ABSTRACT
This chapter devotes the modelling of the reaction vessel in an artificial reactor used for wastewater treatment, or a natural water body, such as a river or a lake. Continuous flow is constantly routed through the reactor, which is continuously stirred to ensure a complete mixing, hence the continuously stirred tank reactors (CSTRs). Considering a pair of cascaded CSTRs with a first-order kinetics in which the output of the first CSTR is the input to the second. In some cases, the flow along the CSTR chain is not unidirectional, as there may exist a counter-current returning part of the flow to the upstream reactor. The amount of reaction provided by a single CSTR may not provide the required extent of reaction. For this reason, CSTRs are often cascaded, as we have already seen in the case of the Nash chain of reservoirs.
