Modified OECD-Screening Test and DOC Die-Away Test

Principle

Determination of the biodegradability via DOC-elimination.

Abstract

Degradability is measured by the decrease of the dissolved organic carbon (DOC) in a batch test with a low inoculum density. The test item is the only carbon source in a mineralic medium which is incubated with the effluent of a municipal sewage treatment plant for 28 days. Degradation is followed by DOC analysis. The degree of biodegradation is calculated by expressing the concentration of DOC removed (corrected for that in the blank inoculum control) as a percentage of the concentration initially present. Primary biodegradation may also be calculated from supplemental chemical analysis of parent compound samples that were taken at the beginning and at the end of incubation.

Criteria

A DOC degradation degree of at least 70% within 28 days and within a "10-days window" after the end of the lag-phase is defined as criterion for classifying a particular test substance as "readily” biodegradable.

Test substance properties

The „OECD Screening Test“ and the „DOC Die-Away Test“ are applicable to determine the “ready” biodegradability of water-soluble and non-volatile organic substances.