Direction: 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 mg/l. The biomass concentration in the aeration tank is 2000 mg/l and the concentration of the net biomass leaving the system is 50 mg/l. The aeration tank has a volume of 200 m³.
-
What is the hydraulic retention time of the waste water in aeration tank?
-
- 0.2 h
- 4.8 h
- 10 h
- 24 h
Correct Option: B
HRT = | ||
Inflow |
= | = 0.2 day | |
1 × 106 per day |
= .2 × 24 = 4.8 hours.