ISO 23043:2021

INTERNATIONAL ISO
STANDARD 23043
First edition
Evaluation methods for industrial
wastewater treatment reuse processes
PROOF/ÉPREUVE
Reference number
ISO 23043:2021(E)
©
ISO 2021

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ISO 23043:2021(E)

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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
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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.
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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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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
5
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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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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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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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
“i”, using Formula (1) and (2).
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For the higher value, the better indicators, using Formula (1):
SS−
i min
I = (1)
i
SS−
maxmin
For the lower value, the better indicators, using Formula (2):
SS−
max i
I = (2)
i
SS−
maxmin
Where
S is the individual evaluation value, of sub-indicators, “i”
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):
i
PI=×K (3)
ii i
Where
I is the normalized value of sub-indicators, “i”
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”,
j
using Formula (4):
n
QP= (4)
∑
ji
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”.
i
Step 4: Individual score of indicators
Calculate the individual score of indicators, “M ”, using Formula (5):
j
MQ=×F (5)
jj j
Where
Q is the individual evaluated value of indicator “ j”.
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):
4
EM= (6)
∑
j
j1=
Where M is the individual score of indicators “ j”.
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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serial number
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Table 2 — Example evaluation table of industrial wastewater treatment reuse processes
Related value of sub-indicators Related value of indicators
Q
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
n
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-
3
cator
Re4. Energy consumption
Re5. Chemicals consumption
……
Comprehensive evaluation score E

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serial number
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Table 2 (continued)
Related value of sub-indicators Related value of indicators
Q
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
n
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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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
o,
Formula (A.1):
t
1
W = (A.1)
o
tt+
12
Where
t is the average days of the equipment in operation per year
1
t is the average days of downtime per year
2
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):
E
T
in
W = (A.2)
E
T
Where
T is the days of equipment in good condition during time T
in
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
...