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Zahn Wellens / EMPA Readily biodegradable assessment

Aqua Enviro utilise three main techniques for assessing feedstocks for aerobic treatment. With these being carbonaceous and nitrification inhibition testing, Zahn Wellens / EMPA RBCOD assessment and laboratory trials using sequence batch reactors.

The Zahn Wellens test is usually the 2nd stage of assessment, comprising of a batch test whereby a known quantity of test material is added to a continually mixed and aerated vessel, containing seed sludge from a suitable activated sludge process. COD degradation is recorded over the 28 day test period.

A report of results will be produced which will show:-

  • % of biodegradable COD
  • COD degradation curve over the test period
  • Amenability of the feedstock for Aerobic treatment
  • Indicate whether the feedstock possesses any inhibitory properties towards carbonaceous bacterial populations

1kg or 1L of test material is required for the testing, for a quotation or general query please contact our Laboratory Manager Andy burgess by tel 01924 242 255 or email

1kg or 1L of test material is required for the testing.

Synonyms / keywords: OECD 302B, EMPA, Zahn Wellens, BCOD, biodegradable chemical oxygen demand, Aerobic biodegradability, aerobic biomass treatability, activated sludge, % COD degradation

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