AS 4351.7-1996

Sets out a method for the evaluation of the 'inherent' biodegradability of organic compounds. The procedure involves the measurement of the dissolved organic carbon content of effluent from a semi-continuous activated sludge unit dosed with a known concentration of the test compound. Comparison of these results with the results obtained with effluent from a control unit allows evaluation of the 'inherent' biodegradability of the test compound. The method generally applies to compounds which are soluble in the test medium, non-volatile, not lost by foaming of the test medium and not inhibitory to the test microorganisms at the concentration chosen for the test. Technically equivalent to ISO 9887:1992.

This Standard specifies a method for the evaluation of the 'inherent' biodegradability of organic compounds. The conditions described in this Standard are much more favourable for biodegradation than those methods for biodegradability described in AS 4351.2, AS 4351.3 and AS 4351.4.The method applies to organic compounds which are -(a) soluble at the concentration used under the test conditions;(b) non-volatile, or which have a negligible vapour pressure under the test conditions;(c) not lost by foaming from the test solution;(d) not significantly adsorbable on glass and activated sludge; and(e) not inhibitory to the test microorganisms at the concentration chosen for the test.Inhibitory effects can be determined by using a suitable test method (e.g. see ISO 8192). If the test compound is toxic, the test concentration has to be lower or a pre-exposed inoculum can be used.NOTE: Additionally, or alternatively, the semi-continuous activated sludge (SCAS) units may be used to provide sludge exposed to the test compound, in order to see whether the sludge becomes adapted, to be used as inocula in other biodegradation tests.WARNING AND SAFETY PRECAUTIONS: ACTIVATED SLUDGE AND SEWAGE MAY CONTAIN POTENTIALLY PATHOGENIC ORGANISMS. THEREFORE APPROPRIATE PRECAUTIONS SHOULD BE TAKEN WHEN HANDLING THEM. TOXIC TEST COMPOUNDS AND THOSE WHOSE PROPERTIES ARE UNKNOWN SHOULD BE HANDLED WITH CARE.

First published as AS 4351.7-1996.