ASM1 were the primary developed
model (Henze et al., 1987). Using facultative consumption of oxygen
or nitrate as the elector acceptor, the model could successfully
describe the removal of organic carbon compounds and ammonium
within municipal activated sludge. After several years, it was
developed to ASM2 (Henze et al., 1999) for addressing the biological
nitrogen and phosphorus removal processes in WWTPs and late to
ASM2d considering the denitrifying process of phosphorus accumulating
organisms (PAOs) (Henze et al., 1999).