The 'Moving Bed Biofilm Reactor' (MBBR) is a biological treatment process where:
Choose the correct answer
Media is fixed and water flows through it (like trickling filter)
Buoyant plastic carriers with biofilm move freely in aeration tank — no sludge recycle needed
Only for primary sedimentation
Chemical dosing only (no biological process)
Correct Answer
B. Buoyant plastic carriers with biofilm move freely in aeration tank — no sludge recycle needed
Why is this the answer?
MBBR: plastic carrier media (polyethylene, specific gravity ~0.95) suspended in aeration tank by airflow and mixing. Biofilm grows on media surface (attached growth). No sludge recirculation needed (attached growth). Compact footprint. Advantages over activated sludge: nitrification + BOD removal; no clarifier sludge recycle needed; no sludge bulking; easy to upgrade existing tanks. Used in India for STP upgrades.
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