Biodegradation Tests of Chemicals under Anaerobic Conditions

An apparatus was devised to determine biodegradability under anaerobic conditions. Dissolved oxygen concentrations were reduced to 0.01ppm in test solutions by replacement with nitrogen gas. Biodegradability of the sample was calculated from the decrease in total organic carbon.With 1, 2-dichloropropane, after 5 days of anaerobic incubation biodegradability was approximately 50%, even though in aerobic conditions, 1, 2-dichloropropane is generally considered nondegradable.Test conditions were as follows: 0.1ppm of dissolved oxygen was kept in the test medium (pH 7.0±0.1), with 100ppm of test sample and 30ppm of activated sludge at a temperature of 25±1°C.The results obtained suggest the necessity of making anaerobic tests when complete information on biodegradability is desired.Total biodegradability is, therefore, estimatable by connecting the apparatus to the Coulometer, and determining aerobic degradation from O2 uptake.