Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 2: Gravimetric measurement of carbon dioxide evolved in a laboratory-scale test (ISO 14855-2:2018)

This document specifies a method for determining the ultimate aerobic biodegradability of plastic
materials under controlled composting conditions by gravimetric measurement of the amount of carbon
dioxide evolved. The method is designed to yield an optimum rate of biodegradation by adjusting the
humidity, aeration and temperature of the composting vessel.
The method applies to the following materials:
— natural and/or synthetic polymers and copolymers, and mixtures of these;
— plastic materials that contain additives such as plasticizers or colorants;
— water-soluble polymers;
— materials that, under the test conditions, do not inhibit the activity of microorganisms present in
the inoculum.
If the test material inhibits microorganisms in the inoculum, another type of mature compost or preexposure
compost can be used.

Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien unter den Bedingungen kontrollierter Kompostierung - Verfahren mittels Analyse des freigesetzten Kohlenstoffdioxides - Teil 2: Gravimetrische Messung des freigesetzten Kohlenstoffdioxides im Labormaßstab (ISO 14855-2:2018)

Dieses Dokument legt ein Verfahren zur Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien unter den Bedingungen kontrollierter Kompostierung durch gravimetrische Messung der Menge des freigesetzten Kohlenstoffdioxids fest. Das Verfahren ist dafür ausgelegt, eine optimale Geschwindigkeit des Bioabbaus durch Anpassung von Feuchte, Begasung und Temperatur des Kompostiergefäßes zu erreichen.
Das Verfahren ist auf folgende Substanzen anwendbar:
—   natürliche und/oder synthetische Polymere und Copolymere sowie Gemische aus diesen;
—   Kunststoffe, die Additive, wie z. B. Weichmacher oder Farbstoffe, enthalten;
—   wasserlösliche Polymere;
—   Substanzen, die unter Prüfbedingungen die Aktivität der im Inokulum vorhandenen Mikroorganismen nicht inhibieren.
Wirkt die Prüfsubstanz inhibierend auf die Mikroorganismen im Inokulum, kann eine andere Art von ausge¬reiftem Kompost oder voradaptierter Kompost verwendet werden.

Détermination de la biodégradabilité aérobique ultime des matériaux plastiques dans des conditions contrôlées de compostage - Méthode par analyse du dioxyde de carbone libéré - Partie 2: Mesurage gravimétrique du dioxyde de carbone libéré lors d'un essai de laboratoire (ISO 14855-2:2018)

Le présent document spécifie une méthode de détermination de la biodégradabilité aérobie ultime des matériaux plastiques, dans des conditions de compostage contrôlées, par mesurage gravimétrique de la teneur en dioxyde de carbone libéré. Cette méthode est conçue pour produire un taux de biodégradation optimal en ajustant l'humidité, l'aération et la température du récipient de compostage.
La méthode s'applique aux matériaux suivants:
— polymères et copolymères naturels et/ou synthétiques, et mélanges des deux;
— matériaux plastiques contenant des additifs tels que plastifiants ou colorants;
— polymères solubles dans l'eau;
— matériaux qui, dans les conditions d'essai, n'inhibent pas l'activité des micro-organismes présents dans l'inoculum.
Si le matériau d'essai inhibe les micro-organismes dans l'inoculum, il est possible d'utiliser un autre type de compost mature ou un compost de pré-exposition.

Določanje končne aerobne biorazgradljivosti in razkroja polimernih materialov pod nadzorovanimi pogoji kompostiranja - Metoda z analizo sproščenega ogljikovega dioksida - 2. del: Gravimetrične metode za določevanje sproščenega ogljikovega dioksida v laboratorijskem merilu (ISO 14855-2:2018)

Ta dokument opisuje metodo za ugotavljanje končne aerobne biorazgradljivosti polimernih materialov pod nadzorovanimi pogoji kompostiranja z gravimetričnim merjenjem količine nastalega ogljikovega dioksida. Namen metode je doseči čim večjo stopnjo biorazgradljivosti s prilagoditvijo vlažnosti, zračenja in temperature posode za kompostiranje.
Ta metoda se uporablja za naslednje materiale:
– naravni in/ali sintetični polimeri in kopolimeri ter njihove mešanice;
– polimerni materiali, ki vsebujejo dodatke, kot so mehčala ali barvila;
– polimeri, topni v vodi;
– materiali, ki v preskusnih pogojih ne zavirajo delovanja mikroorganizmov, prisotnih v
inokulumu.
Če preskusni material zavira mikroorganizme v inokulumu, se lahko uporabi druga vrsta zrelega komposta ali vnaprej izpostavljenega komposta.

General Information

Status
Published
Public Enquiry End Date
30-Jun-2017
Publication Date
27-Sep-2018
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
31-Aug-2018
Due Date
05-Nov-2018
Completion Date
28-Sep-2018

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SLOVENSKI STANDARD
SIST EN ISO 14855-2:2018
01-november-2018
1DGRPHãþD
SIST EN ISO 14855-2:2009

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QDG]RURYDQLPLSRJRMLNRPSRVWLUDQMD0HWRGD]DQDOL]RVSURãþHQHJDRJOMLNRYHJD
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Determination of the ultimate aerobic biodegradability of plastic materials under

controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 2:

Gravimetric measurement of carbon dioxide evolved in a laboratory-scale test (ISO

14855-2:2018)

Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien unter

den Bedingungen kontrollierter Kompostierung - Verfahren mittels Analyse des

freigesetzten Kohlenstoffdioxides - Teil 2: Gravimetrische Messung des freigesetzten

Kohlenstoffdioxides im Labormaßstab (ISO 14855-2:2018)

Détermination de la biodégradabilité aérobique ultime des matériaux plastiques dans des

conditions contrôlées de compostage - Méthode par analyse du dioxyde de carbone

libéré - Partie 2: Mesurage gravimétrique du dioxyde de carbone libéré lors d'un essai de

laboratoire (ISO 14855-2:2018)
Ta slovenski standard je istoveten z: EN ISO 14855-2:2018
ICS:
13.030.99 Drugi standardi v zvezi z Other standards related to
odpadki wastes
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 14855-2:2018 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST EN ISO 14855-2:2018
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SIST EN ISO 14855-2:2018
EN ISO 14855-2
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2018
EUROPÄISCHE NORM
ICS 83.080.01 Supersedes EN ISO 14855-2:2009
English Version
Determination of the ultimate aerobic biodegradability of
plastic materials under controlled composting conditions -
Method by analysis of evolved carbon dioxide - Part 2:
Gravimetric measurement of carbon dioxide evolved in a
laboratory-scale test (ISO 14855-2:2018)

Détermination de la biodégradabilité aérobie ultime Bestimmung der vollständigen aeroben

des matériaux plastiques dans des conditions Bioabbaubarkeit von Kunststoff-Materialien unter den

contrôlées de compostage - Méthode par analyse du Bedingungen kontrollierter Kompostierung -

dioxyde de carbone libéré - Partie 2: Mesurage Verfahren mittels Analyse des freigesetzten

gravimétrique du dioxyde de carbone libéré lors d'un Kohlenstoffdioxides - Teil 2: Gravimetrische Messung

essai de laboratoire (ISO 14855-2:2018) des freigesetzten Kohlenstoffdioxides im
Labormaßstab (ISO 14855-2:2018)
This European Standard was approved by CEN on 21 August 2018.

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

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14855-2:2018 E

worldwide for CEN national Members.
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SIST EN ISO 14855-2:2018
EN ISO 14855-2:2018 (E)
Contents Page

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

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SIST EN ISO 14855-2:2018
EN ISO 14855-2:2018 (E)
European foreword

This document (EN ISO 14855-2:2018) 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 February 2019, and conflicting national standards

shall be withdrawn at the latest by February 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 14855-2:2009.

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 14855-2:2018 has been approved by CEN as EN ISO 14855-2:2018 without any

modification.
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SIST EN ISO 14855-2:2018
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SIST EN ISO 14855-2:2018
INTERNATIONAL ISO
STANDARD 14855-2
Second edition
2018-07
Determination of the ultimate aerobic
biodegradability of plastic materials
under controlled composting
conditions — Method by analysis of
evolved carbon dioxide —
Part 2:
Gravimetric measurement of carbon
dioxide evolved in a laboratory-scale
test
Détermination de la biodégradabilité aérobie ultime des matériaux
plastiques dans des conditions contrôlées de compostage — Méthode
par analyse du dioxyde de carbone libéré —
Partie 2: Mesurage gravimétrique du dioxyde de carbone libéré lors
d'un essai de laboratoire
Reference number
ISO 14855-2:2018(E)
ISO 2018
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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 2018 – All rights reserved
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(E)
Contents Page

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

Introduction ..................................................................................................................................................................................................................................v

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

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

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

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

5 Reagents ........................................................................................................................................................................................................................ 3

6 Apparatus ..................................................................................................................................................................................................................... 4

7 Procedure..................................................................................................................................................................................................................... 5

7.1 Preparation of the inoculum ....................................................................................................................................................... 5

7.2 Preparation of the sea sand ......................................................................................................................................................... 5

7.3 Preparation of test material and reference material .............................................................................................. 5

7.4 Starting up the test .............................................................................................................................................................................. 6

7.5 Measurement of the evolved carbon dioxide ................................................................................................................ 7

7.6 Incubation period ................................................................................................................................................................................. 7

7.7 Termination of the test ..................................................................................................................................................................... 8

8 Calculation .................................................................................................................................................................................................................. 8

8.1 Theoretical amount of carbon dioxide evolved by test material.................................................................. 8

8.2 Percentage biodegradation .......................................................................................................................................................... 8

9 Expression and interpretation of results .................................................................................................................................... 9

10 Validity of results ................................................................................................................................................................................................. 9

11 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Basic principle of the test ................................................................................................................................11

Annex B (informative) Example of an apparatus using an electrically heated composting vessel ...13

Annex C (informative) Derivation of the formula used to calculate the degree of

biodegradation from the amount of carbon dioxide evolved .............................................................................15

Bibliography .............................................................................................................................................................................................................................16

© ISO 2018 – All rights reserved iii
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(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).

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 Technical Committee ISO/TC 61, Plastics, Subcommittee SC 14, Plastics

and environment.

This second edition cancels and replaces the first edition (ISO 14855-2:2007), which has been

technically revised. It also incorporates the Technical Corrigendum ISO 14855-2:2007/Cor.1:2009.

The main changes compared to the previous edition are as follows.

— The correct values for the particle size of soda talc given in the Technical Corrigendum 1

ISO 14855-2:2007/Cor.1:2009 have been adopted.
— The following numbers of composting vessels have been provided:
a) three test vessels for the test mixture;
b) three vessels for blank controls;
c) three vessels for checking inoculum activity using a reference material.

— The next criterion has been added to the list of validity criteria in Clause 10:

c) the inoculum in the blank has produced more than 50 mg but less than 150 mg of carbon

dioxide per gram of volatile solids (mean values) after 10 days of incubation.
A list of all parts in the ISO 14855 series can be found on the ISO website.

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 © ISO 2018 – All rights reserved
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(E)
Introduction

Management of plastics waste is a serious problem in the world. Plastics recovery technologies include

material recovery (mechanical recycling, chemical or feedstock recycling, and biological or organic

recycling) and energy recovery (heat, steam or electricity as a substitute for fossil fuels or other fuel

resources). The use of biodegradable plastics is one valuable recovery option (biological or organic

recycling).

Several ISO standards for determining the ultimate aerobic/anaerobic biodegradability of plastic

materials have been published. In particular, ISO 14855-1 is a common test method that measures

the amount of carbon dioxide evolved using methods such as continuous infrared analysis, gas

chromatography or titration.

Compared with ISO 14855-1, the amounts of compost inoculum and test sample used in this document

are one-tenth the size. In order to ensure the activity of the compost inoculum, inert material that gives

the mixture the same texture as soil is mixed into the inoculum. The carbon dioxide evolved from the

test vessel is determined by absorbing it in a carbon dioxide trap and carrying out gravimetric analysis

of the absorbent. The method described in this document, which uses a closed system to capture the

carbon dioxide evolved, can also be used to obtain valuable information, by means of isotopic-labelling

studies, on the way in which the molecular structure of co-polymers degrades.
© ISO 2018 – All rights reserved v
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SIST EN ISO 14855-2:2018
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SIST EN ISO 14855-2:2018
INTERNATIONAL STANDARD ISO 14855-2:2018(E)
Determination of the ultimate aerobic biodegradability
of plastic materials under controlled composting
conditions — Method by analysis of evolved carbon
dioxide —
Part 2:
Gravimetric measurement of carbon dioxide evolved in a
laboratory-scale test

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 for determining the ultimate aerobic biodegradability of plastic

materials under controlled composting conditions by gravimetric measurement of the amount of carbon

dioxide evolved. The method is designed to yield an optimum rate of biodegradation by adjusting the

humidity, aeration and temperature of the composting vessel.
The method applies to the following materials:
— natural and/or synthetic polymers and copolymers, and mixtures of these;
— plastic materials that contain additives such as plasticizers or colorants;
— water-soluble polymers;

— materials that, under the test conditions, do not inhibit the activity of microorganisms present in

the inoculum.

If the test material inhibits microorganisms in the inoculum, another type of mature compost or pre-

exposure compost 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 11721-1, Textiles — Determination of resistance of cellulose-containing textiles to micro-organisms —

Soil burial test — Part 1: Assessment of rot-retardant finishing

ISO 14855-1, Determination of the ultimate aerobic biodegradability of plastic materials under controlled

composting conditions — Method by analysis of evolved carbon dioxide — Part 1: General method

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
© ISO 2018 – All rights reserved 1
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(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 https: //www .electropedia .org/
3.1
compost

organic soil conditioner obtained by biodegradation of a mixture principally consisting of various

vegetable residues, occasionally with other organic material and having a limited mineral content

3.2
composting
aerobic process designed to produce compost
3.3
total dry solids

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
3.4
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

3.5
ultimate aerobic biodegradation

breakdown of an organic compound by micro-organisms in the presence of oxygen into carbon dioxide,

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

3.6
theoretical amount of evolved carbon dioxide
ThCO

maximum theoretical amount of carbon dioxide evolved after completely oxidizing a chemical

compound, calculated from the molecular formula and expressed as milligrams of carbon dioxide

evolved per milligram or gram of test compound
3.7
lag phase

time from the start of a test until adaptation and/or selection of the degradation 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
Note 1 to entry: It is measured in days.
3.8
maximum level of biodegradation

degree of biodegradation of a chemical compound or organic matter in a test, above which no further

biodegradation takes place during the test
Note 1 to entry: It is measured as a percentage.
3.9
biodegradation phase

time from the end of the lag phase of a test until about 90 % of the maximum level of biodegradation has

been reached
Note 1 to entry: It is measured in days.
2 © ISO 2018 – All rights reserved
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(E)
3.10
plateau phase
time from the end of the biodegradation phase until the end of the test
Note 1 to entry: It is measured in days.
3.11
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 micro-organisms
3.12
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
3.13
water-holding capacity
WHC

mass of water that evaporates from soil saturated with water when the soil is dried to constant mass at

105 °C, divided by the dry mass of the soil
4 Principle

This method is designed to yield the optimum rate of biodegradation of a plastic material in mature

compost by controlling the humidity, aeration ratio and temperature in the composting vessel. It also

aims to determine the ultimate biodegradability of the test material by using a small-scale reactor. The

degradation rate is periodically measured by determining the mass of the evolved carbon dioxide using

an absorption column filled with soda lime and soda talc on an electronic balance.

The test material is mixed with an inoculum derived from mature compost and with an inert material

such as sea sand. The sea sand plays an active part by acting as a holding body for humidity and

microorganisms. Examples of suitable test arrangements are presented in Annexes A and B. The

amount of carbon dioxide evolved is measured at intervals on an electronic balance and the carbon

dioxide content is determined using the following method. The derivation of the formula used to

calculate the degree of biodegradation from the amount of carbon dioxide evolved is given in Annex C.

In this method, the degree of biodegradation, expressed as a percentage, is calculated by comparing the

amount of carbon dioxide evolved with the theoretical amount (ThCO ).

The test is terminated when the plateau phase of biodegradation has been attained. The standard time

for termination is 45 days, but the test could be continued for up to six months.

5 Reagents
Use only analytical-grade reagents. Use only deionized water.
5.1 Soda lime, particle size between 2 mm and 4 mm, for CO absorption.

5.2 Anhydrous calcium chloride, particle size between 2 mm and 3 mm, for water absorption.

5.3 Sodium hydroxide on a talc support (commonly known as soda talc), particle size between 2 mm

and 3 mm, for CO absorption.

5.4 Silica gel (with moisture indicator), particle size between 2 mm and 4 mm, for water absorption.

© ISO 2018 – All rights reserved 3
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(E)
5.5 Sea sand, particle size between 20 mesh and 35 mesh.

5.6 Reference material: thin-layer chromatography (TLC) grade microcrystalline cellulose with a

particle size of less than 20 µm, for use as the reference material in the positive control.

6 Apparatus

Ensure that all glassware is thoroughly cleaned and, in particular, free from organic or toxic matter.

6.1 Air-supply system, capable of supplying each composting vessel with carbon-dioxide-free, water-

saturated air.

The air can be prepared by supplying compressed air through a carbon dioxide trap and a humidifier

(see examples in Annexes A and B), i.e. columns filled with soda lime and water, respectively. The air

flow rate shall be controlled with a flow controller so that it is high enough for aerobic conditions.

6.2 Composting vessels

Use bottles or columns that ensure a supply of water-saturated, carbon-dioxide-free air to the contents.

A suitable volume is 500 ml. If the loss in mass of the test material is to be determined, weigh each

composting vessel empty before starting the test.

6.3 System for the determination of carbon dioxide, capable of determining carbon dioxide directly

from the change in mass of a carbon dioxide trap. The carbon dioxide trap shall consist of columns filled

with soda lime, soda talc and anhydrous calcium chloride. The calcium chloride should preferably be in

a separate column from the soda lime and soda talc (see examples in Annexes A and B). An ammonia

trap (dilute sulfuric acid) and a water trap (silica gel and calcium chloride) are required between the

composting vessel and the carbon-dioxide-absorbing column.

6.4 Gas-tight tubes, used to connect the composting vessels to the air supply and the carbon dioxide

measurement system.

6.5 pH-meter, used for measurement of the pH of the test mixture. It shall be accurate to 0,1 pH-units

or better.

6.6 Analytical equipment, used for the determination of the dry solids (at 105 °C), volatile solids (at

550 °C) and total organic carbon (TOC), for elemental analysis of the test material and, if required, for the

determination of dissolved inorganic carbon (DIC), volatile fatty acids, oxygen in the air, water content

and total nitrogen.

6.7 Balance, used to periodically measure the mass of the carbon-dioxide-absorbing column, in order

to determine the amount of carbon dioxide evolved, and also to measure the mass of the composting

vessel containing compost and test material. A top-loading electronic balance with a display reading

down to 10 mg and a capacity greater than 500 g is preferred.

6.8 Thermostatic-control unit, required to maintain the temperature of the composting vessels at

a controlled temperature during the test (see examples given in Annexes A and B). It shall be capable of

maintaining the temperature of the composting vessels constant to within ±2 °C.

6.9 Composting bioreactor. A box, made from polypropylene or another suitable material, having a

size that allows the contents to be stirred easily with a spatula. The box shall be provided with a tightly

fitting lid to avoid excessive water loss. Three holes with a diameter of about 1 cm shall be made at equal

distances along the centreline of the lid. These holes allow air to enter and gases to leave the box, as well

as the gradual evaporation of excess water.
4 © ISO 2018 – All rights reserved
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SIST EN ISO 14855-2:2018
ISO 14855-2:2018(E)
7 Procedure
7.1 Preparation of the inoculum

Well-aerated compost from a properly operating aerobic composting plant shall be used as the inoculum.

The inoculum shall be homogeneous and free from large inert objects such as glass, stones or pieces of

metal. Remove such items manually and then sieve the compost on a screen of about 3 mm mesh.

Compost can be made as follows. Wood shavings, sawdust, used mushroom beds, chaff or rice straw can

be used as the carbon source. Livestock excrement is added as a source of composting microorganisms

and mineral salt nutrients. This is placed in a container with a volume of about 1 m and mixed well.

It is recommended that the compost be adjusted to a carbon/nitrogen (C/N) ratio of 15 and a carbon/

phosph
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