ABSTRACT
As we have seen in Chapter 1, the sequencing batch reactor (SBR) is an activated sludge process that is operated as a sequence of phases, with reaction and settling taking place in the same vessel. For carbon removal, the typical sequence of phases is fill, reaction, sludge withdrawal, settling and effluent withdrawal, followed by a new feed that starts a new cycle. Sludge withdrawal is typically done either from the completely mixed reactor after the reaction phase or from the settled sludge at the end of the settling phase. In developing the model in this section, we will assume that sludge withdrawal is made from the completely mixed reactor after the reaction phase. Figure 6.1 shows the sequence of phases for an SBR for carbon removal assumed in this section, with the corresponding nomenclature.
