ISO/FDIS 14855-2

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

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. NOTE If the test material inhibits microorganisms in the inoculum, another type of mature compost or pre-exposure compost can be used.

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

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.

General Information

• Status: Not Published
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 61/SC 14 - Environmental aspects
• Drafting Committee: ISO/TC 61/SC 14/WG 2 - Biodegradability
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 19-Jun-2026
• Completion Date: 19-Jun-2026

Relations

• Consolidates: FprEN ISO 14855-2 - 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/FDIS 14855-2:2026)
• Effective Date: 12-Feb-2026
• Revises: ISO 14855-2:2018 - 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
• Effective Date: 28-Sep-2024

Overview

ISO/FDIS 14855-2:2026 establishes an internationally recognized method for determining the ultimate aerobic biodegradability of plastic materials under controlled composting conditions, specifically using gravimetric measurement of carbon dioxide (CO₂) evolved during laboratory-scale tests. Developed by the International Organization for Standardization (ISO), this standard supports consistent and reliable assessment of how plastics break down in composting environments. The method is optimized by adjusting key composting conditions such as humidity, aeration, and temperature, enabling reproducible biodegradation rates.

This document applies to:

• Natural and synthetic polymers and copolymers (including mixtures)
• Plastics containing additives such as plasticizers or colorants
• Water-soluble polymers
• Plastics that do not inhibit microbial activity in compost inocula

Key Topics

• Controlled Composting Conditions:
  The standard outlines how to adjust environmental factors such as temperature, humidity, and aeration to achieve optimal biodegradation in a simulated compost environment.

• Gravimetric CO₂ Measurement:
  The core of the method involves capturing and weighing the mass of carbon dioxide evolved from the degradation of plastics. Soda lime, soda talc, and related absorbents are used as key reagents to trap the CO₂ for accurate gravimetric analysis.

• Material Suitability:
  The test is suitable for a wide range of plastics, including those with additives and water-soluble polymers, provided the material does not inhibit compost microbial activity. Guidance is provided for handling cases where inhibition is observed.

• Test Procedure:
  Detailed steps cover sample preparation, inoculum sourcing and treatment, airflow management, and data analysis. The process is completed by comparing the measured CO₂ to the theoretical maximum value to quantify biodegradability.

• Safety Precautions:
  Appropriate measures are recommended for handling compost, sewage, activated sludge, and unknown test materials, ensuring safe laboratory practice.

Applications

• Product Certification:
  The method is essential for manufacturers seeking certification that their plastic products or materials are industrially compostable and meet global sustainability standards.

• Research & Development:
  R&D teams use this protocol to compare the biodegradability of different plastic formulations or additives under standardized lab-scale composting conditions.

• Regulatory Compliance:
  Producers and importers of biodegradable plastics can demonstrate compliance with international, regional, or local environmental requirements using the procedures defined in ISO/FDIS 14855-2.

• Comparative Testing:
  Institutions and laboratories can employ this method to benchmark new or existing materials against accepted reference materials for biodegradability.

Related Standards

• ISO 14855-1:
  General method for determining the ultimate aerobic biodegradability of plastic materials by analysis of evolved carbon dioxide, with applications for continuous infrared, gas chromatography, or titrimetric measurement.

• ISO 11721-1:
  Method for assessing the resistance of cellulose-containing textiles to microorganisms via soil burial testing - relevant for evaluating organic material breakdown.

• Other ISO 14855 Series Parts:
  Additional documents in this series provide further methodologies for composting biodegradability, supporting a broad range of analysis and testing requirements.

Conclusion

ISO/FDIS 14855-2 offers a reliable, reproducible laboratory-scale protocol for measuring the biodegradability of plastics under controlled composting conditions. Its gravimetric CO₂ analysis supports credible certification, compliance, and research in the growing field of biodegradable plastics, assisting stakeholders across manufacturing, environmental testing, and materials innovation to advance toward sustainable solutions. For robust, internationally harmonized assessment of compostable plastics, ISO/FDIS 14855-2 remains an essential reference.

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/TC 61/SC 14
Determination of the ultimate
Secretariat: DIN
aerobic biodegradability of
Voting begins on:
plastic materials under controlled
2026-06-19
composting conditions — Method
Voting terminates on:
by analysis of evolved carbon
2026-08-14
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
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 61/SC 14
Determination of the ultimate
Secretariat: DIN
aerobic biodegradability of
Voting begins on:
plastic materials under controlled
composting conditions — Method
Voting terminates on:
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
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 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 .6
7.3 Preparation of test material and reference material .6
7.4 Starting up the test .6
7.5 Measurement of the evolved carbon dioxide .7
7.5.1 Gravimetric analysis .7
7.5.2 Alternative quantitative analytical methods .7
7.6 Incubation period .8
7.7 Termination of the test .8
8 Calculation . 9
8.1 Theoretical amount of carbon dioxide evolved by test material .9
8.2 Percentage biodegradation .9
9 Expression and interpretation of results . 9
10 Validity of results . 10
11 Test report . 10
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
Annex D (informative) Determination of the degree of biodegradation of plastics under
composting conditions — Synchronous gas sampling method .16
Bibliography .21

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 14, Environmental
aspects, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 249, Plastics, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 14855-2:2018), which has been technically
revised.
The main changes are as follows:
— the NDIR method to the measurement of evolved carbon dioxide in addition to the conventional
gravimetric method has been added;
— a schematic diagram of the measurement device and an example of biodegradability measurement using
an NDIR sensor have been added to Annex D.
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
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.
In addition to traditional gravimetric methods, this test method adds a new way to measure carbon dioxide
using spectroscopic non-dispersive infrared (NDIR) technology, significantly reducing the routine work and
chemical use required for quantitative measurement without compromising the quantitative accuracy of
chemical methods.
v
FINAL DRAFT International Standard ISO/FDIS 14855-2:2026(en)
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 can 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.
NOTE 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 and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
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 biodegradability
breakdown ratio by expressed as percentage 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
[SOURCE: ISO 14852:2021, 3.1]
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.
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 can 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.
5.5 Sea sand, particle size between 425 μm and 850 μm (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.
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 prepare compost with a particle size of 2 mm to 5 mm using sieves
with 2 mm and 5 mm openings.
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/
phosphorous (C/P) ratio of 30. Insufficient phosphorous and nitrogen levels can be supplemented using
calcium superphosphate and ammonium magnesium phosphate hexahydrate or urea, respectively. Water is
added to reach a water content equal to 65 %. The C/N, C/P and water-content values may also be adjusted
to other values, determined by experience, depending on seasonal variations and climatic differences. The
compost should be removed from the container once a week to turn it and add water, if necessary, before
returning it to the container to continue the composting process. The age of the compost should preferably
be between two and four months.
Normally, non-exposed inoculum is preferred, especially in the case of standard tests simulating
biodegradation behaviour in real composting facilities. Depending on the purpose of the test, however,
pre-exposed compost may be used, provided that this is clearly stated in the test report (e.g. percent
biodegradation = X %, using pre-exposed compost) and provided the method of pre-exposure is detailed in
the test report.
Determine the total dry solids and volatile-solids content of the compost inoculum. The total dry solids
should be between 35 % and 55 % of the wet solids and the volatile solids more than 30 % of the dry solids.
Adjust the water content, if necessary, before the compost is used by adding water or drying gently, e.g. by
aerating the compost with dry air.
Prepare a mixture of 1 part of inoculum to 5 parts of deionized water. Mix by shaking and measure the pH
immediately. It should be between 7,0 and 9,0.
For further characterization of the inoculum, suitable parameters such as the content of total organic carbon,
total nitrogen or fatty acids can optionally be determined at the beginning and the end of the test.
Check the activity of the inoculum during the test by means of a biodegradable reference material and
by measuring carbon dioxide evolution in the blank vessels. The reference material shall be degraded by
70 % or more at the end of the test. The inoculum in the blank should produce between 50 mg and 150 mg
of carbon dioxide per gram of volatile solids over the first 10 days of the test. If the production of carbon
dioxide is too high, stabilize the compost by aeration for several days before using it in a new test.
If biodegradation is inhibited by physicochemical conditions, such as a decrease in the pH of the test system
due to hydrolysis of the sample, solidification or aggregation of the compost due to melting, or a decrease in
water activity due to water absorption, it is recommended to conduct the test under milder conditions in a
water system, soil system, or home compost system.

7.2 Preparation of the sea sand
Dip the sea sand in tap water. After removing floating impurities by decantation, rinse the sand sufficiently,
drain off the water and dry the sand at about 105 °C.
NOTE Sea sand, or another inert mineral material (e.g. quartz sand) with SiO content ≥90 % and particle size
of 0,5 mm to 1 mm can be used. Sea sand plays an important role in maintaining appropriate moisture content and
promoting microbial growth.
7.3 Preparation of test material and reference material
Determine the total organic carbon (TOC) of the test material and the reference material using, for example,
ISO 8245 and report it preferably as grams of TOC per gram of total dry solids. Alternatively, provided that
the materials do not contain inorganic carbon, it is possible to determine the carbon content by elemental
analysis. For this, the test material should contain sufficient organic carbon to yield carbon dioxide in an
amount suitable for determination. Normally, a minimum of 10 g of total dry solids containing 4 g of TOC is
required per 500 ml-vessel.
The test material should preferably be used in powder form, but it may also be introduced as small pieces of
films or as fragments of shaped articles. A maximum particle size of 250 µm in diameter is recommended.
For materials containing inorganic carbon (e.g. carbonate fillers), the inorganic carbon shall be determined
and subtracted, or a suitable pre-treatment shall be applied to remove inorganic carbon before TOC
determination. The applied procedure shall be reported.
7.4 Starting up the test
Provide at least the following numbers of composting vessels:
a) three test vessels for the test mixture (symbol V );
T
b) three vessels for blank controls (symbol V );
B
c) three vessels for checking inoculum activity using a reference material (symbol V ).
R
The amount of test mixture, containing inoculum and the test material, used in the test depends on the
quality of the test material and the size of the composting vessels. The relation between the total dry solids
of the inoculum and the total dry solids of the test material should preferably be about 6:1. If added, inert
material is not considered in this relationship. The test mixture should have the same water content as the
inoculum. The water content of the test mixture should be set at 80 % to 90 % of the water-holding capacity
(
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ISO/TC 61/SC 14
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Date: 2026-05-05
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ISO/FDIS 14855-2:2026(en)
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ISO/TC 61/SC 14/WG 2
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Secretariat: DIN .
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Determination of the ultimate aerobic biodegradability of plastic
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materials under controlled composting conditions — Method by
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analysis of evolved carbon dioxide — Part 2: Gravimetric
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measurement of carbon dioxide evolved in a laboratory scale test
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Part 2:
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scale test
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Détermination de la biodégradabilité aérobie ultime des matériaux plastiques dans des conditions contrôlées de
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compostage — Méthode par analyse du dioxyde de carbone libéré — Partie 2: Mesurage gravimétrique du
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Partie 2: Mesurage gravimétrique du dioxyde de carbone libéré lors d'un essai de laboratoire
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St l D fi iti
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FDIS stage
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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, Formatted: Left: 1.5 cm, Right: 1.5 cm, Gutter: 0 cm,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
Header distance from edge: 1.27 cm
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
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EmailE-mail: [e-mail]
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Website: www.iso.orgwww.iso.org
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Published in Switzerland
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© ISO 2026 – All rights reserved
iii
ISO/DISFDIS 14855-2:2025(E2026(en)
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Contents
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Foreword . vi
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Introduction . vii
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1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 3
5 Reagents . 4
6 Apparatus . 4
7 Procedure . 5
7.1 Preparation of the inoculum . 5
7.2 Preparation of the sea sand . 6
7.3 Preparation of test material and reference material . 6
7.4 Starting up the test . 6
7.5 Measurement of the evolved carbon dioxide . 8
7.6 Incubation period . 8
7.7 Termination of the test . 9
8 Calculation . 9
8.1 Theoretical amount of carbon dioxide evolved by test material. 9
8.2 Percentage biodegradation . 10
9 Expression and interpretation of results . 10
10 Validity of results . 11
11 Test report . 11
Annex A (informative) Basic principle of the test . 12
Annex B (informative) Example of an apparatus using an electrically heated composting vessel15
Annex C (informative) Derivation of the formula used to calculate the degree of biodegradation
from the amount of carbon dioxide evolved . 18
Annex D (informative) Determination of the degree of biodegradation of plastics under
composting conditions — Synchronous gas sampling method . 20
Bibliography . 27

Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
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iv
iv
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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 . 6
7.3 Preparation of test material and reference material . 6
7.4 Starting up the test . 6
7.5 Measurement of the evolved carbon dioxide . 7
7.6 Incubation period . 8
7.7 Termination of the test . 9
8 Calculation . 9
8.1 Theoretical amount of carbon dioxide evolved by test material. 9
8.2 Percentage biodegradation . 9
9 Expression and interpretation of results . 10
10 Validity of results . 10
11 Test report . 10
Annex A (informative) Basic principle of the test . 12
Annex B (informative) Example of an apparatus using an electrically heated composting vessel14
Annex C (informative) Derivation of the formula used to calculate the degree of biodegradation
from the amount of carbon dioxide evolved . 16
Annex D (informative) Determination of the degree of biodegradation of plastics under
composting conditions — Synchronous gas sampling method . 18
D.1 Equipment that uses synchronous gas sampling to collect gases evolved under
composting conditions . 18
D.2 Instruments that use an NDIR gas sensor and a gas burette to measure cumulative gas
volume and carbon dioxide concentration . 19
D.3 Example of cellulose biodegradation from cumulative gas volume and carbon dioxide
concentration using NDIR gas sensor and gas burette . 20
Bibliography . 22
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© ISO 2026 – All rights reserved
v
ISO/DISFDIS 14855-2:2025(E2026(en)
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Foreword
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ISO (the International Organization for Standardization) is a worldwide federation of national standards
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out through Adjust space between Asian text and numbers
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 document 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).
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ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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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
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
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www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 14,
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Environmental aspects, in collaboration with the European Committee for Standardization (CEN) Technical
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Committee CEN/TC 249, Plastics, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement). Formatted: Default Paragraph Font
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This third edition cancels and replaces the firstsecond edition (ISO 14855-2:20072018), which has been
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technically revised. It also incorporates the Technical Corrigendum ISO 14855-2:2007/Cor.1:2009.
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The main changes are as follows:
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+ 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7
— — ISO 14855-2:2026 (3rd edition) adds the NDIR method to the measurement of evolved carbon dioxide
cm
in addition to the conventional gravimetric method. A has been added;
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— a schematic diagram of the measurement device and an example of biodegradability measurement using
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an NDIR sensor have been added to Annex D.Annex D.
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A list of all parts in the ISO 14855 series can be found on the ISO website.
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Any feedback or questions on this document should be directed to the user’s national standards body. A
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complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
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vi
vi
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Introduction
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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
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dioxide evolved using methods such as continuous infrared analysis, gas chromatography or titration.
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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
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mixture the same texture as soil is mixed into the inoculum. The carbon dioxide evolved from the test vessel
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is determined by absorbing it in a carbon dioxide trap and carrying out gravimetric analysis of the absorbent.
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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.
In addition to traditional gravimetric methods, this test method adds a new way to measure carbon dioxide
using spectroscopic non-dispersive infrared (NDIR) technology, significantly reducing the routine work and
chemical use required for quantitative measurement without compromising the quantitative accuracy of
chemical methods.
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© ISO 2026 – All rights reserved
vii
DRAFT International Standard ISO/DIS 14855-2:2025(en)

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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
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Part 2:
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Gravimetric measurement of carbon dioxide evolved in a laboratory-
1.27 cm
scale test
WARNING — Sewage, activated sludge, soil and compost can contain potentially pathogenic
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organisms. Therefore, appropriate precautions should be taken when handling them. Toxic test Adjust space between Asian text and numbers
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;
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— — plastic materials that contain additives such as plasticizers or colorants;
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3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
— — water-soluble polymers;
— — materials that, under the test conditions, do not inhibit the activity of microorganisms present in the
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inoculum.
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NOTE If the test material inhibits microorganisms in the inoculum, another type of mature compost or pre-exposure Formatted: Default Paragraph Font
compost can be used.
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2 Normative references
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The following documents are referred to in the text in such a way that some or all of their content constitutes
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requirements of this document. For dated references, only the edition cited applies. For undated references,
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the latest edition of the referenced document (including any amendments) applies.
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3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
ISO 11721--1, Textiles — Determination of resistance of cellulose-containing textiles to micro-organisms —
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Soil burial test — Part 1: Assessment of rot-retardant finishing
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ISO 14855--1, Determination of the ultimate aerobic biodegradability of plastic materials under controlled
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composting conditions — Method by analysis of evolved carbon dioxide — Part 1: General method
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ISO/DISFDIS 14855-2:2025(E2026(en)
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3 Terms and definitions
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For the purposes of this document, the following terms and definitions apply.
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ISO and IEC maintain terminologicalterminology databases for use in standardization at the following
addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
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— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
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3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
3.1 3.1
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compost
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organic soil conditioner obtained by biodegradation of a mixture principally consisting of various vegetable
numbers
residues, occasionally with other organic material and having a limited mineral content
3.2 3.2
composting
aerobic process designed to produce compost
3.3 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 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.
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3.5 3.5
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ultimate aerobic biodegradability
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breakdown ratio by expressed as percentage of an organic compound by microorganisms in the presence of
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oxygen into carbon dioxide, water and mineral salts of any other elements present (mineralization) plus new
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biomass
numbers
[SOURCE: ISO 14852:2021, 3.1]
3.6 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 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
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Note 1 to entry: It is measured in days.
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3.8 3.8
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maximum level of biodegradation
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degree of biodegradation of a chemical compound or organic matter in a test, above which no further
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biodegradation takes place during the test
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numbers
Note 1 to entry: It is measured as a percentage.
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3.9 3.9
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biodegradation phase
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time from the end of the lag phase of a test until about 90 % of the maximum level of biodegradation has been
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3.10 3.10
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plateau phase
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time from the end of the biodegradation phase until the end of the test
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and Asian text, Adjust space between Asian text and
numbers
3.11 3.11
pre-exposure Formatted: Adjust space between Latin and Asian text,
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the aim of enhancing the ability of the inoculum to biodegrade the test material by adaptation and/or selection
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of the micro-organisms
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3.12 3.12
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pre-conditioning
numbers
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 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.
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The test material is mixed with an inoculum derived from mature compost and with an inert material such as
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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 AAnnexes A and B.B. The amount of carbon Formatted: Font: 10 pt
dioxide evolved is measured at intervals on an electronic balance and the carbon dioxide content is
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determined using the following method. The derivation of the formula used to calculate the degree of
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biodegradation from the amount of carbon dioxide evolved is given in Annex C.Annex C. In this method, the
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© ISO 2026 – All rights reserved
ISO/DISFDIS 14855-2:2025(E2026(en)
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degree of biodegradation, expressed as a percentage, is calculated by comparing the amount of carbon dioxide
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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 can be continued for up to six months.
5 Reagents
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Use only analytical-grade reagents. Use only deionized water. Formatted: Font: Not Bold
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5.1 5.1 Soda lime, particle size between 2 mm and 4 mm, for CO absorption.
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5.2 5.2 Anhydrous calcium chloride, particle size between 2 mm and 3 mm, for water absorption.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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5.3 5.3 Sodium hydroxide on a talc support (commonly known as soda talc), particle size
between 2 mm and 3 mm, for CO2 absorption.
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5.4 5.4 Silica gel (with moisture indicator), particle size between 2 mm and 4 mm, for water
absorption. Formatted: Font: Not Bold
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5.5 5.5 Sea sand, particle size between 425 μm and 850 μm (20 mesh and 35 mesh).
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5.6 5.6 Reference material: thin-layer chromatography (TLC) grade microcrystalline cellulose with
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a particle size of less than 20 µm, for use as the reference material in the positive control.
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6 Apparatus
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Ensure that all glassware is thoroughly cleaned and, in particular, free from organic or toxic matter.
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6.1 6.1 Air-supply system, capable of supplying each composting vessel with carbon-dioxide-free,
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The air can be prepared by supplying compressed air through a carbon dioxide trap and a humidifier (see
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examples in Annexes A and B), i.e.Annexes A and B), i.e. columns filled with soda lime and water, respectively.
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The air flow rate shall be controlled with a flow controller so that it is high enough for aerobic conditions.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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6.2 6.2 Composting vessels
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suitable volume is 500 ml. If the loss in mass of the test material is to be determined, weigh each composting
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vessel empty before starting the test.
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6.3 6.3 System for the determination of carbon dioxide, capable of determining carbon dioxide
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directly from the change in mass of a carbon dioxide trap. The carbon dioxide trap shall consist of
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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 Formatted
...
B).Annexes A and B). An ammonia trap (dilute sulfuric acid) and a water trap (silica gel and calcium
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chloride) are required between the composting vessel and the carbon-dioxide-absorbing column.
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6.4 6.4 Gas-tight tubes, used to connect the composting vessels to the air supply and the carbon
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dioxide measurement system.
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6.5 6.5 pH-meter, used for measurement of the pH of the test mixture. It shall be accurate to 0,1 pH-
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units or better.
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6.6 6.6 Analytical equipment, used for the determination of the dry solids (at 105 °C), volatile
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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.
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6.7 6.7 Balance, used to periodically measure the mass of the carbon-dioxide-absorbing column, in
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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.
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6.8 6.8 Thermostatic-control unit, required to maintain the temperature of the composting
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vessels at a controlled temperature during the test (see examples given in Annexes A and
B).Annexes A and B). It shall be capable of maintaining the temperature of the composting vessels
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constant to within ±2 °C.
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6.9 6.9 Composting bioreactor. A box, made from polypropylene or another suitable material,
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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.
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7 Procedure
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7.1 Preparation of the inoculum
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Well-aerated compost from a properly operating aerobic composting plant shall be used as the inoculum. The
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inoculum shall be homogeneous and free from large inert objects such as glass, stones or pieces of metal.
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Remove such items manually and prepare compost with a particle size of 2 mm to 5 mm using sieves with
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2 mm and 5 mm openings.
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/phosphorous
(C/P) ratio of 30. Insufficient phosphorous and nitrogen levels can be supplemented using calcium
superphosphate and ammonium magnesium phosphate hexahydrate or urea, respectively. Water is added to
reach a water content equal to 65 %. The C/N, C/P and water-content values may also be adjusted to other
values, determined by experience, depending on seasonal variations and climatic differences. The compost
should be removed from the container once a week to turn it and add water, if necessary, before returning it
to the container to continue the composting process. The age of the compost should preferably be between
two and four months.
Normally, non-exposed inoculum is preferred, especially in the case of standard tests simulating
biodegradation behaviour in real composting facilities. Depending on the purpose of the test, however, pre-
exposed compost may be used, provided that this is clearly stated in the test report (e.g. percent
biodegradation = X %, using pre-exposed compost) and provided the method of pre-exposure is detailed in
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the test report.
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Determine the total dry solids and volatile-solids content of the compost inoculum. The total dry solids should
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be between 35 % and 55 % of the wet solids and the volatile solids more than 30 % of the dry solids. Adjust
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the water content, if necessary, before the compost is used by adding water or drying gently, e.g. by aerating
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the compost with dry air.
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© ISO 2026 – All rights reserved
ISO/DISFDIS 14855-2:2025(E2026(en)
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Prepare a mixture of 1 part of inoculum to 5 parts of deionized water. Mix by shaking and measure the pH
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immediately. It should be between 7,0 and 9,0.
For further characterization of the inoculum, suitable parameters such as the content of total organic carbon,
total nitrogen or fatty acids can optionally be determined at the beginning and the end of the test.
Check the activity of the inoculum during the test by means of a biodegradable reference material and by
measuring carbon dioxide evolution in the blank vessels. The reference material shall be degraded by 70 % or
more at the end of the test. The inoculum in the blank should produce between 50 mg and 150 mg of carbon
dioxide per gram of volatile solids over the first 10 days of the test. If the production of carbon dioxide is too
high, stabilize the compost by aeration for several days before using it in a new test.
If biodegradation is inhibited by physicochemical conditions, such as a decrease in the pH of the test system
due to hydrolysis of the sample, solidification or aggregation of the compost due to melting, or a decrease in
water activity due to water absorption, it is recommended to conduct the test under milder conditions in a
water system, soil system, or home compost system.
7.2 Preparation of the sea sand
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Dip the sea sand in tap water. After removing floating impurities by decantation, rinse the sand sufficiently,
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drain off the water and dry the sand at about 105 °C.
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NOTE Sea sand, or another inert mineral material (e.g. quartz sand) with SiO₂SiO2 content ≥90 % and particle size
of 0,5 mm to 1 mm can be used. Sea sand plays an important role in maintaining appropriate moisture content and Formatted: Line spacing: At least 11 pt, Adjust space
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promoting microbial growth.
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7.3 Preparation of test material and reference material 1.4 cm + 2.1 cm + 2.8 cm + 3.5 cm + 4.2 cm + 4.9
cm + 5.6 cm + 6.3 cm + 7 cm
Determine the total organic carbon (TOC) of the test material and the reference material using, for example,
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ISO 8245 and report it preferably as grams of TOC per gram of total dry solids. Alternatively, provided that the
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materials do not contain inorganic carbon, it is possible to determine the carbon content by elemental analysis.
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For this, the test material should contain sufficient organic carbon to yield carbon dioxide in an amount
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suitable for determination. Normally, a minimum of 10 g of total dry solids containing 4 g of TOC is required
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per 500 ml-vessel.
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The test material should preferably be used in powder form, but it may also be introduced as small pieces of
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films or as fragments of shaped articles. A maximum particle size of 250 µm in diameter is recommended.
For materials containing inorganic carbon (e.g. carbonate fillers), the inorganic carbon shall be determined
and subtracted, or a suitable pre-treatment shall be applied to remove inorganic carbon before TOC
...