The digestion chamber volume per capita is specified as what range in cubic feet?

• A. 3.5 to 4.0
• B. 2.5 to 3.0
• C. 4.5 to 5.0
• D. 3.0 to 3.5

Answer: (A)

The question tests how to size a digestion chamber based on the number of people served. You allocate a fixed volume for each person to ensure there’s enough space for waste to digest and for gases to escape, without crowding the chamber.

The specified range, 3.5 to 4.0 cubic feet per person, is chosen because it provides a practical balance between sufficient retention for anaerobic digestion and a reasonable overall tank size. In gallons, that’s about 26 to 30 gallons per person. Multiply this per-person volume by the number of people using the facility to get the total digestion chamber volume needed. If you used less per person, digestion might be incomplete and solids could accumulate; using more per person would make the tank larger and more costly without proportional benefit.