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After secondary treatment, a part of act...

After secondary treatment, a part of activated sludge is passes back to aeration tank as inoculum while most of the part of activated sludge passed to

A

Anaerobic sludge digesters

B

Rivers and streams

C

Aeration tank

D

Settling tank

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### Step-by-Step Solution: 1. **Understanding Sewage Treatment**: Sewage treatment involves three main stages: primary treatment, secondary treatment, and tertiary treatment. Each stage has a specific role in purifying wastewater. 2. **Primary Treatment**: This stage focuses on removing large solids and debris from wastewater through processes like filtration and sedimentation. It primarily targets physical contaminants. 3. **Secondary Treatment**: This stage employs biological processes to degrade organic matter that remains after primary treatment. Microorganisms, particularly bacteria, are used to break down these organic materials. 4. **Activated Sludge Process**: In secondary treatment, activated sludge is formed, which consists of a mixture of microorganisms and organic matter. A portion of this activated sludge is returned to the aeration tank to maintain the microbial population, acting as an inoculum. 5. **Disposal of Remaining Activated Sludge**: After the secondary treatment, most of the activated sludge is not returned to the aeration tank. Instead, it is sent to an anaerobic sludge digester. This process helps in further breaking down the sludge and reducing its volume. 6. **Conclusion**: Therefore, after secondary treatment, while a part of the activated sludge is passed back to the aeration tank as inoculum, the majority of the activated sludge is directed to the anaerobic sludge digester. ### Final Answer: Most of the part of activated sludge passes to **anaerobic sludge digester** (Option 1). ---
### Step-by-Step Solution: 1. **Understanding Sewage Treatment**: Sewage treatment involves three main stages: primary treatment, secondary treatment, and tertiary treatment. Each stage has a specific role in purifying wastewater. 2. **Primary Treatment**: This stage focuses on removing large solids and debris from wastewater through processes like filtration and sedimentation. It primarily targets physical contaminants. 3. **Secondary Treatment**: This stage employs biological processes to degrade organic matter that remains after primary treatment. Microorganisms, particularly bacteria, are used to break down these organic materials. ...
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