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 5mgIL. The aeration tank has a volume of 200 m3.

What is the average time for which the biomass stays in the system?

  1. 5 h

  2. 8 h

  3. 2 days

  4. 8 days

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation