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BOD Load Calculator

Work out bod load instantly with clear inputs, formula shown and shareable results.

About BOD Load Calculator

BOD load is flow times concentration: 1 mg/L on 1000 cubic metres is 1 kilogram. Population equivalent converts that load to the number of people it represents at a standard rate, commonly 60 grams of BOD per person per day, which is how treatment works are sized and industrial dischargers are charged.

Formulas

BOD load

Load (kg/day) = flow (m3/day) x BOD (mg/L) / 1000

Population equivalent

PE = load (g/day) / load per person per day

Worked example

With the default values below, BOD Load Calculator returns BOD Load of 1,400.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Wastewater Flowminimum 0 m3/day
5,000 m3/day
BOD Concentrationminimum 0 mg/L
280 mg/L
Population Contributingminimum 0
50,000
Design Load Per Personminimum 0 g BOD/person/day
60 g BOD/person/day

Results

BOD Load
1,400.000
Population Equivalent
23,333
Actual Load Per Person
28.000
Design Load At Standard Rate
3,000.000

Step by step

  1. 1Values used
  2. 2BOD load
  3. 3Population equivalent
  4. 4BOD Load= 1,400.000
  5. 5Population Equivalent= 23,333
  6. 6Actual Load Per Person= 28.000
  7. 7Design Load At Standard Rate= 3,000.000

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Discharge consents specify BOD limits as both concentration and load. Exceeding either is an offence in most jurisdictions.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Discharge consents specify BOD limits as both concentration and load. Exceeding either is an offence in most jurisdictions.

Frequently Asked Questions

Why does load matter more than concentration?

Treatment capacity is limited by mass of organic matter, not concentration. A dilute high-flow discharge and a strong low-flow one can impose identical load and require identical aeration.

What is the difference between BOD5 and ultimate BOD?

BOD5 is oxygen consumed in five days at 20 C, roughly 65-70% of ultimate BOD. Design standards specify which is meant, and they must not be interchanged.

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