CEN/TR 15252:2006

Characterization of sludges - Protocol for validating methods for physical properties of sludges

This Technical Report specifies procedures for validating characterization methods for physical properties of sludge.
This Technical Report is applicable to sludge and sludge suspensions from:
-   storm water handling;
-   urban wastewater collecting systems;
-   urban wastewater treatment plants;
-   treating industrial wastewater similar to urban wastewater (as defined in Directive 91/271/EEC);
-   water supply treatment plants.
This method is also applicable to sludge suspensions from other origin.

Charakterisierung von Schlämmen - Protokoll für Validierungsmethoden von physikalischen Schlammeigenschaften

Caractérisation des boues - Protocole de validation des méthodes de détermination des propriétés physiques des boues

Karakterizacija blata - Protokol za metode validacije fizikalnih lastnosti blata

General Information

• Status: Published
• Publication Date: 04-Jul-2006
• ICS: 13.030.20 - Liquid wastes. Sludge
• Technical Committee: CEN/TC 308 - Characterization of sludges
• Drafting Committee: CEN/TC 308/WG 1 - Characterization methods
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 05-Jul-2006
• Due Date: 11-Aug-2006
• Completion Date: 05-Jul-2006
• Ref Project: SIST-TP CEN/TR 15252:2007 - Characterization of sludges - Protocol for validating methods for physical properties of sludges

Overview

CEN/TR 15252:2006 is a Technical Report developed by the European Committee for Standardization (CEN) that establishes a protocol for validating methods used to characterize the physical properties of sludges. This standard is essential for ensuring accuracy, repeatability, and reproducibility of sludge physical property measurements across different laboratories and geographic locations.

The scope covers sludges and sludge suspensions originating from various sources such as:

• Stormwater handling systems
• Urban wastewater collection and treatment plants
• Industrial wastewater treatment plants treating wastewater similar to urban sources (per Directive 91/271/EEC)
• Water supply treatment plants
• Other sludge suspensions from miscellaneous origins

CEN/TR 15252:2006 addresses the challenges of analyzing fresh sludge samples-where physical properties may change rapidly over time and under different storage and transport conditions-and proposes structured validation methods to improve reliability of measurement techniques.

Key Topics

• Validation Procedures: The report outlines three main approaches to validate physical property measurement methods:

  • Conventional Round Robin Tests (C-RRT): Circulation of real or synthetic sludge samples to multiple laboratories for independent analysis.
  • Modified Round Robin Tests (M-RRT): Circulation of analysts to a single laboratory near sample sources to conduct tests using their own apparatuses.
  • Confidence Level Evaluation (CLE): Statistical analysis of sludge tests conducted in laboratories near treatment works without actual sample circulation.

• Statistical Evaluation: Based on ISO 5725, the standard emphasizes:

  • Repeatability: Precision under unchanged conditions.
  • Reproducibility: Precision under different conditions.
  • Outlier detection and elimination procedures.
  • Use of robust statistics appropriate for sludge sample variability.

• Handling of Samples: Special considerations include:

  • Avoiding frozen storage to prevent altering sludge characteristics.
  • Maintaining aerobic conditions by appropriate sample container filling.
  • Use of cooling techniques for biodegradable sludge during transport.

• Sample Preparation: Procedures for preparing and circulating synthetic sludge (a mixture of inorganic and organic ingredients) to mimic natural sludge for validation purposes.

• Interlaboratory Collaboration: Recommendations to engage at least nine laboratories from three different countries, encouraging participation by specialized and experienced labs.

Applications

The standard has practical value for:

• Environmental Laboratories: To validate their analysis methods and ensure consistent, comparable results on sludge characterization.
• Wastewater Treatment Facilities: To support process optimization by obtaining reliable physical property data of sludge.
• Industrial Wastewater Management: For monitoring sludge treatment processes under regulatory compliance.
• Research & Development: In innovating new sludge treatment technologies that rely on validated measurement methods.
• Regulatory Authorities: To establish uniform testing frameworks for sludge quality control in accordance with EU directives.

By adhering to CEN/TR 15252:2006, organizations ensure that their sludge measurements align with accepted European standards, improving decision-making, reporting accuracy, and enabling international benchmarking.

Related Standards

• Directive 91/271/EEC: Council Directive concerning urban wastewater treatment, defining terms for wastewater systems and relevant sludge origins.
• ISO 5725 (all parts): International standard on accuracy of measurement methods including trueness and precision, which underpins statistical approaches in this report.
• Additional CEN Standards on sludge characterization and treatment may complement the procedures for physical properties validation.

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Keywords: CEN/TR 15252:2006, sludge characterization, physical properties of sludge, sludge validation methods, round robin tests, repeatability, reproducibility, wastewater treatment, sludge suspensions, synthetic sludge, statistical validation, ISO 5725, environmental laboratory standards, sludge analysis protocol.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2007
Karakterizacija blata - Protokol za metode validacije fizikalnih lastnosti blata
Characterization of sludges - Protocol for validating methods for physical properties of
sludges
Charakterisierung von Schlämmen - Protokoll für Validierungsmethoden von
physikalischen Schlammeigenschaften
Caractérisation des boues - Protocole de validation des méthodes de détermination des
propriétés physiques des boues
Ta slovenski standard je istoveten z: CEN/TR 15252:2006
ICS:
13.030.20 7HNRþLRGSDGNL%ODWR Liquid wastes. Sludge
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 15252
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
July 2006
ICS 13.030.20
English Version
Characterization of sludges - Protocol for validating methods for
physical properties of sludges
Caractérisation des boues - Protocole de validation des Charakterisierung von Schlämmen - Protokoll für
méthodes de détermination des propriétés physiques des Validierungsmethoden von physikalischen
boues Schlammeigenschaften
This Technical Report was approved by CEN on 7 February 2006. It has been drawn up by the Technical Committee CEN/TC 308.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15252:2006: E
worldwide for CEN national Members.

Contents Page
Foreword.3
Introduction.4
1 Scope .5
2 Normative references .5
3 Preliminary arrangements .5
4 Conventional round robin tests (C-RRT).5
5 Modified round robin tests (M-RRT) .7
6 Confidence level evaluation (CLE).8
Bibliography. 10

Foreword
This Technical Report (CEN/TR 15252:2006) has been prepared by Technical Committee CEN/TC 308
“Characterization of sludges”, the secretariat of which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
Introduction
To be published as a “standard”, all the methods defined by CEN must be validated through interlaboratory
trials. The validation procedure is carried out after the 6-months enquiry and before the formal vote, in order to
incorporate comments received during enquiry into the final version to be officially approved.
Validation usually consists in analyzing reference samples circulated to many laboratories in different
countries and in evaluating the “repeatability/reproducibility” of measurements, where:
 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 at a different 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) makes things worse;
 the sludge physical characteristics are strongly affected by transport and handling;
 fresh sludge requires particular precautions and authorization for transport by ordinary delivering systems.
This involves that “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 could 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 could 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 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).
In all cases, preliminary planning and arrangements are required.
1 Scope
This Technical Report specifies procedures for validating characterization methods for physical properties of
sludge.
This Technical Report is applicable to sludge and sludge suspensions from:
 storm water handling;
 urban wastewater collecting systems;
 urban wastewater treatment plants;
 treating industrial wastewater similar to urban wastewater (as defined in Directive 91/271/EEC);
 water supply treatment plants.
This method is also applicable to sludge suspensions from other origin.
2 Normative references
Not applicable
3 Preliminary arrangements
For each material to be tested, the statistical evaluation must be based on the results obtained from at least
nine laboratories, of at least three different countries.
National members of interested CEN/TCs will 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; it is favourable for him having a
computer based calculation program of the defined statistical method.
Preliminary arrangements 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.
4 Conventional round robin tests (C-RRT)
4.1 General
In this case, the “organizer”:
a) prepares real sludge samples, and circulates them to the participating laboratories; or
b) prepares the necessary ingredients to produce synthetic sludge samples, and circulate them to the
participating laboratories, together with the relevant recipe.
NOTE Synthetic sludge must be obtained by suspending in distilled water various ingredients which could be
“inorganic”, e. g. kaolin, quartz sand etc., and “organic”, e. g. alginate, yeast etc.
4.2 Procedure
4.2.1 Preparation of samples by the organizer. The amount of circulate
...