To solve this problem, we need to identify which component is put into the Anaerobic sludge digester for further sewage treatment. Let's analyze each option:$\newline \bullet$Option 1: Floating debris$\newline$ - Floating debris consists of materials like plastic, leaves, and other non-biodegradable items that are removed during the initial stages of sewage treatment.$\newline$ - These are not suitable for anaerobic digestion as they do not decompose easily.$\newline$ - Therefore, floating debris is not put into the Anaerobic sludge digester.$\newline \bullet$Option 2: Effluents of primary treatment$\newline$ - Effluents from primary treatment are typically liquid waste that has been settled and clarified.$\newline$ - These effluents are usually directed to secondary treatment processes, not to anaerobic digesters.$\newline$ - Hence, effluents of primary treatment are not put into the Anaerobic sludge digester.$\newline \bullet$Option 3: Activated sludge$\newline$ - Activated sludge is a byproduct of secondary sewage treatment, rich in microorganisms that help in further breaking down organic matter.$\newline$ - It is commonly put into anaerobic digesters to undergo further decomposition in the absence of oxygen.$\newline$ - Therefore, activated sludge is indeed put into the Anaerobic sludge digester.$\newline \bullet$Option 4: Primary sludge$\newline$ - Primary sludge is the solid waste settled out during primary treatment.$\newline$ - While it can be treated anaerobically, it is not the primary material used in anaerobic digesters for further treatment.$\newline$ - Thus, primary sludge is not typically put into the Anaerobic sludge digester for further treatment.$\newline$Based on the analysis, the correct answer is:$\newline$Option 3: Activated sludge$\newline$This corresponds to the correct option, which is Option 3.