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From: Laila Bahgat
What is exactly meant by O2 set point in an uncontrolled system? As far as I remember this set point is the means to calculate the error in a PI controller for example or the deviation of the actual concentration from a pre-set level. Please comment whether this parameter (the O2 set point) is used correctly in the following situation or not: In the simulation of an oxidation ditch system using ASIM 4.0: influent enters at the middle zone exactly before the aerator & oxygen conc. = 3 mg/ litre, in the following zone O2 conc. decreases to 1 mg/l while it approaches zero in zone 1 that may be considered as an anoxic zone. The aeration process is not controlled. Is it correct to represent the aerobic/ anoxic state of the different zones of the ditch via the O2 set point of the reactors (zones) i.e. By setting O2 set point of zone 1 = 0, zone 2 = 3 mg/ litre and zone 3 = 1 mg/l. What about the initial values of O2 in all reactors? Thanks in advance for your feedback.
If O2 setpoint is not zero, then aeration is controlled to keep the O2 concentration to the value set by O2 setpoint. If O2 setpoint is zero, aeration is constant according to the kla value set under 'Edit Flowscheme / Reactors and secondary clarifiers'. Please note that an english tutorial is now available at the ASIM homepage.