4. Elaboration Question 3
Course subject(s)
4. Activated sludge process
Question 3: Activated sludge process in dry and wet weather conditions
A small wastewater treatment plant is designed for an average flow of 30,000 m3/day, with an influent concentration of 200 mgBOD/l.
- a. Calculate the volume of the aeration tank for a treatment plant with nitrification. The activated sludge concentration in the aeration tank is 4 g/l.
- b. Calculate the diameter of the settling tank.
- Use a usual peak factor for Dutch treatment plants (2.5)
- The sludge volume loading rate (\(SVLR = v_0 \cdot X_{AT} \cdot \frac{SVI}{1000}\)) is 0.4 m3/m2/h
- SVI = 150 ml/g
- Sludge recycle flow ratio (fr) = 0.6 (-)
- c. Heavy rainfall during 1 hour increases the maximum flow to the maximum hydraulic capacity of the influent works, 6,250 m3/hr. Calculate the effect on the sludge retention if the recycle flow remains unchanged.
In which v0 is the surfae loading rate
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