ISO/TS 4240-1:2023

Fine bubble technology — Environmental applications — Part 1: Inspection method using online particle counter in dissolved air flotation (DAF) plant

This document specifies the bubble volume concentration and bubble bed depth measurement methods by online particle counter for checking DAF process performance in plant. The test method of bubble volume concentration is made by measuring bubble size distribution in contact zone of DAF tank and calculating using formula. And bubble bed depth is evaluated by measuring the number of bubbles and particles according to the depth at five points in separation zone of DAF tank. This document provides the advantages and limitations of using online particle counter in plant.

Titre manque — Partie 1: Titre manque

General Information

• Status: Published
• Publication Date: 30-Mar-2023
• ICS: 07.030 - Physics. Chemistry
• Technical Committee: ISO/TC 281 - Fine bubble technology
• Drafting Committee: ISO/TC 281/WG 3 - Applications of fine bubble technology
• Current Stage: 6060 - International Standard published
• Start Date: 31-Mar-2023
• Due Date: 21-Dec-2023
• Completion Date: 31-Mar-2023

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 4240-1
First edition
2023-03
Fine bubble technology —
Environmental applications —
Part 1:
Inspection method using online
particle counter in dissolved air
flotation (DAF) plant
Reference number
ISO/TS 4240-1:2023(E)
© ISO 2023

---------------------- Page: 1 ----------------------
ISO/TS 4240-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 4240-1:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 BVC measurement technique . 2
5.1 Test equipment . 2
5.2 Procedure . 3
6 Bubble bed depth measurement technique . 4
6.1 Test equipment . 4
6.2 Procedure . 5
7 Advantages and limitations . 6
7.1 Advantages . . 6
7.2 Limitations . 7
Annex A (informative) Measurement of bubble size and size distribution by PCM .8
Annex B (informative) Height from the water surface to the bubble bed depth .9
Annex C (informative) Comparison of the results of bubble bed depth obtained by using the
naked eye and by using a particle counting method .10
Annex D (informative) Measuring bubble bed depth of DAF process in full scale .12
Annex E (informative) Change of bubble bed depth at different operating conditions .14
Annex F (informative) Contribution of particles and bubbles in particle count
measurements .15
Annex G (informative) Effect of sampling tube length .17
Bibliography .18
iii
© ISO 2023 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/TS 4240-1:2023(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 281, Fine bubble technology.
A list of all parts in the ISO 4240 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2023 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 4240-1:2023(E)
Introduction
The dissolved air flotation process is widely used for water treatment plant. This process used micro
bubbles to remove particles by floating them on the surface. There are various factors to check the
operation of the DAF plant. Many of these factors can be measured in field scale DAF plant. However,
some factors are very difficult to measure in the field.
One of these factors is bubble volume concentration (BVC). BVC is usually used as index of the number
of bubbles. Generally, BVC is evaluated by the water displacement method. This method measures the
volume of bubbles as the volume of water displaced. The water displacement method is a direct way
to give accurate BVC of bubble water. However, this method needs large equipment depending on the
capacity of the bubble generator. So, it is almost impossible to measure BVC directly from the DAF plant.
Lab and pilot test with the same nozzle of DAF plant and predictions based on the test results are most
widely used.
Bubble bed depth is also difficult to measure in DAF plant. It is easy to observe the creation of a bubble
bed interface in the middle part of the reactor by the naked eye in a lab and pilot scale DAF reactor
manufactured with a transparent wall. Although it is not possible to present the interface by a single
straight line, a bubble interface zone exists in which above the interface there are clouds of bubbles and
below the interface almost no bubbles are observed. The centre of the bubble interface zone is defined
as the bubble bed interface. Bubble bed depth is defined by the height from the water surface to the
bubble bed interface as presented in Figure A.1. However, in a full-scale DAF plant, it is not easy to
locate the bubble bed interface. The difficulty is that observation by the naked eye is not possible due to
structural constraints.
Therefore, this document specifies indirect measurement methods of BVC and bubble bed depth. This
approach can be useful for on-site inspection of DAF plant.
v
© ISO 2023 – All rights reserved

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4240-1:2023(E)
Fine bubble technology — Environmental applications —
Part 1:
Inspection method using online particle counter in
dissolved air flotation (DAF) plant
1 Scope
This document specifies the bubble volume concentration and bubble bed depth measurement methods
by online particle counter for checking DAF process performance in plant.
The test method of bubble volume concentration is made by measuring bubble size distribution
in contact zone of DAF tank and calculating using formula. And bubble bed depth is evaluated by
measuring the number of bubbles and particles according to the depth at five points in separation zone
of DAF tank.
This document provides the advantages and limitations of using online particle counter in plant.
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 20480-4, Fine bubble technology — General principles for usage and measurement of fine bubbles —
Part 4: Terminology related to microbubble beds
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20480-4 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org
3.1
bubble volume concentration
BVC
index of the volume of bubbles contained in the unit volume of water
Note 1 to entry: It is calculated by the ratio of the total bubble volume to the volume of generated bubble water
during any given time, expressed in %.
[SOURCE: ISO 20480-4:2021, 3.16, modified — "index" has been removed from the term.]
3.2
particle counting method
indirect method to count the number of bubbles and its size distribution in a measurement
Note 1 to entry: Particle counting method (PCM) can trace the variation tendency of the BVC index.
1
© ISO 2023 – All rights reserved

---------------------- Page: 6 ----------------------
ISO/TS 4240-1:2023(E)
Note 2 to entry: Effective range of particle counter to measure bubble size is from 1 μm to 100 μm.
Note 3 to entry: The sampling flowrate is normally adjusted, and the numbers of bubble are counted in the
applied volume of sample.
3.3
bubble and particle size distribution
range (minimum to maximum) of bubble and particle size in a measurement
4 Principle
A particle counter is an instrument which is widely used for the determination of bubble size
[1]-[4]
distribution (see Annex A) . Based on this characteristic, it can be used to evaluate BVC in DAF
plant. Even though the result of this method is not accurate, it can be used to show the tendency of BVC
according to time by real-time monitoring in DAF plant.
5 BVC measurement technique
5.1 Test equipment
This document aimed to evaluate BVC in DAF plant. Therefore, test equipment should be easy to move.
Figure 1 shows the example of equipment for BVC evaluation. The list of equipment is shown below.
a) Online particle counter:
— detecting range: approximately 10 μm to 100 μm;
— support online-mode;
— portable.
b) Metering pump which can be operated at flowrate approximately 100 l/min to 200 l/min.
c) Tube of sufficient length (the effect of sampling tube length is shown in Annex G).
2
  © ISO 2023 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/TS 4240-1:2023(E)
Key
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
Figure 1 — Schematic diagram of equipment for BVC evaluation
5.2 Procedure
a) To minimize errors caused by particles entering the DAF tank, the inflow valve is locked in the DAF
tank to prevent entry of untreated water. In this state, the bubble generator is operated to remove
residual particles in the DAF tank and to make a stable state.
b) The test equipment should be installed near the contact zone for evaluating BVC. The sample is
taken in the middle of the point at the contact zone of the inlet and the outlet. Sampling depth is
at half the depth of the contact zone. Tube for sampling is installed 1 m away from the sidewall to
prevent from interruption of sidewall. Metering pump flowrate shall be approximately 100 l/min to
200 l/min to minimize the influence on the DAF bubble bed.
c) The bubble size distribution is measured using online particle counter. The measurement time
shall be 5 ± 1 min to obtain stable data.
d) Based on the measurement results, the bubble size distribution graph shall be drawn. The
horizontal axis represents the bubble size range, and the vertical axis represents the number of
bubbles. The example is shown in Figure A.1.
e) Calculate BVC using Formula (1).
*
∑×ni
*
i
BVC= ×100 (1)
Q
3
© ISO 2023 – All rights reserved

---------------------- Page: 8 ----------------------
ISO/TS 4240-1:2023(E)
where
BVC
is the bubble volume concentration in %;
*
is the volume of median size bubble of a certain range in ml;
i
*
n

* is the number of bubbles of a certain range whose median size bubble volume is i ;
i
Q
is the volume of sampled water from the contact zone in ml.
6 Bubble bed depth measurement technique
In the case of laboratory and pilot test, bubble bed depth can be measured with the naked eye by
making DAF tank of transparent wall. However, it is impossible in DAF plant. This document provides
the measurement method of bubble bed depth based on particle counting method. The accuracy of
particle counting method was verified in Annex C through the experiments in pilot plant.
6.1 Test equipment
This document aimed to measure bubble bed depth in plant. Therefore, test equipment should be easy
to move. Figure 2 shows the typical example of equipment for bubble bed depth measurement. The list
of equipment is shown below.
a) Online particle counter:
— detecting range: approximately 10 μm to 100 μm;
— support online-mode;
— portable.
b) Metering pump which can be operated at flowrate 100 l/min stably.
c) Tube of sufficient length from the bottom of DAF tank to online particle counter.
d) Scaled pole with sufficient length for marking the position of the hose.
4
  © ISO 2023 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/TS 4240-1:2023(E)
Key
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
7 scaled pole
Figure 2 — Schematic diagram of equipment for bubble bed depth measurement
6.2 Procedure
a) In order to determine the horizontal profile, five points are selected as investigating point. They
are inflow and outflow points of separate zone and three more points with equal interval between
them.
b) At each point, bubble and particle size distribution is investigated using
...

TECHNICAL ISO/TS
SPECIFICATION 4240-1
First edition
Fine bubble technology —
Environmental applications —
Part 1:
Inspection method using online
particle counter in dissolved air
flotation (DAF) plant
PROOF/ÉPREUVE
Reference number
ISO/TS 4240-1:2023(E)
© ISO 2023

---------------------- Page: 1 ----------------------
ISO/TS 4240-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
PROOF/ÉPREUVE © ISO 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 4240-1:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 BVC measurement technique . 2
5.1 Test equipment . 2
5.2 Procedure . 3
6 Bubble bed depth measurement technique . 4
6.1 Test equipment . 4
6.2 Procedure . 5
7 Advantages and limitations . 6
7.1 Advantages . . 6
7.2 Limitations . 7
Annex A (informative) Measurement of bubble size and size distribution by PCM .8
Annex B (informative) Height from the water surface to the bubble bed depth .9
Annex C (informative) Comparison of the results of bubble bed depth obtained by using the
naked eye and by using a particle counting method .10
Annex D (informative) Measuring bubble bed depth of DAF process in full scale .12
Annex E (informative) Change of bubble bed depth at different operating conditions .14
Annex F (informative) Contribution of particles and bubbles in particle count
measurements .15
Annex G (informative) Effect of sampling tube length .17
Bibliography .18
iii
© ISO 2023 – All rights reserved PROOF/ÉPREUVE

---------------------- Page: 3 ----------------------
ISO/TS 4240-1:2023(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 281, Fine bubble technology.
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 2023 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 4240-1:2023(E)
Introduction
The dissolved air flotation process is widely used for water treatment plant. This process used micro
bubbles to remove particles by floating them on the surface. There are various factors to check the
operation of the DAF plant. Many of these factors can be measured in field scale DAF plant. However,
some factors are very difficult to measure in the field.
One of these factors is bubble volume concentration (BVC). BVC is usually used as index of the number
of bubbles. Generally, BVC is evaluated by the water displacement method. This method measures the
volume of bubbles as the volume of water displaced. The water displacement method is a direct way
to give accurate BVC of bubble water. However, this method needs large equipment depending on the
capacity of the bubble generator. So, it is almost impossible to measure BVC directly from the DAF plant.
Lab and pilot test with the same nozzle of DAF plant and predictions based on the test results are most
widely used.
Bubble bed depth is also difficult to measure in DAF plant. It is easy to observe the creation of a bubble
bed interface in the middle part of the reactor by the naked eye in a lab and pilot scale DAF reactor
manufactured with a transparent wall. Although it is not possible to present the interface by a single
straight line, a bubble interface zone exists in which above the interface there are clouds of bubbles and
below the interface almost no bubbles are observed. The centre of the bubble interface zone is defined
as the bubble bed interface. Bubble bed depth is defined by the height from the water surface to the
bubble bed interface as presented in Figure A.1. However, in a full-scale DAF plant, it is not easy to
locate the bubble bed interface. The difficulty is that observation by the naked eye is not possible due to
structural constraints.
Therefore, this document specifies indirect measurement methods of BVC and bubble bed depth. This
approach can be useful for on-site inspection of DAF plant.
v
© ISO 2023 – All rights reserved PROOF/ÉPREUVE

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4240-1:2023(E)
Fine bubble technology — Environmental applications —
Part 1:
Inspection method using online particle counter in
dissolved air flotation (DAF) plant
1 Scope
This document specifies the bubble volume concentration and bubble bed depth measurement methods
by online particle counter for checking DAF process performance in plant.
The test method of bubble volume concentration is made by measuring bubble size distribution
in contact zone of DAF tank and calculating using formula. And bubble bed depth is evaluated by
measuring the number of bubbles and particles according to the depth at five points in separation zone
of DAF tank.
This document provides the advantages and limitations of using online particle counter in plant.
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 20480-4:2021, Fine bubble technology — General principles for usage and measurement of fine bubbles
— Part 4: Terminology related to microbubble beds
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20480-4 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org
3.1
bubble volume concentration
BVC
index of the volume of bubbles contained in the unit volume of water
Note 1 to entry: It is calculated by the ratio of the total bubble volume to the volume of generated bubble water
during any given time, expressed in %.
[SOURCE: ISO 20480-4:2021, 3.16, modified — "index" has been removed from the term.]
3.2
particle counting method
indirect method to count the number of bubbles and its size distribution in a measurement
Note 1 to entry: Particle counting method (PCM) can trace the variation tendency of the BVC index.
1
© ISO 2023 – All rights reserved PROOF/ÉPREUVE

---------------------- Page: 6 ----------------------
ISO/TS 4240-1:2023(E)
Note 2 to entry: Effective range of particle counter to measure bubble size is from 1 μm to 100 μm.
Note 3 to entry: The sampling flowrate is normally adjusted, and the numbers of bubble are counted in the
applied volume of sample.
3.3
bubble and particle size distribution
range (minimum to maximum) of bubble and particle size in a measurement
4 Principle
A particle counter is an instrument which is widely used for the determination of bubble size distribution
[1-4]
(see Annex A). Based on this characteristic, it can be used to evaluate BVC in DAF plant. Even though
the result of this method is not accurate, it can be used to show the tendency of BVC according to time
by real-time monitoring in DAF plant.
5 BVC measurement technique
5.1 Test equipment
This document aimed to evaluate BVC in DAF plant. Therefore, test equipment should be easy to move.
Figure 1 shows the example of equipment for BVC evaluation. The list of equipment is shown below.
a) Online particle counter:
— detecting range: approximately 10 μm to 100 μm;
— support online-mode;
— portable.
b) Metering pump which can be operated at flowrate approximately 100 l/min to 200 l/min.
c) Tube of sufficient length (the effect of sampling tube length is shown in Annex G).
2
PROOF/ÉPREUVE © ISO 2023 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/TS 4240-1:2023(E)
Key
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
Figure 1 — Schematic diagram of equipment for BVC evaluation
5.2 Procedure
a) To minimize errors caused by particles entering the DAF tank, the inflow valve is locked in the DAF
tank to prevent entry of untreated water. In this state, the bubble generator is operated to remove
residual particles in the DAF tank and to make a stable state.
b) The test equipment should be installed near the contact zone for evaluating BVC. The sample is
taken in the middle of the point at the contact zone of the inlet and the outlet. Sampling depth is
at half the depth of the contact zone. Tube for sampling is installed 1 m away from the sidewall to
prevent from interruption of sidewall. Metering pump flowrate shall be approximately 100 l/min to
200 l/min to minimize the influence on the DAF bubble bed.
c) The bubble size distribution is measured using online particle counter. The measurement time
shall be 5 ± 1 min to obtain stable data.
d) Based on the measurement results, the bubble size distribution graph shall be drawn. The
horizontal axis represents the bubble size range, and the vertical axis represents the number of
bubbles. The example is shown in Figure A.1.
e) Calculate BVC using Formula (1).
*
∑×ni
*
i
BVC= ×100 (1)
Q
3
© ISO 2023 – All rights reserved PROOF/ÉPREUVE

---------------------- Page: 8 ----------------------
ISO/TS 4240-1:2023(E)
where
is the bubble volume concentration in %;
BVC
* is the volume of median size bubble of a certain range in ml;
i

*
n
*
is the number of bubbles of a certain range whose median size bubble volume is i ;
i
is the volume of sampled water from the contact zone in ml.
Q
6 Bubble bed depth measurement technique
In the case of laboratory and pilot test, bubble bed depth can be measured with the naked eye by
making DAF tank of transparent wall. However, it is impossible in DAF plant. This document provides
the measurement method of bubble bed depth based on particle counting method. The accuracy of
particle counting method was verified in Annex C through the experiments in pilot plant.
6.1 Test equipment
This document aimed to measure bubble bed depth in plant. Therefore, test equipment should be easy
to move. Figure 2 shows the typical example of equipment for bubble bed depth measurement. The list
of equipment is shown below.
a) Online particle counter:
— detecting range: approximately 10 μm to 100 μm;
— support online-mode;
— portable.
b) Metering pump which can be operated at flowrate 100 l/min stably.
c) Tube of sufficient length from the bottom of DAF tank to online particle counter.
d) Scaled pole with sufficient length for marking the position of the hose.
4
PROOF/ÉPREUVE © ISO 2023 – All rights reserved

---------------------- Page: 9 ----------------------
ISO/TS 4240-1:2023(E)
Key
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
7 scaled pole
Figure 2 — Schematic diagram of equipment for bubble bed depth measurement
6.2 Procedure
a) In order to determine the horizontal profile, five points are selected as investigating point. They
are inflow and outflow points of separate zone and three more points with equal interval between
them.
b) At each point, bubble and particle size distribution is investigated using online particle counter
and metering pump according to depth while DAF process is operated. To make bubble bed depth
constant, pressure of bubble generator and recycle ratio should remain constant during the
measurement (see Anne
...

© ISO/DTS 4240-1 – All rights reserved
ISO/DTSTS 4240-1:20222023(E)
Date: 2023-02-01
ISO TC 281/WG 3
Secretariat: JISC

Fine bubble technology — Environmental applications —
Part 1:
Inspection method using online particle counter in dissolved air flotation (DAF) plant

DTS stage

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This document is not an ISO International Standard. It is distributed for review and comment. It is subject to
change without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of
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To help you, this guide on writing standards was produced by the ISO/TMB and is available at
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A model manuscript of a draft International Standard (known as “The Rice Model”) is available at
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---------------------- Page: 1 ----------------------
© ISO 2022

---------------------- Page: 2 ----------------------
ISO/DTS TS 4240-1:20222023(E)
© ISO 2023
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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
© ISO 2022 – All rights reserved 19
© ISO 2023 – All rights reserved xix

---------------------- Page: 3 ----------------------
ISO/DTSTS 4240-1:20222023(E)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 BVC measurement technique . 2
5.1 Test equipment . 2
5.2 Procedure . 3
6 Bubble bed depth measurement technique . 4
6.1 Test equipment . 4
6.2 Procedure . 5
7 Advantages and limitations . 6
7.1 Advantages . 6
7.2 Limitations . 7
Annex A (informative) Measurement of bubble size and size distribution by
PCM . 8
Annex B (informative) Height from the water surface to the bubble bed depth
.10
Annex C (informative) Comparison of the results of bubble bed depth
obtained by using the naked eye and by using a particle counting
method .11
Annex D (informative) Measuring bubble bed depth of DAF process in full
scale .13
Annex E (informative) Change of bubble bed depth at different operating
conditions .15
Annex F (informative) Contribution of particles and bubbles in particle count
measurements .16
Annex G (informative) Effect of sampling tube length .17
Bibliography .18

20 © ISO 2022 – All rights reserved
xx © ISO 2023 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/DTS TS 4240-1:20222023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of
national standards bodies (ISO member bodies). The work of preparing International
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the subject of patent rights. ISO shall not be held responsible for identifying any or all such
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(see www.iso.org/patents).
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This document was prepared by Technical Committee ISO/TC 281, Fine bubble technology.
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ISO/DTSTS 4240-1:20222023(E)
Introduction
The dissolved air flotation process is widely used for water treatment plant. This process
used micro bubbles to remove particles by floating them on the surface. There are various
factors to check the operation of the DAF plant. Many of these factors can be measured in
field scale DAF plant. However, some factors are very difficult to measure in the field.
One of these factors is bubble volume concentration (BVC). BVC is usually used as index of
the number of bubbles. Generally, BVC is evaluated by the water displacement method.
This method measures the volume of bubbles as the volume of water displaced. The water
displacement method is a direct way to give accurate BVC of bubble water. However, this
method needs large equipment depending on the capacity of the bubble generator. So, it
is almost impossible to measure BVC directly from the DAF plant. Lab and pilot test with
the same nozzle of DAF plant and predictions based on the test results are most widely
used.
Bubble bed depth is also difficult to measure in DAF plant. It is easy to observe the creation
of a bubble bed interface in the middle part of the reactor by the naked eye in a lab and
pilot scale DAF reactor manufactured with a transparent wall. Although it is not possible
to present the interface by a single straight line, a bubble interface zone exists in which
above the interface there are clouds of bubbles and below the interface almost no bubbles
are observed. The centre of the bubble interface zone is defined as the bubble bed
interface. Bubble bed depth is defined by the height from the water surface to the bubble
bed interface as presented in Figure A.1. However, in a full-scale DAF plant, it is not easy
to locate the bubble bed interface. The difficulty is that observation by the naked eye is not
possible due to structural constraints.
Therefore, this document specifies indirect measurement methods of BVC and bubble bed
depth. This approach can be useful for on-site inspection of DAF plant.

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ISO/DTS TS 4240-1:20222023(E)
Fine bubble technology — Environmental applicationapplications
—
Part 1:
Inspection method using online particle counter in dissolved air
flotation (DAF) plant
1 Scope
This document specifies the bubble volume concentration and bubble bed depth measurement methods
by online particle counter for checking DAF process performance in plant.
The test method of bubble volume concentration is made by measuring bubble size distribution in contact
zone of DAF tank and calculating using formula. And bubble bed depth is evaluated by measuring the
number of bubbles and particles according to the depth at five points in separation zone of DAF tank.
TheThis document provides the advantages and limitations of using online particle counter in plant is
indicated. .
2 Normative references
There are no normative references in this document.
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 20480-4:2021, Fine bubble technology — General principles for usage and measurement of fine bubbles
— Part 4: Terminology related to microbubble beds
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20480-4:2021 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
•  — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
•  — IEC Electropedia: available at https://www.electropedia.orghttps://www.electropedia.org
3.1
Bubblebubble volume concentration (
BVC)
index of the volume of bubbles contained in the unit volume of water
Note 1 to entry: It is calculated by the ratio of the total bubble volume to the volume of generated bubble water
during any given time, with % as the unitexpressed in %.
[SourceSOURCE: ISO 20480-4:2021, 3.16, modified – — "index" has been removed ]from the term.]

3.2
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ISO/DTSTS 4240-1:20222023(E)
particle counting method
indirect method to count the number of bubbles and its size distribution in a measurement
Note 1 to entry: Particle counting method (PCM) can trace the variation tendency of the BVC index.
Note 2 to entry: Effective range of particle counter to measure bubble size is from 1 μm to 100 μm.
Note 3 to entry: The sampling flowrate is normally adjusted, and the numbers of bubble are counted in the applied
volume of sample.

3.3
bubble and particle size distribution
range (minimum to maximum) of bubble and particle size in a measurement
4 Principle
A particle counter is an instrument which is widely used for the determination of bubble size distribution
[1-4 ]
(see Annex A) [). ]. Based on this characteristic, it can be used to evaluate BVC in DAF plant. Even
though the result of this method is not accurate, it can be used to show the tendency of BVC according to
time by real-time monitoring in DAF plant.
5 BVC measurement technique
5.1 Test equipment
This document aimed to evaluate BVC in DAF plant. Therefore, test equipment should be easy to move.
Figure 1 shows the example of equipment for BVC evaluation. The list of equipment is shown below.

a) Online particle counter
- :
— detecting range: approximately 10~100 μm
- to 100 μm;
— support online-mode
- ;
— portable.
b) metering Metering pump which can be operated at flowrate approximately 100~200 l/min to
200 l/min.
c) tube Tube of sufficient length (the effect of sampling tube length is shown in Annex G)).


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ISO/DTS TS 4240-1:20222023(E)


Key
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
1 online particle counter
2 pump
3 tube
4 flocculation basin
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ISO/DTSTS 4240-1:20222023(E)
5 contact zone
6 separation zone
Figure 1 –— Schematic diagram of equipment for BVC evaluation
5.2 Procedure
a) To minimize errors caused by particles entering the DAF tank, the inflow valve is locked in the DAF
tank to prevent entry of untreated water. In this state, the bubble generator is operated to remove
residual particles in the DAF tank and to make a stable state.
b) Test The test equipment should be installed near the contact zone for evaluating BVC. The sample is
taken in the middle of the point whereat the contact zone of the inlet toand the outlet. Sampling depth
is at half the depth of the contact zone. Tube for sampling is installed 1 m away from the sidewall to
prevent from interruption of sidewall. Metering pump flowrate shall be approximately 100 l/min
to200 to 200 l/min to minimize the influence on the DAF bubble bed.
c) The bubble size distribution is measured using online particle counter. The measurement time shall
be 5 ± 1 5 ± 1 min to obtain stable data.
d) Based on the measurement results, the bubble size distribution graph shall be drawn. The horizontal
axis represents the bubble size range, and the vertical axis represents the number of bubbles. The
example is shown in Figure A.1.
e) Calculate BVC using Formula (1).

∗
∑𝑛𝑛∗×𝑖𝑖
𝑖𝑖
BVC(%) = × 100        (1)
𝑄𝑄

*
Field Code Changed
∑×ni
*
i
BVC ×100 (1)
Q
where
BVC(%) is the bubble volume concentration (%)
∗
𝑖𝑖 is the volume of median size bubble of a certain range (ml)
∗
𝑛𝑛 ∗ is the number of bubbles of a certain range whose median size bubble volume is 𝑖𝑖
𝑖𝑖
Q is the volume of sampled water from contact zone (ml)

 BVC is the bubble volume concentration in %;
*
 is the volume of median size bubble of a certain range in ml;
i
*

n
* is the number of bubbles of a certain range whose median size bubble volume is i ;
i
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ISO/DTS TS 4240-1:20222023(E)
Q
 is the volume of sampled water from the contact zone in ml.
6 Bubble bed depth measurement technique
In the case of lablaboratory and pilot test, bubble bed depth can be measured with the naked eye by
making DAF tank of transparent wall. However, it is impossible in DAF plant. This document provides the
measurement method of bubble bed depth based on particle counting method. The accuracy of particle
counting method was verified in Annex C through the experiments in pilot plant.
6.1 Test equipment
This document aimed to measure bubble bed depth in plant. Therefore, test equipment should be easy to
move. Figure 2 shows the typical example of equipment for bubble bed depth measurement. The list of
equipment is shown below.
a) online Online particle counter
- :
— detecting range: approximately 10~ μm to 100 ㎛
- μm;
— support online-mode
- ;
— portable.
b) metering Metering pump which can be operated at flowrate 100 l/min stably.
c) tube Tube of enoughsufficient length from the bottom of DAF tank to online particle counter.
d) scaled Scaled pole with enoughsufficient length for marking the position of the hose.


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ISO/DTSTS 4240-1:20222023(E)

Key
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
7 scaled pole
1 online particle counter
2 pump
3 tube
4 flocculation basin
5 contact zone
6 separation zone
7 scaled pole
Figure 2 –— Schematic diagram of equipment for bubble bed depth measurement


6.46.2 Procedure
a) In order to determine the horizontal profile, five points are selected as investigating point. They are
inflow and outflow points of separate zone and three more points with equal interval between them.
b) At each point, bubble and particle size distribution is investigated using online particle counter and
metering pump according to depth while DAF process is operated. To make bubble bed depth
constant, pressure of bubble generator and recycle ratio should remain constant during the
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ISO/DTS TS 4240-1:20222023(E)
measurement (see Annex E). Particles from inflow don’tdo not affect the measurement of the bubble
layer (see Annex F). Detection range shall be set to approximately 10 μm to100 to 100 μm. The
samples are taken from 1 m away from the sidewall using a tube tied on a scaled pole at different
depths. In this time, measuring depths shall have same interval. Metering pump flowrate shall be
100 l/min to minimize the influence on the DAF bubble bed.
c) Based on the results of investigation at each point, bubble bed depth of the point is
...