ISO 20304-1:2020

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 20304-1
ISO/TC 281
Fine bubble technology — Water
Secretariat: JISC
treatment applications —
Voting begins on:
2020-09-10
Part 1:
Voting terminates on:
Test method for evaluating ozone fine
2020-11-05
bubble water generating systems by
the decolorization of methylene blue
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OF ANY RELEVANT PATENT RIGHTS OF WHICH
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IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 20304-1:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
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LIGHT OF THEIR POTENTIAL TO BECOME STAN-
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©
NATIONAL REGULATIONS. ISO 2020

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ISO/FDIS 20304-1:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO/FDIS 20304-1:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Decolorization test by ozone fine bubble water . 2
4.1 Principle . 2
4.2 Test environment conditions . 2
4.3 Configuration of test equipment . 2
4.4 Raw material gas supply unit (A unit) . 3
4.5 Ozone generator supply unit (B unit) . 3
4.6 Chemical reaction unit by ozone (C unit) . 4
4.7 Discharged ozone treatment unit (D unit) . 5
4.8 Calibration procedure . 5
4.9 Test procedure . 5
5 Expression of test results of the decolorization effect . 6
5.1 Evaluation object . 6
5.2 Functional processing . 6
5.3 Uncertainty evaluation . 7
6 Measurement of size and number concentration classification using air .7
7 Test report . 7
Annex A (informative) Examples of in-line measuring instruments . 9
Annex B (informative) Example of test results for ozone bubble and ozone fine bubble
water generating systems .11
Bibliography .13
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ISO/FDIS 20304-1:2020(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 20304 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.
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ISO/FDIS 20304-1:2020(E)

Introduction
Ozone is used to improve water quality e.g. for purification and decomposition of hardly decomposable
substances and decolorization. The conventional method often uses diffuser tubes. However, it has
been found that with ozone fine bubbles, it is possible to use the strong oxidizing power of ozone more
efficiently.
In recent years, the establishment of fine bubble generating technology has made ozone utilization
efficiency higher than that of diffuser tube systems. Test results demonstrate that ozone fine bubble
water generating systems are about 1,6 times more efficient than diffuser tube systems. With this
efficiency increase, cost reduction has become possible.
Decolorization is mainly used for factory wastewater, regeneration and sewage water. It is also used
on a regular basis for sewage treatment facilities, as advanced treatment technology in the dye-house
effluent, etc.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 20304-1:2020(E)
Fine bubble technology — Water treatment applications —
Part 1:
Test method for evaluating ozone fine bubble water
generating systems by the decolorization of methylene blue
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
1 Scope
This document specifies a test method to assess the performance of ozone fine bubble water generating
systems used for decolorizing water-soluble dye in e.g. wastewater and industrial water. This document
does not address the impact of ozone on health and environment.
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 10678, Fine ceramics (advanced ceramics, advanced technical ceramics) — Determination of
photocatalytic activity of surfaces in an aqueous medium by degradation of methylene blue
ISO 20480-1, Fine bubble technology — General principles for usage and measurement of fine bubbles —
Part 1: Terminology
ISO 20480-2:2018, Fine bubble technology — General principles for usage and measurement of fine
bubbles — Part 2: Categorization of the attributes of fine bubbles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20480-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
fine bubble water
water containing air fine bubbles
3.2
ozone fine bubble water
water containing ozone fine bubbles
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ISO/FDIS 20304-1:2020(E)

3.3
absorbance
natural logarithm of the ratio of the light amount before and after transmission of the test water-soluble
dye with the photometric amount defined in ISO 80000-7:2019, 7-32.1
3.4
half-life of absorbance
time required for the change in absorbance to reach 50 % of the initial concentration
4 Decolorization test by ozone fine bubble water
4.1 Principle
A measured quantity of ozone is sent to a water-soluble dye tank through a fine bubble water generating
system. The absorbance in the tank is optically measured to determine the half-life of absorbance.
Absorbance is measured using e.g. a colorimeter, spectrophotometer or absorbance meter. It is desirable
to use an inline type absorbance measuring instrument. Examples of inline measuring instruments are
shown in Annex A.
4.2 Test environment conditions
The temperature of the test room should be 23 °C ± 3 °C and the relative humidity should be 50 % ± 10 %.
In addition, it should be taken care not to mix fine particles in the test environment.
4.3 Configuration of test equipment
The testing apparatus comprises a raw material gas supply unit, an ozone generator supply unit, a
chemical reaction unit by ozone, and a discharged ozone treatment unit. The configuration of the test
equipment is shown in Figure 1. The ozone reaction unit is indicated by a double line in Figure 1.
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ISO/FDIS 20304-1:2020(E)

Key
1 fine bubble water generating system
2 fine bubble water with dissolved methylene blue
3 test tank
4 circulating pump
5 measurement instrument unit
6 valve
7 untreated O
3
A raw material gas supply unit
B ozone generator supply unit
C chemical reaction unit by ozone
D discharged ozone treatment unit
Figure 1 — Configuration of test equipment
4.4 Raw material gas supply unit (A unit)
The raw material gas supply unit (A unit) is shown in Figure 1. Figure 1 shows a material gas supply unit
when using an oxygen cylinder or an oxygen gas generator. The oxygen concentration of the material
gas supply should be 90 % or more.
4.5 Ozone generator supply unit (B unit)
The conditions for supply of ozone to the ozone reaction unit shall be as follows:
a) The ozone flow rate shall be 0,5 l/min, the ozone yield shall be 3 g/h, it is important that the gas
gauge pressure is set and maintained at a certain level of pressure. In addition, the numerical value
of the gas gauge pressure shall be given in the test report, see Clause 7.
NOTE The conversion between ozone mass concentration and volume fraction is standardized by
ISO 13964:1998, 7.2. The results are reported as micrograms per cubic meter at the chosen reference
−6
conditions, or as volume fraction. For ozone, a volume fraction of 1,0 × 10 at 0 °C, 101,3 kPa (standard
3 3
condition) is equivalent to 2 141 μg/m and 1 995 μg/m at 20 °C, 101, 3 kPa.
b) The ozone generator supply unit (B unit) is shown in Figure 1.
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ISO/FDIS 20304-1:2020(E)

4.6 Chemical reaction unit by ozone (C unit)
This C unit is composed of a fine bubble
...