SIST EN ISO 17556:2005
(Main)Plastics - Determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved (ISO 17556:2003)
Plastics - Determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved (ISO 17556:2003)
ISO 17556:2003 specifies a method for determining the ultimate aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a closed respirometer or the amount of carbon dioxide evolved. The method is designed to yield an optimum degree of biodegradation by adjusting the humidity of the test soil.
If a non-adapted soil is used as an inoculum, the test simulates the biodegradation processes which take place in a natural soil environment; if a pre-exposed soil is used, the method can be used to investigate the potential biodegradability of a test material.
This method applies to the following materials:
Natural and/or synthetic polymers, copolymers or mixtures of these.
Plastic materials which contain additives such as plasticizers or colorants.
Water-soluble polymers.
Materials which, under the test conditions, do not inhibit the activity of the microorganisms present in the soil. Inhibitory effects can be measured using an inhibition control or by another suitable method (see e.g. ISO 8192). If the test material inhibits the microorganisms in the soil, a lower test material concentration, another type of soil or a pre-exposed soil can be used.
Kunststoffe - Bestimmung der vollständigen aeroben biologischen Abbaubarkeit im Boden durch Messung des Sauerstoffbedarfs in einem Respirometer oder der Menge des entstandenen Kohlendioxids (ISO 17556:2003)
Diese Internationale Norm legt ein Verfahren zum Bestimmen der vollständigen aeroben biologischen Abbaubarkeit von Kunststoffmaterialien im Boden durch Messen des Sauerstoffbedarfs in einem geschlossenen Respirometer oder durch Messen der Menge des entwickelten Kohlendioxids fest. Das Verfahren wurde so entwickelt, dass ein bestmöglicher Grad der biologischen Abbaubarkeit durch Einstellen der Feuchtigkeit des Prüfbodens erhalten wird.
Wenn ein nicht angepasster Boden als Inokulum verwendet wird, simuliert die Prüfung den biologischen Abbauprozess, der in einer natürlichen Bodenumgebung abläuft; wird ein vorexponierter Boden verwendet, kann das Verfahren zum Untersuchen der potenziellen biologischen Abbaubarkeit eines Prüfmaterials angewendet werden.
Dieses Verfahren gilt für folgende Materialien:
- natürliche und/oder künstliche Polymere, Copolymere und deren Gemische;
- Kunststoffmaterialien, die Zusatzstoffe wie Weichmacher oder Farbmittel enthalten;
- wasserlösliche Polymere;
Materialien, die unter Prüfbedingungen nicht die Aktivität der im Boden vorhandenen Mikroorganismen beeinträchtigen. Inhibierungseffekte können durch Anwendung eines Inhibierungskontrollversuchs oder durch ein anderes geeignetes Verfahren (siehe z. B. ISO 8192) gemessen werden. Wenn das Prüfmaterial die Mikroorganismen im Boden hemmt, kann eine geringere Konzentration des Prüfmaterials, ein anderer Bodentyp oder ein vorexponierter Boden eingesetzt werden.
Plastiques - Détermination de la biodégradabilité aérobie ultime dans le sol par mesure de la demande en oxygene dans un respirometre ou de la teneur en dioxyde de carbone libéré (ISO 17556:2003)
L'ISO 17556:2003 spécifie une méthode pour l'évaluation de la biodégradabilité aérobie ultime des matériaux plastiques dans le sol en mesurant la demande en oxygène dans un respiromètre fermé ou la teneur en dioxyde de carbone libéré. La méthode est conçue pour produire une biodégradabilité optimale en ajustant l'humidité du sol d'essai.
Si un sol non modifié est utilisé comme inoculum, l'essai simule les processus de biodégradation qui a lieu dans un environnement de sol naturel; si un sol préexposé est utilisé, la méthode peut être employée pour étudier la biodégradabilité potentielle d'un matériau d'essai.
Cette méthode est applicable aux matériaux suivants:
Polymères, copolymères naturels et/ou synthétiques ou leurs mélanges.
Matériaux plastiques contenant des additifs tels que plastifiants ou colorants.
Polymères solubles dans l'eau.
Matériaux d'essai n'ayant pas d'effets inhibiteurs sur les micro-organismes présents dans le sol, dans les conditions de l'essai. Les effets inhibiteurs peuvent être déterminés au moyen d'un contrôle de l'inhibition ou par une autre méthode appropriée (voir par exemple l'ISO 8192). Si le matériau d'essai a un effet inhibiteur vis-à-vis des micro-organismes présents dans le sol, il est possible d'utiliser une concentration d'essai plus faible, un autre type de sol ou un sol préexposé.
Polimerni materiali - Ugotavljanje končne aerobne biorazgradljivosti v zemlji z merjenjem porabe kisika v respirometru ali količine nastalega ogljikovega dioksida (ISO 17556:2003)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 17556:2005
01-marec-2005
3ROLPHUQLPDWHULDOL8JRWDYOMDQMHNRQþQHDHUREQHELRUD]JUDGOMLYRVWLY]HPOML]
PHUMHQMHPSRUDEHNLVLNDYUHVSLURPHWUXDOLNROLþLQHQDVWDOHJDRJOMLNRYHJDGLRNVLGD
,62
Plastics - Determination of the ultimate aerobic biodegradability in soil by measuring the
oxygen demand in a respirometer or the amount of carbon dioxide evolved (ISO
17556:2003)
Kunststoffe - Bestimmung der vollständigen aeroben biologischen Abbaubarkeit im
Boden durch Messung des Sauerstoffbedarfs in einem Respirometer oder der Menge
des entstandenen Kohlendioxids (ISO 17556:2003)
Plastiques - Détermination de la biodégradabilité aérobie ultime dans le sol par mesure
de la demande en oxygene dans un respirometre ou de la teneur en dioxyde de carbone
libéré (ISO 17556:2003)
Ta slovenski standard je istoveten z: EN ISO 17556:2004
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 17556:2005 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 17556:2005
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SIST EN ISO 17556:2005
EUROPEAN STANDARD
EN ISO 17556
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2004
ICS 83.080.01
English version
Plastics - Determination of the ultimate aerobic biodegradability
in soil by measuring the oxygen demand in a respirometer or the
amount of carbon dioxide evolved (ISO 17556:2003)
Plastiques - Détermination de la biodégradabilité aérobie Kunststoffe - Bestimmung der vollständigen aeroben
ultime dans le sol par mesure de la demande en oxygène biologischen Abbaubarkeit im Boden durch Messung des
dans un respiromètre ou de la teneur en dioxyde de Sauerstoffbedarfs in einem Respirometer oder der Menge
carbone libéré (ISO 17556:2003) des entstandenen Kohlendioxids (ISO 17556:2003)
This European Standard was approved by CEN on 21 December 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 17556:2004: E
worldwide for CEN national Members.
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SIST EN ISO 17556:2005
EN ISO 17556:2004 (E)
Foreword
The text of ISO 17556:2003 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
17556:2004 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 June 2005, and conflicting national
standards shall be withdrawn at the latest by June 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 17556:2003 has been approved by CEN as EN ISO 17556:2004 without any
modifications.
2
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SIST EN ISO 17556:2005
INTERNATIONAL ISO
STANDARD 17556
First edition
2003-08-01
Plastics — Determination of the ultimate
aerobic biodegradability in soil by
measuring the oxygen demand in a
respirometer or the amount of carbon
dioxide evolved
Plastiques — Détermination de la biodégradabilité aérobie ultime dans
le sol par mesure de la demande en oxygène dans un respiromètre ou
de la teneur en dioxyde de carbone libéré
Reference number
ISO 17556:2003(E)
©
ISO 2003
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SIST EN ISO 17556:2005
ISO 17556:2003(E)
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SIST EN ISO 17556:2005
ISO 17556:2003(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 3
5 Test environment . 3
6 Materials . 3
7 Apparatus . 4
8 Procedure . 4
9 Calculation and expression of results . 7
10 Validity of results . 9
11 Test report . 9
Annex A (informative) Principle of a manometric respirometer . 10
Annex B (informative) Example of a system for measuring the amount of carbon dioxide evolved . 11
Annex C (informative) Examples of methods for the determination of evolved carbon dioxide . 12
Annex D (informative) Theoretical oxygen demand (ThOD) . 14
Annex E (informative) Example of a determination of the amount and the molecular mass of water-
insoluble polymer remaining at the end of a biodegradation test . 15
Bibliography . 16
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SIST EN ISO 17556:2005
ISO 17556:2003(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 17556 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-chemical
properties.
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SIST EN ISO 17556:2005
ISO 17556:2003(E)
Introduction
With the increasing use of plastics, their recycling and disposal have become a major issue. As a first priority,
recycling needs to be promoted. Complete recycling of plastics, however, is difficult. For example, plastic litter,
which comes mainly from consumers, is difficult to recycle completely. Other examples of plastic materials
which are difficult to recycle are fishing tackle, agricultural mulch films and water-soluble polymers. These
materials tend to “leak” from closed waste-management infrastructures into the natural environment.
Biodegradable plastics are now emerging as one of the options available to solve such environmental issues.
Several International Standards specifying methods for determining the ultimate aerobic/anaerobic
biodegradability of plastic materials in aqueous/compost conditions have been published. In view of the use and
disposal of biodegradable plastics, it is therefore very important to establish a method of determining the
ultimate aerobic biodegradability of such materials in soil.
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SIST EN ISO 17556:2005
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SIST EN ISO 17556:2005
INTERNATIONAL STANDARD ISO 17556:2003(E)
Plastics — Determination of the ultimate aerobic
biodegradability in soil by measuring the oxygen demand in a
respirometer or the amount of carbon dioxide evolved
WARNING — Appropriate precautions should be taken when handling soil because it may contain
potentially pathogenic organisms. Toxic test compounds and those whose properties are unknown
should be handled with care.
1Scope
This International Standard specifies a method for determining the ultimate aerobic biodegradability of plastic
materials in soil by measuring the oxygen demand in a closed respirometer or the amount of carbon dioxide
evolved. The method is designed to yield an optimum degree of biodegradation by adjusting the humidity of the
test soil.
If a non-adapted soil is used as an inoculum, the test simulates the biodegradation processes which take place
in a natural soil environment; if a pre-exposed soil is used, the method can be used to investigate the potential
biodegradability of a test material.
This method applies to the following materials:
— Natural and/or synthetic polymers, copolymers or mixtures of these.
— Plastic materials which contain additives such as plasticizers or colorants.
— Water-soluble polymers.
— Materials which, under the test conditions, do not inhibit the activity of the microorganisms present in the
soil. Inhibitory effects can be measured using an inhibition control or by another suitable method (see e.g.
ISO 8192). If the test material inhibits the microorganisms in the soil, a lower test material concentration,
another type of soil or a pre-exposed soil can be used.
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 10381-6, Soil quality — Sampling — Part 6: Guidance on the collection, handling and storage of soil for the
assessment of aerobic microbial processes in the laboratory
ISO 10390, Soil quality — Determination of pH
ISO 10634, Water quality — Guidance for the preparation and treatment of poorly water-soluble organic
compounds for the subsequent evaluation of their biodegradability in an aqueous medium
ISO 10694, Soil quality — Determination of organic and total carbon after dry combustion (elementary analysis)
ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods
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SIST EN ISO 17556:2005
ISO 17556:2003(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
ultimate aerobic biodegradation
breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide, water
and mineral salts of any other elements present (mineralization) plus new biomass
3.2
biochemical oxygen demand
BOD
mass concentration of dissolved oxygen consumed under specified conditions by the aerobic biological
oxidation of a chemical compound or organic matter in water, expressed as milligrams of oxygen uptake per
milligram or gram of test compound
3.3
dissolved organic carbon
DOC
that part of the organic carbon in water which cannot be removed by specified phase separation, for example by
−2
centrifugation at 40 000 m·s for 15 min or by membrane filtration using membranes with pores of 0,2µm to
0,45µm diameter
3.4
theoretical oxygen demand
ThOD
maximum theoretical amount of oxygen required to oxidize a chemical compound completely, calculated from
the molecular formula; expressed as milligrams of oxygen uptake per milligram or gram of test compound
3.5
theoretical amount of carbon dioxide evolved
ThCO
2
maximum theoretical amount of carbon dioxide evolved after completely oxidizing a chemical compound,
calculated from the molecular formula; expressed as milligrams of carbon dioxide evolved per milligram or gram
of test compound
3.6
lag phase
time, measured in days, from the start of a test until adaptation and/or selection of the degrading
microorganisms is achieved and the degree of biodegradation of a chemical compound or organic matter has
increased to about 10 % of the maximum level of biodegradation
3.7
biodegradation phase
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
3.8
maximum level of biodegradation
degree of biodegradation, measured in per cent, of a chemical compound or organic matter in a test, above
which no further biodegradation takes place during the test
3.9
plateau phase
time, measured in days, from the end of the biodegradation phase until the end of the test
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3.10
pre-conditioning
pre-incubation of soil 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 performance of the test by acclimatization of the
microorganisms to the test conditions
3.11
pre-exposure
pre-incubation of soil in the presence of the chemical compound or organic matter under test, with the aim of
enhancing the ability of the soil to biodegrade the test material by adaptation and/or selection of the
microorganisms
3.12
water content
◦
mass of water which evaporates from the soil when the soil is dried to constant mass at 105 C, divided by the
dry mass of the soil (i.e. the ratio between the mass of the water and that of the soil particles in a soil sample)
3.13
water-holding capacity
mass of water which 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 a test soil by
controlling the humidity of the soil, and to determine the ultimate biodegradability of the material.
The plastic material, which is the sole source of carbon and energy, is mixed with the soil. The mixture is
allowed to stand in a flask over a period of time during which the amount of oxygen consumed (BOD) or the
amount of carbon dioxide evolved is determined. The BOD is determined, for example, by measuring the
amount of oxygen required to maintain a constant gas volume in a respirometer flask, or by measuring either
automatically or manually the change in volume or pressure (or a combination of the two). An example of a
suitable respirometer is shown in Annex A. The amount of carbon dioxide evolved is measured at intervals
dependent on the biodegradation kinetics of the test substance by passing carbon-dioxide-free air over the soil
and then determining the carbon dioxide content of the air by a suitable method. Examples of suitable methods
are given in Annexes B and C.
The level of biodegradation, expressed in per cent, is determined by comparing the BOD with the theoretical
oxygen demand (ThOD) or by comparing the amount of carbon dioxide evolved with the theoretical amount
(ThCO ). The influence of possible nitrification processes on the BOD has to be considered. The test is
2
terminated when a constant level of biodegradation has been attained or, at the latest, after six months.
Unlike ISO 11266, which is used for a variety of organic compounds, this International Standard is specially
designed to determine the biodegradability of plastic materials.
5 Test environment
Incubation shall take place in the dark or in diffused light in an enclosure which is free from vapours toxic to
◦ ◦
microorganisms and is maintained at a temperature constant to within ± 1C2, preferably between 0 C and
◦
25 C, but other temperatures may be used for particular test environments.
6 Materials
6.1 Distilled water, containing less than 2 mg/l of DOC.
6.2 Carbon dioxide absorber, preferably soda lime pellets.
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7 Apparatus
Ensure that all glassware is thoroughly cleaned and, in particular, free from organic or toxic matter.
7.1 Closed respirometer, including test flasks and all other necessary equipment, located in a constant-
temperature enclosure or in a thermostatted apparatus (e.g. water-bath). For an example, see Annex A.
NOTE Any respirometer capable of determining with sufficient accuracy the biochemical oxygen demand is suitable,
preferably an apparatus which measures and automatically replaces the oxygen consumed so that no oxygen deficiency
and no inhibition of the microbial activity occurs during the degradation process.
7.2 Apparatus for determining the amount of carbon dioxide evolved.
7.2.1 Test flasks: glass vessels (e.g. conical flasks or bottles), fitted with tubing impermeable to carbon
dioxide to allow purging with gas, and located in a constant-temperature enclosure or in a thermostatted
apparatus (e.g. water-bath).
7.2.2 CO -free-air production system, capable of supplying CO -free air at a flow rate of several ml/min to
2 2
each test flask, held constant to within ± 10 % (see example of system, including test vessels, in Annex B).
Alternatively, the incubation apparatus shown in ASTM D 5988 may be used.
7.2.3 Analytical instrument for determining carbon dioxide, consisting of any suitable apparatus with
sufficient accuracy, e.g. a carbon dioxide or DIC analyser or apparatus for titrimetric determination after
complete absorption in a basic solution (see examples in Annex C).
7.3 Analytical balance.
7.4 pH-meter.
8 Procedure
8.1 Preparation of test material
The test material shall be of known mass and contain sufficient carbon to yield a BOD or a quantity of carbon
dioxide that can be adequately measured by the analytical equipment used. Calculate the TOC from the
chemical formula or determine it by a suitable analytical technique (e.g. elemental analysis or measurement in
accordance with ISO 8245) and calculate the ThOD or ThCO (see Annexes C and D).
2
NOTE1 Although elemental analysis is generally less precise for macromolecules than for low-molecular-mass
compounds, the precision is usually acceptable for the purposes of calculating the ThOD or ThCO .
2
The amount of test material shall be sufficient to outweigh any variations in the background oxygen
300 mg
consumption or any carbon dioxide evolved from the test soil: 100 mg to of test material to 100 g to
300 g of soil is usually adequate. The maximum amount of test material is limited by the oxygen supply to the
test system. The use of 200 mg of test material with 200 g of soil is recommended unless the soil contains an
excessively large amount of organic matter.
NOTE 2 Pre-aeration of the test material or the addition of inert material is recommended, as and when necessary, to
reduce the influence on respiration of the soil in blank flasks.
The test material should preferably be used in powder form, but it may also be introduced in the form of films,
fragments or shaped articles.
Experiments have shown that the ultimate degree of biodegradation is almost independent of the form and
shape of the test material. The speed of biodegradation, however, does depend on the form and shape of the
material. Test materials of similar form and shape should therefore be used if different kinds of plastic material
are to be compared in tests of the same length. If the test material is in the form of a powder, small particles of
known size distribution should be used. A particle-size distribution with its maximum at 250µm diameter is
recommended. If the test material is not in powder form, the size of the pieces of material should not be greater
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ISO 17556:2003(E)
than 5mm×5mm. Also, the size of the test equipment used may depend on the form of the test material. It
should be ascertained that no substantial mechanical aberrations occur due to the design of the equipment.
Normally, processing of the test material will not significantly influence the degradation behaviour of the material
(e.g. the use of powder in the case of composites).
Optionally, determine the hydrogen, oxygen, nitrogen, phosphorus and sulfur contents, as well as the molecular
mass of the test material using, for example, size exclusion chromatography. Preferably plastic materials without
additives such as plasticizers should be tested. When the material does contain such additives, information on
their biodegradability will be needed to assess the biodegradability of the polymeric material itself.
For details on how to handle poorly water-soluble compounds, see ISO 10634.
8.2 Preparation of reference material
Use as reference material a well-defined biodegradable polymer (for example, microcrystalline cellulose
powder, ashless cellulose filters or poly-β-hydroxybutyrate) with a biodegradability similar to that of the test
material. If possible, the form and size of the reference material should be comparable to that of the test
material.
As a negative control, a non-biodegradable polymer (e.g. polyethylene) in the same form as the test material
can be used.
8.3 Preparation of the test soil
8.3.1 Collection and sieving of soil
Use natural soil collected from the surface layer of fields and/or forests, or a soil which has been pre-exposed to
the test material. Sieve the soil to give particles of less than 2mm in size and remove obvious plant material,
stones and other inert materials.
NOTE 1 It is important to remove organic solids, such as straw, as far as practicable because they can decompose during
the test.
NOTE2 The soil may be pre-conditioned but normally pre-exposed soil should not be used, especially when
biodegradation behaviour in natural environments is being simulated. Depending on the purpose of the test, however, pre-
exposed soil may be used, provided that this is clearly stated in the test report (e.g. per cent biodegradation =x %, using
pre-exposed soil) and the method of pre-exposure detailed in the test report. Pre-exposed soil can be obtained from suitable
laboratory biodegradation tests conducted under a variety of conditions or from samples collected from locations where
relevant environmental conditions exist (e.g. contaminated areas or industrial treatment plants).
Record the sampling site, its location, the presence of plants or previous crops, the sampling date, the sampling
depth and, if possible, the history such as details of fertilizer and pesticide application.
8.3.2 Measurement of soil characteristics
Knowledge of the soil characteristics is essential for full interpretation of the results of the study. It is therefore
recommended that at least the following tests be performed on the soil selected:
a) total water-holding capacity, in accordance with ISO 11274;
b) pH of the soil, in accordance with ISO 10390;
c) organic-matter content, in accordance with ISO 10694.
8.3.3 Adjustment of the water content and the pH of the soil
Adjust the water content of the soil to a suitable value for the test material by adding an appropriate amount of
water to the soil, or by drying the soil in the air in a shaded place followed by addition of an appropriate amount
of water. Adjust the pH of the soil to between 6,0 and 8,0 if it is not already within this range.
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NOTE 1 The optimum water content of the test soil is dependent on the test material. It is usually between 40 % and 60 %
of the total water-holding capacity.
NOTE 2 It is recommended that the ratio of organic carbon in the test or reference material to nitrogen in the soil (C:N ratio)
be adjusted to at least 40:1, if it is not already at this level, so as to ensure good biodegradation. This may be done by adding
nitrogen as, for example, an aqueous solution of ammonium chloride.
8.3.4 Handling and storage of the soil
◦ ◦
Store the soil in a sealed container at 4 C± 2 C until it is used in the test. Do not handle the soil in any way
that could inhibit the activity of the microorganisms in it.
It is important that ISO 10381-6 is followed to ensure that the microbial activity of the soil is not affected by
sampling.
8.4 Start-up and execution of the test
Prepare a sufficient number of flasks so that the test includes at least the following:
a) two test flasks for the test material (symbol );
F
T
b) two flasks for the blank (symbol F );
B
c) two flasks for checking the soil activity using a reference material (symbol F );
C
and, if required:
d) one flask for checking for possible abiotic degradation or non-biological changes in the test material (symbol
F );
S
e) one flask for checking for any possible inhibiting effect of the test material (symbol F ).
I
Place between 100 g and 300 g of soil (see 8.3) at the bottom of each flask to a depth of not more than 3cm
and add test material (see 8.1) or reference material (see 8.2), as indicated in Table 1, to the soil. Record the
mass of each flask containing test mixture.
Table 1 — Final distribution of test and reference materials
Flask Test material Reference material Test soil
F Test + − +
T
F Test + − +
T
F Blank −− +
B
F Blank −− +
B
F Soil activity check − ++
C
F Soil activity check − ++
C
F Abiotic degradation check (optional) + −−
S
F Inhibition check (optional) +++
I
NOTE 1 It is important that the test material be homogeneously mixed with the soil, in the case of powder, and as widely
spread a
...
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