This Test Guideline describes a method to assess the extent and kinetics of primary and ultimate biodegradation of organic chemicals whose route of entry into the environment begins with their discharge to wastewater. It consists of five simulation tests in a) sewer systems, b) activated sludge, c) anaerobic digester sludge, d) treated effluent in the mixing zone of surface water, and e) untreated wastewater that is directly discharged to surface water. These tests are appropriate for chemicals released continuously or episodically to wastewater.
The five test methods described are open batch systems or closed gas flow-through batch systems. The principle objectives are to i) measure the rate of primary biodegradation, ii) measure the rate of mineralization and iii ) follow the formation and decay of major transformation products when appropriate.
Typically, a test chemical, radiolabelled (14C) in an appropriate position, is incubated with a representative environmental sample. Abiotic and biotic treatments are prepared for each test chemical and condition. The level of parent and degradation products is determined using chromatographic separation and radio-analytical detection methods.