ABSTRACT
This chapter shows the importance of using mathematical models for biological wastewater treatment systems. It presents a classification of the models depending on the number of parameters in use at one time and dependent on the homogeneity of the activated sludge system at another time. Mathematical models are powerful tools that the designers of biological wastewater treatment systems can use to investigate the performance of potential systems under a variety of conditions. Models can be classified into simple and complex depending on the number of parameters describing microbial growth processes. The simplest kinetic model has been, and is used for the analysis of many microbial growth processes. Complex models have different degrees of complexity. Their microbial kinetics are based on the knowledge accumulated in the fields of microbiology and biochemistry. In hydrolysis processes, microorganisms secrete enzymes to be able to catalyze the degrading organic substrates.
