EVS-EN ISO 11733:2004

This International Standard specifies   a method for the determination of the  
elimination and the biodegradability of  organic compounds by aerobic
micro-organisms.  
The conditions described simulate a waste-water treatment plant. Two test systems can be used:
activated sludge plants or porous pots. The tests can optionally be performed under conditions  of
nitrification and denitrification
(Annex A) and coupling of the units (Annex B).
The method applies to organic compounds which, under the conditions of the test, are
a)    soluble in tap water at the test concentration and not expected to be transformed to insoluble metabolites if biodegradation, in addition to elimination, is determined;
b)    poorly  water-soluble, but  which  are  satisfactorily dispersible  in  water  and  allow  detection  with  suitable analytical means (e.g. organic carbon measurements);
c)    non-volatile, or which have a negligible vapour pressure under the test conditions;
d)    not inhibitory to the test micro-organisms at the concentration chosen for the test.
Inhibitory effects can be determined by using a suitable test method (e.g. ISO 8192[151 or ISO 15522[271). Compounds inhibitory at concentrations used in this test may be tested at concentrations less than their EC20 value, followed by
higher practical concentrations after a period of acclimatization.
The method can also be used to measure the biodegradation and elimination of dissolved organic
compounds in waste water (also called "test compound" in the method).
If more or different information is required to predict the behaviour of test compounds or waste water in a treatment plant, other degradation  tests may be performed. For appropriate use of this method and  for alternative biodegradation  methods, see ISO/TR 15462 and for  general information on biotesting,   see ISO 5667-16.