How can you calculate BOD Mathmaticly?

Answer 1

The Biochemical Oxygen Demand (BOD) of a sample is the amount of dissolved oxygen required by aerobic microorganisms to breakdown organic matter in the sample.

The test is simple:

Measure the Dissolved Oxygen content of the sample (a)

Place in a sealed darkened bottle

Incubate for 5 days at 20'C

Measure the Dissolved Oxygen content of the incubated sample (b)

Generally you're using this test to analyse contaminated water, so you'll want to dilute it first - it may be that aren't enough aerobic microorganisms present to give you a measurable result, in which case you'll need to inoculate the sample with a suitable culture.

The BOD of the sample = a - b

BOD is expressed in mg O2/L of sample.

Extra Credit

Generally you're using this test to analyse contaminated water, so you'll want to dilute it first - it may be that aren't enough aerobic microorganisms present to give you a measurable result, in which case you'll need to inoculate the sample with a suitable culture.

The BOD of a diluted innoculated sample = ((a - b) - BOD of inoculated culture) * dilution factor