Hach-Lange WTOS P-RTC - Manual (Page 34)

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Parameterization and operation
4.5.7 Inclusion of return sludge quantity
To be able to record the entire flow at the measuring point, the
return sludge quantity must also be taken into account,
depending on the specific application. For this purpose, the
minimum and maximum flow rate of the return activated sludge
pump(s) can be specified, as well as the ratio of return activated
sludge transport relative to the measured flow rate.
The flow rate, e.g. for simultaneous precipitation with a
measuring point in the activated sludge tank, is calculated as
follows:
Q
total
= Q
to
+ QRSL
Where: QRLS = QRS
ratio
× Q
to
Within the limits of Q RS
minimum
and Q RS
maximum
Q RS
minimum
and Q RS
maximum
thus represent the limits within
which the calculated return activated sludge volume is varied
according to Q RS
ratio
.
If the measuring location is at a measuring point that is not
influenced by the return activated sludge volume, all variables
described below must be set to "
0 ".
Under MIN RET SLUDGE , the minimum flow rate of the return
sludge pump(s) must be specified in m³/h. In the case of a
constant return sludge flow rate, the relevant value must also be
specified here.
Under MAX RET SLUDGE , the maximum flow rate of the return
sludge pump(s) must be specified in m³/h. If a constant return
activated sludge volume is pumped, Q RS
maximum
can be set to
" 0 ".
In the event of a return activated sludge volume that is
proportional to the flow rate (Q), the percentage ratio must be
specified under
Q RET RATIO . If the same return activated sludge
volume is pumped continuously, this volume must be specified
under Q RS
minimum
. The Q RS
ratio
must then be selected as " 0 ".
A heavily fluctuating flow rate signal (e.g. caused by pumping
stations) that is integrated in the RTC module via the 4-20 mA
current loop can be smoothed using
Q INFL SMOOTH . As a result,
only a marginally fluctuating target value is issued.
Q INFL SMOOTH can lie between 1 and 99.
• Q INFL SMOOTH = 1. The influent signal is not smoothed.
• Q INFL SMOOTH = 2. The influent signal is smoothed over 3
minutes.
• Q INFLUENT SMOOTH = 3. The influent signal is smoothed
over 2 minutes.
• Q INFLUENT SMOOTH = 5. The influent signal is smoothed
over 12 minutes.
• Q INFLUENT SMOOTH = 10. The influent signal is smoothed
over 25 minutes.
Example: