During the activated sludge process__________________?
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Answer: B. Aeration is done with an admixture of previously aerated sludge
Explanation
The activated sludge process utilizes a suspension of living microorganisms to degrade dissolved organic pollutants. Microbes are recycled from secondary clarifiers and mixed with incoming wastewater before entering aeration tanks. This continuous admixture of previously aerated biological sludge drives rapid and efficient organic oxidation. Activated sludge is a biological treatment technology developed over a century ago for municipal sewage. Aeration basins supply dissolved oxygen to sustain high concentrations of aerobic bacteria and protozoa. Secondary clarifiers separate treated water from biological flocks through gravity settling before final discharge.
Municipalities worldwide rely on the activated sludge process for secondary wastewater treatment plants. Controlling return sludge rates ensures stable biological populations capable of handling variable organic loads. Properly managed biological systems produce high quality effluent meeting stringent environmental standards. Option A suggests aerating until absolute stability which is impractical for continuous flow plants. Option C proposes activation through constant stirring ignoring the essential biological sludge component. Option D describes centrifugal dewatering which is used for sludge processing rather than biological treatment.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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