engineering recuitment GATE CE 2023-24 Test Series Environmental Engineering Sewage Sewage Treatment
Activated sludge process is used to treat a wastewater flow of 2 MLD having a BOD5 of 250 mg/l. The biomass concentration in the aeration tank is 2500 mg/l and the concentration of biomass leaving the system is 80 mg/l, the aeration tank has a volume of 200 m3.
Which of the following are true for the Activated sludge treatment
1
The hydraulic retention time of wastewater in the aeration tank is 2.4 h
2
The hydraulic retention time of wastewater in the aeration tank is 24 h
3
Average time for which biomass stays in the system is 3.125 day
4
Average time for which biomass stays in the system is 75 hour