ISO 20468-5:2021

INTERNATIONAL ISO
STANDARD 20468-5
First edition
2021-06
Guidelines for performance evaluation
of treatment technologies for water
reuse systems —
Part 5:
Membrane filtration
Lignes directrices pour l’évaluation des performances des techniques
de traitement des systèmes de réutilisation de l’eau —
Partie 5: Filtration sur membrane
Reference number
©
ISO 2021
© ISO 2021
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 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 List of abbreviated terms . 4
4 Concepts of membrane filtration technology for water reuse . 5
4.1 General . 5
4.2 Membrane type and treatment objectives . 5
4.3 Filtration unit process . 6
4.4 Membrane filtration process design and pre- and post-shipment tests . 7
5 Principles and general guidelines for performance evaluation . 7
5.1 General . 7
5.2 Functional requirements for membrane filtration process. 7
5.3 Non-functional requirements for membrane filtration process . 8
6 Performance evaluation for functional requirement. 8
6.1 General . 8
6.2 Water quality based performance evaluation . 8
6.3 Process based performance evaluation . 9
6.4 Integrity monitoring. 9
6.4.1 Direct Integrity Monitoring . 9
6.4.2 Indirect integrity monitoring .11
7 Performance evaluation for non-functional requirements .12
7.1 General .12
7.2 Energy consumption .12
7.3 Chemical consumption .13
7.4 Brine water disposal or treatment.13
7.5 Solid waste for disposal .14
7.6 Life cycle cost.14
Annex A (informative) Examples of parameters on the specification sheet .15
Annex B (informative) Recommended frequency of data collection .17
Annex C (informative) .18
Bibliography .19
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO 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 the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 282, Water Reuse, Subcommittee SC 3,
Risk and performance evaluation of water reuse systems.
A list of all parts in the ISO 20468 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

Introduction
Guidelines for performance evaluation of water reclamation systems are essential for municipalities,
utilities and reclaimed water users to meet water quality requirements without compromising public
health. ISO 20468-1, Guidelines for performance evaluation of treatment technologies for water reuse
systems specifies fundamental requirements for the overall water reuse system, which mainly focuses
on the finished water quality. When operating a water reclamation system, performance evaluations
at the point of an individual water reclamation process, helps to provide early warnings to enable
operator response in avoiding adverse impacts on public health, and to comply with the targets of final
water quality. It is particularly important for membrane-based water reclamation processes that are
often employed as the most important barriers for the removal of major constituents in wastewater
(e.g. particulates, dissolved solids, and pathogens). In addition, guidelines for performance evaluation
of individual treatment processes in terms of environmental and economic performances can also
assist decisions on the appropriate selection of water reclamation technologies, which is of paramount
importance in water reuse. This document is intended to provide stakeholders typical performance
evaluation approaches designed for membrane filtration technologies. In addition, this document is
expected to assist the development and operation of water reuse projects, in which process designers,
plant managers, and operators are involved. Similar to ISO 20468-1, this document is mainly comprised
of functional and non-functional requirements for the performance evaluation of membrane filtration
technologies.
INTERNATIONAL STANDARD ISO 20468-5:2021(E)
Guidelines for performance evaluation of treatment
technologies for water reuse systems —
Part 5:
Membrane filtration
1 Scope
This document provides guidelines for performance evaluation methods of water reclamation systems
using membrane technologies. This document provides guidance in ensuring treated wastewater
quality levels at the point of exit from the membrane filtration processes. It also provides potential
methods for evaluating the environmental and economic performance of membrane filtration processes
in water reuse. This document helps plant designers, operators and end users to effectively design and
operate the membrane-based water reclamation systems.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 20670:2018, Water reuse — Vocabulary
3 Terms, definitions, and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO 20670, and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 Terms and definitions
3.1.1
backwash
reverse flow of water with/without air across a membrane (i.e. from permeate side to feed side)
Note 1 to entry: It is designated to remove the deposited foreign substances (foulants) from the membrane.
3.1.2
bubble point pressure
pressure differential at which bubbles first appear on one surface of an immersed porous membrane, as
pressure is applied to the other side
3.1.3
cleaning
operation during which membranes are cleaned using a membrane cleaning system with or without
chemical reagents
EXAMPLE backwashing, flushing, chemical cleaning.
[SOURCE: AWWA B110-09]
3.1.4
concentrate
rejected stream exiting a membrane module under a cross-flow (3.1.5) mode
Note 1 to entry: Concentrate stream contains increased concentrations of constituents over the feed stream due
to the accumulation of rejected constituents by membranes in the feed stream.
3.1.5
cross-flow
flow orientation through a membrane module in which the fluid on the upstream side of the membrane
moves parallel to the membrane surface
Note 1 to entry: Fluid on the downstream side of the membrane moves away from the membrane in the direction
normal to the membrane surface.
[SOURCE: AWWA B130-13]
3.1.6
dead-end flow
flow through a membrane module in which the only outlet for the upstream fluid is through the
membrane
[SOURCE: ASTM D6161-19]
3.1.7
feed
input solution entering the inlet of a membrane module or system
3.1.8
flux
membrane throughput, usually expressed in volume of permeate (3.1.
...