Question

3. A river with a discharge of 10 m3/s carries a concentration of 10 ppb of benzene and discharges into a 5,000,000 m3 lake. At time zero, a plant begins discharging 1 m3/s with 20 ppb of benzene. What is the concentration of benzene leaving the lake 7 days after the plant begins discharging? The benzene decay coefficient for the lake is 0.001mg/L-day.

a. 5.0 ppb

b. 5.1 ppb

c. 5.2 ppb

d. 5.3 ppb

e. 5.4 ppb

f. 5.5 ppb

g. 5.6 ppb

h. 5.7 ppb

Answer 1

Taking into consideration of the above factors ,the answer is :

Concentration of benzene =5.6 ppb