Question

An activated sludge tank has the following characteristics: Q = 4.18 m³/sec; Influent BOD₅ = 225 mg/L; Effluent BOD₅ = 4.5 mg/L; K_s = 100 mg/L; μ_m = 2.5 day^-1; k_d = 0.05 day^-1. The mean cell residence time (MCRT) in days is most nearly:

a.12.4

b.7.0

c.2.5

d.17.4

QUESTION 38

The hydraulic detention time, θ_c, of the activated sludge tank above (in Question #37) in hours is most nearly: (Note: Cells in the activated sludge tank, X = 3,500 mg/L; Y = 0.5)

a.7.0

b.0.3

c.0.7

d.5.0

The hydraulic detention time, θ_c, of the activated sludge tank above (in Question #37) in hours is most nearly: (Note: Cells in the activated sludge tank, X = 3,500 mg/L; Y = 0.5)

a.7.0

b.0.3

c.0.7

d.5.0

4 points   

QUESTION 39

The volume of the activate sludge tank above (in Question #37) in m³ is most nearly:

a.1,800

b.53,000

c.105,000

d.30   

QUESTION 40

The value of the F/M ratio of the activated sludge tank (in Question #37) in mg BOD/mg cells-day is most nearly:

a.0.22

b.0.01

c.0.5

d.1.0

Answer 1