Question

If 2% solution of a sewage sample is incubated for 5 days at 20°c and depletion of oxygen was found to be 5 ppm,

b.o.d. of the sewage is

Answer 1

The standard BOD is calculated by
BOD = (Initial DO - Final DO) * Dilution factor
where Dilution factor = (volume of diluted sample) / (volume of undiluted sample)
Since,depletion of oxygen is given as 5 ppm i.e.
(Initial DO - Final DO) = 5 ppm
also,Dilution factor = (100)/(2) = 50
Therefore,
BOD = (5) *(50) = 250 ppm or 250 mg/l