ÖNORM EN ISO 11734

This International Standard specifies a screening method for the evaluation of the biodegradability of organic compounds at a given concentration by anaerobic microorganisms. The conditions described in this test do not necessarily correspond to the optimal conditions allowing the maximum value of biodegradation to occur, since a dilute sludge is used with a relatively high concentration of test chemical. The test allows exposure of sludge to the chemical for a period of up to 60 d, which is langer than the normal sludge retention time (25 d to 30 d) in anaerobic digesters, though digesters at industrial sites can have much longer retention times. The method applies to organic compounds with a known carbon content and which are soluble in water; poorly soluble in water, provided that a method of exact dosing is applicable; not inhibitory to the test microorganisms at the concentration chosen for the test; inhibitory effects can be determined in separate tests or by an additional inhibition assay. For volatile substances a case by case decision is necessary. Some can be tested if handled with special care, for example no release of gas during the test.