An Imhoff tank combines sedimentation and sludge digestion in two separate zones. The upper zone:
Choose the correct answer
Digests sludge at elevated temperature
Provides quiescent sedimentation for 2-4 hours; settled solids slip into the lower digestion zone
Aerates the wastewater
Disinfects with chlorine
Correct Answer
B. Provides quiescent sedimentation for 2-4 hours; settled solids slip into the lower digestion zone
Why is this the answer?
Imhoff tank: upper compartment = sedimentation (2-4 h detention); lower compartment = anaerobic sludge digestion (separated by slot, prevents gas bubbles rising into settling zone). Advantages: simple, no mechanical parts. Disadvantages: inefficient digestion, limited gas recovery.
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