General Information

Abstract

This part of the European Standard specifies a method for determining the flowability, as defined in CEN/TR 15463, of sludge by means of the extrusion tube apparatus.
This part of this European Standard is applicable to sludge and sludge suspensions from:
—   storm water handling;
—   urban wastewater collecting systems;
—   urban wastewater treatment plants;
—   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 and sludge suspensions of other origins.

Status
Published
Publication Date
17-May-2016
Current Stage
9093 - Decision to confirm - Review Enquiry
Start Date
06-Dec-2021
Completion Date
23-Sep-2026

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Overview

EN 16720-1:2016 (CEN) defines a standard laboratory method for assessing the flowability of sludges using an extrusion tube apparatus (often referred to as a Kasumeter). The method quantifies whether a sludge behaves as a liquid or a paste-like material by measuring how much of a sample remains above a discharge pipe when flow becomes intermittent. The result is expressed as a Flowability index (Fi), which is used to support sludge handling, treatment and disposal decisions.

Key topics and technical requirements

  • Scope: Applicable to sludges from stormwater, urban wastewater collection and treatment, similar industrial wastewater, water supply treatment plants and other origins.
  • Equipment: Transparent cylindrical vessel (100 mm internal diameter, ~350 mm deep) fitted with standardized discharge pipes (PVC or similar) 200 mm long and internal diameters of 5 mm, 10 mm and 20 mm; graduated scale, thermometer (±0.5 °C), and sieve (max 2.5 mm).
  • Sample and preparation: Requires ~3 L sample; avoid air entrainment, sieve out coarse particles >2.5 mm if necessary, homogenize to limit settling.
  • Procedure (summary):
    • Level apparatus and fill cylinder, keeping discharge pipe closed.
    • Open the pipe and allow flow until it becomes clearly discontinuous (≈ one drop per second).
    • Measure the height h of sludge remaining above the pipe opening; repeat for each pipe diameter.
    • Calculate Fi using the simplified hydraulic/Bingham model from measured h, sludge density (ρ), pipe radius (r) and length (l).
  • Test conditions and validity:
    • Standard temperature: 20 ± 0.5 °C (report other temperatures).
    • Fi values are averaged from results with the three pipe sizes; statistical checks define results as valid, indicative or not valid (differences >20% trigger flags).
    • Guidance: Fi < 25 Pa generally indicates a liquid physical state. Results with very large h (e.g., >30 cm) are not significant.

Applications

  • Design and optimization of sludge pumping, transportation, storage, dewatering, drying and land spreading operations.
  • Field and laboratory screening for rheological behaviour to inform process control and equipment selection.
  • Supporting regulatory compliance and operational decision-making in wastewater and water works.
  • Useful for research, comparative testing and quality control of sludge treatment processes.

Who should use this standard

  • Wastewater treatment plant operators and process engineers
  • Environmental and analytical laboratories performing sludge characterization
  • Consultants designing sludge handling and transport systems
  • Regulatory agencies and auditors assessing sludge physical properties
  • Researchers studying sludge rheology and treatment performance

Related standards

  • CEN/TR 15463 - Definitions for physical consistency (thixotropic/piling behaviour)
  • EN 16323 - Glossary of wastewater engineering terms
  • EN 16720-2 (under preparation) - Determination of solidity

Keywords: EN 16720-1:2016, flowability, Flowability index, extrusion tube apparatus, Kasumeter, sludge characterization, sludge flowability test, CEN.

Relations

Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026

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Frequently Asked Questions

EN 16720-1:2016 is a standard published by the European Committee for Standardization (CEN). Its full title is "Characterization of sludges - Physical consistency - Part 1: Determination of flowability - Method by extrusion tube apparatus". This standard covers: This part of the European Standard specifies a method for determining the flowability, as defined in CEN/TR 15463, of sludge by means of the extrusion tube apparatus. This part of this European Standard is applicable to sludge and sludge suspensions from: — storm water handling; — urban wastewater collecting systems; — urban wastewater treatment plants; — 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 and sludge suspensions of other origins.

This part of the European Standard specifies a method for determining the flowability, as defined in CEN/TR 15463, of sludge by means of the extrusion tube apparatus. This part of this European Standard is applicable to sludge and sludge suspensions from: — storm water handling; — urban wastewater collecting systems; — urban wastewater treatment plants; — 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 and sludge suspensions of other origins.

EN 16720-1:2016 is classified under the following ICS (International Classification for Standards) categories: 13.030.20 - Liquid wastes. Sludge. The ICS classification helps identify the subject area and facilitates finding related standards.

EN 16720-1:2016 has the following relationships with other standards: It is inter standard links to CEN/TR 15463:2007, EN 16323:2014, EN 17183:2018, EN 14735:2021. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

EN 16720-1:2016 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Charakterisierung von Schlämmen - Physikalische Beschaffenheit - Teil 1: Bestimmung des Fließverhaltens - Verfahren mit Gerät mit ExtrusionsrohrCaractérisation des boues - Consistance physique - Partie 1: Détermination de l'aptitude à l'écoulement - Méthode utilisant un appareil à tube d'extrusionCharacterization of sludges - Physical consistency - Part 1: Determination of flowability - Method by extrusion tube apparatus13.030.20Liquid wastes. SludgeICS:Ta slovenski standard je istoveten z:EN 16720-1:2016SIST EN 16720-1:2017en,fr,de01-april-2017SIST EN 16720-1:2017SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16720-1
May
t r s x ICS
s uä r u rä t r English Version
Characterization of sludges æ Physical consistency æ Part
sã Determination of flowability æ Method by extrusion tube apparatus Caractßrisation des boues æ Consistance physique æ Partie
sã Dßtermination de l 5aptitude à l 5ßcoulement æ Mßthode utilisant un appareil à tube d 5extrusion
Charakterisierung von Schlämmen æ Physikalische Beschaffenheit æ Teil
sã Bestimmung des Fließverhaltens æ Verfahren mit Gerät mit Extrusionsrohr This European Standard was approved by CEN on
s { March
t r s xä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey andUnited Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
t r s x CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s x y t ræ sã t r s x ESIST EN 16720-1:2017

European foreword . 3 Introduction . 4 1 Scope . 5 2 Normative references . 5 3 Terms and definitions . 5 4 Principle . 6 5 Equipment . 6 6 Test sample . 7 7 Procedure . 7 8 Expression of the results. 7 9 Precision . 8 10 Test report . 8 Annex A (informative)
Flow behaviour of fluids . 9 Annex B (informative)
Extrusion tube apparatus . 10 Annex C (informative)
Results of validation trials . 12 Bibliography . 16
3 European foreword This document (EN 16720-1:2016) has been prepared by Technical Committee CEN/TC 308 “Characterization and management of sludge”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2016 and conflicting national standards shall be withdrawn at the latest by November 2016. 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. EN 16720, Characterization of sludges - Physical consistency consists of the following two parts: — Part 1: Determination of flowability - Method by extrusion tube apparatus
— Part 2: Determination of solidity (in preparation) According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16720-1:2017

5 1 Scope This part of the European Standard specifies a method for determining the flowability, as defined in CEN/TR 15463, of sludge by means of the extrusion tube apparatus. This part of this European Standard is applicable to sludge and sludge suspensions from: — storm water handling; — urban wastewater collecting systems; — urban wastewater treatment plants; — 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 and sludge suspensions of other origins. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 16323:2014, Glossary of wastewater engineering terms CEN/TR 15463:2007, Characterization of sludges - Physical consistency - Thixotropic behaviour and piling behaviour 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 16323:2014 and the following apply. 3.1 dynamic viscosity ratio of the applied shear stress to the shear rate (velocity gradient) in a rotating viscometer Note 1 to entry: Dynamic viscosity is the measure of the resistance to flow of a liquid. 3.2 flowability index Fi parameter indicating whether a sludge is in the “liquid” physical state or not, i.e. is able to flow under the effect of gravity or pressure below a certain threshold 3.3 non-Newtonian fluid fluid having a non-constant shear stress to shear rate ratio SIST EN 16720-1:2017

7 6 Test sample Sufficient volume of the test sample to fill up the apparatus (about 3 l) is required. The presence of coarse particles or lumps of aggregate in the suspension can cause clogging phenomena. If necessary, the sample shall be sieved to exclude particles larger than 2,5 mm (see 5.4). Furthermore, test could be negatively affected by fast-settling particles, clogging phenomena and presence of air bubbles, especially in the discharge pipes. Pour carefully the sludge in the cylinder along the wall to minimize bubbles. If necessary, homogenization at adequate stirring speed in the cylinder should be guaranteed to limit settling. Pre-sieving could limit clogging, but if it appears during test appropriate de-clogging actions could be adopted. 7 Procedure 7.1 Level the apparatus to assure verticality. 7.2 Fill up the cylinder with the sample by keeping closed the end side of the pipe(s) fitted at the bottom and while avoiding the presence of air bubbles. Make the transfer in such a manner th
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