ISO INTERNATIONAL STANDARD 21939-1 First edition 2019-05 A method to calculate and express energy consumption of industrial wastewater treatment for the purpose of water reuse - Part 1: Biological processes Reference number ISO 21939-1:2019(E) ISO @ IS0 2019 IS0 21939-1:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ ISO 2019 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or Iso's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122 749 0111 Fax: +41 22 749 09 47 Email: [email protected] Website: www.iso.org Published in Switzerland ii @ IS0 2019 - All rights reserved IS0 21939-1:2019(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. ..1 2 Normative references 3 Terms and definitions, symbols and abbreviated terms .2 3.1 Terms and definitions. .2 3.2 Symbols and abbreviated terms. .2 4 Expression and normalization of energy consumption .2 4.1 Energy consumption indicator. .2 4.2 Calculation.. .4 5 Components contribution to the energy consumption .4 5.1 General 4 5.1.1 Steadystateconditions 4 5.1.2 Consideration of flow rate 5 5.1.3 Calculation ofvariable consumptions .5 5.1.4 Accounting for addition of oxidizing chemicals .5 5.1.5 Physico-chemical separation pre-treatment processes ..5 5.2 List of system components .6 5.2.1 General. .6 5.2.2 Aeration and combined mixing and aeration equipment .6 5.2.3 Mixing .6 5.2.4 Solid-liquid separation .6 5.2.5 Internal circulation pumping .6 5.2.6 Circulation of settled sludge. ..6 5.2.7 Other pumping. .6 5.2.8 Air driven pumping and/or mixing .6 6 Factoring of different process conditions .7 6.1 General .7 6.2 Temperature adjustments. .7 6.3 Barometric pressure adjustment 1 6.4 Type of wastewater. .7 Annex A (informative) References to formulae and calculations .8 Annex B (informative) Example calculations .9 Bibliography ..12 @ IS0 2019 - All rights reserved iii