“…At the time of the first calibration effort, the interrelationship between Y obs , Y, and k d described in Equation 2 was not fully understood. The outcome of this first calibration attempt was perplexing as can be seen in Table 10 and Table 11 (Boe et al, 2009 andKim et al, 2011). In the case of the example plant the process flow diagram depicts the waste activated sludge stream originating from the flow stream between the reactor and the clarifier.…”