GATE Exam Questions - Engineering

Q1:

In a BOD test, 5 ml of waste is added to 295 ml of aerated pure water. Initial dissolved oxygen (D.O) content of the diluted sample is 7.8 mg/l. After 5 days of incubation at 20°C, the D.O. content of the sample is reduced to 4.4 mg/l. The BOD of the waste water is :

A 196 mg/l

B 200 m/l

C 204 mg/l

D 208 mg/l

ANS:B - 200 m/l

The volume of dilution sample over the undiluted raw sample is a formula not aerated water over an undiluted raw sample.

204 is the right answer.