OECD 301/ OECD 306
Biodegradation is a process by which microbial organisms transform or alter (through metabolic or enzymatic action) the structure of chemicals introduced into the environment.
Ready biodegradability is a screening test for biodegradation of chemicals.
A solution of the test substance – as the sole source of organic carbon – in mineral medium is inoculated by a relatively small number of microorganisms and incubated under aerobic conditions in the dark or in diffuse light.
The degradation is followed for 28 days, at least, by the determination of non-specific parameters such as oxygen uptake.
The pass-level for biodegradability (60 % removal of the theorical oxygen demand) should be reached in a 10-day window within the 28-day period of the test.
OECD 301D – Closed-bootle test is convenient for every chemicals including low soluble, volatile and/or adsorbing substances. The test solution (2-5 mg/L) is kept in completely full closed bottles. The biodegradation, if any, is determined by analysis of oxygen uptake by the microorganisms.
OECD 301F – Manometric respirometry test is convenient for any chemical except volatile substances. The test solution (100 mg/L) is continuously stirred in closed flasks. Evolved carbon dioxide is adsorbed and the biodegradation, if any, is determined by the change in pressure due to the consumption of oxygen by the microorganisms.
OECD 306 – Biodegradability in sea water includes sea water variants of the Closed-bottle test (OECD 301D).