ISO 23070:2020

INTERNATIONAL ISO
STANDARD 23070
First edition
2020-12
Water Reuse in Urban Areas —
Guidelines for reclaimed water
treatment: Design principles of a
RO treatment system of municipal
wastewater
Reference number
©
ISO 2020
© ISO 2020
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Application of RO treatment systems for reclaimed water . 3
5.1 Overview . 3
5.2 Design considerations. 4
5.2.1 Safety considerations . 4
5.2.2 Stability considerations . 4
5.2.3 Economy considerations . 4
5.3 RO system components . 4
5.3.1 General. 4
5.3.2 Feed water source . 5
5.3.3 Pre-treatment unit. 5
5.3.4 RO treatment unit . 5
5.3.5 Auxiliary equipment . 5
5.3.6 Post treatment unit . 5
5.3.7 Water quality and performance monitoring system . 5
6 Technical considerations of pre-treatments . 5
6.1 Quality considerations of feed water . 5
6.1.1 General water quality index . 5
6.1.2 Silt density index. 6
6.1.3 Organic index . 6
6.1.4 Biological index . 7
6.1.5 Oxidation-reduction potential. 7
6.2 Selection of mechanical pre-treatments . 7
6.2.1 Clarification . 7
6.2.2 Media/Multimedia filtration . 7
6.2.3 Activated carbon filtration. 7
6.2.4 Microfiltration and ultrafiltration . 8
6.2.5 Cartridge filtration . 8
6.3 Chemical pre-treatments . 8
6.3.1 Antiscalants . 8
6.3.2 Chemical oxidizers for disinfection of the feed . 8
6.3.3 Reductants . 8
6.3.4 Non-oxidizing biocides . 8
7 Technical and structural considerations of RO unit . 8
7.1 Components . 8
7.1.1 RO feed pumps . 8
7.1.2 RO membrane modules . 9
7.1.3 Pressure vessels. 9
7.2 Selection of RO membranes . 9
7.2.1 Membrane materials . 9
7.2.2 Membrane modules . .10
7.3 RO unit configuration .10
8 Operating conditions and maintenance system.11
8.1 Operating conditions .11
8.1.1 Pressure .11
8.1.2 Temperature .11
8.1.3 Feed water flow and permeate flux .11
8.1.4 Concentrate flow .11
8.1.5 pH .12
8.2 RO performance parameters . .12
8.2.1 Permeate flow rate .12
8.2.2 Salt rejection .13
8.2.3 Pressure drop .13
8.3 Automatic chemical dosing system .13
8.3.1 Dosing point .13
8.3.2 Dosing method .13
8.4 Control and monitor system of RO performance .13
8.4.1 Instrumentation .13
8.4.2 Control system .14
8.4.3 Monitoring system.14
8.5 Cleaning system .14
8.5.1 Physical cleaning .14
8.5.2 Chemical cleaning .14
8.6 Integrity testing of RO systems .15
8.7 System failure .16
9 Post-treatment unit .17
10 RO concentrate management .17
11 Emergency response plan .17
Annex A (informative) Example of an RO treatment system for reclaimed water .19
Annex B (informative) Information of chlorine disinfection for the influent of an RO system .20
Annex C (informative) Maturity level of technologies applied to RO concentrate treatme
...