Grau second-order substrate removal model
The formula of Second-order substrate removal model is [17]:
S0HRT
S0 S ¼ a þ bHRT ð4Þ
In which HRT is the hydraulic retention time and (S0-S)/S0
expresses the substrate removal efficiency and is symbolized
as E. Therefore, the last equation can be written as:
HRT
E ¼ a þ bHRT