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Oxygen Requirement For Aeration Calculator

Work out oxygen requirement for aeration instantly with clear inputs, formula shown and shareable results.

About Oxygen Requirement For Aeration Calculator

Oxygen demand is about 1.1 kg per kg of BOD removed plus 4.57 kg per kg of ammonia nitrogen oxidised — nitrification often accounts for a third or more of total demand. Field requirement divides by the alpha factor for wastewater's poorer transfer, and air volume follows from oxygen content and transfer efficiency.

Formulas

Oxygen demand

O2 = 1.1 x BOD removed + 4.57 x ammonia N oxidised

Air requirement

Air (kg) = field O2 / (transfer efficiency x 0.232 oxygen mass fraction)

Worked example

With the default values below, Oxygen Requirement For Aeration Calculator returns Oxygen Required of 2,069.80. Change any input above and every figure here is recalculated in your browser.

Inputs used

BOD Load Removedminimum 0 kg/day
1,300 kg/day
Ammonia Nitrogen Oxidisedminimum 0 kg N/day
140 kg N/day
Standard Oxygen Transfer Efficiencyaccepts 0–100 %
25 %
Alpha Correction Factoraccepts 0.01–1
0.6

Results

Oxygen Required
2,069.80
Field Oxygen Requirement
3,449.67
Air Required
49,564.2
Oxygen For Nitrification
639.80

Step by step

  1. 1Values used
  2. 2Oxygen demand
  3. 3Air requirement
  4. 4Oxygen Required= 2,069.80
  5. 5Field Oxygen Requirement= 3,449.67
  6. 6Air Required= 49,564.2
  7. 7Oxygen For Nitrification= 639.80

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 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

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

Frequently Asked Questions

Why is the alpha factor needed?

Surfactants and dissolved organics reduce oxygen transfer compared with clean water, typically to 0.4-0.7 of the standard rate. Blower sizing on clean-water performance alone under-sizes the system badly.

Why does nitrification cost so much oxygen?

Oxidising ammonia to nitrate needs two moles of oxygen per mole of nitrogen, which is 4.57 kg per kg of nitrogen. Aeration for nitrification is often the largest single energy consumer at a works.

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