## Cfstrinseries Model

The CFSTR-in-series model is used as an approximation to the PF model. A PF reactor is divided into n compartments arranged in series, with each compartment modelled as a CFSTR. Since Se is usually small compared to Ks, the hyperbolic relationship depicted in Figure 7.25.9 can be simplified to a linear relationship with K = k/Ks. Therefore, Equation 7.25(6) becomes the following equation:

Applying Equation 7.25(14) to each compartment of a PF reactor yields the following equations:

SeA = 1/(1 + K1XA) Se2/Se1 = 1/(1 + K2X202) 7.25(15)

If all n compartments are sized for equal volume and mean K and X values are adopted for all compartments, then Equation 7.25(17) can be simplified to the following equation:

Table 7.25.4 summarizes typical kinetic coefficients for municipal wastewater applications. Environmental engineers must correct all kinetic coefficients used in design equations to account for temperature effects (see Equation 7.22[4]).

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