ISO/FDIS 19658

Sludge recovery, recycling, treatment and disposal — Protocol for validating methods for physical properties of sludges

This international standard is intended to provide a protocol for the interlab validation of methods for the characterization of sludge/biosolids physical properties considered that in most cases fresh sludge samples cannot be circulated to several laboratories in different countries for validation purposes as uncontrolled variations of their characteristics would occur.

Valorisation, recyclage, traitement et élimination des boues — Protocole de validation des méthodes de détermination des propriétés physiques des boues

General Information

• Status: Not Published
• ICS: 13.030.20 - Liquid wastes. Sludge
• Technical Committee: ISO/TC 275 - Sludge recovery, recycling, treatment and disposal
• Drafting Committee: ISO/TC 275 - Sludge recovery, recycling, treatment and disposal
• Current Stage: 5000 - FDIS registered for formal approval
• Start Date: 14-May-2025
• Completion Date: 31-Mar-2025

Relations

• Parent: ISO 12891-4:2000 - Retrieval and analysis of surgical implants — Part 4: Analysis of retrieved ceramic surgical implants
• Effective Date: 13-Apr-2024

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/TC 275
Sludge recovery, recycling,
Secretariat: AFNOR
treatment and disposal — Protocol
Voting begins on:
for validating methods for physical
2025-07-23
properties of sludges
Voting terminates on:
2025-09-17
Valorisation, recyclage, traitement et élimination des boues —
Protocole de validation des méthodes de détermination des
propriétés physiques des boues
This document has not been edited by the ISO Central Secretariat.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
FAST TRACK PROCEDURE
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 275
Sludge recovery, recycling,
Secretariat: AFNOR
treatment and disposal — Protocol
Voting begins on:
for validating methods for physical
properties of sludges
Voting terminates on:
Valorisation, recyclage, traitement et élimination des boues —
Protocole de validation des méthodes de détermination des
propriétés physiques des boues
This document has not been edited by the ISO Central Secretariat.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
FAST TRACK PROCEDURE
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Preliminary arrangements . 1
5 Conventional round robin tests (C-RRT) . 2
5.1 General .2
5.2 Procedure .2
5.3 Statistical calculations .3
6 Modified round robin tests (M-RRT) . 3
6.1 General .3
6.2 Procedure .4
6.3 Statistical calculations .4
7 Confidence level evaluation (CLE) . 5
7.1 General .5
7.2 Procedure .5
Bibliography . 6

iii
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 the European Committee for Standardization (CEN)(as CEN/TR 15252:2006)
and was adopted, without modification other than those given below, by Technical Committee ISO/TC 275,
Sludge recovery, recycling, treatment and disposal.
— The applicability of the document has been defined in the Scope;
— Clause 3 has been added.
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
Introduction
To be published as an ISO document, all the methods for physical properties of sludges need to be validated
through interlaboratory trials.
Validation usually consists in analysing reference samples circulated to many laboratories in different
countries and in evaluating the repeatability and reproducibility of measurements.
— Repeatability is defined as the ability of a method to reproduce a measurement while being tested under
an unchanging set of conditions. This does not imply that the obtained value is correct, but rather that it
is the same every time.
— Reproducibility is the same as repeatability, but for a specific set of conditions. It is therefore a more
realistic indication of a method to reproduce a measurement, whenever a predefined set of conditions is
recreated.
However, for physical parameters, with the exception of calorific value, samples of “dried sludge” cannot be
used for analysis, but only “fresh sludge” samples, with the consequence that many problems arise because:
— the sludge physical characteristics change with time of storage, also considered that any preservation
practice (e.g. freezing) can affect sludge properties;
— the sludge physical characteristics are strongly affected by transport and handling;
— fresh sludge requires particular precautions and authorization for transport by ordinary delivering
systems.
Therefore, “fresh sludge” samples need to be examined by laboratories close to wastewater or waterworks
plants and analysed as soon as possible, minimising their manipulation, so the circulation of fresh sludge
samples to laboratories in several places and in different countries requires well defined procedures to
guarantee the reliability of results.
A valid alternative can consist in the examination of “synthetic sludge” samples to be on-site prepared on the
base of a defined recipe and ingredients.
Another possibility is carrying out validation tests through “circulation of analysts”, and not “circulation
of samples”, thus allowing analysts from the participating laboratories to meet in a laboratory close to the
place where samples are collected.
Finally, if any of the above options cannot be followed, validation can be limited to a “confidence level
evaluation” through the statistical evaluation of sludge samples taken in different works and examined in
laboratories located close to the respective works.
Therefore, one of the following three procedures should be followed:
— the first by examining “real or synthetic reference” samples in different laboratories (conventional round
robin tests);
— the second in examining “reference” samples in one laboratory, close to the place where samples are
collected, where analysts from the participating laboratories will meet and work with their own
apparatuses (modified round robin tests);
— the third including the statistical evaluation of sludge samples taken in different works and examined in
laboratories located close to the respective works (confidence level evaluation).
In all cases, preliminary planning and arrangements are required.

v
FINAL DRAFT International Standard ISO/FDIS 19658:2025(en)
Sludge recovery, recycling, treatment and disposal — Protocol
for validating methods for physical properties of sludges
1 Scope
This document specifies procedures for validating the characterization methods for physical properties
of sludge.
The method applies to sludges and suspensions from:
— storm water handling;
— urban wastewater collecting systems;
— urban wastewater treatment plants;
— storm water handling;
— industrial wastewater that has been treated similarly to urban wastewater;
— water supply plants.
In accordance with ISO/TC 275 scope this document is applicable to sludge and products from urban
wastewater collection systems, night soil, storm water handling, water supply treatment plants, wastewater
treatment plants for urban and similar industrial waters.
This document is applicable to all sludge that may have similar environmental and/or health impacts with
exclusion of hazardous sludge from industry and dredged sludge.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
sludge
accumulated settled solids separated from various types of water as a result of natural or artificial processes
[SOURCE: ISO 6707-1:2020, 3.8.27]
4 Preliminary arrangements
For each material to be tested, the statistical evaluation should be based on the results obtained from at
least nine laboratories, of at least three different countries.

National members of interested committees take care t
...

ISO/TC 275/WG 6
Secretariat: AFNOR
Date: 2025-0307-08
Sludge recovery, recycling, treatment and disposal — Protocol for
validating methods for physical properties of sludges
Valorisation, recyclage, traitement et élimination des boues — Protocole de validation des méthodes de
détermination des propriétés physiques des boues
FDIS stage
ISO #####-#:####(X/FDIS 19658:2025(en)
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
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
© ISO #### 2025 – All rights reserved
ii
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Preliminary arrangements . 2
5 Conventional round robin tests (C-RRT) . 2
5.1 General . 2
5.2 Procedure . 2
5.3 Statistical calculations . 3
6 Modified round robin tests (M-RRT) . 4
6.1 General . 4
6.2 Procedure . 4
6.3 Statistical calculations . 5
7 Confidence level evaluation (CLE) . 6
7.1 General . 6
7.2 Procedure . 6
Bibliography . 7

iii
ISO #####-#:####(X/FDIS 19658:2025(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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'sISO’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 the European Committee for Standardization (CEN) [3] and was changed to
this document)(as CEN/TR 15252:2006) and was adopted, without modification other than those given
below, by Technical Committee ISO/TC 275, Sludge recovery, recycling, treatment and disposal.
— The applicability of the document has been defined in the Scope;
— Clause 3 has been added.
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.
© ISO #### 2025 – All rights reserved
iv
Introduction
To be published as an ISO document, all the methods for physical properties of sludges shallneed to be
validated through interlaboratory trials.
Validation usually consists in analysing reference samples circulated to many laboratories in different
countries and in evaluating the repeatability and reproducibility of measurements.
— — Repeatability is defined as the ability of a method to reproduce a measurement while being tested
under an unchanging set of conditions. This does not imply that the obtained value is correct, but rather
that it is the same every time.
— — Reproducibility is the same as repeatability, but for a specific set of conditions. It is therefore a more
realistic indication of a method to reproduce a measurement, whenever a predefined set of conditions is
recreated.
However, for physical parameters, with the exception of calorific value, samples of “dried sludge” cannot be
used for analysis, but only “fresh sludge” samples, with the consequence that many problems arise because:
— — the sludge physical characteristics change with time of storage, also considered that any preservation
practice (e.g. freezing) can affect sludge properties;
— — the sludge physical characteristics are strongly affected by transport and handling;
— — fresh sludge requires particular precautions and authorization for transport by ordinary delivering
systems.
Therefore, “fresh sludge” samples need to be examined by laboratories close to wastewater or waterworks
plants and analysed as soon as possible, minimising their manipulation, so the circulation of fresh sludge
samples to laboratories in several places and in different countries requires well defined procedures to
guarantee the reliability of results.
A valid alternative can consist in the examination of “synthetic sludge” samples to be on-site prepared on the
base of a defined recipe and ingredients.
Another possibility is carrying out validation tests through “circulation of analysts”, and not “circulation of
samples”, thus allowing analysts from the participating laboratories to meet in a laboratory close to the place
where samples are collected.
Finally, if any of the above options cannot be followed, validation can be limited to a “confidence level
evaluation” through the statistical evaluation of sludge samples taken in different works and examined in
laboratories located close to the respective works.
Therefore, one of the following three procedures, which are described in the following, should be followed:
— — the first by examining “real or synthetic reference” samples in different laboratories (conventional
round robin tests);
— — the second in examining “reference” samples in one laboratory, close to the place where samples are
collected, where analysts from the participating laboratories will meet and work with their own
apparatuses (modified round robin tests);
— — the third including the statistical evaluation of sludge samples taken in different works and examined
in laboratories located close to the respective works (confidence level evaluation).
v
ISO #####-#:####(X/FDIS 19658:2025(en)
In all cases, preliminary planning and arrangements are required.
© ISO #### 2025 – All rights reserved
vi
FINAL DRAFT International Standard ISO/FDIS 19658:2025(en)

Sludge recovery, recycling, treatment and disposal — Protocol for
validating methods for physical properties of sludges
1 Scope
This document provides guidelinesspecifies procedures for validating the characterization methods for
physical properties of sludge.
The method applies to sludges and suspensions from:
— — storm water handling;
— — urban wastewater collecting systems;
— — urban wastewater treatment plants;
— — storm water handling;
— — industrial wastewater that has been treated similarly to urban wastewater;
— — water supply plants.
inIn accordance with ISO/TC 275 scope dealing with standardization of the methods for characterizing,
categorizing, preparing, treating, recycling and managingthis document is applicable to sludge and products
from urban wastewater collection systems, night soil, storm water handling, water supply treatment plants,
wastewater treatment plants for urban and similar industrial waters.
This document is applicable to all sludge that may have similar environmental and/or health impacts with
exclusion of hazardous sludge from industry and dredged sludge already covered by ISO/TC 190 “Soil
Quality”.
2 Normative references
Validated standardsThere are no normative references are quoted in the bibliographythis document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 3.1
sludge
accumulated settled solids separated from various types of water as a result of natural or artificial
processes [1]
[SOURCE: ISO 6707-1:2020, 3.8.27]
4 Preliminary arrangements
For each material to be tested, the statistical evaluation should be based on the results obtained from at least
nine laboratories, of at least three different countries.
National members of interested committees take care to select special laboratories in their countries; these
laboratories should preferably have been successfully involved in round robin tests in the past.
In addition, the analysts should have enough experience in statistics; they should have a computer-based
calculation program of the defined statistical method.
Preliminary arrangements should involve the definition of:
— — the method to be tested;
— — the nature of samples;
— — methods of statistical calculation;
— — a list of all participants to testing, including address, contact person, telephone, fax and e-mail;
— — costs and agreement about the coverage of the expenses.
5 Conventional round robin tests (C-RRT)
5.1 General
This procedure is applicable to dried real sludge samples and/or synthetic sludge samples to be prepared on-
site at the analysis site.
In this case, the organizer:
a) a) prepares real sludge samples, and circulates them to the participating laboratories; or
b) b) prepares the necessary ingredients to produce synthetic sludge samples, and
circulatecirculates them to the participating laboratories, together with the relevant recipe.
NOTE Synthetic sludge can be obtained by suspending in distilled water various ingredients which can be
“inorganic”, e.g. kaolin, quartz sand etc.,, and “organic”, e.g. alginate, yeast etc.
5.2 Procedure
Concerning the preparation of samples by the organizer, the number of circulated samples shall be defined
depending on the type of the parameter to be investigated. In all cases an additional 20 % of samples shall be
prepared and held by the organizer; these can be used if any problems are encountered during the exercise.
To have enough statistical material, aan RRT shall include at least 3 samples at different concentrations of the
investigated parameter.
The sample container should tolerate a slight increase of the inner pressure; possible alternatives are wide
neck bottles made from polyethylene or polypropylene (only for inorganic determinations) and metal bottles
(when organics are the targets).
Sample bottles shall be half-filled to favour maintaining aerobic conditions.
...