SIST EN ISO 14855:2004
(Main)Determination of the ultimate aerobic biodegradability and disintegration of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide (ISO 14855:1999)
Determination of the ultimate aerobic biodegradability and disintegration of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide (ISO 14855:1999)
Bestimmung der vollständigen aeroben Bioabbaubarkeit und Zersetzung von Kunststoff-Materialien unter den Bedingungen kontrollierter Kompostierung - Verfahren mittels Analyse des freigesetzten Kohlenstoffdioxides (ISO 14855:1999)
Evaluation de la biodégradabilité aérobie ultime et de la désintégration des matériaux plastiques dans des conditions contrôlées de compostage - Méthode par analyse du dioxyde de carbone libéré (ISO 14855:1999)
Določanje končne aerobne biorazgradljivosti in razkroja polimernih materialov pod nadzorovanimi pogoji kompostiranja – Metoda z analizo sproščenega ogljikovega dioksida (ISO 14855:1999)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 14855:2004
01-oktober-2004
'RORþDQMHNRQþQHDHUREQHELRUD]JUDGOMLYRVWLLQUD]NURMDSROLPHUQLKPDWHULDORYSRG
QDG]RURYDQLPLSRJRMLNRPSRVWLUDQMD±0HWRGD]DQDOL]RVSURãþHQHJDRJOMLNRYHJD
GLRNVLGD ,62
Determination of the ultimate aerobic biodegradability and disintegration of plastic
materials under controlled composting conditions - Method by analysis of evolved carbon
dioxide (ISO 14855:1999)
Bestimmung der vollständigen aeroben Bioabbaubarkeit und Zersetzung von Kunststoff-
Materialien unter den Bedingungen kontrollierter Kompostierung - Verfahren mittels
Analyse des freigesetzten Kohlenstoffdioxides (ISO 14855:1999)
Evaluation de la biodégradabilité aérobie ultime et de la désintégration des matériaux
plastiques dans des conditions contrôlées de compostage - Méthode par analyse du
dioxyde de carbone libéré (ISO 14855:1999)
Ta slovenski standard je istoveten z: EN ISO 14855:2004
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 14855:2004 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 14855:2004
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SIST EN ISO 14855:2004
EUROPEAN STANDARD
EN ISO 14855
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2004
ICS 83.080.01
English version
Determination of the ultimate aerobic biodegradability and
disintegration of plastic materials under controlled composting
conditions - Method by analysis of evolved carbon dioxide (ISO
14855:1999)
Evaluation de la biodégradabilité aérobie ultime et de la
désintégration des matériaux plastiques dans des
conditions contrôlées de compostage - Méthode par
analyse du dioxyde de carbone libéré (ISO 14855:1999)
This European Standard was approved by CEN on 21 June 2004.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14855:2004: E
worldwide for CEN national Members.
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SIST EN ISO 14855:2004
EN ISO 14855:2004 (E)
Foreword
The text of ISO 14855:1999 has been prepared by Technical Committee ISO/TC 61 "Plastics” of
the International Organization for Standardization (ISO) and has been taken over as EN ISO
14855:2004 by Technical Committee CEN/TC 249 "Plastics", the secretariat of which is held by
IBN.
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 January 2005, and conflicting national
standards shall be withdrawn at the latest by January 2005.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 14855:1999 has been approved by CEN as EN ISO 14855:2004 without any
modifications.
NOTE Normative references to International Standards are listed in Annex ZA (normative).
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SIST EN ISO 14855:2004
EN ISO 14855:2004 (E)
Annex ZA
(normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of
any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications, indicated
by (mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 5663 1984 Water quality - Determination of EN 25663 1993
Kjeldahl nitrogen - Method after
mineralization with selenium
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SIST EN ISO 14855:2004
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SIST EN ISO 14855:2004
INTERNATIONAL ISO
STANDARD 14855
First edition
1999-05-15
Determination of the ultimate aerobic
biodegradability and disintegration of
plastic materials under controlled
composting conditions — Method by
analysis of evolved carbon dioxide
Évaluation de la biodégradabilité aérobie ultime et de désintégration des
matériaux plastiques dans des conditions contrôlées de compostage —
Méthode par analyse du dioxyde de carbone libéré
A
Reference number
ISO 14855:1999(E)
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SIST EN ISO 14855:2004
ISO 14855:1999(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.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 14855 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5,
Physical-chemical properties.
Annexes A to E of this International Standard are for information only.
© ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
ii
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SIST EN ISO 14855:2004
INTERNATIONAL STANDARD © ISO ISO 14855:1999(E)
Determination of the ultimate aerobic biodegradability and
disintegration of plastic materials under controlled composting
conditions — Method by analysis of evolved carbon dioxide
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 International Standard specifies a method for the determination of the ultimate aerobic biodegradability of
plastics, based on organic compounds, under controlled composting conditions by measurement of the amount of
carbon dioxide evolved and the degree of disintegration of the plastic at the end of the test. This method is designed
to simulate typical aerobic composting conditions for the organic fraction of solid mixed municipal waste. The test
material is exposed to an inoculum which is derived from compost. The composting takes place in an environment
wherein temperature, aeration and humidity are closely monitored and controlled. The test method is designed to
yield the percentage conversion of the carbon in the test material to evolved carbon dioxide as well as the rate of
conversion.
The conditions described in this International Standard may not always correspond to the optimum conditions for
the maximum degree of biodegradation to occur.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 5663:1984, Water quality — Determination of Kjeldahl nitrogen — Method after mineralization with selenium.
ISO 8245:1999, Water quality — Guidelines for the determination of total organic carbon (TOC) and dissolved
organic carbon (DOC).
3 Definitions
For the purposes of this International Standard, the following definitions apply:
3.1
ultimate aerobic biodegradation
the breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide, water
and mineral salts of any other elements present (mineralization) plus new biomass
3.2
composting
an aerobic process designed to produce compost
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NOTE Compost is an organic soil conditioner obtained by biodegradation of a mixture consisting principally of vegetable
residues, occasionally with other organic material, and having a limited mineral content.
3.3
disintegration
the physical breakdown of a material into very small fragments
3.4
total dry solids
the amount of solids obtained by taking a known volume of test material or compost and drying at about 105 °C to
constant mass
3.5
volatile solids
the 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 The volatile-solids content is an indication of the amount of organic matter present.
3.6
theoretical amount of evolved carbon dioxide
ThCO
2
the 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
the time, measured in days, from the start of a test until adaptation and/or selection of the degrading
microorganisms is achieved and the degree of biodegradation of a chemical compound or organic matter has
increased to about 10 % of the maximum level of biodegradation
3.8
maximum level of biodegradation
the degree of biodegradation, measured in per cent, of a chemical compound or organic matter in a test, above
which no further biodegradation takes place during the test
3.9
biodegradation phase
the time, measured in days, from the end of the lag phase of a test until about 90 % of the maximum level of
biodegradation has been reached
3.10
plateau phase
the time, measured in days, from the end of the biodegradation phase until the end of a test
4 Principle
The test method determines the ultimate biodegradability and degree of disintegration of test material under
conditions simulating an intensive aerobic composting process. The inoculum used consists of stabilized, mature
compost derived, if possible, from composting the organic fraction of solid municipal waste.
The test material is mixed with the inoculum and introduced into a static composting vessel where it is intensively
composted under optimum oxygen, temperature and moisture conditions for a test period not exceeding 6 months.
During the aerobic biodegradation of the test material, carbon dioxide, water, mineral salts and new microbial
cellular constituents (biomass) are the ultimate biodegradation products. The carbon dioxide produced is
continuously monitored, or measured at regular intervals, in test and blank vessels to determine the cumulative
carbon dioxide production. The percentage biodegradation is given by the ratio of the carbon dioxide produced from
the test material to the maximum theoretical amount of carbon dioxide that can be produced from the test material.
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The maximum theoretical amount of carbon dioxide produced is calculated from the measured total organic carbon
(TOC) content. The percentage biodegradation does not include that amount of carbon converted to new cell
biomass which is not metabolized in turn to carbon dioxide during the course of the test.
Additionally, the degree of disintegration of the test material is determined at the end of the test, and the loss in
mass of the test material may also be determined.
5 Test environment
Incubation shall be in the dark or in diffused light, in an enclosure or room maintained at a constant temperature of
58 °C ± 2 °C and free from vapours inhibitory to microorganisms.
In special cases, e.g. when the melting point of the test material is low, another temperature may be chosen. This
temperature shall be kept constant during the test to within ± 2 °C. Any change in temperature shall be justified and
clearly indicated in the test report.
6 Reagents
Use only analytical-grade reagents.
Use TLC (thin-layer chromatography) grade cellulose with a particle size of less than 20 mm as the positive-control
reference material.
7 Apparatus
Ensure that all glassware is thoroughly cleaned and, in particular, free from organic or toxic matter.
7.1 Composting vessels: Glass flasks or bottles that allow an even gas purge in an upward direction.
A minimum volume of 2 litres is required to meet the requirements specified in 8.2 and 8.3. Depending on the test
material, a smaller volume may be used for screening purposes. If the loss in mass of the test material is to be
determined, weigh each composting vessel empty.
7.2 Air-supply system, capable of supplying each composting vessel with dry or water-saturated, if required
carbon-dioxide-free, air at a pre-set flow rate which shall be high enough to provide truly aerobic conditions during
the test (see example given in annex A).
7.3 Apparatus for the determination of carbon dioxide, designed to determine carbon dioxide directly or by
complete absorption in a basic solution and determination of the dissolved inorganic carbon (DIC) (see example
given in annex A). If the carbon dioxide in the exhaust air is measured directly, for example with a continuous
infrared analyser or a gas chromatograph, exact control or measurement of the air-flow rate is required.
7.4 Gas-tight tubes, to connect the composting vessels with the air supply and the carbon dioxide measurement
system.
7.5 pH meter.
7.6 Analytical equipment, for the determination of 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).
7.7 Balance (optional), to measure the mass of test vessels containing compost and test material, which is
normally in the range between 3 kg and 5 kg.
7.8 Analytical equipment (optional), for the determination of oxygen in the air, moisture, volatile fatty acids and
total nitrogen (e.g. by the Kjeldahl method as specified in ISO 5663).
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8 Procedure
8.1 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
them manually and then sieve the compost on a screen of about 0,5 cm to 1 cm.
NOTE 1 It is recommended that compost from a plant composting the organic fraction of solid municipal waste be used in
order to ensure sufficient diversity of microorganisms. The age of the compost should preferably be between 2 and 4 months. If
such compost is not available, compost from plants treating garden or farmyard waste or mixtures of garden waste and solid
municipal waste may be used.
NOTE 2 It is recommended that compost with sufficient porosity be used to enable aerobic conditions to be maintained as
much as possible. Addition of structural material such as small wood particles or inert or poorly biodegradable material may
prevent the compost sticking together and clogging during the test.
Determine the total dry solids and the volatile-solids content of the inoculum. The total dry solids content shall be
between 50 % and 55 % of the wet solids and the volatile solids no more than about 15 % of the wet or 30 % of the
dry solids. Adjust the water content, if necessary, before the compost is used by adding water or gentle drying, e.g.
by aerating the compost with dry air.
Prepare a mixture of 1 part of inoculum with 5 parts of deionized water. Mix by shaking and measure the pH
immediately. It shall be between 7,0 and 9,0.
NOTE 3 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 (see clause 6)
and by measuring the carbon dioxide evolution in the blank vessels. The reference material shall be degraded by
70 % or more at the end of the test (see clause 10). The inoculum in the blank shall produce between 50 mg and
150 mg of carbon dioxide per gram of volatile solids over the first 10 days of the test (see clause 10). 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 the activity is too low, use another compost for the inoculum.
8.2 Preparation of test material and reference material
Determine the total organic carbon (TOC) of the test material and the reference material using e.g. ISO 8245 and
report it, preferably, as grams of TOC per gram of total dry solids. Alternatively, provided the materials do not
contain inorganic carbon, it is possible to determine the carbon content by elemental analysis. The test material
shall have sufficient organic carbon to yield carbon dioxide in an amount suitable for the determination. Normally, a
minimum of 50 g of total dry solids containing 20 g of TOC is required per vessel.
If the loss in mass is to be determined, determine the total dry solids and volatile solids of the test material.
NOTE The loss in mass of the test material and reference material during the test can be determined, optionally, as
additional information. In the example given in annex C, the volatile-solids content of the test material is determined at the
beginning of the test and compared with that at the end of the test.
Use test material in the form of granules, powder, film or simple shapes (e.g. dumb-bells). The maximum surface
area of any individual piece of test material shall be about 2 cm ´ 2 cm. If any pieces in the original test material are
larger, reduce them in size.
8.3 Start-up of the test
Set up at least the following numbers of composting vessels (7.1):
a) three vessels for the test material;
b) three vessels for the reference material;
c) three vessels for the blank.
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The amount of test mixture, containing inoculum and test material, used in the test will depend on the quality of the
test material (see 8.2) and the size of the composting vessels. The ratio of the dry mass of the inoculum to the dry
mass of the test material shall be about 6:1. Be sure that the same amount of compost is in each vessel. Inert
material, if added (see note 2 to 8.1), is not considered in this relationship. Fill about three-quarters of the volume of
the composting vessel with the test mixture. Leave sufficient headspace to allow manual shaking of the test mixture.
In a typical case, prepare composting vessels which have a volume of about 3 litres, weigh out an amount of
inoculum containing 600 g of total dry solids and an amount of test material containing 100 g of dry solids and mix
well. The test mixture shall have the same water content (about 50 %) as the inoculum (see 8.1). It should feel
somewhat sticky and have some free water available when gently pressed by hand. Adjust the moisture content of
the mixture, if required, by adding water or by aerating with dry air. Introduce the mixture into the composting
vessels.
NOTE 1 It is recommended that the ratio between organic carbon and nitrogen (C/N ratio) of the test mixture is optimized so
as to ensure a good composting process. The C/N ratio for the test mixture should preferably be between 10 and 40. It may be
adjusted with urea, if necessary. The organic-carbon content can be calculated from the TOC of the inoculum and the test
material. The total nitrogen content can be measured in a representative sample of the test mixture, e.g. by using the Kjeldahl
method as specified in ISO 5663.
Place the composting vessels in the test environment at 58 °C ± 2 °C (see clause 5) and initiate aeration using
water-saturated, carbon-dioxide-free air. This can be produced by passing the air through wash-bottles filled with
sodium hydroxide solution (see annex A).
NOTE 2 Normal air, rather than carbon-dioxide-free air, can be used if the carbon dioxide concentration in the exhaust air is
directly measured. In this case, measurement of the carbon dioxide concentration at the inlet and outlet of each test vessel is
recommended. For correction, subtract the inlet concentration from the outlet concentration (which will be much higher).
Use a sufficiently high flow rate to ensure that aerobic conditions are maintained during the test throughout each
composting vessel. Check the air flow regularly at each outlet, e.g. by using wash-bottles, to ensure that there are
no leaks in any part of the system.
NOTE 3 Regular measurement of the oxygen concentration in the exhaust air from the composting vessels will help maintain
aerobic conditions. If this is done, the oxygen concentration should not be allowed to drop below about 6 %. Oxygen levels
should be closely monitored during the first week, e.g. by measuring at least twice daily. Afterwards, the measurement
frequency can be reduced. Adjust air flow rates as needed.
Handle the reference material in the same way as the test material. The vessels for the blank contain only inoculum.
It shall have the same amount of total dry solids as the vessels with test material.
8.4 Incubation period
Measure the amount of carbon dioxide evolved from the exhaust air of each composting vessel at intermediate time
intervals directly using a gas chromatograph, a TOC or an infrared analyser or, alternatively, measure the
cumulative carbon dioxide evolved as dissolved inorganic carbon (DIC) after absorption in sodium hydroxide
solution using e.g. ISO 8245 (see annex A). The frequency of measurement will depend on the measurement
method used, the desired precision of the biodegradation curve and the biodegradability of the test mixture. If direct
measurement is used, measure the carbon dioxide evolved at least twice per day at time intervals of about 6 h
during the biodegradation phase and once per day later on during the plateau phase. If the cumulative method is
used, measure the DIC once per day during the biodegradation phase and about twice per week during the plateau
phase.
Shake the composting vessels weekly to prevent extensive channelling and to ensure uniform attack of the
microorganisms on the test material.
NOTE 1 It is recommended that the air-supply system and the carbon dioxide measurement system be disconnected before
shaking the compost vessels.
Ensure that the humidity of the test mixture in the composting vessels is neither too high nor too low by visual
observation. No free-standing water or clumps of material shall be present. Very dry conditions are, typically,
revealed by the absence of condensate in the headspace of the composting vessel. Moisture can also optionally be
measured by suitable instruments. In this case, the moisture content should be kept at about 50 % (see 8.1). The
desired moisture content is achieved by aerating with humidified or dry air. A more drastic change in the moisture
content can be obtained by adding water or by drainage via the air inlet. The weekly shaking of the compost vessels
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is helpful in ensuring an even distribution of moisture. If adjustments are made, monitor the carbon dioxide evolution
closely.
During the weekly agitation of the composting vessels and at the end of the test period, record any visual
observations with regard to the appearance of the compost, such as structure, moisture content, colour, fungal
development, smell of the exhaust air and disintegration of the test material.
Incubate the composting vessels for a period not exceeding 6 months at a constant temperature of 58 °C ± 2 °C
which is representative of full-scale composting. The incubation period can be extended until a constant plateau
phase is reached, if significant biodegradation of the test material is still observable. Alternatively, the incubation
period can be shortened if the plateau phase is reached earlier.
Measure the pH at regular intervals, as at the start of the test (see 8.1).
NOTE 2 If the pH is less than 7,0, biodegradation could be inhibited due to acidification of the compost by rapid degradation
of an easily degradable test material. In this case, measurement of the volatile fatty acids spectrum is recommended to check
for souring of the contents of the composting vessel. If more than 2 g of volatile fatty acids per kilogram of total dry solids has
been formed, then the test must be regarded as invalid due to acidification and inhibition of the microbial activity. To prevent
acidification, add more compost to all vessels or repeat the test using, for example, less test material or more compost.
8.5 Termination of the test
If the loss in mass of the test material is to be determined (see the note to 8.2), weigh the composting vessels with
their test mixture Take samples of the test mixture from all vessels. Determine the total dry solids and the volatile
solids.
Record any visual observations with regard to the appearance of the test material to determine its degree of
disintegration.
NOTE It is recommended that further investigations be carried out with any test material remaining, such as measuring
relevant physical properties, chemical analysis and photography.
9 Calculation and expression of results
9.1 Calculation of the theoretical amount of carbon dioxide
Calculate the theoretical amount of carbon dioxide ThCO , in grams per vessel, which can be produced by the test
2
material using equation (1):
44
ThCO=·MC·. . . (1)
2 TOT TOT
12
where
M is the total dry solids, in grams, in the test material introduced into the composting vessels at the
TOT
start of the test;
is the proportion of total organic carbon in the total dry solids in the test material, in grams per gram;
C
TOT
44 and 12 are the molecular mass of carbon dioxide and the atomic mass of carbon, respectively.
9.2 Calculation of the percentage biodegradation
From the cumulative amounts of carbon dioxide released, calculate the percentage biodegradation D of the test
t
material for each measurement interval using equation (2):
(CO )-(CO )
2T 2 B
=·100 . . . (2)
D
t
ThCO
2
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where
(CO ) is the cumulative amount of carbon dioxide evolved in each composting vessel containing test
2 T
material, in grams per vessel;
(CO ) is the mean cumulative amount of carbon dioxide evolved in the blank vessels, in grams per vessel;
2 B
ThCO is the theoretical amount of carbon dioxide which can be produced by the test material, in grams per
2
vessel.
If the differences between the individual results are less than 20 %, calculate the average percentage
biodegradation. If this is not the case, use the values for each composting vessel separately.
Use the same equation to calculate the degree of biodegradation of the reference material.
9.3 Calculation of loss in mass
An example of the optional calculation of loss in mass, based on the volatile-solids content, is given in annex C.
9.4 Expression of resu
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