D60 QUIZ OF THE DAY

What is the typical detention period for a septic tank?

• 6-12 hours
• 24–48 hours
• 48–72 hours
• 12–24 hours

Answer explanation

The typical detention period in septic tanks is between 24 to 48 hours.

What is the minimum width of a septic tank?

• 50 cm
• 75 cm
• 100 cm
• 125 cm

Answer explanation

The minimum width of a septic tank is 75 cm as per standards.

Which material is used for the ventilating pipe in septic tanks?

• PVC
• Cast iron
• Steel
• Aluminium

Answer explanation

Cast iron or asbestos is commonly used for ventilating pipes.

What is the purpose of a baffle wall in a septic tank?

• Aesthetic design
• To allow light inside
• Enhance scum thickness
• Control scum and sludge movement

Answer explanation

Baffle walls help in controlling the movement of scum and sludge.

What is the minimum capacity of a septic tank?

• 0.5 cubic metre
• 1 cubic metre
• 2 cubic metres
• 3 cubic metres

Answer explanation

Minimum septic tank capacity recommended is 1 cubic metre.

The average sewage flow considered per capita per day for septic tank design is:

• 25 litres
• 45 litres
• 90 litres
• 120 litres

Answer explanation

The average sewage flow is considered 45 L per capita/day.

What is the typical cleaning period for septic tanks?

• 3–6 months
• 6–12 months
• 12–24 months
• 1–2 years

Answer explanation

Tanks are cleaned every 6 to 12 months depending on usage.

What is the detention period in the sedimentation chamber of an Imhoff tank?

• 1 hour
• 2 hours
• 3 hours
• 4 hours

Answer explanation

The Imhoff tank sedimentation chamber has a detention period of about 2 hours.

Which of the following materials is NOT suitable for Imhoff tanks when sewage is highly acidic?

• RCC
• Cast iron
• Asbestos
• HDPE

Answer explanation

Cast iron is preferred as RCC is not suitable for acidic sewage.

Which device is used to control velocity in a grit chamber?

• Notch weir
• Proportional flow weir
• Inlet baffle
• Outlet trap

Answer explanation

Proportional flow weir is used to maintain constant flow velocity.