Guidelines for performance evaluation of treatment technologies for water reuse systems — Part 1: General

This document gives guidelines on performance evaluation of treatment technologies for water reuse systems. It provides typical parameters of water quality and treatment efficiency that are associated with the performances of treatment technologies. It also includes a comparison of measured and target values, and provides treatment technology functional requirements and non-functional requirements.

Lignes directrices pour l’évaluation des performances des techniques de traitement des systèmes de réutilisation de l’eau — Partie 1: Généralités

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Published
Publication Date
30-Oct-2018
Current Stage
6060 - International Standard published
Start Date
31-Oct-2018
Completion Date
31-Oct-2018
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INTERNATIONAL ISO
STANDARD 20468-1
First edition
2018-11
Guidelines for performance evaluation
of treatment technologies for water
reuse systems —
Part 1:
General
Lignes directrices pour l’évaluation des performances des techniques
de traitement des systèmes de réutilisation de l’eau —
Partie 1: Généralités
Reference number
ISO 20468-1:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 20468-1:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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ii © ISO 2018 – All rights reserved
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ISO 20468-1:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and list of abbreviated terms ............................................................................................................... 1

3.1 Terms and definitions ....................................................................................................................................................................... 1

3.2 List of abbreviated terms ............................................................................................................................................................... 4

4 Concepts of treatment technology for water reuse systems ................................................................................... 4

4.1 General ........................................................................................................................................................................................................... 4

4.2 Treatment objective ............................................................................................................................................................................ 5

4.3 Treatment technologies used in fit-for-purpose water reuse ........................................................................ 6

5 Principles and general guidelines for performance evaluation ......................................................................... 8

5.1 General ........................................................................................................................................................................................................... 8

5.2 Performance requirements .......................................................................................................................................................... 9

5.2.1 Treatment technology functional requirements .................................................................................. 9

5.2.2 Treatment technology non-functional requirements ...................................................................... 9

5.2.3 Characteristics of functional and non-functional requirements in

performance evaluation .........................................................................................................................................10

5.3 P erformance evaluation and meeting requirements ..........................................................................................10

5.3.1 General...................................................................................................................................................................................10

5.3.2 Monitoring plan .............................................................................................................................................................11

5.4 Application of the guidelines to treatment systems ............................................................................................11

5.4.1 Treatment system design ......................................................................................................................................11

5.4.2 Treatment system configuration .....................................................................................................................11

6 Functional requirements ..........................................................................................................................................................................12

6.1 General ........................................................................................................................................................................................................12

6.2 P erformance evaluation procedures .................................................................................................................................12

7 Non-functional requirements ..............................................................................................................................................................14

7.1 Examples of performance indicators ................................................................................................................................14

7.2 E valuation method of environmental performance .............................................................................................14

7.2.1 Energy consumption .................................................................................................................................................14

7.2.2 Chemical consumption ............................................................................................................................................15

7.2.3 Amount of solid and liquid waste generated and requiring disposal .............................15

7.2.4 Performance indicators — Integrated considerations.................................................................16

7.3 E valuation method of economic performance..........................................................................................................16

Annex A (informative) Dependability of treatment technology............................................................................................17

Annex B (informative) Dependability evaluation ................................................................................................................................19

Bibliography .............................................................................................................................................................................................................................21

© ISO 2018 – All rights reserved iii
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ISO 20468-1:2018(E)
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 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 2018 – All rights reserved
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ISO 20468-1:2018(E)
Introduction

The rapidly growing global market for water reuse technologies inevitably demands standards

which are applicable on a world-wide basis be developed. Many regions in the world are facing water

shortages, and there is great interest in fit-for-purpose water reuse technologies that can treat and

reclaim wastewater to a water quality level that is suitable for a wide range of reuse applications that

can satisfy non-potable water demands, thereby conserving precious potable water resources. The

implementation of water reuse programs raises public and regulatory concern regarding potential

human health, environmental and societal impacts. This has led to an increasing need to specify

various aspects of water reuse projects, and regulators, reuse technology suppliers, and users of those

technologies have a growing need for international standardization. A great number of opportunities

for sustainable water use and development based on water reclamation can be lost without ISO water

reuse standards.

Standardization needs to 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 the most appropriate technologies in an unbiased way to achieve the objectives of

water reuse projects. 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 wastewater reclamation 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 for a multitude of applications. This

document provides treatment technology functional requirements and non-functional requirements,

the former based on water quality parameter concentration or removal efficiency and the latter based

on performance indicators. A step-by-step procedure for evaluating the functional requirements and

examples of non-functional key performance indicators and evaluation methods are provided.

This document is intended for use by planners and managers of water reuse projects, technical advisors,

designers, operators of the treatment systems, those involved in monitoring, assessing, regulating and

other activities of third-party organizations or relevant authorities, as well as treatment technology

manufacturers.

The application of the guidelines for performance evaluation at the stages of procurement, designing

and operation of treatment systems can enable, for example:

— designers to identify and evaluate an optimal treatment system design which will meet regulatory

performance requirements;
— manufacturers to determine technology performance expectations;

— operators to evaluate and improve the operating efficiency and performance of water reuse

treatment systems.

This document is not intended to address the design and integration of specific unit treatment processes

or overall treatment system design.

This document can be useful for the application of management system standards, such as ISO 9001,

ISO 14001, ISO 22301, ISO 50001, and ISO 55001.
© ISO 2018 – All rights reserved v
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INTERNATIONAL STANDARD ISO 20468-1:2018(E)
Guidelines for performance evaluation of treatment
technologies for water reuse systems —
Part 1:
General
1 Scope

This document gives guidelines on performance evaluation of treatment technologies for water reuse

systems. It provides typical parameters of water quality and treatment efficiency that are associated

with the performances of treatment technologies. It also includes a comparison of measured and target

values, and provides treatment technology functional requirements and non-functional requirements.

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 reference, 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 list of 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
availability

ability of a treatment technology to be in a state to perform a required function under

given conditions at a given instant of time or over a given time interval, assuming that the required

external resources are provided

Note 1 to entry: This ability depends on the combined aspects of the reliability performance, the maintainability

performance, and the maintenance support performance.

Note 2 to entry: Required external resources, other than maintenance resources, do not affect the availability

performance of the treatment technologies.
[SOURCE: IEC 60050-191:1990, 191-02-05]
3.1.2
benchmarking

tool for performance improvement through systematic search and adaptation of leading practices

[SOURCE: Benchmarking Water Services - Guiding water utilities to excellence (2011)]

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ISO 20468-1:2018(E)
3.1.3
correction
action to eliminate a detected nonconformity

[SOURCE: ISO 9000:2015, 3.12.3, modified — Notes 1 and 2 to entry have been deleted.]

3.1.4
corrective action
action to eliminate the cause of a nonconformity and to prevent recurrence

[SOURCE: ISO 9000:2015, 3.12.2, modified — Notes 1 to 3 to entry have been deleted.]

3.1.5
dependability

collective term used to describe the availability performance and its influencing factors

EXAMPLE Reliability performance, maintainability performance and maintenance support performance.

[SOURCE: IEC 60050-191:1990, 191-02-03]
3.1.6
downtime

amount of time that a system or a component is not able to operate or meet required functions

3.1.7
failure

state in which a treatment technology does not meet a functional or a non-functional requirement

3.1.8
functional requirement

requirement related to the transformation of water quality by a treatment technology

3.1.9
maintainability

ability of a treatment technology under given conditions of use, to be retained in, or

restored to, a state in which it can perform a required function, when maintenance is performed under

given conditions and using stated procedures and resources

[SOURCE: IEC 60050-191:1990, 191-02-07, modified — Notes 1 to entry has been deleted.]

3.1.10
maintenance support performance

ability of a maintenance organisation, under given conditions and maintenance policy, to provide, upon

demand, the resources required to maintain the treatment technology

Note 1 to entry: The given conditions are related to the treatment technology and to the conditions under which

the treatment technology is used and maintained.

Note 2 to entry: When evaluating the treatment technologies, required maintenance support performance can be

used as a given condition to evaluate the maintainability.

[SOURCE: IEC 60050-191:1990, 191-02-08, modified — Note 2 to entry has been added.]

3.1.11
nonconformity
non-fulfilment of a requirement
[SOURCE: ISO 30000:2009, 3.8]
3.1.12
non-functional requirement

requirement that specifies criteria or constraints on the design or implementation of a treatment

technology
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ISO 20468-1:2018(E)
3.1.13
performance evaluation

overall process to judge whether, or to measure the extent to which the outputs or state of a system, or

a component, fulfill the requirements
Note 1 to entry: See ISO 9001:2015, Clause 9.
3.1.14
performance indicator

parameter, or a value derived from parameters, which provides information about the performance of

a subject matter with a significance extending beyond that directly associated with a parameter value

Note 1 to entry: See ISO 24511:2007, 2.16.
3.1.15
predictive analysis

practice of extracting information from existing data sets in order to determine patterns and predict

future outcomes and trends
3.1.16
removal efficiency
efficiency of removal of a constituent

Note 1 to entry: Removal efficiency and log removal value for some specific constituent are defined by the

following Formula (1) and Formula (2):
RE =−1 (1)
 
loglRV =− og 1−=RE  −log (2)
() ()
 
10 10
 
 
 
where
RE is the removal efficiency;
C is the effluent constituent concentration;
C is the influent constituent concentration;
RV is the removal value.

Note 2 to entry: Removal efficiency is often expressed as a percentage. A value of indicator for the constituent can

be used in place of concentration of the constituent. Log removal value is often used for microbial constituents.

3.1.17
requirement
need or expectation that is stated, generally implied or obligatory

[SOURCE: ISO 9000:2015, 3.6.4, modified — Notes 1 to 6 to entry have been deleted.]

3.1.18
robustness

ability of a structure to withstand adverse and unforeseen events or consequences of human errors

without being damaged to an extent disproportionate to the original cause
[SOURCE: ISO 2394:2015, 2.1.46, modified.]
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ISO 20468-1:2018(E)
3.1.19
safety
freedom from risk which is not tolerable
[SOURCE: ISO/IEC GUIDE 51:2014, 3.14]
3.2 List of abbreviated terms
BOD biochemical oxygen demand
COD chemical oxygen demand
E. coli Escherichia coli
LCA life cycle assessment
LCC life cycle cost
LRV log removal value
MBR membrane bioreactor
PAA peracetic acid
QA quality assurance
QC quality control
RO reverse osmosis
TDS total dissolved solids
TSS total suspended solids
UV ultraviolet
4 Concepts of treatment technology for water reuse systems
4.1 General

Clause 4 outlines information on treatment technologies including treatment systems and processes.

The constituents found in untreated wastewater are derived from the substances that come into

contact with water used for various domestic, commercial, and industrial uses; as well as those carried

by stormwater which flows into sanitary system. The focus of this document is on the performance of

the processes and systems with respect to constituents of concern for water reuse applications that

include suspended solids, colloidal turbidity, dissolved constituents (i.e. dissolved organic and inorganic

substances such as sugars and fats, heavy metals, nutrients, etc.), and pathogens (disease causing

viruses, bacteria, protozoa and helminths) assessed by indicator microorganisms. Various treatment

processes can be used individually or combined to remove a target constituent.

The water quality requirements of a given reuse application governs the type of treatment needed and

the degree of treatment reliability. Because health and environmental concerns are primary issues in

implementing water reuse, attention should be focused on developing treatment systems to ensure

whether water quality requirements are consistently met. With respect to performance of disinfection

technologies, a multi-barrier approach is recommended (i.e. two or more different processes including

at least one form of disinfection and additional barriers with accepted levels of pathogen reduction).

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ISO 20468-1:2018(E)
4.2 Treatment objective

Because of the importance of water quality in water reuse applications, different technologies are

often combined to achieve desired levels of constituent removal. Figure 1 shows progressive stages of

wastewater treatment processes.
NOTE Post-chlorination is applied depending on the end use.
[20]
Figure 1 — Wastewater treatment stages as per reuse applications

One of the primary objectives of treatment technologies for water reuse is to reduce the pathogen

content to reduce public health risk associated with exposure to reuse water. While disinfection

requirements can vary depending on the specific water reuse application, disinfection is most

commonly accomplished by the use of chemical oxidants (e.g. chlorine based oxidants, and ozone),

UV, membrane filtration and (more recently) PAA. Disinfection can include treatment strategies that

incorporate multiple disinfection technologies or ultrafiltration/reverse osmosis treatments in series

as necessary – referred to as a multi-barrier approach to disinfection. The purpose of the multi-barrier

approach is, in part, to provide a back-up disinfection mechanism in the event one of the technologies

relied upon for disinfection should underperform because of design or equipment failure; however, it is

also carried out in recognition that not all pathogens are equally affected by a particular disinfection

technology, and that combinations of disinfection/treatment technologies can achieve a more effective

and broader range of pathogen reduction. A multi-barrier approach can also include the maintenance of

a residual level of disinfectant (e.g. post-chlorination) in water to prevent recontamination.

[20]

The general categories of treatment technologies in this document are shown below .

— Preliminary treatment

Preliminary treatment is to remove from the wastewater any constituents which can clog or damage

pumps or other equipment, or interfere with the operation or maintenance of the subsequent

treatment processes. It consists of removal of large size, suspended or floating materials and also

heavy settleble solids such as rags, sticks, grit, and grease.
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ISO 20468-1:2018(E)
— Primary treatment

Primary treatment targets the removal of settleable organic and inorganic solids by sedimentation,

and the removal of materials that will float (scum) by skimming. Enhanced removal of suspended

solids and organic matter from the wastewater can be accomplished by chemical addition or

filtration (e.g. fine mesh filtration).
— Secondary treatment

In secondary treatment, biological, chemical and physical processes are used to reduce most of

the soluble organic matter and organic and inorganic particulates, measured as BOD or COD and

TSS. There is a very wide range of biological processes used for secondary treatment including

those that incorporate suspended bacteria, fixed film and hybrid (i.e. suspended and fixed film

bacteria) followed by a solid-liquid separation step, typically by sedimentation (e.g. clarifier).

Typical biological processes used for secondary treatment include activated sludge, trickling

filters, rotating biological contactors and non-conventional treatment processes such as lagoons,

wetlands that are capable of achieving secondary treatment water quality criteria. Secondary

biological treatment can also remove nutrients. MBR is an alternative biological treatment process

for secondary treatment.
— Tertiary treatment

Tertiary treatment follows the secondary treatment of wastewater, and aims at producing higher

quality treated wastewater. Effluent from secondary treatment plants typically contains residual

dissolved organic constituents, suspended solids and colloidal particulate matter that, in certain

jurisdictions, and/or depending on the particular reuse application, can require further reduction.

Their removal can be achieved by filtration. Color and odor can also be constituents targeted for

removal by tertiary treatment. Tertiary treatment can include additional removal of nitrogen and

phosphorus.
— Advanced treatment

Advanced treatment targets the removal of TDS and/or trace constituents as required for

specific water reuse applications. This can include, for example, complex and/or toxic organic

compounds, heavy metals, color, odor compounds remaining after tertiary treatment and emerging

contaminants (e.g. pharmaceuticals, nanotechnology byproducts, etc.). Technologies to achieve

advanced treatment can include chemical or physical processes such as ozonation, advanced

oxidation, adsorption, or ion exchange, either singly or in combination with membrane technologies.

— Disinfection

Disinfection is enhanced by the upstream removal of particulate matter that often shields

pathogenic organisms from the disinfecting agent, and this is especially critical for UV disinfection.

Technologies used to remove particulates (e.g. filtration) not only improve the efficacy of

disinfection technologies, but can also reduce the number of pathogens present prior to disinfection

and form part of a multi-barrier approach to disinfection to ensure public health protection and

maximize process reliability. Disinfection can be used after secondary, tertiary, or advanced

treatment as necessary (see Figure 1).
— Post-chlorination

Post-chlorination is a method of adding and maintaining a minimum level of chlorine within the

reuse water distribution system. It provides the control of chlorine residual for the prevention

of regrowth of microorganisms or recontamination in distribution systems. Post-chlorination is

typically performed before reuse water is delivered to end users.
4.3 Treatment technologies used in fit-for-purpose water reuse

The required water quality for reuse water depends on the intended non-potable reuse application

and the degree of health and environmental risks associated with that application. As a rule, domestic,

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ISO 20468-1:2018(E)

commercial and irrigation water demands can be met using reclaimed water with a water quality lower

than drinking water, with the primary consideration being the degree of disinfection required to protect

public health. As a result, many jurisdictions have multiple reuse water quality standards, or treatment

objectives, that reflect the public health and environmental risks associated with specific categories of

water application. Treatment to remove the risks of clogging, biofilms, etc. is also necessary for some

industrial, urban or irrigation (for example, drip, sprinkler etc.) reuse applications. This framework

can be called “fit-for-purpose water reuse”, which achieves beneficial, safe and sustainable water reuse

with minimum energy and cost while protecting human health and the environment. The primary goal

to the success of this framework is to reclaim water to the water quality level that is acceptable for its

intended use, while ensuring the economic viability of water reuse projects, especially in the case of

decentralized small wastewater treatment systems, without significant impact on the environment.

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