ISO 21939-1:2019
(Main)A method to calculate and express energy consumption of industrial wastewater treatment for the purpose of water reuse — Part 1: Biological processes
A method to calculate and express energy consumption of industrial wastewater treatment for the purpose of water reuse — Part 1: Biological processes
This document sets out the general principles for, and provides guidance on, the quantitative characterization of the energy consumed by industrial biological wastewater treatment systems. It does not aim to characterize the treatment pollutants removal performance or process reliability or any other consideration in the selection of a wastewater treatment system. This document includes the following sub-systems of biological treatment system: — Biological reactors, which might be suspended growth or fixed film processes or a combination thereof, and can include anaerobic, anoxic and/or aerobic tanks and/or zones. — Solid-liquid separation processes such as sedimentation, flotation, or membrane filtration, used for clarification of the water before discharge to downstream processes, which can also involve the return of a the separated solids as sludge back to the biological reactor. — Any pumps, blowers and mixers for water circulation, mixing and air supply in and between the sub-systems listed herein. — Heating or cooling of the water for treatment. This document does not include the following subsystems of the biological treatment system: — Wastewater feed pumps. — Pre-treatment systems, which for the purposes of this document also include preliminary and primary treatment processes, such as but not limited to, screening, sedimentation, dissolved air flotation, chemical oxidation, oil separation. — Post-treatment processes, such as but not limited to, disinfection, desalination, ion exchange, sludge treatment and handling systems. — Site lighting or any energy consumption involved in office operation. — Energy recovery from processes such as anaerobic reactors producing biogas. Filtration processes, which are sometimes part of the biological treatment process and at other times part of the post treatment, are referred to separately within this document.
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INTERNATIONAL ISO
STANDARD 21939-1
First edition
2019-05
A method to calculate and express
energy consumption of industrial
wastewater treatment for the purpose
of water reuse —
Part 1:
Biological processes
Reference number
©
ISO 2019
© ISO 2019
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions, symbols and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Symbols and abbreviated terms. 2
4 Expression and normalization of energy consumption . 2
4.1 Energy consumption indicator . . 2
4.2 Calculation . 4
5 Components contribution to the energy consumption . 4
5.1 General . 4
5.1.1 Steady state conditions . 4
5.1.2 Consideration of flow rate . 5
5.1.3 Calculation of variable consumptions . 5
5.1.4 Accounting for addition of oxidizing chemicals . 5
5.1.5 Physico-chemical separation pre-treatment processes . 5
5.2 List of system components . 6
5.2.1 General. 6
5.2.2 Aeration and combined mixing and aeration equipment . 6
5.2.3 Mixing . 6
5.2.4 Solid-liquid separation . 6
5.2.5 Internal circulation pumping . 6
5.2.6 Circulation of settled sludge . 6
5.2.7 Other pumping. 6
5.2.8 Air driven pumping and/or mixing . 6
6 Factoring of different process conditions . 7
6.1 General . 7
6.2 Temperature adjustments . 7
6.3 Barometric pressure adjustment . 7
6.4 Type of wastewater . 7
Annex A (informative) References to formulae and calculations . 8
Annex B (informative) Example calculations. 9
Bibliography .12
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 2019 – All rights reserved
Introduction
Biological wastewater treatment is a major process step in many cases of industrial wastewater
treatment for reuse.
In the field of biological wastewater treatment, the energy consumption of the process is commonly
normalized in order to account for difference in flow and concentration when comparing different
treatment options. For example, energy consumption is reported per unit volume of wastewater treated
(e.g. kWh/m ) or per unit of pollutant removed BOD (e.g. kWh/kg BOD ), TN (e.g. kWh/kg TN).
5 5
The disadvantages and limitations of these indicators include:
— Neither of the existing indicators are agreed to and accepted as a standard in the industry;
— They do not provide means to compare nitrifying processes to non-nitrifying processes;
— There is no differentiation between design values and measured values, and there are no standard
methods to obtain the indicator for each case.
Another approach is to report on the results from standard tests in water as oxygen transfer capacity
per unit energy consumed (e.g. kg O /kWh).
The disadvantages and limitations of this type of indicator include:
— It is less convenient for the market to apply to its cases, (for example because not all removal is by
oxidation, some is by metabolic consumption);
— It only considers oxygen transfer equipment or processes able to dissolve oxygen in water, which
does not apply to all biological treatment processes (such as rotating biological contactor (RBC) and
trickling filter (TF)).
These issues are discussed in the literature, which compares results expressed in different ways and
correspondingly provides contradicting indications (see References [4], [5] and [10]).
Therefore this document aims to create a quantitative measure for universal characterization of the
energy consumption for aerobic biological wastewater treatment systems. Such standardization will
benefit engineers in specification of systems and comparison of systems. The need arises especially in
consideration of life cycle cost of a wastewater treatment system.
NOTE 1 Normalized energy consumption of wastewater treatment systems typically decreases with
increasing size of the system, mainly due to higher efficiency of larger electromechanical equipment such as
pumps and blowers. Thus, large wastewater treatment plants will have lower normalized energy consumption
than small wastewater treatment systems. In order to neutralize the influence of plant size in comparison of
energy consumption, a correlation such as published by Silva, C., et al. (see Reference [11]) can be used, regardless
of this document.
NOTE 2 Higher effluent quality requirements are generally associated with higher normalized energy
consumption. Typically, normalized energy consumption will be compared for similarly performing systems.
However, it is possible, for example, to present the normalized energy consumption for different treatment
qualities as such.
NOTE 3 This document quantifies the energy consumption, regardless of treatment efficiency that can vary
for different types of wastewater. Treatment efficiency might typically be characterized by retention time and/or
volumetric loading rate and/or volumetric removal rate or other indicators which are not part of this document.
INTERNATIONAL STANDARD ISO 21939-1:2019(E)
A method to calculate and express energy consumption
of industrial wastewater treatment for the purpose of
water reuse —
Part 1:
Biological processes
1 Scope
This document sets out the general principles for, and provides guidance on, the quantitative
characterization of the energy consumed by industrial biological wastewater treatment systems. It
does not aim to characterize the treatment pollutants removal performance or process reliability or
any other consideration in the selection of a wastewater treatment system.
This document includes the following sub-systems of biological treatment system:
— Biological reactors, which might be suspended growth or fixed film processes or a combination
thereof, and can include anaerobic, anoxic and/or aerobic tanks and/or zones.
— Solid-liquid separation processes such as sedimentation, flotation, or membrane filtration, used for
clarification of the water before discharge to downstream processes, which can also involve the
return of a the separated solids as sludge back to the biological reactor.
— Any pumps, blowers and mixers for water circulation, mixing and air supply in and between the
sub-systems listed herein.
— Heating or cooling of the water for treatment.
This document does not include the following subsystems of the biological treatment system:
— Wastewater feed pumps.
— Pre-treatment systems, which for the purposes of this document also include preliminary and
primary treatment processes, such as but not limited to, screening, sedimentation, dissolved air
flotation, chemical oxidation, oil separation.
— Post-treatment processes, such as but not limited to, disinfection, desalination, ion exchange, sludge
treatment and handling systems.
— Site lighting or any energy consumpt
...
INTERNATIONAL ISO
STANDARD 21939-1
First edition
2019-05
A method to calculate and express
energy consumption of industrial
wastewater treatment for the purpose
of water reuse —
Part 1:
Biological processes
Reference number
©
ISO 2019
© ISO 2019
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions, symbols and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Symbols and abbreviated terms. 2
4 Expression and normalization of energy consumption . 2
4.1 Energy consumption indicator . . 2
4.2 Calculation . 4
5 Components contribution to the energy consumption . 4
5.1 General . 4
5.1.1 Steady state conditions . 4
5.1.2 Consideration of flow rate . 5
5.1.3 Calculation of variable consumptions . 5
5.1.4 Accounting for addition of oxidizing chemicals . 5
5.1.5 Physico-chemical separation pre-treatment processes . 5
5.2 List of system components . 6
5.2.1 General. 6
5.2.2 Aeration and combined mixing and aeration equipment . 6
5.2.3 Mixing . 6
5.2.4 Solid-liquid separation . 6
5.2.5 Internal circulation pumping . 6
5.2.6 Circulation of settled sludge . 6
5.2.7 Other pumping. 6
5.2.8 Air driven pumping and/or mixing . 6
6 Factoring of different process conditions . 7
6.1 General . 7
6.2 Temperature adjustments . 7
6.3 Barometric pressure adjustment . 7
6.4 Type of wastewater . 7
Annex A (informative) References to formulae and calculations . 8
Annex B (informative) Example calculations. 9
Bibliography .12
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 2019 – All rights reserved
Introduction
Biological wastewater treatment is a major process step in many cases of industrial wastewater
treatment for reuse.
In the field of biological wastewater treatment, the energy consumption of the process is commonly
normalized in order to account for difference in flow and concentration when comparing different
treatment options. For example, energy consumption is reported per unit volume of wastewater treated
(e.g. kWh/m ) or per unit of pollutant removed BOD (e.g. kWh/kg BOD ), TN (e.g. kWh/kg TN).
5 5
The disadvantages and limitations of these indicators include:
— Neither of the existing indicators are agreed to and accepted as a standard in the industry;
— They do not provide means to compare nitrifying processes to non-nitrifying processes;
— There is no differentiation between design values and measured values, and there are no standard
methods to obtain the indicator for each case.
Another approach is to report on the results from standard tests in water as oxygen transfer capacity
per unit energy consumed (e.g. kg O /kWh).
The disadvantages and limitations of this type of indicator include:
— It is less convenient for the market to apply to its cases, (for example because not all removal is by
oxidation, some is by metabolic consumption);
— It only considers oxygen transfer equipment or processes able to dissolve oxygen in water, which
does not apply to all biological treatment processes (such as rotating biological contactor (RBC) and
trickling filter (TF)).
These issues are discussed in the literature, which compares results expressed in different ways and
correspondingly provides contradicting indications (see References [4], [5] and [10]).
Therefore this document aims to create a quantitative measure for universal characterization of the
energy consumption for aerobic biological wastewater treatment systems. Such standardization will
benefit engineers in specification of systems and comparison of systems. The need arises especially in
consideration of life cycle cost of a wastewater treatment system.
NOTE 1 Normalized energy consumption of wastewater treatment systems typically decreases with
increasing size of the system, mainly due to higher efficiency of larger electromechanical equipment such as
pumps and blowers. Thus, large wastewater treatment plants will have lower normalized energy consumption
than small wastewater treatment systems. In order to neutralize the influence of plant size in comparison of
energy consumption, a correlation such as published by Silva, C., et al. (see Reference [11]) can be used, regardless
of this document.
NOTE 2 Higher effluent quality requirements are generally associated with higher normalized energy
consumption. Typically, normalized energy consumption will be compared for similarly performing systems.
However, it is possible, for example, to present the normalized energy consumption for different treatment
qualities as such.
NOTE 3 This document quantifies the energy consumption, regardless of treatment efficiency that can vary
for different types of wastewater. Treatment efficiency might typically be characterized by retention time and/or
volumetric loading rate and/or volumetric removal rate or other indicators which are not part of this document.
INTERNATIONAL STANDARD ISO 21939-1:2019(E)
A method to calculate and express energy consumption
of industrial wastewater treatment for the purpose of
water reuse —
Part 1:
Biological processes
1 Scope
This document sets out the general principles for, and provides guidance on, the quantitative
characterization of the energy consumed by industrial biological wastewater treatment systems. It
does not aim to characterize the treatment pollutants removal performance or process reliability or
any other consideration in the selection of a wastewater treatment system.
This document includes the following sub-systems of biological treatment system:
— Biological reactors, which might be suspended growth or fixed film processes or a combination
thereof, and can include anaerobic, anoxic and/or aerobic tanks and/or zones.
— Solid-liquid separation processes such as sedimentation, flotation, or membrane filtration, used for
clarification of the water before discharge to downstream processes, which can also involve the
return of a the separated solids as sludge back to the biological reactor.
— Any pumps, blowers and mixers for water circulation, mixing and air supply in and between the
sub-systems listed herein.
— Heating or cooling of the water for treatment.
This document does not include the following subsystems of the biological treatment system:
— Wastewater feed pumps.
— Pre-treatment systems, which for the purposes of this document also include preliminary and
primary treatment processes, such as but not limited to, screening, sedimentation, dissolved air
flotation, chemical oxidation, oil separation.
— Post-treatment processes, such as but not limited to, disinfection, desalination, ion exchange, sludge
treatment and handling systems.
— Site lighting or any energy consumpt
...
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