GPS-X Technical Reference

POND/LAGOON
Suspended Growth Models 176
In the manual SBR model, there are no cycle settings as in the simple and advanced
models. The timing of mixing, aeration and pumping all must be controlled directly.
The decant flow rate (pumped flow parameter) and waste flow rate (underflow rate
parameter) can be entered in the Parameters > Operational - Flow Control form.
The influent flow to the SBR is taken from the upstream object (e.g. influent object) if the
influent #1 pump label parameter is left blank in the Flow Control form. The user must
then make sure that the influent flow is synchronized with the SBR cycle (i.e. entering
the SBR during the appropriate phase). Alternatively, in the Flow Control form, you can
enter a stream label for the influent #1 pump label parameter, a flow rate for the first
influent flow parameter, and the SBR influent flow will be automatically taken from that
stream during the appropriate phase within the cycle (automatic synchronization). The
stream label must be associated with a pumped flow stream (`qcon' variable), for example
an influent icon or pumped flow from a tank. The influent #2 pump label parameter is
ignored in this cycle type.
The pond object contains only the empiric model, which simulates the transformation, dilution
and mixing of state variables in a pond. Unlike the activated sludge models, the empiric model is
empirical in nature. It does not use fundamental mechanistic dynamic processes to determine the
rate of change of the states (such as those found in the Model Matrices in Appendix A), but
simulates behavior that has been observed in existing ponds, bench-scale studies and pilot-scale
studies.
The empiric model simulates three different kinds of ponds: anaerobic, facultative, and
aerated. The pond models are discussed in detail below.
Anaerobic Ponds
In the anaerobic pond model, the BOD and TSS removal is simulated using a simple
regression model derived from anaerobic pond behavior in North America (Beier, 1987).
The following equations describe the amount of BOD and TSS removal:
Equation 6.49
GPS-X Technical Reference