ISO INTERNATIONAL STANDARD 9888 Second edition 1999-06-01 Water quality Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium Static test (Zahn-Wellens method) Qualité de I'eau - Evaluation, en milieu aqueux, de la biodégradabilite aérobie ultime des composés organiques-Essai statique (méthode Zahn-Wellens) ISO Reference number ISO9888:1999(E) IHS unde Not for Resale ISO 9888:1999(E) Contents 1Scope 2 Normative reference 3 Terms and definitions 4 Principle. 5 Test environment 3 6 Reagents 7 Apparatus 8 Procedure 9 Calculation and expression of results.. .7 10 Validity of results 8 11Test report. ...8 Annex A (informative) Example ofa biodegradation curve 10 Bibliography. ?ISO1999 Allrights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic InternationalOrganizationforStandardization Casepostale56·CH-1211Geneve20·Switzerland [email protected] Printed in Switzerland onal Organization for Standardization Not for Resal @ISO ISO9888:1999(E) Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(lSo member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has liaison with isO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 9888 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 5, Biological methods. Thissecondeditioncancelsandreplacesthefirstedition(lsO9888:1991),whichhasbeentechnicallyrevised. Annex A of this International Standard is for information only. ii