Could someone help me with this question? Thank you! 2. (15 pts; 5,10) A storage
ID: 701911 • Letter: C
Question
Could someone help me with this question? Thank you!
2. (15 pts; 5,10) A storage tank in a drinking water distribution system contains 22.5 m3 of water. There is residual chlorine disinfectant present in the water at 3.25 mg/L. The chlorine is found to decay with a rate constant of 0.35 d1. Assume no water is added or removed during the time period of interest and that the tank contents are well mixed a) What equation from the equation sheet would be useful in calculating changes in the chlorine concentration with time? Why does the equation match this problem? b) What is the chlorine concentration after 24 hours?Explanation / Answer
a) The following equation can be used to calculate the change in concentration of chlorine in water.
Co = C*exp(-K*t) ..........(1)
Where Co = intial concentration (mg/l)
C = Concentration at anytime t (mg/l)
t = time (d)
K = rate constant (d-1)
This is equation can be used here because only tank is considered from the whole water distribution system. Also the tank is well mixed which makes this equation more apt.
b) Putting the values of Co , t and K in equation (1)
C = 3.25*exp(-0.35*1)
C = 2.29 mg/l