Fiber Module | OPERATION MANUAL
MICRODYN-NADIR | REVISION: B | DATE: 01/08/2020
9
3.
Change flow direction for 1 minute
4.
Flush for 5 seconds
5.
Repeat steps 1-4
4.3.1
Feed pH
Set the feed pH to 4-8 for long-term operation. Regular adjustments of the feed pH are recommended to keep the feed pH
inside this range. Operation outside of this suggested range may
shorten the module’s lifetime due to possible membrane
degradation.
4.3.2
Feed Temperature
The maximum feed temperature for long-term operation is 35°C (95°F). However, the UF modules may be operated outside
of this range for short periods (up to 3 months per year). In some cases, operation may occur at up to 40°C (104°F).
Operation outside of this suggested range may shorten the module’s lifetime due to possible membrane or module
degradation.
4.3.3
Turbidity Level
Turbidimeters should be used to measure and help maintain acceptable turbidity levels prior to the UF system. If feed water
with high turbidity levels is directly sent to the UF modules, the set membrane flux may not be sustainable.
4.3.4
Membrane Flux
Set the module’s operating flux within the range described
on the product specification sheet. The operating flux depends on
the quality of the feed water. If an overly aggressive flux is chosen for a given feed water, the transmembrane pressure will
increase in a short period of time.
4.3.5
Flow Rate
Set the flow so that the liquid linear velocity along the membrane surface on the outlet port side (concentration water port)
of the module is 0.1-0.2 m/sec. Note that the proper module supply flow rate changes if the permeate flow rate changes. For
example, if the permeate flow rate is 3.0 m/day, the proper module flow rate should be 10-14 m
3
/h.
4.3.6
Transmembrane Pressure (TMP)
The maximum transmembrane pressure (TMP) a module can tolerate is 0.2 MPa (29 psi). However, UF modules are typically
operated at a TMP of 0.01-0.1 MPa (1.5-14.5 psi) and the desirable operation range is 0.01-0.07 MPa (1.5-10.2 psi). If the
TMP reaches 0.1 MPa, it is recommended to implement a backwash or chemical cleaning to improve membrane
performance. In many cases, the TMP increases at a quicker rate after 0.07 MPa, so it is difficult to keep the membrane flux
at the original set value.
4.3.7
Backwash
In order to maintain the operating membrane flux, it is necessary to implement periodic backwashes. For more information
on backwashing, please refer to
Chapter 5. Backwash
.
4.3.8
Flushing
The procedure for flushing the module after backwashing without implementing filtration (valve on the pemreate water side
is closed) helps clean the feed water side of the hollow fibers more effectively. Flushing washes away the contaminants
accumulated in the circulation line on the feed water and concentrate side.
