Activated sludge should have the ability to settle quickly so that it can:
a. be rapidly pumped back from sedimentation tank to aeration tank
b. absorb pathogenic bacteria present in wastewater while sinking to the bottom of the settling tank
c. be discarded and anaerobically digested
d. absorb colloidal organic matter
The answer is the option (c) be discarded and anaerobically digested