aerobic granulation [12–15].
The presence of divalent metal ions, such as Ca2+ and Mg2+, is an
important factor that reinforces the granulation through the strong
effect of the ions on the self-immobilization of microbial biomass
during start-up aerobic granulation. EPSs would rather bind with
multivalent metals to form stable complexes; e.g., Ca2+ affects the
physical characteristics of aerobic granules, while the additio