Comparison of 20‐d bod and oecd closed‐bottle biodegradation tests

Abstract

This study correlated the 20‐d Biochemical Oxygen Demand (BOD) test widely used in the United States with the closed‐bottle test selected and refined by the Organization for Economic Cooperation and Development (OECD) for determining biodegradability of a product. Many chemical producers in the United States have 20‐d BOD data on their products; it is important to use this information when valid both in the interim until OECD tests can be completed on these myriad products and in support of the OECD data when available. This paper presents comparative biooxidation data on 16 chemicals using both sealed‐bottle tests. Similar data were obtained at the end of each test, after 20 d in the BOD test and 28 d in the closed‐bottle test. The reduced microbial seed concentration in the closed‐bottle test required longer incubation time to achieve these similar results. The best correlations were obtained at days 10 and 15, and the poorest was indicated at day 5. The environmental classification specified by the European Community is the same for these chemicals, >60% biooxidation for readily biodegradable classification or not, regardless of the biooxidation test. OECD biodegradation screening test data are included in this report; results from this test, which monitors dissolved organic carbon (DOC), support the biooxidation values obtained in both the OECD closed‐bottle test and the 20‐d BOD test.

Standardization of activated sludge for biodegradation tests

“…After biodegradation of 29 chemicals in several OECD tests, it was found that the 301 D and E assays gave 14 and 38% of positive results whereas the 301 B test provided 54% [6]. During a study of the biodegradability of 16 chemicals [28], the 301 D test was found to be as stringent as the 20-day BOD test (BOD: biochemical oxygen demand), irrespective of the inoculum used (i.e., filtered sewage, secondary effluent, or Polyseed, a commercial BOD seed). It was concluded that both tests can be interchangeably used, which also suggests that these sources have equivalent biodegradation potential toward readily biodegradable substances.…”