COD Load Calculator

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

About COD Load Calculator

COD measures all chemically oxidisable matter and is always higher than BOD. The BOD to COD ratio indicates biodegradability: above 0.5 the effluent treats readily in a biological plant, 0.3-0.5 needs acclimatised biomass and longer sludge age, and below 0.3 biological treatment alone will not achieve consent.

Formulas

COD load

Load (kg/day) = flow x COD / 1000

Biodegradability

BOD/COD ratio indicates the fraction amenable to biological treatment

Worked example

With the default values below, COD Load Calculator returns COD Load of 3,100.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Wastewater Flowminimum 0 m3/day: 5,000 m3/day
COD Concentrationminimum 0 mg/L: 620 mg/L
BOD Concentrationminimum 0 mg/L: 280 mg/L
Consent COD Limitminimum 0 mg/L: 250 mg/L

Results

COD Load: 3,100.000
BOD To COD Ratio: 0.4516
Removal Required For Consent: 59.677%
Treatability Assessment: Biodegradable with acclimatised biomass

Step by step

1Values used
2COD load
3Biodegradability
4COD Load= 3,100.000
5BOD To COD Ratio= 0.4516
6Removal Required For Consent= 59.677
7Treatability Assessment= Biodegradable with acclimatised biomass

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, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
COD and BOD limits are consent conditions. Persistent non-biodegradable load may require pretreatment at source under trade effluent controls.

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

COD and BOD limits are consent conditions. Persistent non-biodegradable load may require pretreatment at source under trade effluent controls.

Frequently Asked Questions

Why measure COD rather than BOD?

COD takes two hours against five days for BOD, so it is the practical control parameter. A site-specific COD to BOD correlation is established and then COD is used for day-to-day monitoring.

What raises COD without raising BOD?

Refractory organics, some solvents, surfactants and reduced inorganics such as sulphide and nitrite. A widening COD to BOD gap often signals an industrial discharge to the sewer.