ISO 20468-4:2021

INTERNATIONAL ISO
STANDARD 20468-4
First edition
2021-05
Guidelines for performance evaluation
of treatment technologies for water
reuse systems —
Part 4:
UV Disinfection
Lignes directrices pour l’évaluation des performances des techniques
de traitement des systèmes de réutilisation de l’eau —
Partie 4: Désinfection aux UV
Reference number
©
ISO 2021
© ISO 2021
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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 . 3
4 Purpose and function of UV disinfection . 3
4.1 Purpose . 3
4.2 Function . 3
5 System configuration . 3
5.1 General . 3
5.2 UV unit . 4
5.3 Influent water quality monitoring devices . 4
5.4 Flow meter . 4
5.5 Power control panel . 4
6 Functional requirements . 5
6.1 General . 5
6.2 Evaluation of the UV unit performance . 5
6.3 Method of monitoring UV treatment system performance . 5
6.3.1 Monitoring of influent water flow [M1] . 6
6.3.2 Quality control of influent water [M2] . 6
6.3.3 Monitoring of UV irradiation [M3] . 6
6.3.4 Monitoring of treated water quality [M4] . 7
6.4 Diagnosis of causes for system failure . 8
7 Non-Functional requirements . 8
7.1 Environmental performance . 8
7.1.1 Energy efficiency. 8
7.1.2 Chemical consumption . 8
7.2 Safety . 8
7.3 Cost effectiveness of systems — Economic evaluation by LCC. 9
7.4 Reliability and resilience . 9
Annex A (informative) Main treatment technologies and target constituents for water reuse .10
Annex B (informative) Experimental evaluation method for UV units .11
Annex C (informative) Experimental evaluation method in combination with CFD-I simulations .12
Bibliography .18
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
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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 systems.
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
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 reclaimed 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 include objective specification and evaluation of levels of service and water
reuse system performance dependability including safety, environmental protection, resilience and
cost-effectiveness considerations. Hence, appropriate methods are needed to evaluate the performance
of treatment technologies for water reuse systems.
The performance of treatment technologies for water reuse, inter alia, should be evaluated properly
in order to select 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. Performance evaluations are
also useful for assessing the efficiency of existing water reuse systems and operations, including the
identification of continuous improvement opportunities. 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 which can be
applied to a variety of wastewater treatment technologies and their combinations, while descriptions
specific to the representative technologies should be included in individual standards being submitted
subsequently to ISO 20468-1. In this context, this document stipulating specific ways of performance
evaluation of UV treatment technology for water reuse systems, based on ISO 20468-1 as the generic
standard is established herein.
In non-potable water reuse systems, UV technology is used mainly for disinfection as indicated in
Table A.1 and works well with secondary or tertiary treated water as shown in ISO 20468-1:2018,
Figure 1.
This guideline is intended as an integrated part of a framework for UV systems, consistent with other
items in the work of TC 282. This framework includes several important aspects such as design,
validation and verification (ISO 9000) and evaluation.
Guidelines focused on UV System Design, Validation and Evaluation are found in ISO 16075-5:2021,
Clause 7.
Guidelines focused on UV system Design, Verification and Evaluation are found in ISO 20468-4.
INTERNATIONAL STANDARD ISO 20468-4:2021(E)
Guidelines for performance evaluation of treatment
technologies for water reuse systems —
Part 4:
UV Disinfection
1 Scope
This document provides guidelines for performance evaluation methods of UV disinfection for full scale
water reuse systems. It deals with the methods of measurement of typical parameters which indicate
performance of UV disinfection 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, 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
...