ISO 20466:2024

International
Standard
ISO 20466
First edition
Guidance for performance grading
2024-12
of recovered reverse osmosis (RO)
membranes for water reuse
Reference number
© ISO 2024
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ii
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 .3
4 Concept of grade classification for recovered RO membranes . 3
4.1 General .3
4.2 Purpose of classifying the grade of recovered RO membranes .3
4.3 Applications of recovered RO membranes .3
4.4 Recommended information for recovered RO membranes .3
4.5 Displaying of the information .4
5 Grade classification. 5
5.1 Method of performance tests .5
5.2 Classification of membrane type .5
5.3 Grade of rejection .5
5.4 Grade of flow rate .6
5.5 Example of classification .7
Annex A (informative) Standard test methods and conditions for recovered RO membranes . 8
Bibliography .12

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 3, Risk and
performance evaluation of water reuse systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
Reverse osmosis (RO) membranes are used in various applications such as seawater desalination, ultrapure
water production, wastewater treatment, advanced treatment of secondary treated wastewater for reuse,
etc. However, the performance of RO membranes gradually declines due to aging and membrane fouling
caused by long-term use. At present, used RO membranes are disposed of as consumable materials after
[1]
several years of use.
However, used RO membranes, if recovered by an appropriate process such as chemical cleaning, can
be reused for various water reclamation and reuse applications, with lower costs than those involved in
[2][3]
new membrane production. For example, in Japan, disposed RO membranes from Fukuoka seawater
desalination plant have been reused for boiler feed water production in the waste water processing centre
(sewage plant).
If a used membrane is graded based on its performance, then an appropriate membrane can be selected for
each purpose for water reuse. For example, a Grade C1 membrane (lower salt rejection rate and higher flow
rate) is suitable for reuse in treating sewage for irrigation usage, while a Grade A1 membrane (higher salt
rejection and higher flow rate) is preferable for processing treated sewage for boiler feed water usage.
By reducing membrane disposal, the use of recovered RO membranes can contribute to sustainable
development goals (SDGs). Membrane life extension will promote the reduction of old membrane disposal
(GOAL12), and less production of new membranes will reduce the carbon footprint (GOAL13). Furthermore,
reusing and repurposing RO membranes will also result in an inexpensive and safe water supply to more
people (GOAL6).
In order to promote the use of recovered RO membranes, users need information on the membranes,
including their performance. This will enable new users to apply the membranes to their intended purpose.

v
International Standard ISO 20466:2024(en)
Guidance for performance grading of recovered reverse
osmosis (RO) membranes for water reuse
1 Scope
This document provides guidance and requirements for grade classification of performance of recovered
reverse osmosis (RO) membranes for water reuse systems.
This standard is applicable to the spiral-wound type of recovered membranes from seawater reverse
osmosis (SWRO) and brackish water reverse osmosis (BWRO) systems.
This standard is to ensure consistency in the performance of recovered RO membranes. It does not specify
any method or process for the recovery of RO membranes.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 20670:2023, Water reuse — Vocabulary
3 Terms, definitions and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO 20670 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 Terms and definitions
3.1.1
differential pressure
delta-P
hydraulic pressure drop across the element feed channel that is a differential pressure from the feed water
inlet to the concentrate outlet
[SOURCE: AWWA M53]
3.1.2
element
component containing the membrane, generally replaceable, such as a spiral wound cartridge
[SOURCE: ASTM D6161]
3.1.3
flux
membrane throughput
Note 1 to entry: Flux is usually expressed in volume of permeate (3.1.6) per unit membrane surface area, for example
litre per square metre per hour (l/m ·h) at a given temperature or normalized temperature (more than 20 °C).

Note 2 to entry: Flux can also be expressed in number of moles, or volume or mass of specified component per unit
time per unit membrane surface area.
[SOURCE: ISO 20468-5:2021, 3.1.8, modified — part of the original definition was moved to Note 1 to entry.]
3.1.4
flow rate
mass or volume of fluid passing through the primary device per unit time
[SOURCE: ISO 5167-1:2022, 3.3.1, modified — the admitted term “rate of flow” was removed.]
3.1.5
new membrane manufacturer
company organizations or firms that produce new reverse osmosis (RO) (3.1.10) membranes
3.1.6
permeate
portion of the feed stream that passes through a membrane
[SOURCE: ISO 20468-5:2021, 3.1.16]
3.1.7
recovered membrane supplier
company or organization that supplies or sells recovered reverse osmosis (RO) (3.1.10) membranes and takes
responsibility for quality and performance characteristics of the recovered membranes
3.1.8
recovered RO membrane
used reverse osmosis (RO) (3.1.10) membrane that can be reused after recovery (3.1.9) process
3.1.9
recovery process
recovery
process to restore performance of a used reverse osmosis (RO) (3.1.10) membrane to a certain applicable
level by washing, chemical cleaning, reforming, surface coating, etc.
3.1.10
reverse osmosis
RO
separation process in which one component of a solution is removed from another component by flowing the
feed stream under pressure across a semipermeable membrane that causes selective movement of solvent
against its osmotic pressure difference
Note 1 to entry: Reverse osmosis (RO) removes ions based on electrochemical forces, colloids, and organics down to a
molecular weight of 150, practically reported in units of Daltons. It can also be called hyperfiltration.
[SOURCE: ISO 20468-5:2021, 3.1.19]
3.1.11
used RO membrane
reverse osmosis (RO) (3.1.10) membrane that has been used for a certain period of time and is in need of
replacement
3.1.12
water reuse
use of treated wastewater for beneficial use
Note 1 to entry: Synonymous with water reclamation.
[SOURCE: ISO 20670:2023, 3.109, modified — Note 1 to entry was added.]

3.2 Abbreviated terms
SWRO seawater reverse osmosis
BWRO brackish water reverse osmosis
RO reverse osmosis
4 Concept of grade classification for recovered RO membranes
4.1 General
During a long-term operation period, RO membranes are regularly and repeatedly cleaned with chemicals.
When the membranes reach their end-of-life due to deterioration of performance, they are typically disposed
as waste.
A used RO membrane that is treated by an appropriate recovery process is regarded as a recovered RO
membrane. A recovered RO membrane that conforms to the requirements of this document is a marketable
product.
Even if the membrane is reused several times, it may be referred to as a recovered RO membrane as long as it
is subjected to an appropriate recovery step.
This document does not require any guarantee or warranty of performance of the recovered RO membrane.
Depending on the requirements of users, a guarantee or warranty, or both, can be specified as the
responsibility of the supplier.
4.2 Purpose of classifying the grade of recovered RO membranes
Classifying the grade of a recovered RO membrane based on its performance characteristics, as well as
verifying that a comprehensive performance test has been performed, can help users choose an appropriate
membrane for their applications.
Successful system design and construction or installation of a recovered RO membrane process for water
reuse can be achieved by the appropriate grading of the membrane.
Engineers should design the recovered RO membrane process after verifying membrane specifications such
as rejection and flow rate.
Clarifying these performance parameters and their expected ranges is a mandatory requirement for the
appropriate design of a system, including the feed pump head, piping size and system capacity.
In addition, the design philosophy which is specified in ISO 20468-5 can also be applied to systems with
recovered RO membranes.
4.3 Applications of recovered RO membranes
A recovered RO membrane may be applied for water reuse applications, but should not be applied for potable
use as per ISO 20469.
There are various possible applications; these include cascade implementations in which RO membranes
that are initially used for seawater desalination are subsequently reused for tertiary treatment of sewage or
reused in the same process, or both.
4.4 Recommended information for
...