Evaluation methods for industrial wastewater treatment reuse processes

This document specifies the principles and framework for comprehensive evaluation of industrial wastewater treatment reuse processes, including: a) establishing goals and scope; b) illustrating the evaluation procedure; and c) determination of evaluation indicators (technology indicator/sub-indicators, environment indicator/sub-indicators, resource indicator/sub-indicators, economy indicator/sub-indicators). This document describes how to comprehensively evaluate industrial wastewater treatment reuse processes using the proposed calculation approaches and recommended indicators. It does not specify methodologies for single evaluation indicators. The document is intended to provide assistance to a broad range of industrial wastewater treatment and reuse project stakeholders including professionals (planning, management, designers, and operators), administrative agencies (monitoring, assessment, regulation and administration) and local authorities. This document is applicable to a) evaluating comparing and selecting industrial wastewater treatment reuse processes, b) implementing continuous improvements, c) upgrading processes and improving performance for existing treatment and reuse facilities. The intended application of the comprehensive evaluation result is considered within the goal and scope definition.

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Status
Published
Publication Date
16-Mar-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
19-Feb-2021
Completion Date
19-Feb-2021
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INTERNATIONAL ISO
STANDARD 23043
First edition
2021-03
Evaluation methods for industrial
wastewater treatment reuse processes
Reference number
ISO 23043:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23043:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© 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
---------------------- Page: 2 ----------------------
ISO 23043:2021(E)
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 Evaluation principles ....................................................................................................................................................................................... 2

4.1 Comprehensiveness ............................................................................................................................................................................ 2

4.2 Operability .................................................................................................................................................................................................. 3

4.3 Relevance ..................................................................................................................................................................................................... 3

4.4 Transparency ............................................................................................................................................................................................ 3

5 Evaluation procedure ...................................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Procedure description ...................................................................................................................................................................... 4

6 Evaluation .................................................................................................................................................................................................................... 5

6.1 Evaluation indicators ......................................................................................................................................................................... 5

6.2 Evaluation method description ................................................................................................................................................ 6

6.2.1 General...................................................................................................................................................................................... 6

6.2.2 Evaluation steps ............................................................................................................................................................... 6

6.2.3 Example evaluation table ......................................................................................................................................... 8

Annex A (informative) List of evaluation indicators and sub-indicators .....................................................................12

Annex B (informative) Quantify qualitative sub-indicators ......................................................................................................17

Annex C (informative) Determination of weights ................................................................................................................................18

Annex D (informative) Example of evaluation case ...........................................................................................................................20

Bibliography .............................................................................................................................................................................................................................30

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23043:2021(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 4,

Industrial water reuse.

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
---------------------- Page: 4 ----------------------
ISO 23043:2021(E)
Introduction

Reuse of industrial wastewater is an important strategy for reducing freshwater consumption and

[6,10,14]

wastewater generation. Treated industrial wastewater can be used for various purposes . The

dominant industrial applications are cooling water for power generation, boiler feed water, equipment

cleaning and general process water uses. Reused water may also be applied for non-industrial

[9,13,14]

applications most typically including toilet and urinal flushing, and landscape irrigation .

Currently, various methods are applied to evaluate the resource use, energy and environmental

performance respectively, which can be also used in industrial systems, including Life Cycle Assessment

(ISO 14040), Environmental Risk Assessment (IEC 31010), Best Available Technology (Directive

2010/75/EU), Ecological Footprint (ISO 14046), Circular Economy (BS 8001) and other methods

[1,2,16,17]

. The primary evaluation criteria selection for industrial wastewater treatment reuse processes

has historically been based on a cost-benefit analysis, however, economic factors are no longer the main

decision factor, nowadays, industries take into consideration a number of sustainable factors, including

[2,7,9,10,15-18]
economics, environment, social and technology characteristics .

The evaluation of wastewater treatment reuse processes requires systematic methods to evaluate the

[2,10,18]
performance expectations of alternative wastewater treatment reuse processes .

This document provides guidelines for assessing wastewater treatment reuse processes through

enhanced information analysis, to ensure protection of environmental and human health, to promote

the transition of the circular economy and improve water management.
© ISO 2021 – All rights reserved v
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INTERNATIONAL STANDARD ISO 23043:2021(E)
Evaluation methods for industrial wastewater treatment
reuse processes
1 Scope

This document specifies the principles and framework for comprehensive evaluation of industrial

wastewater treatment reuse processes, including:
a) establishing goals and scope;
b) illustrating the evaluation procedure; and

c) determination of evaluation indicators (technology indicator/sub-indicators, environment

indicator/sub-indicators, resource indicator/sub-indicators, economy indicator/sub-indicators).

This document describes how to comprehensively evaluate industrial wastewater treatment reuse

processes using the proposed calculation approaches and recommended indicators. It does not specify

methodologies for single evaluation indicators.

The document is intended to provide assistance to a broad range of industrial wastewater treatment and

reuse project stakeholders including professionals (planning, management, designers, and operators),

administrative agencies (monitoring, assessment, regulation and administration) and local authorities.

This document is applicable to

a) evaluating comparing and selecting industrial wastewater treatment reuse processes,

b) implementing continuous improvements,

c) upgrading processes and improving performance for existing treatment and reuse facilities.

The intended application of the comprehensive evaluation result is considered within the goal and

scope definition.
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
3.1 Terms and definitions

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/
© ISO 2021 – All rights reserved 1
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ISO 23043:2021(E)
3.1.1
Delphi method

information-gathering technique used as a way to reach consensus of experts on a subject

Note 1 to entry: The Delphi method is applied as consensus tool for determining weights of indicators/sub-

indicators in this document.

Note 2 to entry: A facilitator uses a questionnaire to solicit ideas about the important project points related to the

subject. The responses are summarized and are then recirculated to the experts for further comment. Consensus

may be reached in a few rounds of this process.
[SOURCE: ISO/IEC/IEEE 24765:2017, 3.1102]
3.1.2
indicator
quantitative or qualitative measure of impacts
[SOURCE: ISO 19208:2016, 3.8]
3.2 Abbreviated terms
The abbreviated terms in Table 1 apply.
Table 1 — Abbreviated terms
Abbreviation Full term
BOD 5-day biochemical oxygen demand
COD chemical oxygen demand
ELR environment load ratio
ESI energy sustainability index
EYR the energy yield ratio
GHG greenhouse gas
GWP global warming potential
LCY local currency
PAC poly-aluminum chloride
PAM polyacrylamide
TDS total dissolved solids
TSS total suspended solids
4 Evaluation principles
4.1 Comprehensiveness

The evaluation system provides a multi-criteria analysis framework to evaluate alternatives using

parameters that are relevant to the proposed processes. The analysis considers all attributes of multiple

indicators (technology, environment, resource, and economy) and address specific requirements by

using sub-indicators based on the evaluation indicators, which are consistent with factors involved

[2,7]

in a Sustainability Analysis to a certain extent . Other social or political criteria can be taken into

[9]
account according to local policy or regulations .
a) Technology

Address the technological parameters of the industrial wastewater treatment processes applied for

water reuse.
b) Environment
2 © ISO 2021 – All rights reserved
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ISO 23043:2021(E)

Address the environmental parameters and impacts of the industrial wastewater treatment processes

applied for water reuse system.
c) Resource
Address the resource recovery, allocation and utilization for water reuse.
d) Economy

Address the economic impacts of the industrial wastewater treatment processes applied for water reuse.

4.2 Operability

The selection of evaluation indicators is general, reasonable and attainable, so that the evaluation

indicators are concise, clear and easy to get. It is also in line with the actual needs to manage the water

environment.
4.3 Relevance

The evaluation process and parameters of the industrial wastewater treatment reuse processes should

be extracted in a relevant manner and appropriately quantified.
4.4 Transparency

Due to the inherent complexity for evaluation, transparency is an important guiding principle to ensure

proper results. Calculating process of sub-indicators should be recorded and available for clarification

when requested.
5 Evaluation procedure
5.1 General
Figure 1 illustrates the general framework.
Figure 1 — Framework of evaluation procedure
© ISO 2021 – All rights reserved 3
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ISO 23043:2021(E)
5.2 Procedure description
5.2.1 Evaluation preparation
Step 1: Request evaluation

The enterprises, industry managers or related organizations develop evaluation requirements and

submit the relevant documents. The documents can include, but not limited to the following:

a) The basic information form, which includes:
— the actual position of enterprises;
— major processes and equipment;
— water quality parameters of industrial influents and effluents;
— type of reuse and reuse demands.
b) record files of major pollutants emissions;
c) record files of resources and energy consumption;
d) assessment reports of environmental impact;
e) assessment reports of public safety impact;
f) other essential documents.

NOTE 1 Data (list b, c) can be obtained from relevant research reports and references or statistics for new

projects without record files. Reports (list d) include the assessment of freshwater consumption and possible

effects of respective direct reduction in the effluent quality, i.e., possible increase of pollutants concentration.

Step 2: Organize a project committee

Establish a project committee which may be composed of experts, skilled operators, industrial

shareholders or managers, supervisors, etc. The project committee is asked to undertake the following

objectives, respectively.
a) Carry out the evaluation task.
b) Supervise field surveys and sampling tests.

c) Validate the integrity and accuracy of the data on the base of the statistical reports and original

records provided by the enterprises.
Step 3: Collect data

Collect raw and supporting data from related industries or enterprises via basic information surveys,

please refer to Table D.4 in Annex D. Field surveys, sample tests, and enterprises’ record files can be

used to collect data if evaluated processes have adequate operational recording data. Research reports

and references analysis also can be used to collect data if it is a new process and/or new project with

little or no existing operating record.

NOTE 2 Step 1, step 2 and step 3 are recommended steps of evaluation preparation whose main task is to

collect data. Other optional steps are also allowed to carry out the evaluation preparation as long as they satisfy

the need of collecting adequate information.
5.2.3 Preliminary evaluation
The preliminary evaluation procedure is as following:

a) Analyse and summarize the existing treatment and reuse technologies globally according to the

category of industrial wastewater, and determine which technologies or processes are evaluated.

4 © ISO 2021 – All rights reserved
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ISO 23043:2021(E)

b) Make a simple primary selection of the above processes. The main considerations include:

— Whether the processes achieve the required constituent removal performance.
[10]

— According to "Guidelines for Water Reuse 2012" and relevant standards (e.g., ISO 20468-1)

to determine whether the technology can meet its corresponding reuse water quality

[2,3]
requirements .

— Whether it is convenient for updating construction considering site, public facilities and other

conditions.
— Other necessary conditions and considerations.

c) The project committee (see step 2 in 5.2.1) combined with stakeholders, engineers, technicians

and relevant experts to discuss, and distinguish the two major categories: preliminary feasible

processes and infeasible processes based on the actual situation of the enterprises. The former

processes are selected for further evaluation.
5.2.4 Evaluation

The preliminary feasible processes are comprehensively evaluated from four aspects: technology

indicator, environment indicator, resource indicator and economy indicator. See Clause 6.

Social effects which are outside the scope of this document, including education, cultural values,

operator training requirements, job creation and other social criteria should be taken into account

according to local policy or regulations.
5.2.5 Evaluation report
Step 1: Evaluation results analysis

Compare the comprehensive scores of proposed evaluated processes. Then, make the evaluation

report by combining analysis of the evaluation results with consideration on the actual situation of the

industrial enterprise. The whole processes that meet the requirements are identified along with the

recommended processes, are referred as solutions available for users and decision makers.

Step 2: Prepare evaluation reports

The evaluation report should include the basic condition of the industrial enterprise, the relevant

technical conditions, the evaluation process and results, etc.
6 Evaluation
6.1 Evaluation indicators

The evaluation system consists of four primary indicators: technology, environment, resource and

economy. Each indicator category is divided into a few sub-indicators. The sub-indicators are refinement

of the primary indicators. The overall indicator framework of evaluation system is shown in Table 1.

The further details are given in Annex A; calculation of the qualitative sub-indicators refers to Annex B.

© ISO 2021 – All rights reserved 5
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ISO 23043:2021(E)
Table 1 — Example indicators of industrial wastewater treatment reuse processes
Indicators Sub-indicators Note Related reference
Te1. Technology maturity Qualitative A.1.1
Te2. Equipment utilization ratio Quantitative A.1.2
Te3. Equipment readiness ratio Quantitative A.1.3
Technology Te4. Stability Qualitative A.1.4
Te5. System management Qualitative A.1.5
Te6. Maintainability and complexity of implementation Qualitative A.1.6
En1. Conventional pollutants removal rate Quantitative A.2.1
En2. Other concerned pollutants removal rate Quantitative A.2.2
En3. Sludge production rate Quantitative A.2.3
Environment En4. Total GHG emissions Quantitative A.2.4
En5. Energy sustainability index (ESI) Quantitative A.2.5
En6. Odour control and ventilation Qualitative A.2.6
Re1. Wastewater reuse rate Quantitative A.3.1
Re2. Resource recovery Quantitative A.3.2
Re3. Energy recovery Quantitative A.3.3
Resource
Re4. Energy consumption Quantitative A.3.4
Re5. Chemicals consumption Quantitative A.3.5
Ec1. Capital cost Quantitative A.4.1
Ec2. Operating cost Quantitative A.4.2
Economy Ec3. Disposal cost Quantitative A.4.3
Ec4. Revenues Quantitative A.4.4

NOTE: Not all sub-indicators in Table 1 are mandatory in carrying out an evaluation. Other sub-indicators (such as risk

management, environmental and public safety, etc.) can be selected or added depending on situation.

6.2 Evaluation method description
6.2.1 General

A step by step method is illustrated as the following steps (step 1~step 5) and a sample evaluation table

is given in Table 2.
6.2.2 Evaluation steps
Step 1: Individual evaluation of sub- indicators
[7]

To deal with sub-indicators through normalization, the values should be dimensionless .

Calculate the individual evaluated value, “I ”, expressed as dimensionless number of the sub-indicators,

“i”, using Formulae (1) and (2).
6 © ISO 2021 – All rights reserved
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ISO 23043:2021(E)
For the higher value, the better indicators, using Formula (1):
SS−
i min
I = (1)
SS−
maxmin
For the lower value, the better indicators, using Formula (2):
SS−
max i
I = (2)
SS−
maxmin
where
S is the individual evaluation value, of sub-indicators, “i”;
i is the serial number of sub-indicators, i=1, 2, 3…n.

S and S are the maximum and minimum value, respectively, of the same evaluation sub-indicator

max min
in different processes to be evaluated.
Step 2: Individual score of sub-indicators
Calculate the individual score of the sub-indicator, “P ”, using Formula (3):
PI=×K (3)
ii i
where
I is the normalized value of sub-indicators, “i”;

K is the weight coefficient of sub-indicators, “i”. Refer to Annex C to determine K .

i i
Step 3: Individual evaluation of indicators

Calculate the individual evaluated value, “Q ”, expressed as dimensionless number, of the indicators, “ j”,

using Formula (4):
QP= (4)
i=1
where
j is the serial number of indicators, j=1, 2, 3, 4;
n is the total number of sub-indicators under indicator, “ j”;
P is the individual score of sub-indicators “i”, under indicator, “ j”.
Step 4: Individual score of indicators
Calculate the individual score of indicators, “M ”, using Formula (5):
MQ=×F (5)
jj j
where
Q is the individual evaluated value of indicator “ j”;

F is the weight coefficient of indicator “ j”. Refer to Annex C to determine F .

j j
Step 5: Calculate comprehensive evaluation score
© ISO 2021 – All rights reserved 7
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ISO 23043:2021(E)

Calculate the comprehensive score of the evaluated industrial wastewater treatment technology for

reuse, “E”, and using Formula (6):
EM= (6)
j1=
where M is the individual score of indicators “ j”.

Sort the comprehensive scores (E) of proposed evaluated processes in descending order. Make the

evaluation report by combining analysis of evaluation results with consideration on the actual situation

of the industrial enterprise.
6.2.3 Example evaluation table
8 © ISO 2021 – All rights reserved
---------------------- Page: 13 ----------------------
ISO 23043:2021(E)
serial number
© ISO 2021 – All rights reserved 9

Table 2 — Example evaluation table of industrial wastewater treatment reuse processes

Related value of sub-indicators Related value of indicators
P Individual M
K I F
evaluated
Individual Individual
Weight of Individual Weight of
Indicators Sub-indicators
value of
score of score of
sub-indica- evaluated indicator
indicator
sub-indicator indicator
tor (refer to value of (refer to
Annex C) sub-indicator Annex C)
P =I ×K M =Q ×F
i i i j j j
QP= i
j ∑
i=1
Te1. Technology maturity
Te2. Equipment utilization ratio
Te3. Equipment readiness ratio
Technology
1 Te4. Stability
indicator
Te5. System management
Te6. Maintainability and complexity of implementation
En1. Conventional pollutants removal rate
En2. Other concerned pollutants removal rate
En3. Sludge production rate
Environment
2 En4. Total GHG emissions
indicator
En5. Energy sustainability index (ESI)
En6. Odour control and ventilation
Re1. Wastewater reuse rate
Re2. Resource recovery
Re3. Energy recovery
Resource
indicator
Re4. Energy consumption
Re5. Chemicals consumption
Comprehensive evaluation score E
---------------------- Page: 14 ----------------------
ISO 23043:2021(E)
serial number
10 © ISO 2021 – All rights reserved
Table 2 (continued)
Related value of sub-indicators Related value of indicators
P M
Individual
K I F
evaluated
Individual Individual
Indicators Sub-indicators Weight of Individual Weight of
value of
score of score of
sub-indica- evaluated indicator
indicator
sub-indicator indicator
tor (refer to value of (refer to
Annex C) sub-indicator Annex C)
P =I ×K M =Q ×F
i i i j j j
QP= i
j ∑
i=1
Ec1. Capital cost
Ec2. Operating cost
Economy
4 Ec3. Disposal cost
indicator
Ec4. Revenues
Comprehensive evaluation score E
---------------------- Page: 15 ----------------------
ISO 23043:2021(E)
NOTE An example of evaluation case is given in Annex D.
© ISO 2021 – All rights reserved 11
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ISO 23043:2021(E)
Annex A
(informative)
List of evaluation indicators and sub-indicators
A.1 Technology indicator
A.1.1 Te1 Technology maturity

The technology maturity is a qualitative sub-indicator classified as five levels: R & D phase, field test,

industrial demonstration, industrial application, and commercialization.
A.1.2 Te2 Equipment utilization ratio

Calculate the average operation ratio, expressed as a percentage, of the equipment, W , using

Formula (A.1):
W = (A.1)
tt+
where
t is the average days of the equipment in operation per year;
t is the average days of downtime per year.
A.1.3 Te3 Equipment readiness ratio

The readiness (perfectness) ratio of critical equipment of the selected process flow should be taken into

full account.

Calculated the equipment readiness ratio, W , of equipment, using the Formula (A.2):

W = (A.2)
where
T is the days of equipment in good condition during time T;
T is the time, expressed in days, of total statistic days.
A.1.4 Te4 Stability

The operational stability of the selected process is a qualitative sub-indicator including the shock

[5,7]
resistance load capacity and the water quality stability rate .

Shock resistance load capacity: It makes a certain impact on the wastewater treatment facilities when

influent water changed extremely. Time required for system back to the previous state shows the

strength of anti-shock loading capability.
12 © ISO 2021 – All rights reserved
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ISO 23043:2021(E)

Water quality stability rate: It shows the probability of the treated wastewater that can meet the

discharge standard. It is the ratio of number of days meeting effluent quality standards to the number

of days throughout the year.
NOTE This sub-indicator can refer to ISO 20468-1.
A.1.5 Te5 System management

It is a qualitative sub-indicator considering the following aspects: a) the rules and regulations, b)

[12] [5]

training and technical data, c) level of system automation , and d) general data requirements .

A.1.6 Te6 Maintainability and complexity of implementation

Maintainability is an inherent quality characteristic of product/equipment, which measures the

maintenance difficulty and cost when mechanical/equipment products go wrong. Maintainability can

[15]
reflect system effectiveness and life-cycle cost of products .
The complexity of implementation is correl
...

INTERNATIONAL ISO
STANDARD 23043
First edition
Evaluation methods for industrial
wastewater treatment reuse processes
PROOF/ÉPREUVE
Reference number
ISO 23043:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23043:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© 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 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23043:2021(E)
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 Evaluation principles ....................................................................................................................................................................................... 2

4.1 Comprehensiveness ............................................................................................................................................................................ 2

4.2 Operability .................................................................................................................................................................................................. 3

4.3 Relevance ..................................................................................................................................................................................................... 3

4.4 Transparency ............................................................................................................................................................................................ 3

5 Evaluation procedure ...................................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Procedure description ...................................................................................................................................................................... 4

6 Evaluation .................................................................................................................................................................................................................... 5

6.1 Evaluation indicators ......................................................................................................................................................................... 5

6.2 Evaluation method description ................................................................................................................................................ 6

6.2.1 General...................................................................................................................................................................................... 6

6.2.2 Evaluation steps ............................................................................................................................................................... 6

6.2.3 Example evaluation table ......................................................................................................................................... 8

Annex A (informative) List of evaluation indicators and sub-indicators .....................................................................12

Annex B (informative) Quantify qualitative sub-indicators ......................................................................................................17

Annex C (informative) Determination of weights ................................................................................................................................18

Annex D (informative) Example of evaluation case ...........................................................................................................................20

Bibliography .............................................................................................................................................................................................................................30

© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO 23043:2021(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 on 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 4,

Industrial water reuse.

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 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23043:2021(E)
Introduction

Reuse of industrial wastewater is an important strategy for reducing freshwater consumption and

[6,10,14]

wastewater generation. Treated industrial wastewater can be used for various purposes . The

dominant industrial applications are cooling water for power generation, boiler feed water, equipment

cleaning and general process water uses. Reused water may also be applied for non-industrial

[9,13,14]

applications most typically including toilet and urinal flushing, and landscape irrigation .

Currently, various methods are applied to evaluate the resource use, energy and environmental

performance respectively, which can be also used in industrial systems, including Life Cycle Assessment

(ISO 14040), Environmental Risk Assessment (IEC 31010), Best Available Technology (Directive

2010/75/EU), Ecological Footprint (ISO 14046), Circular Economy (BS 8001) and other methods

[1,2,16,17]

. The primary evaluation criteria selection for industrial wastewater treatment reuse processes

has historically been based on a cost-benefit analysis, however, economic factors are no longer the main

decision factor, nowadays, industries take into consideration a number of sustainable factors, including

[2,7,9,10,15-18]
economics, environment, social and technology characteristics .

The evaluation of wastewater treatment reuse processes requires systematic methods to evaluate the

[2,10,18]
performance expectations of alternative wastewater treatment reuse processes .

This document provides guidelines for assessing wastewater treatment reuse processes through

enhanced information analysis, to ensure protection of environmental and human health, to promote

the transition of the circular economy and improve water management.
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INTERNATIONAL STANDARD ISO 23043:2021(E)
Evaluation methods for industrial wastewater treatment
reuse processes
1 Scope

This document specifies the principles and framework for comprehensive evaluation of industrial

wastewater treatment reuse processes, including:
a) establishing goals and scope;
b) illustrating the evaluation procedure; and

c) determination of evaluation indicators (technology indicator/sub-indicators, environment

indicator/sub-indicators, resource indicator/sub-indicators, economy indicator/sub-indicators).

This document describes how to comprehensively evaluate industrial wastewater treatment reuse

processes using the proposed calculation approaches and recommended indicators. It does not specify

methodologies for single evaluation indicators.

The document is intended to provide assistance to a broad range of industrial wastewater treatment and

reuse project stakeholders including professionals (planning, management, designers, and operators),

administrative agencies (monitoring, assessment, regulation and administration) and local authorities.

This document is applicable to

a) evaluating comparing and selecting industrial wastewater treatment reuse processes,

b) implementing continuous improvements,

c) upgrading processes and improving performance for existing treatment and reuse facilities.

The intended application of the comprehensive evaluation result is considered within the goal and

scope definition.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. 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
3.1 Terms and definitions

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/
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ISO 23043:2021(E)
3.1.1
Delphi method

information-gathering technique used as a way to reach consensus of experts on a subject

Note 1 to entry: The Delphi method is applied as consensus tool for determining weights of indicators/sub-

indicators in this document.

Note 2 to entry: A facilitator uses a questionnaire to solicit ideas about the important project points related to the

subject. The responses are summarized and are then recirculated to the experts for further comment. Consensus

may be reached in a few rounds of this process.
[SOURCE: ISO/IEC/IEEE 24765:2017, 3.1102]
3.1.2
indicator
quantitative or qualitative measure of impacts
[SOURCE: ISO 19208:2016, 3.8]
3.2 Abbreviated terms
The abbreviated terms in Table 1 apply.
Table 1 — Abbreviated terms
Abbreviation Full term
BOD 5-day biochemical oxygen demand
COD chemical oxygen demand
ELR environment load ratio
ESI energy sustainability index
EYR the energy yield ratio
GHG greenhouse gas
GWP global warming potential
LCY local currency
PAC poly-aluminum chloride
PAM polyacrylamide
TDS total dissolved solids
TSS total suspended solids
4 Evaluation principles
4.1 Comprehensiveness

The evaluation system provides a multi-criteria analysis framework to evaluate alternatives using

parameters that are relevant to the proposed processes. The analysis considers all attributes of multiple

indicators (technology, environment, resource, and economy) and address specific requirements by

using sub-indicators based on the evaluation indicators, which are consistent with factors involved

[2,7]

in a Sustainability Analysis to a certain extent . Other social or political criteria can be taken into

[9]
account according to local policy or regulations .
a) Technology

Address the technological parameters of the industrial wastewater treatment processes applied for

water reuse.
b) Environment
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ISO 23043:2021(E)

Address the environmental parameters and impacts of the industrial wastewater treatment processes

applied for water reuse system.
c) Resource
Address the resource recovery, allocation and utilization for water reuse.
d) Economy

Address the economic impacts of the industrial wastewater treatment processes applied for water reuse.

4.2 Operability

The selection of evaluation indicators is general, reasonable and attainable, so that the evaluation

indicators are concise, clear and easy to get. It is also in line with the actual needs to manage the water

environment.
4.3 Relevance

The evaluation process and parameters of the industrial wastewater treatment reuse processes should

be extracted in a relevant manner and appropriately quantified.
4.4 Transparency

Due to the inherent complexity for evaluation, transparency is an important guiding principle to ensure

proper results. Calculating process of sub-indicators should be recorded and available for clarification

when requested.
5 Evaluation procedure
5.1 General
Figure 1 illustrates the general framework.
Figure 1 — Framework of evaluation procedure
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ISO 23043:2021(E)
5.2 Procedure description
5.2.1 Evaluation preparation
Step 1: Request evaluation

The enterprises, industry managers or related organizations develop evaluation requirements and

submit the relevant documents. The documents can include, but not limited to the following:

a) The basic information form, which includes:
— The actual position of enterprises;
— Major processes and equipment;
— Water quality parameters of industrial influents and effluents;
— Type of reuse and reuse demands;
b) Record files of major pollutants emissions;
c) Record files of resources and energy consumption;
d) Assessment reports of environmental impact;
e) Assessment reports of public safety impact;
f) Other essential documents.

NOTE 1 Data (list b, c) can be obtained from relevant research reports and references or statistics for new

projects without record files. Reports (list d) include the assessment of freshwater consumption and possible

effects of respective direct reduction in the effluent quality, i.e., possible increase of pollutants concentration.

Step 2: Organize a project committee

Establish a project committee which may be composed of experts, skilled operators, industrial

shareholders or managers, supervisors, etc. The project committee is asked to undertake the following

objectives, respectively.
a) Carry out the evaluation task;
b) Supervise field surveys and sampling tests;

c) Validate the integrity and accuracy of the data on the base of the statistical reports and original

records provided by the enterprises.
Step 3: Collect data

Collect raw and supporting data from related industries or enterprises via basic information surveys,

please refer to Table D.4 in Annex D. Field surveys, sample tests, and enterprises’ record files can be

used to collect data if evaluated processes have adequate operational recording data. Research reports

and references analysis also can be used to collect data if it is a new process and/or new project with

little or no existing operating record.

NOTE 2 Step 1, step 2 and step 3 are recommended steps of evaluation preparation whose main task is to

collect data. Other optional steps are also allowed to carry out the evaluation preparation as long as they satisfy

the need of collecting adequate information.
5.2.3 Preliminary evaluation
The preliminary evaluation procedure is as following:

a) Analyse and summarize the existing treatment and reuse technologies globally according to the

category of industrial wastewater, and determine which technologies or processes are evaluated.

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b) Make a simple primary selection of the above processes. The main considerations include:

— Whether the processes achieve the required constituent removal performance.
[10]

— According to "Guidelines for Water Reuse 2012" and relevant standards (e.g., ISO 20468-1)

to determine whether the technology can meet its corresponding reuse water quality

[2,3]
requirements .

— Whether it is convenient for updating construction considering site, public facilities and other

conditions.
— Other necessary conditions and considerations.

c) The project committee (see step 2 in 5.2.1) combined with stakeholders, engineers, technicians

and relevant experts to discuss, and distinguish the two major categories: preliminary feasible

processes and infeasible processes based on the actual situation of the enterprises. The former

processes are selected for further evaluation.
5.2.4 Evaluation

The preliminary feasible processes are comprehensively evaluated from four aspects: technology

indicator, environment indicator, resource indicator and economy indicator. See Clause 6.

Social effects which are outside the scope of this document, including education, cultural values,

operator training requirements, job creation and other social criteria should be taken into account

according to local policy or regulations.
5.2.5 Evaluation report
Step 1: Evaluation results analysis

Compare the comprehensive scores of proposed evaluated processes. Then, make the evaluation

report by combining analysis of the evaluation results with consideration on the actual situation of the

industrial enterprise. The whole processes that meet the requirements are identified along with the

recommended processes, are referred as solutions available for users and decision makers.

Step 2: Prepare evaluation reports

The evaluation report should include the basic condition of the industrial enterprise, the relevant

technical conditions, the evaluation process and results, etc.
6 Evaluation
6.1 Evaluation indicators

The evaluation system consists of four primary indicators: technology, environment, resource and

economy. Each indicator category is divided into a few sub-indicators. The sub-indicators are refinement

of the primary indicators. The overall indicator framework of evaluation system is shown in Table 1.

The further details are given in Annex A; Calculation of the qualitative sub-indicators refers to Annex B.

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ISO 23043:2021(E)
Table 1 — Example indicators of industrial wastewater treatment reuse processes
Indicators Sub-indicators Note Related reference
Te1. Technology maturity Qualitative A.1.1
Te2. Equipment utilization ratio Quantitative A.1.2
Te3. Equipment readiness ratio Quantitative A.1.3
Technology Te4. Stability Qualitative A.1.4
Te5. System management Qualitative A.1.5
Te6. Maintainability and complexity of implementation Qualitative A.1.6
En1. Conventional pollutants removal rate Quantitative A.2.1
En2. Other concerned pollutants removal rate Quantitative A.2.2
En3. Sludge production rate Quantitative A.2.3
Environment En4. Total GHG emissions Quantitative A.2.4
En5. Energy sustainability index (ESI) Quantitative A.2.5
En6. Odour control and ventilation Qualitative A.2.6
Re1. Wastewater reuse rate Quantitative A.3.1
Re2. Resource recovery Quantitative A.3.2
Re3. Energy recovery Quantitative A.3.3
Resource
Re4. Energy consumption Quantitative A.3.4
Re5. Chemicals consumption Quantitative A.3.5
Ec1. Capital cost Quantitative A.4.1
Ec2. Operating cost Quantitative A.4.2
Economy Ec3. Disposal cost Quantitative A.4.3
Ec4. Revenues Quantitative A.4.4

NOTE: Not all sub-indicators in Table 1 are mandatory in carrying out an evaluation. Other sub-indicators (such as risk

management, environmental and public safety, etc.) can be selected or added depending on situation.

6.2 Evaluation method description
6.2.1 General

A step by step method is illustrated as the following steps (step 1~step 5) and a sample evaluation table

is given in Table 2.
6.2.2 Evaluation steps
Step 1: Individual evaluation of sub- indicators
[7]

To deal with sub-indicators through normalization, the values should be dimensionless .

Calculate the individual evaluated value, “I ”, expressed as dimensionless number of the sub-indicators,

“i”, using Formula (1) and (2).
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ISO 23043:2021(E)
For the higher value, the better indicators, using Formula (1):
SS−
i min
I = (1)
SS−
maxmin
For the lower value, the better indicators, using Formula (2):
SS−
max i
I = (2)
SS−
maxmin
Where
S is the individual evaluation value, of sub-indicators, “i”
i is the serial number of sub-indicators, i=1, 2, 3…n

S and S are the maximum and minimum value, respectively, of the same evaluation sub-indicator

max min
in different processes to be evaluated.
Step 2: Individual score of sub-indicators
Calculate the individual score of the sub-indicator, “P ”, using Formula (3):
PI=×K (3)
ii i
Where
I is the normalized value of sub-indicators, “i”

K is the weight coefficient of sub-indicators, “i”. Refer to Annex C to determine K

i i
Step 3: Individual evaluation of indicators

Calculate the individual evaluated value, “Q ”, expressed as dimensionless number, of the indicators, “ j”,

using Formula (4):
QP= (4)
i=1
Where
j is the serial number of indicators, j=1, 2, 3, 4.
n is the total number of sub-indicators under indicator, “ j”.
P is the individual score of sub-indicators “i”, under indicator, “ j”.
Step 4: Individual score of indicators
Calculate the individual score of indicators, “M ”, using Formula (5):
MQ=×F (5)
jj j
Where
Q is the individual evaluated value of indicator “ j”.

F is the weight coefficient of indicator “ j”. Refer to Annex C to determine F .

j j
Step 5: Calculate comprehensive evaluation score
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ISO 23043:2021(E)

Calculate the comprehensive score of the evaluated industrial wastewater treatment technology for

reuse, “E”, and using Formula (6):
EM= (6)
j1=
Where M is the individual score of indicators “ j”.

Sort the comprehensive scores (E) of proposed evaluated processes in descending order. Make the

evaluation report by combining analysis of evaluation results with consideration on the actual situation

of the industrial enterprise.
6.2.3 Example evaluation table
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ISO 23043:2021(E)
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Table 2 — Example evaluation table of industrial wastewater treatment reuse processes

Related value of sub-indicators Related value of indicators
P Individual M
K I F
evaluated
Individual Individual
Weight of Individual Weight of
Indicators Sub-indicators
value of
score of score of indi-
sub-indica- evaluated indicator
indicator
sub-indicator cator
tor (refer to value of (refer to
Annex C) sub-indicator Annex C)
P =I ×K M =Q ×F
i i i j j j
QP= i
j ∑
i=1
Te1. Technology maturity
Te2. Equipment utilization ratio
Te3. Equipment readiness ratio
Technology
1 Te4. Stability
indicator
Te5. System management
Te6. Maintainability and complexity of implementation
En1. Conventional pollutants removal rate
En2. Other concerned pollutants removal rate
En3. Sludge production rate
Env ironment
2 En4. Total GHG emissions
indicator
En5. Energy sustainability index (ESI)
En6. Odour control and ventilation
Re1. Wastewater reuse rate
Re2. Resource recovery
Re3. Energy recovery
Resource indi-
cator
Re4. Energy consumption
Re5. Chemicals consumption
Comprehensive evaluation score E
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ISO 23043:2021(E)
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Table 2 (continued)
Related value of sub-indicators Related value of indicators
P M
Individual
K I F
evaluated
Individual Individual
Indicators Sub-indicators Weight of Individual Weight of
value of
score of score of indi-
sub-indica- evaluated indicator
indicator
sub-indicator cator
tor (refer to value of (refer to
Annex C) sub-indicator Annex C)
P =I ×K M =Q ×F
i i i j j j
QP= i
j ∑
i=1
Ec1. Capital cost
Ec2. Operating cost
Economy indi-
4 Ec3. Disposal cost
cator
Ec4. Revenues
Comprehensive evaluation score E
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ISO 23043:2021(E)
NOTE An example of evaluation case is given in Annex D.
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ISO 23043:2021(E)
Annex A
(informative)
List of evaluation indicators and sub-indicators
A.1 Technology indicator
A.1.1 Te1 Technology maturity

The technology maturity is a qualitative sub-indicator classified as five levels: R & D phase, field test,

industrial demonstration, industrial application, and commercialization.
A.1.2 Te2 Equipment utilization ratio

Calculate the average operation ratio, expressed as a percentage, of the equipment, W using

Formula (A.1):
W = (A.1)
tt+
Where
t is the average days of the equipment in operation per year
t is the average days of downtime per year
A.1.3 Te3 Equipment readiness ratio

The readiness (perfectness) ratio of critical equipment of the selected process flow should be taken into

full account.

Calculated the equipment readiness ratio, W , of equipment, using the Formula (A.2):

W = (A.2)
Where
T is the days of equipment in good condition during time T
T is the time, expressed in days, of total statistic days
A.1.4 Te4 Stability

The operational stability of the selected process is a qualitative sub-indicator including the shock

[5,7]
resistance load capacity and the water quality stability rate .

Shock resistance load capacity: It makes a certain impact on the wastewater treatment facilities when

influent water changed extremely. Time required for system back to the previous state shows the

strength of anti-shock loading capability.
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Water quality stability rate: It shows the probability of the treated wastewater that can meet the

discharge standard. It is the ratio of number of days meeting effluent quality standards to the number

of days throughout the year.
NOTE This sub-indicator can refer to ISO 20468-1.
A.1.5 Te5 System management

It is a qualitative sub-indicator considering the following aspects: a) the rules and regulations, b)

[12] [5]

training and technical data, c) level of system automation, and d) general data requirements .

A.1.6 Te6 Maintainability and complexity of implementation

Maintainability is an inherent quality characteristic of product/equipment, which measures the

maintenance difficulty and cost w
...

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