ISO 9408 pdf download

ISO 9408 pdf download.Water quality — Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium by determination of oxygen demand in a closed respirometer 1 Scope This International Standard specifies a method, by determination of the oxygen demand in a closed respirometer, for the evaluation in aqueous medium of the ultimate biodegradability of organic compounds and waste waters at a given concentration by aerobic microorganisms. The method applies to organic compounds which a) are water-soluble under the conditions of the test; b) are poorly water-soluble under the conditions of the test, in which case special measures may be necessary to achieve good dispersion of the compound (see for example, ISO 1 0634); c) do not reach and react with the CO 2 absorbent; d) are volatile, provided that a suitable respirometer or suitable conditions (e.g. a smaller ratio of volume head space to volume liquid medium) are used; e) are not inhibitory to the test microorganisms at the concentration chosen for the test. The presence of inhibitory effects can be determined as specified in 7.3, or by using any other method for determining the inhibitory effect of a compound on bacteria (see, for example, ISO 8192). NOTE The conditions described in this International Standard do not always correspond to the optimal conditions for allowing the maximum degree of biodegradation to occur. For alternative biodegradation methods, see ISO 1 5462. 2 Terms and definitions For the purposes of this International Standard, the following terms and definitions apply. 2.1 ultimate aerobic biodegradation breakdown of a chemical compound or organic matter by microorganisms in the presence of oxygen to carbon dioxide, water and mineral salts of any other elements present (mineralization) and the production of new biomass 2.2 primary biodegradation structural change (transformation) of a chemical compound by microorganisms, resulting in the loss of a specific property 2.3 activated sludge biomass produced in the aerobic treatment of wastewater by the growth of bacteria and other microorganisms in the presence of dissolved oxygen 2.4 concentration of suspended solids of an activated sludge amount of solids obtained by filtration or centrifugation of a known volume of activated sludge and drying at about 1 05 °C to constant mass 2.5 biochemical oxygen demand BOD mass concentration of dissolved oxygen consumed under specified conditions by the aerobic biological oxidation of a chemical compound or organic matter in water NOTE It is expressed in this case...