Class 12 Botany simulations · Microbes in Human Welfare

Sewage treatment and BOD

Run sewage through primary settling and secondary aeration tanks. Aerobic microbes in flocs consume organic matter and lower the BOD.

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What to notice

Once BOD is reduced significantly the effluent is passed to a settling tank; the activated sludge digests anaerobically to give biogas.

Key relation

BOD(t) ≈ BOD₀e^(−kt) during aeration

Try this

How long must the sewage be aerated to remove 90% of its BOD?

What you can change

• BOD of incoming sewage: 100 to 500 mg/L
• Aeration time: 0 to 12 h

More in Microbes in Human Welfare

• Biogas plant

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