Multiple choice

A completely mixed activated sludge process is used to treat a wastewater flow of 1 million litres per day (1 MLD) having a BOD5 of 200 mgIL. The biomass concentration in the aeration tank is 2000 mg/L and the concentration of the net biomass leaving the system of 5 mgIL. The aeration tank has a volume of 200 m3.

What is the hydraulic retention time of the wastewater in aeration tank?

  1. 0.2 h

  2. 4.8 h

  3. 10 h

  4. 24 h

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B Correct answer
Explanation