Determination of the ultimate aerobic biodegradability of plastic materials in an aqueous medium - Method by measuring the oxygen demand in a closed respirometer (ISO 14851:2019)

This document specifies a method, by measuring the oxygen demand in a closed respirometer, for the
determination of the degree of aerobic biodegradability of plastic materials, including those containing
formulation additives. The test material is exposed in an aqueous medium under laboratory conditions
to an inoculum from activated sludge.
If an unadapted activated sludge is used as the inoculum, the test simulates the biodegradation
processes which occur in a natural aqueous environment; if a mixed or pre-exposed inoculum is used,
the method is used to investigate the potential biodegradability of a test material.
The conditions used in this document do not necessarily correspond to the optimum conditions
allowing maximum biodegradation to occur, but this document is designed to determine the potential
biodegradability of plastic materials or give an indication of their biodegradability in natural
environments.
The method enables the assessment of the biodegradability to be improved by calculating a carbon
balance (optional, see Annex E).
The method applies to the following materials.
— Natural and/or synthetic polymers, copolymers or mixtures thereof.
— Plastic materials which contain additives such as plasticizers, colorants or other compounds.
— Water-soluble polymers.
— Materials which, under the test conditions, do not inhibit the microorganisms present in the
inoculum. Inhibitory effects can be determined using an inhibition control or by another appropriate
method (see, for example, ISO 8192[2]). If the test material is inhibitory to the inoculum, a lower test
concentration, another inoculum or a pre-exposed inoculum can be used.

Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien in einem wässrigen Medium - Verfahren mittels Messung des Sauerstoffbedarfs in einem geschlossenen Respirometer (ISO 14851:2019)

Dieses Dokument legt ein Verfahren fest, mit dem durch Messung des Sauerstoffbedarfs in einem geschlossenen Respirometer der Grad der aeroben Bioabbaubarkeit von Kunststoffen, einschließlich solcher Kunststoffe, die Formulierungs Additive enthalten, bestimmt werden kann. Die Prüfsubstanz wird in einem wässrigen Medium unter Laborbedingungen einem Inokulum aus Belebtschlamm ausgesetzt.
Wird ein nicht adaptierter Belebtschlamm als Inokulum verwendet, werden durch die Prüfung die Bioabbauprozesse simuliert, die in einer natürlichen wässrigen Umgebung auftreten; wird ein gemischtes oder voradaptiertes Inokulum verwendet, dient das Verfahren dazu, die potentielle Bioabbaubarkeit einer Prüfsubstanz zu untersuchen.
Die in diesem Dokument angewendeten Bedingungen entsprechen nicht notwendigerweise den optimalen Bedingungen, die das Auftreten eines maximalen Bioabbaus zulassen, sondern dieses Dokument ist für die Bestimmung der potentiellen Bioabbaubarkeit von Kunststoffen ausgelegt oder dafür vorgesehen, Erkenntnisse hinsichtlich deren Bioabbaubarkeit in natürlichen Umgebungen zu liefern.
Das Verfahren ermöglicht durch die Berechnung einer Kohlenstoffbilanz (wahlweise, siehe Anhang E) die Verbesserung der Beurteilung der Bioabbaubarkeit.
Das Verfahren ist auf folgende Substanzen anwendbar:
   natürliche und/oder synthetische Polymere, Copolymere oder Gemische aus diesen;
   Kunststoffe, die Additive, wie z. B. Weichmacher, Farbstoffe oder andere Verbindungen, enthalten;
   wasserlösliche Polymere;
   Substanzen, die unter den Prüfbedingungen die im Inokulum vorhandenen Mikroorganismen nicht inhibieren. Inhibierungswirkungen können durch eine Inhibierungskontrolle oder ein anderes geeignetes Verfahren bestimmt werden (siehe zum Beispiel ISO 8192 [2]). Wirkt die Prüfsubstanz inhibierend auf das Inokulum, kann eine geringere Prüfkonzentration, ein anderes oder ein voradaptiertes Inokulum verwendet werden.

Évaluation de la biodégradabilité aérobie ultime des matériaux plastiques en milieu aqueux - Méthode par détermination de la demande en oxygène dans un respiromètre fermé (ISO 14851:2019)

Le présent document spécifié une méthode d'évaluation du taux de biodégradation aérobie des matériaux plastiques, y compris ceux contenant des additifs, par la détermination de la demande d'oxygène dans un respiromètre fermé. Le matériau d'essai en milieu aqueux est exposé dans des conditions de laboratoire à un inoculum provenant de boues activées.
La méthode simule les processus de biodégradation d'un environnement aquatique naturel si l'on utilise, par exemple, des boues activées non adaptées; si on utilise un inoculum mélangé ou pré-exposé, la méthode permet d'étudier la biodégradabilité potentielle du matériau d'essai.
Les conditions utilisées dans le présent document ne correspondent pas nécessairement aux conditions optimales permettant d'obtenir le taux maximal de biodégradation; cependant, le présent document est conçu pour déterminer la biodégradabilité potentielle ou pour donner une indication de la biodégradabilité des matériaux plastiques dans le milieu naturel.
La méthode permet d'affiner l'évaluation de la biodégradabilité par le calcul d'un bilan de carbone (facultatif, voir l'Annexe E).
La présente méthode s'applique aux matériaux suivants:
— polymères naturels et/ou synthétiques, copolymères ou mélanges de ceux-ci;
— matériaux plastiques contenant des additifs tels que plastifiants, colorants ou tout autre composé;
— polymères hydrosolubles;
— matériaux n'ayant pas d'effet inhibiteur dans les conditions d'essai sur les micro-organismes présents dans l'inoculum. Les effets inhibiteurs peuvent être déterminés en utilisant un dispositif de contrôle de l'inhibition ou par toute autre méthode appropriée (voir, par exemple, l'ISO 8192[2]). Si le matériau d'essai a un effet inhibiteur vis-à-vis de l'inoculum, il est possible d'utiliser une plus faible concentration, un autre inoculum ou un inoculum pré-exposé.

Določanje končne aerobne biorazgradljivosti polimernih materialov v vodnem mediju - Metoda z merjenjem porabe kisika v zaprtem respirometru (ISO 14851:2019)

Ta dokument določa metodo za določanje stopnje aerobne biorazgradljivosti polimernih materialov, vključno s takimi, ki vsebujejo formulacijske dodatke, z merjenjem porabe kisika v zaprtem respirometru. Preskusni material je v vodnem mediju pod laboratorijskimi pogoji izpostavljen inokulumu iz aktivnega blata.
Če se kot inokulum uporabi neprilagojeno aktivno blato, preskus simulira postopke biorazgradnje, ki potekajo v naravnem vodnem okolju; če se uporabi mešan ali predhodno izpostavljen inokulum, se metoda uporabi za preiskavo potencialne biorazgradljivosti preskusnega materiala.
Pogoji, uporabljeni v tem dokumentu, niso nujno enaki optimalnim pogojem, pri katerih pride do največje stopnje biorazgradnje, vendar je ta dokument zasnovan za merjenje potencialne biorazgradljivosti polimernih materialov in podaja oceno njihove biorazgradljivosti v naravnih okoljih.
Metoda omogoča izboljšanje ocene biorazgradljivosti z izračunom ravnovesja ogljika (izbirno, glej dodatek E).
Metoda se uporablja za naslednje materiale:
– naravne in/ali sintetične polimere, kopolimere ali njihove mešanice;
– polimerne materiale, ki vsebujejo dodatke, kot so mehčala, barvila ali druge spojine;
– polimere, topne v vodi;
– materiale, ki v preskusnih pogojih ne zavirajo delovanja mikroorganizmov, prisotnih v inokulumu. Zaviralne učinke je mogoče določiti na podlagi spremljanja zaviranja ali z drugo ustrezno metodo (glej npr. standard ISO 8192[2]). Če preskusni material zavira inokulum, se lahko uporabi manjša preskusna koncentracija, drug inokulum ali predhodno izpostavljeni inokulum.

General Information

Status
Published
Public Enquiry End Date
06-Sep-2016
Publication Date
07-May-2019
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
18-Apr-2019
Due Date
23-Jun-2019
Completion Date
08-May-2019

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SLOVENSKI STANDARD
SIST EN ISO 14851:2019
01-junij-2019
Nadomešča:
SIST EN ISO 14851:2004
Določanje končne aerobne biorazgradljivosti polimernih materialov v vodnem
mediju - Metoda z merjenjem porabe kisika v zaprtem respirometru (ISO
14851:2019)

Determination of the ultimate aerobic biodegradability of plastic materials in an aqueous

medium - Method by measuring the oxygen demand in a closed respirometer (ISO
14851:2019)

Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien in

einem wässrigen Medium - Verfahren mittels Messung des Sauerstoffbedarfs in einem

geschlossenen Respirometer (ISO 14851:2019)

Évaluation de la biodégradabilité aérobie ultime des matériaux plastiques en milieu

aqueux - Méthode par détermination de la demande en oxygène dans un respiromètre
fermé (ISO 14851:2019)
Ta slovenski standard je istoveten z: EN ISO 14851:2019
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 14851:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 14851:2019
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SIST EN ISO 14851:2019
EN ISO 14851
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2019
EUROPÄISCHE NORM
ICS 83.080.01 Supersedes EN ISO 14851:2004
English Version
Determination of the ultimate aerobic biodegradability of
plastic materials in an aqueous medium - Method by
measuring the oxygen demand in a closed respirometer
(ISO 14851:2019)

Évaluation de la biodégradabilité aérobie ultime des Bestimmung der vollständigen aeroben

matériaux plastiques en milieu aqueux - Méthode par Bioabbaubarkeit von Kunststoff-Materialien in einem

détermination de la demande en oxygène dans un wässrigen Medium - Verfahren mittels Messung des

respiromètre fermé (ISO 14851:2019) Sauerstoffbedarfs in einem geschlossenen
Respirometer (ISO 14851:2019)
This European Standard was approved by CEN on 12 March 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14851:2019 E

worldwide for CEN national Members.
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SIST EN ISO 14851:2019
EN ISO 14851:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 14851:2019
EN ISO 14851:2019 (E)
European foreword

This document (EN ISO 14851:2019) has been prepared by Technical Committee ISO/TC 61 "Plastics"

in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by

NBN.

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 October 2019, and conflicting national standards shall

be withdrawn at the latest by October 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 14851:2004.

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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 14851:2019 has been approved by CEN as EN ISO 14851:2019 without any modification.

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SIST EN ISO 14851:2019
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SIST EN ISO 14851:2019
INTERNATIONAL ISO
STANDARD 14851
Second edition
2019-03
Determination of the ultimate aerobic
biodegradability of plastic materials
in an aqueous medium — Method by
measuring the oxygen demand in a
closed respirometer
Évaluation de la biodégradabilité aérobie ultime des matériaux
plastiques en milieu aqueux — Méthode par détermination de la
demande en oxygène dans un respiromètre fermé
Reference number
ISO 14851:2019(E)
ISO 2019
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SIST EN ISO 14851:2019
ISO 14851:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 14851:2019
ISO 14851:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Test environment ................................................................................................................................................................................................. 3

6 Reagents ........................................................................................................................................................................................................................ 3

6.1 Distilled or deionized water ........................................................................................................................................................ 4

6.2 Test medium .............................................................................................................................................................................................. 4

6.2.1 Standard test medium ................................................................................................................................................. 4

6.2.2 Optimized test medium ........................................................................................................................................... ... 4

6.3 Pyrophosphate solution .................................................................................................................................................................. 6

6.4 Carbon dioxide absorber ................................................................................................................................................................ 6

7 Apparatus ..................................................................................................................................................................................................................... 6

8 Procedure..................................................................................................................................................................................................................... 6

8.1 Test material ............................................................................................................................................................................................. 6

8.2 Reference material ............................................................................................................................................................................... 7

8.3 Preparation of the inoculum ....................................................................................................................................................... 7

8.4 Test .................................................................................................................................................................................................................... 8

9 Calculation and expression of results ............................................................................................................................................. 9

9.1 Calculation .................................................................................................................................................................................................. 9

9.2 Expression and interpretation of results ......................................................................................................................10

10 Validity of results ..............................................................................................................................................................................................10

11 Test report ................................................................................................................................................................................................................11

Annex A (informative) Theoretical oxygen demand (ThOD)....................................................................................................12

Annex B (informative) Correction of BOD values for interference by nitrification ..........................................13

Annex C (informative) Principle of a closed manometric respirometer ......................................................................15

Annex D (informative) Two-phase closed-bottle version of the respirometric test.........................................17

Annex E (informative) Example of the determination of a carbon balance ..............................................................20

Annex F (informative) Example of a determination of the amount of water-insoluble

polymer remaining at the end of a biodegradation test and the molecular mass of

the polymer .............................................................................................................................................................................................................22

Annex G (informative) Example of the determination of the CO absorbed in the absorbent ..............23

Bibliography .............................................................................................................................................................................................................................25

© ISO 2019 – All rights reserved iii
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SIST EN ISO 14851:2019
ISO 14851:2019(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).

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 on 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 the following

URL: www .iso .org/iso/foreword .html.

The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 14, Environmental

aspects.

This second edition cancels and replaces the first edition (ISO 14851:1999), which has been technically

revised. It also incorporates the Technical Corrigendum ISO 14851:1999/Cor.1:2005. The main changes

compared to the previous edition are as follows:
— the footnotes have been renumbered;

— in Annex C, errors in the key to Figure C.1 have been corrected and minor improvements made to

the figure itself;

— in scope and Clause 8, soil and compost have been excluded for the inoculums used in this document;

iv © ISO 2019 – All rights reserved
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SIST EN ISO 14851:2019
ISO 14851:2019(E)

— in 8.4, numbers of test flask for the test material and blank control have been changed from two

to three;
— references in this document have been updated for latest active version;
— the Bibliography has been updated.

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 2019 – All rights reserved v
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SIST EN ISO 14851:2019
ISO 14851:2019(E)
Introduction

With the increasing use of plastics, their recovery and disposal have become a major issue. As a first

priority, recovery is promoted. Complete recovery of plastics, however, is difficult. For example, plastic

litter, which comes mainly from consumers, is difficult to recover completely. Additional examples of

plastics which are difficult to recover are fishing tackle, plastic microbeads in personal care products

and water-soluble polymers. These plastic materials tend to leak from closed waste-management

cycles into the environment. Biodegradable plastics are now emerging as one of the options available

to solve such environmental problems. Plastic materials, such as products or packaging, which are sent

to composting facilities are expected to be potentially biodegradable. Therefore, it is very important

to determine the potential biodegradability of such materials and to obtain an indication of their

biodegradability in natural environments.
vi © ISO 2019 – All rights reserved
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SIST EN ISO 14851:2019
INTERNATIONAL STANDARD ISO 14851:2019(E)
Determination of the ultimate aerobic biodegradability
of plastic materials in an aqueous medium — Method by
measuring the oxygen demand in a closed respirometer

WARNING — Sewage, activated sludge, soil and compost may contain potentially pathogenic

organisms. Therefore, appropriate precautions should be taken when handling them. Toxic test

compounds and those whose properties are unknown should be handled with care.
1 Scope

This document specifies a method, by measuring the oxygen demand in a closed respirometer, for the

determination of the degree of aerobic biodegradability of plastic materials, including those containing

formulation additives. The test material is exposed in an aqueous medium under laboratory conditions

to an inoculum from activated sludge.

If an unadapted activated sludge is used as the inoculum, the test simulates the biodegradation

processes which occur in a natural aqueous environment; if a mixed or pre-exposed inoculum is used,

the method is used to investigate the potential biodegradability of a test material.

The conditions used in this document do not necessarily correspond to the optimum conditions

allowing maximum biodegradation to occur, but this document is designed to determine the potential

biodegradability of plastic materials or give an indication of their biodegradability in natural

environments.

The method enables the assessment of the biodegradability to be improved by calculating a carbon

balance (optional, see Annex E).
The method applies to the following materials.
— Natural and/or synthetic polymers, copolymers or mixtures thereof.

— Plastic materials which contain additives such as plasticizers, colorants or other compounds.

— Water-soluble polymers.

— Materials which, under the test conditions, do not inhibit the microorganisms present in the

inoculum. Inhibitory effects can be determined using an inhibition control or by another appropriate

[2]

method (see, for example, ISO 8192 ). If the test material is inhibitory to the inoculum, a lower test

concentration, another inoculum or a pre-exposed inoculum can be used.
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 8245, Water quality — Guidelines for the determination of total organic carbon (TOC) and dissolved

organic carbon (DOC)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
© ISO 2019 – All rights reserved 1
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SIST EN ISO 14851:2019
ISO 14851:2019(E)

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
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

3.2
activated sludge

biomass produced in the aerobic treatment of waste water by the growth of bacteria and other

microorganisms in the presence of dissolved oxygen
3.3
concentration of suspended solids in an activated sludge

amount of solids obtained by filtration or centrifugation of a known volume of activated sludge (3.2)

and drying at about 105 °C to constant mass
3.4
biochemical oxygen demand
BOD

mass concentration of the dissolved oxygen consumed under specified conditions by the aerobic

biological oxidation of a chemical compound or organic matter in water

Note 1 to entry: It is expressed as milligrams of oxygen uptake per milligram or gram of test compound.

3.5
theoretical oxygen demand
ThOD

theoretical maximum amount of oxygen required to oxidize a chemical compound completely, calculated

from the molecular formula

Note 1 to entry: It is expressed as milligrams of oxygen uptake per milligram or gram of test compound.

3.6
total organic carbon
TOC
amount of carbon bound in an organic compound
3.7
dissolved organic carbon
DOC

part of the organic carbon in water which cannot be removed by specified phase separation, for example

by centrifugation at 40 000 m·s for 15 min or by membrane filtration using membranes with pores of

0,2 µm to 0,45 µm diameter
3.8
lag phase

time, measured in days, from the start of a test until adaptation and/or selection of the degrading

microorganisms is achieved and the degree of biodegradation of a chemical compound or organic

matter has increased to about 10 % of the maximum level of biodegradation (3.9)
3.9
maximum level of biodegradation

degree of biodegradation, measured in per cent, of a chemical compound or organic matter in a test,

above which no further biodegradation takes place during the test
2 © ISO 2019 – All rights reserved
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SIST EN ISO 14851:2019
ISO 14851:2019(E)
3.10
biodegradation phase

time, measured in days, from the end of the lag phase (3.8) of a test until about 90 % of the maximum

level of biodegradation (3.9) has been reached
3.11
plateau phase

time, measured in days, from the end of the biodegradation phase (3.10) until the end of a test

3.12
pre-exposure

pre-incubation of an inoculum in the presence of the chemical compound or organic matter under test,

with the aim of enhancing the ability of the inoculum to biodegrade the test material by adaptation

and/or selection of the microorganisms
3.13
pre-conditioning

pre-incubation of an inoculum under the conditions of the subsequent test in the absence of the chemical

compound or organic matter under test, with the aim of improving the test by acclimatization of the

microorganisms to the test conditions
4 Principle

The biodegradability of a plastic material is determined using aerobic microorganisms in an aqueous

system. The test mixture contains an inorganic medium, the organic test material (the sole source of

carbon and energy) with a concentration between 100 mg/l and 2 000 mg/l of organic carbon, and

activated sludge as the inoculum. The mixture is stirred in closed flasks in a respirometer for a period

not exceeding 2 months. The carbon dioxide evolved is absorbed in a suitable absorber in the headspace

of the flasks. The consumption of oxygen (BOD) is determined, for example by measuring the amount

of oxygen required to maintain a constant volume of gas in the respirometer flasks, or by measuring

the change in volume or pressure (or a combination of the two) either automatically or manually. An

example of a respirometer is given in Annex C. Alternatively, the two-phase closed-bottle version

[3]
described in ISO 10708 may be used (see Annex D).

The level of biodegradation is determined by comparing the BOD with the theoretical amount (ThOD)

and expressed in per cent. The influence of possible nitrification processes on the BOD has to be

considered. The test result is the maximum level of biodegradation determined from the plateau

phase of the biodegradation curve. Optionally, a carbon balance may be calculated to give additional

information on the biodegradation (see Annex E). Moreover, also the absorbed carbon dioxide in the

adsorber at the end of the test may be determined to give additional information on the biodegradation

(see Annex G).
[6]

Unlike ISO 9408 , which is used for a variety of organic compounds, this document is specially designed

for the determination of the biodegradability of plastic materials. The special requirements necessary

affect the choice of the inoculum and the test medium, and there is the possibility of improving the

evaluation of the biodegradability by calculating a carbon balance.
5 Test environment

Incubation shall take place in the dark or in diffuse light in an enclosure which is free from vapours

inhibitory to microorganisms and which is maintained at a constant temperature, preferably between

20 °C and 25 °C, to an accuracy of ±1 °C, or at any other appropriate temperature depending on the

inoculum used and the environment to be assessed.
6 Reagents
Use only reagents of recognized analytical grade.
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SIST EN ISO 14851:2019
ISO 14851:2019(E)
6.1 Distilled or deionized water

Distilled or deionized water, free of toxic substances (copper in particular) and containing less than

2 mg/l of DOC.
6.2 Test medium

Depending on the purpose of the test, different test media may be used. For example, if simulating

a natural environment use the standard test medium (6.2.1). If a test material is used at higher

concentrations, use the optimized test medium (6.2.2) with higher buffering capacity and nutrient

concentrations.
6.2.1 Standard test medium
6.2.1.1 Solution A
Dissolve the following in water (6.1) and make up to 1 000 ml.
anhydrous potassium dihydrogen phosphate (KH PO ) 8,5 g
2 4
anhydrous dipotassium hydrogen phosphate (K HPO ) 21,75 g
2 4
disodium hydrogen phosphate dihydrate (Na HPO ·2H O) 33,4 g
2 4 2
ammonium chloride (NH Cl) 0,5 g

The correct composition of the solution can be checked by measuring the pH, which should be 7,4.

6.2.1.2 Solution B

Dissolve 22,5 g of magnesium sulfate heptahydrate (MgSO ·7H O) in water (6.1) and make up to

4 2
1 000 ml.
6.2.1.3 Solution C

Dissolve 36,4 g of calcium chloride dihydrate (CaCl ·2H O) in water (6.1) and make up to 1 000 ml.

2 2
6.2.1.4 Solution D

Dissolve 0,25 g of iron(III) chloride hexahydrate (FeCl ·6H O) in water (6.1) and make up to 1 000 ml.

3 2

Prepare this solution freshly before use to avoid precipitation, or add a drop of concentrated

hydrochloric acid (HCl) or a drop of 0,4 g/l aqueous solution of ethylenediaminetetraacetic acid (EDTA).

6.2.1.5 Preparation
To prepare 1 l of test medium, add the following to about 500 ml of water (6.1),
— 10 ml of solution A;
— 1 ml of each of solutions B to D.

Make up to 1 000 ml with water (6.1). Prepare the test medium freshly before use. The solutions A up to

C may be stored up to 6 months in the dark at room temperature.
6.2.2 Optimized test medium

This optimized medium is highly buffered and contains more inorganic nutrients. This is necessary to

keep the pH constant in the system during the test, even at high concentrations of the test material. The

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