ClearFox®Control Unit CU-M
9
o
Level measurement via Filling. If below switching level 1 => eco
o
Filling
o
Level measurement via Filling. If above switching level 2 => overfill alarm
o
Denitrification (can be deactivated by setting step time to 0s)
o
Aeration
o
Sludge (before Settling, option, can be deactivated by setting step time to 0s)
–
sludge return will not take place within the first 90 days after bringing into
service. This value can be changed, the parameter is called
Biology Build-Up
Time
.
o
Settling
o
Sludge (after Settling, option, can be deactivated by setting step time to 0s)
–
sludge return will not take place within the first 90 days after bringing into
service. This value can be changed, the parameter is called
Biology Build-Up
Time
.
o
Clearwater removal
o
Option: Check DI1, if closed => overfill alarm (if no float switch is connected,
there will not be an alarm)
-
Eco mode
o
Aeration
o
Level measurement via Filling. If above switching level 1 => normal
o
Each 6 eco cycles (frequency can be changed) => At least one normal mode
9.1.2
Water level measurement
Water level measurement at this process is performed using the filling airlift in the pretreatment
tank.
If the level before filling is higher than the calibrated value plus Offset 1, filling will be
performed, and the control unit will follow the normal mode program. If the level is lower, filling
will not be performed, and the program follows the eco mode process.
If the level after filling is higher than the calibrated value plus Offset 2, this means, filling could
not be performed. Likely the problem was that the reactor is (still) full because clearwater
removal did not work and thus the water pumped from the pretreatment to the reactor during
filling simply flowed back. An overfill alarm will be signalized in this case.
calibrated minimum
Offset 1
(Eco / Normal)
Offset 2
(overfill alarm)
Figure 4: Pretreatment tank with filling airlift and calibrated minimum, Offset 1 and 2