Question

Design of septic tank requires consideration of space for the following item(s).

• A. Settling of incoming sewage
• B. Storage of digested sludge
• C. Installation of liner to allow seepage of effluent
• D. Digestion of the settled sludge

Hint:

Septic tank = Settling + Digestion + Sludge Storage. Effluent seepage occurs in soak pits, not in the septic tank itself.

Answer 1

The Correct Option is A, B, D

Step 1: Septic Tank Function.
A septic tank's purpose is to receive sewage, facilitate solid settling, and partially break down organic matter anaerobically.

Step 2: Space Requirements.
- (A) Correct → Adequate space is required for incoming sewage to settle, allowing heavier solids to sink. ✓
- (B) Correct → Septic tanks must accommodate the accumulation of sludge over time. ✓
- (C) Wrong → Tanks are sealed; liners prevent effluent leakage (this occurs in soak pits, not septic tanks). ✗
- (D) Correct → Space is needed for the anaerobic digestion of sludge. ✓

Step 3: Conclusion.
Valid considerations are (A), (B), and (D).

Final Answer: \[\boxed{\text{(A), (B), and (D)}}\]