Question

A city has a population of 50,000 people, an average household generated water flow of 430L/day-person, and the average BOD5 of the untreated wastewater in population equivalents is 0.1kg BOD5/day-person. If the BOD reaction rate coefficient for the waste stream is 0.4/day, determine the ultimate (L0) BOD of the wastewater.

Answer 1

The Ultimate B.O.D for the waste water is found to be 268.9597 mg/L

Formula to Calculate Ultimate BOD

(L​​​​​​o​​​) = y​​​​​​​​​5/(1-e(-k x t) )

Where

k = BOD Reaction rate Co-efficient

Volume of water used by the city population in 5 days = 107.5 x 10^6 L

Mass of the BOD for the city population required in 5 days = 2.5 x 10^4 kg

5 days BOD for the waste water (y​​​​​​5​​​​​) = 232.56 mg/L

For detail calculations please refer to the uploaded image