SIST EN ISO 14855-1:2007
(Main)Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 1: General method (ISO 14855-1:2005)
Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 1: General method (ISO 14855-1:2005)
This part of ISO 14855 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. Subclauses 8.6 and 8.7 specify a variant of the method, using a mineral bed (vermiculite) inoculated with thermophilic microorganisms obtained from compost with a specific activation phase, instead of mature compost. This variant is designed to yield the percentage of carbon in the test substance converted to carbon dioxide and the rate of conversion. The conditions described in this part of ISO 14855 may not always correspond to the optimum conditions for the maximum degree of biodegradation to occur.
Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien unter den Bedingungen kontrollierter Kompostierung — Verfahren mittels Analyse des freigesetzten Kohlenstoffdioxides — Teil 1: Allgemeines Verfahren (ISO 14855-1:2005)
Dieser Teil der ISO 14855 legt ein Verfahren fest, mit dem unter geregelten Kompostierbedingungen durch Messung der Menge des gebildeten Kohlendioxids und des Grades des Zerfalls des Kunststoffs am Ende der Prüfung die vollständige aerobe Bioabbaubarkeit von Kunststoffen, die auf organischen Verbindungen beruhen, bestimmt wird. Dieses Verfahren ist dafür ausgelegt, typische aerobe Kompostierbedingungen für den organischen Anteil in festem gemischtem städtischem Abfall zu simulieren. Die Prüfsubstanz wird einem Inokulum ausgesetzt, das aus Kompost gewonnen wird. Die Kompostierung erfolgt in einer Umgebung, in der Temperatur, Begasung und Feuchte genau überwacht und geregelt werden. Das Prüfverfahren dient der Feststellung der prozentualen Umwandlung des Kohlenstoffs in der Prüfsubstanz in freigesetztes Kohlendioxid sowie der Geschwindigkeit dieser Umwandlung.
Die Unterabschnitte 8.6 und 8.7 legen eine Variante des Verfahrens fest, bei der anstelle des ausgereiften Kompostes ein mineralisches Festbett (Vermiculit) mit thermophilen Mikroorganismen, die aus dem Kompost innerhalb einer spezifischen Aktivierungsphase gewonnen werden, beimpft wird. Diese Variante wurde entwickelt, um den prozentualen Anteil des in Kohlendioxid umgewandelten Kohlenstoffs in der Prüfsubstanz und die Geschwindigkeit dieser Umwandlung festzustellen.
Die in diesem Teil der ISO 14855 beschriebenen Bedingungen entsprechen möglicherweise nicht immer den optimalen Bedingungen, unter denen der maximale Grad an Bioabbau erreicht wird.
Évaluation de la biodégradabilité aérobie ultime des matériaux plastiques dans des conditions contrôlées de compostage - Méthode par analyse du dioxyde de carbone libéré - Partie 1: Méthode générale (ISO 14855-1:2005)
L'ISO 14855-1:2005 prescrit une méthode d'évaluation, d'une part, de la biodégradabilité aérobie ultime des plastiques à partir de composés organiques dans des conditions contrôlées de compostage, par mesurage du dioxyde de carbone libéré, et d'autre part, de leur désintégration à la fin de l'essai. La présente méthode est conçue pour se rapprocher des conditions de compostage aérobies caractéristiques de la fraction organique des déchets municipaux solides non triés. Le matériau d'essai est exposé dans le cadre d'un essai de laboratoire à un inoculum provenant d'un échantillon de compost. Le compostage aérobie a lieu dans un environnement où la température, l'aération et l'humidité, en particulier, sont étroitement contrôlées et maîtrisées. La méthode permet d'accéder au pourcentage et au taux de conversion du carbone contenu dans la substance à analyser, en dioxyde de carbone libéré.
Elle spécifie également une variante de la méthode utilisant un lit minéral de vermiculite, ensemencé par des micro-organismes thermophiles obtenus à partir d'un compost à une phase d'activation spécifique, à la place d'un compost mature. Cette variante a pour objet de permettre d'obtenir un pourcentage et un taux de conversion du carbone de la substance d'essai en dioxyde de carbone dégagé.
Določanje končne aerobne biorazgradljivosti in razkroja polimernih materialov pod nadzorovanimi pogoji kompostiranja - Metoda z analizo sproščenega ogljikovega dioksida - 1. del: Splošna metoda (ISO 14855-1:2005)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 14855-1:2007
01-oktober-2007
1DGRPHãþD
SIST EN ISO 14855:2004
'RORþDQMHNRQþQHDHUREQHELRUD]JUDGOMLYRVWLLQUD]NURMDSROLPHUQLKPDWHULDORYSRG
QDG]RURYDQLPLSRJRMLNRPSRVWLUDQMD0HWRGD]DQDOL]RVSURãþHQHJDRJOMLNRYHJD
GLRNVLGDGHO 6SORãQDPHWRGD ,62
Determination of the ultimate aerobic biodegradability of plastic materials under
controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 1:
General method (ISO 14855-1:2005)
Bestimmung der vollständigen aeroben Bioabbaubarkeit von Kunststoff-Materialien unter
den Bedingungen kontrollierter Kompostierung — Verfahren mittels Analyse des
freigesetzten Kohlenstoffdioxides — Teil 1: Allgemeines Verfahren (ISO 14855-1:2005)
Évaluation de la biodégradabilité aérobie ultime des matériaux plastiques dans des
conditions contrôlées de compostage - Méthode par analyse du dioxyde de carbone
libéré - Partie 1: Méthode générale (ISO 14855-1:2005)
Ta slovenski standard je istoveten z: EN ISO 14855-1:2007
ICS:
13.030.99 Drugi standardi v zvezi z Other standards related to
odpadki wastes
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 14855-1:2007 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD
EN ISO 14855-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2007
ICS 13.030.99; 83.080.01 Supersedes EN ISO 14855:2004
English Version
Determination of the ultimate aerobic biodegradability of plastic
materials under controlled composting conditions - Method by
analysis of evolved carbon dioxide - Part 1: General method
(ISO 14855-1:2005)
Évaluation de la biodégradabilité aérobie ultime des Bestimmung der vollständigen aeroben Bioabbaubarkeit
matériaux plastiques dans des conditions contrôlées de von Kunststoff-Materialien unter den Bedingungen
compostage - Méthode par analyse du dioxyde de carbone kontrollierter Kompostierung - Verfahren mittels Analyse
libéré - Partie 1: Méthode générale (ISO 14855-1:2005) des freigesetzten Kohlenstoffdioxides - Teil 1: Allgemeines
Verfahren (ISO 14855-1:2005)
This European Standard was approved by CEN on 16 August 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, 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
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14855-1:2007: E
worldwide for CEN national Members.
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EN ISO 14855-1:2007 (E)
Foreword
The text of ISO 14855-1:2005 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
14855-1:2007 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 February 2008, and conflicting national
standards shall be withdrawn at the latest by February 2008.
This document supersedes EN ISO 14855:2004.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United
Kingdom.
Endorsement notice
The text of ISO 14855-1:2005 has been approved by CEN as EN ISO 14855-1:2007 without any
modifications.
2
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INTERNATIONAL ISO
STANDARD 14855-1
First edition
2005-10-15
Determination of the ultimate aerobic
biodegradability of plastic materials
under controlled composting
conditions — Method by analysis of
evolved carbon dioxide —
Part 1:
General method
Évaluation de la biodégradabilité aérobie ultime des matériaux
plastiques dans des conditions contrôlées de compostage — Méthode
par analyse du dioxyde de carbone libéré —
Partie 1: Méthode générale
Reference number
ISO 14855-1:2005(E)
©
ISO 2005
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ISO 14855-1:2005(E)
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ii © ISO 2005 – All rights reserved
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ISO 14855-1:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Principle. 3
5 Test environment. 3
6 Reagents. 3
7 Apparatus . 4
8 Procedure . 5
9 Calculation and expression of results. 9
10 Validity of results. 10
11 Test report . 10
Annex A (informative) Principle of test system. 12
Annex B (informative) Examples of graphical representation of carbon dioxide evolution and
biodegradation curves . 13
Annex C (informative) Example of mass-loss determination . 15
Annex D (informative) Round-robin testing. 17
Annex E (informative) Examples of forms . 18
Bibliography . 21
© ISO 2005 – All rights reserved iii
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ISO 14855-1:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14855-1 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5,
Physical-chemical properties.
It cancels and replaces ISO 14855:1999, the main aims of the revision being to combine the parent standard
with its amendment ISO 14855:1999/Amd.1:2004 and to renumber the standard as Part 1.
ISO 14855 consists of the following parts, under the general title Determination of the ultimate aerobic
biodegradability of plastic materials under controlled composting conditions — Method by analysis of evolved
carbon dioxide:
⎯ Part 1: General method
⎯ Part 2: Gravimetric measurement of carbon dioxide evolved in a laboratory-scale test [in preparation]
iv © ISO 2005 – All rights reserved
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ISO 14855-1:2005(E)
Introduction
The main method specified in this part of ISO 14855 uses a solid-phase respirometric test system based on
mature compost used as a solid bed, a source of nutrients, and an inoculum rich in thermophilic
microorganisms. Mature compost is a very heterogeneous and complex material. Therefore, it can be difficult
to quantify the residual polymeric material left in the bed at the end of the test, to detect possible
low-molecular-mass molecules released into the solid bed by the polymeric material during degradation, and
to assess the biomass. As a result, it can be difficult to perform a complete carbon balance. Another difficulty
which is sometimes encountered with mature compost is a “priming effect”: the organic matter present in large
amounts in the mature compost can undergo polymer-induced degradation, known as the “priming effect”,
which affects the measurement of the biodegradability.
To overcome these difficulties and to improve the reliability of the method, the mature compost can be
replaced by a solid mineral medium which is used as the composting bed, thus facilitating analyses. This
variant can be used to measure the biodegradation in terms of CO evolution, to quantify and analyse the
2
biomass and the residues of polymeric material left in the solid bed at the end of the test, and to perform a
complete carbon balance. Furthermore, the method is not sensibly affected by the priming effect and can,
therefore, be used to assess materials known to cause this problem with mature compost. The mineral bed
can also be subjected to an ecotoxicological analysis to verify the absence of any ecotoxic activity in the bed
after biodegradation.
© ISO 2005 – All rights reserved v
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INTERNATIONAL STANDARD ISO 14855-1:2005(E)
Determination of the ultimate aerobic biodegradability of plastic
materials under controlled composting conditions — Method by
analysis of evolved carbon dioxide —
Part 1:
General method
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 part of ISO 14855 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.
Subclauses 8.6 and 8.7 specify a variant of the method, using a mineral bed (vermiculite) inoculated with
thermophilic microorganisms obtained from compost with a specific activation phase, instead of mature
compost. This variant is designed to yield the percentage of carbon in the test substance converted to carbon
dioxide and the rate of conversion.
The conditions described in this part of ISO 14855 may not always correspond to the optimum conditions for
the maximum degree of biodegradation to occur.
2 Normative references
The following referenced documents are indispensable for the application 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 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)
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ISO 14855-1:2005(E)
3 Terms and definitions
For the purposes of this document, the following terms and 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
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
3.11
activated vermiculite
vermiculite colonized by an active microbial population during a preliminary growth phase
2 © ISO 2005 – All rights reserved
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ISO 14855-1:2005(E)
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. 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.
Vermiculite should be used instead of mature compost
a) whenever the determination of the degree of biodegradation is affected by a priming effect induced by the
test material
and/or
b) when performing a final carbon balance with biomass determination and retrieval of the residual test
material.
The vermiculite bed, being inorganic, substantially reduces the priming effect, thus improving the reliability of
the method. A further advantage of using vermiculite is the very small amount of carbon dioxide evolved in the
blank vessels (nearly zero), because of the low level of microbial activity. This permits low levels of
degradation activity to be evaluated precisely.
The mineralization rates obtained with the activated vermiculite are identical, or very similar, to those obtained
with mature compost, both in terms of the final degradation level and the degradation rate.
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
6.1 TLC (thin-layer chromatography) grade cellulose
Use TLC (thin-layer chromatography) grade cellulose with a particle size of less than 20 µm as the
positive-control reference material.
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ISO 14855-1:2005(E)
6.2 Vermiculite
Vermiculite is a clay mineral used for building purposes, known to be particularly suitable as a microbial carrier,
allowing survival and full activity of microbes. The composition of the native mineral, before heat treatment, is
Al O 10 %, MgO 30 %, CaO 5 %, SiO 50 % and combined H O 5 %. When the mineral is subjected to heat
2 3 2 2
treatment, it loses the combined water and expands, giving “expanded vermiculite”. Expanded vermiculite in
flake form shall be used. Expanded vermiculite has a large capacity for water storage, and a water content
comparable with that of mature compost can be obtained in the bed.
Vermiculite can be classified into three types, as follows:
3 3
“Concrete” type: apparent density 80 kg/m ± 16 kg/m (at the time the material is put into sacks); particle
size: 80 % between 12 mm and 4 mm, 2 % passing through a 0,5 mm sieve.
3 3
“Medium” type: apparent density 90 kg/m ± 16 kg/m ; particle size: 80 % between 6 mm and 1 mm, 2 %
passing through a 0,5 mm sieve.
3 3
“Fine” type: apparent density 100 kg/m ± 20 kg/m ; particle size: 80 % between 3 mm and 0,7 mm, 5 %
passing through a 0,5 mm sieve.
1)
For the purposes of this part of ISO 14855, the concrete type is used.
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).
1) A possible source of this type of vermiculite is BPB plc, Park House, 15 Bath Road, Slough SL1 3UF, UK
(www.bpb.com). This information is given for the convenience of users of this part of ISO 14855 and does not constitute
an endorsement by ISO of the source named.
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ISO 14855-1:2005(E)
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).
7.9 Bioreactors for activation of the vermiculite: Containers, with a volume between 5 l and 20 l, which
are not actively aerated. The containers shall be closed in such a way as to avoid excessive drying out of the
contents. Openings shall, however, be provided to allow gas exchange with the atmosphere and ensure
aerobic conditions throughout the activation phase.
An example of a suitable bioreactor is a box, made of polypropylene or another suitable material, having the
following dimensions: 30 cm × 20 cm × 10 cm (l, w, h). The box shall have a tightly fitting lid in order to avoid
excessive loss of water vapour. In the middle of the two 20-cm-wide sides, a hole 5 mm in diameter shall be
made at a height of about 6,5 cm from the bottom of the box. It is these two holes which allow gas exchange
between the atmosphere inside the box and the outside environment.
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
© ISO 2005 – All rights reserved 5
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ISO 14855-1:2005(E)
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
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