ISO 20468-3:2020

INTERNATIONAL ISO
STANDARD 20468-3
First edition
2020-06
Guidelines for performance evaluation
of treatment technologies for water
reuse systems —
Part 3:
Ozone treatment technology
Lignes directrices pour l’évaluation des performances des techniques
de traitement des systèmes de réutilisation de l’eau —
Partie 3: Technique de traitement à l'ozone
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 .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 Abbreviated terms . 2
4 System configuration . 2
4.1 General . 2
4.2 Ozone system for water treatment . 3
4.2.1 Feed gas supply unit. 3
4.2.2 Ozone generation unit . 3
4.2.3 Ozone contact unit . . 3
4.2.4 Off-gas ozone treatment unit . 3
4.2.5 Ozone measuring system . 4
5 Principles and general guidelines for performance evaluation . 4
5.1 General . 4
5.2 Functional requirements . 4
5.2.1 General. 4
5.2.2 Performance evaluation procedures . 5
5.3 Non-functional requirements . 7
5.3.1 Performance characteristics . 7
5.3.2 Environmental and economic key factors . 7
5.3.3 Safety requirements . 8
Annex A (informative) Main treatment technologies and target constituents for water reuse .9
Annex B (informative) Reuse water quality parameters .10
Annex C (informative) Ozone concentration monitoring points .23
Annex D (informative) Ozone generation control methods .25
Bibliography .26
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 of 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 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 system.
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 2020 – All rights reserved

Introduction
The rapidly growing global market for water reuse technologies inevitably demands standards which
are applicable on a world-wide basis. Many regions in the world are facing water shortages, and there is
great interest in the use of technologies that can treat wastewater and make the reuse water available
for a wide range of reuse applications that can satisfy non-potable water demands, thereby conserving
precious potable water supplies. Simultaneously, the implementation of water reuse schemes is raising
public and regulatory concerns regarding potential human health, environmental and societal impacts.
This has led to an increasing need to specify various aspects of water reuse projects and there is a
growing need on behalf of regulators, reuse technology suppliers, and users of those technologies for
international standardization. Without ISO water reuse standards, a great number of opportunities for
sustainable development based on water reuse will be lost.
Standardization needs to include objective specification and evaluation of levels of service and water
reuse system performance dependability, including safety, environmental protection, and resilience and
cost-effectiveness considerations. Hence, appropriate methods are needed to evaluate the performance
of water reuse systems.
The performance of treatment technologies for water reuse, inter alia, should be evaluated properly in
order to select the most appropriate technologies in an unbiased way to achieve the objectives of the
water reuse project. Despite considerable research and development on treatment technologies, such
scientific knowledge is largely held within commercial interests. Given less than ideal communication
between producers and users of reuse technologies with regards to treatment performance, clear
information as to what to measure on the one hand and what level of performance is required on the
other is currently missing. To address these challenges, this document provides methods and tools,
which can be accepted by most stakeholders, to evaluate the performance of treatment technologies for
water reuse systems from multitude of applications.
Based on the discussion in the meetings of ISO/TC 282/SC 3, ISO 20468-1 titled “Guidelines for
performance evaluation of treatment technologies for water reuse systems — Part 1: General” has been
developed to establish the standard of generic aspects for performance evaluation. In this context,
this document stipulating specific ways of performance evaluation of ozone treatment technology,
commonly known as ozonation, for water reuse systems, based on ISO 20468-1 as the generic standard,
is established herein.
Ozone (O ) is an allotrope of oxygen (O ) and is the second strongest oxidiser after fluorine. Its strong
3 2
oxidative decomposition power makes it effective as a disinfectant and in removal of oxidizable
constituents in water. There are cases where ozonation at high doses is used to remove micro-pollutants
in wastewater for environmental protection.
In various types of water reuse systems, the disinfection and the removal of colour and odour are
essential. Then it can be said that ozone technology plays an important role to improve these water
qualities for the purpose of water reuse, working well with secondary or tertiary treated water as
shown in Figure 1 of ISO 20468-1:2018 and in Annex A.
In this guideline, the dedicated features to ozone technology for water reuse are described and the
requirements for proper and accurate evaluation of ozone system for water reuse are offered.
INTERNATIONAL STANDARD ISO 20468-3:2020(E)
Guidelines for performance evaluation of treatment
technologies for water reuse systems —
Part 3:
Ozone treatment technology
1 Scope
This document specifies performance evaluation methods of treatment technology using ozone for
water reuse systems. It deals with how to measure typical parameters which indicate performance of
ozone treatment technology.
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, Water reuse — Vocabulary
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following 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
ambient ozone concentration
concentration of ozone existing in the air or surrounding the ozone treatment apparatus
3.1.2
exhaust residual ozone concentration
ozone concentration (3.1.6) at the outlet of an off-gas ozone treatment unit
3.1.3
generated ozone amount
mass of ozone generated in a unit time
3.1.4
generated ozone concentration
ozone concentration (3.1.6) in the gas phase at the outlet of an ozone generator
3.1.5
off-gas ozone concentration
ozone concentration at the outlet of an ozone contactor
3.1.6
ozone concentration
volume, mass or mole of ozone in a unit volume or mass of gas or liquid
3.1.7
ozone concentration monitor
instrument capable of measuring ozone concentration in samples continuously
3.1.8
ozone demand
amount of ozone consumed to oxidize material in water
3.1.9
ozone dose
...

INTERNATIONAL ISO
STANDARD 20468-3
First edition
2020-06
Guidelines for performance evaluation
of treatment technologies for water
reuse systems —
Part 3:
Ozone treatment technology
Lignes directrices pour l’évaluation des performances des techniques
de traitement des systèmes de réutilisation de l’eau —
Partie 3: Technique de traitement à l'ozone
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 .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 Abbreviated terms . 2
4 System configuration . 2
4.1 General . 2
4.2 Ozone system for water treatment . 3
4.2.1 Feed gas supply unit. 3
4.2.2 Ozone generation unit . 3
4.2.3 Ozone contact unit . . 3
4.2.4 Off-gas ozone treatment unit . 3
4.2.5 Ozone measuring system . 4
5 Principles and general guidelines for performance evaluation . 4
5.1 General . 4
5.2 Functional requirements . 4
5.2.1 General. 4
5.2.2 Performance evaluation procedures . 5
5.3 Non-functional requirements . 7
5.3.1 Performance characteristics . 7
5.3.2 Environmental and economic key factors . 7
5.3.3 Safety requirements . 8
Annex A (informative) Main treatment technologies and target constituents for water reuse .9
Annex B (informative) Reuse water quality parameters .10
Annex C (informative) Ozone concentration monitoring points .23
Annex D (informative) Ozone generation control methods .25
Bibliography .26
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 of 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 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 system.
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 2020 – All rights reserved

Introduction
The rapidly growing global market for water reuse technologies inevitably demands standards which
are applicable on a world-wide basis. Many regions in the world are facing water shortages, and there is
great interest in the use of technologies that can treat wastewater and make the reuse water available
for a wide range of reuse applications that can satisfy non-potable water demands, thereby conserving
precious potable water supplies. Simultaneously, the implementation of water reuse schemes is raising
public and regulatory concerns regarding potential human health, environmental and societal impacts.
This has led to an increasing need to specify various aspects of water reuse projects and there is a
growing need on behalf of regulators, reuse technology suppliers, and users of those technologies for
international standardization. Without ISO water reuse standards, a great number of opportunities for
sustainable development based on water reuse will be lost.
Standardization needs to include objective specification and evaluation of levels of service and water
reuse system performance dependability, including safety, environmental protection, and resilience and
cost-effectiveness considerations. Hence, appropriate methods are needed to evaluate the performance
of water reuse systems.
The performance of treatment technologies for water reuse, inter alia, should be evaluated properly in
order to select the most appropriate technologies in an unbiased way to achieve the objectives of the
water reuse project. Despite considerable research and development on treatment technologies, such
scientific knowledge is largely held within commercial interests. Given less than ideal communication
between producers and users of reuse technologies with regards to treatment performance, clear
information as to what to measure on the one hand and what level of performance is required on the
other is currently missing. To address these challenges, this document provides methods and tools,
which can be accepted by most stakeholders, to evaluate the performance of treatment technologies for
water reuse systems from multitude of applications.
Based on the discussion in the meetings of ISO/TC 282/SC 3, ISO 20468-1 titled “Guidelines for
performance evaluation of treatment technologies for water reuse systems — Part 1: General” has been
developed to establish the standard of generic aspects for performance evaluation. In this context,
this document stipulating specific ways of performance evaluation of ozone treatment technology,
commonly known as ozonation, for water reuse systems, based on ISO 20468-1 as the generic standard,
is established herein.
Ozone (O ) is an allotrope of oxygen (O ) and is the second strongest oxidiser after fluorine. Its strong
3 2
oxidative decomposition power makes it effective as a disinfectant and in removal of oxidizable
constituents in water. There are cases where ozonation at high doses is used to remove micro-pollutants
in wastewater for environmental protection.
In various types of water reuse systems, the disinfection and the removal of colour and odour are
essential. Then it can be said that ozone technology plays an important role to improve these water
qualities for the purpose of water reuse, working well with secondary or tertiary treated water as
shown in Figure 1 of ISO 20468-1:2018 and in Annex A.
In this guideline, the dedicated features to ozone technology for water reuse are described and the
requirements for proper and accurate evaluation of ozone system for water reuse are offered.
INTERNATIONAL STANDARD ISO 20468-3:2020(E)
Guidelines for performance evaluation of treatment
technologies for water reuse systems —
Part 3:
Ozone treatment technology
1 Scope
This document specifies performance evaluation methods of treatment technology using ozone for
water reuse systems. It deals with how to measure typical parameters which indicate performance of
ozone treatment technology.
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, Water reuse — Vocabulary
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following 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
ambient ozone concentration
concentration of ozone existing in the air or surrounding the ozone treatment apparatus
3.1.2
exhaust residual ozone concentration
ozone concentration (3.1.6) at the outlet of an off-gas ozone treatment unit
3.1.3
generated ozone amount
mass of ozone generated in a unit time
3.1.4
generated ozone concentration
ozone concentration (3.1.6) in the gas phase at the outlet of an ozone generator
3.1.5
off-gas ozone concentration
ozone concentration at the outlet of an ozone contactor
3.1.6
ozone concentration
volume, mass or mole of ozone in a unit volume or mass of gas or liquid
3.1.7
ozone concentration monitor
instrument capable of measuring ozone concentration in samples continuously
3.1.8
ozone demand
amount of ozone consumed to oxidize material in water
3.1.9
ozone dose
...