# **B**iochemical **O**xygen **D**emand (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** (BOD_{5}). If you determine the BOD after 20 days, this is called **the 20 day BOD** (BOD_{20}). These are really BOD exerted values.

__Formula__ :

y_{t} = L(1 - e^{-k × t})

Where,

y_{t} 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 BOD_{L} 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) y_{3} = 120(1-e^{-0.28×3}) = 68 mg/L

(a) y_{5} = 120(1-e^{-0.28×5}) = 90 mg/L

(a) y_{10} = 120(1-e^{-0.28×10}) = 113 mg/L