Biochemical Oxygen Demand (BOD) Exertion Calculator

Solve for biochemical oxygen demand to measure the amount of oxygen used by bacteria to metabolize organic material in water.


How BOD Exertion Equations calculator works

The BOD calculator gives a measure of the oxygen utilized by bacteria during the oxidation organic material contained in a waste water sample.

If you determine the BOD after 5 days, this is called the 5 day BOD (BOD5). If you determine the BOD after 20 days, this is called the 20 day BOD (BOD20). These are really BOD exerted values.

Formula :

yt = L(1 - e-k × t)


yt is amount of BOD exerted at time t in mg/L

L is ultimate BOD in mg/L

t is time in days

k is deoxygenation rate constant in days-1 or 1/days

Solved Examples :

The BODL of a sample is 120 mg/L. If 'k' for this sample is 0.28 day-1.How much of the BOD is exerted and how much remains after the following time intervals (a) 3 days , (b)5 days and (c) 10 days ?

(a) y3 = 120(1-e-0.28×3) = 68 mg/L

(a) y5 = 120(1-e-0.28×5) = 90 mg/L

(a) y10 = 120(1-e-0.28×10) = 113 mg/L