Question

During secondary aerobic wastewater treatment, some of the activated sludge goes ________ while the rest goes ________.

A) back to the aerator / to the anoxic sludge digestor
B) back to the primary system / to the aerator
C) to the anoxic digestor / back to the primary system
D) back to the primary system / to the tertiary digestor

Answer 1

Option (A), In secondary aerobic wastewater treatment, some activated sludge is recycled back to the aerator to improve breakdown of organic matter, while the rest is sent to the anoxic sludge digestor for further treatment.

Step-by-step explanation:

During secondary aerobic wastewater treatment, some of the activated sludge goes back to the aerator while the rest goes to the anoxic sludge digestor. The process includes exposure of wastewater to air, which allows microorganisms to break down contaminants.

The sludge that results from the microbial decomposition in the secondary clarifier is partly recycled back into the aerator to introduce more microorganisms and speed up the breakdown of organic matter. The remaining sludge is then directed to the anoxic sludge digestor for further processing, which could include anaerobic digestion to produce methane gas or processing into fertilizers after careful contamination testing.