ISO 14853:2016
(Main)Plastics — Determination of the ultimate anaerobic biodegradation of plastic materials in an aqueous system — Method by measurement of biogas production
Plastics — Determination of the ultimate anaerobic biodegradation of plastic materials in an aqueous system — Method by measurement of biogas production
ISO 14853:2016 specifies a method for the determination of the ultimate anaerobic biodegradability of plastics by anaerobic microorganisms. The conditions described in ISO 14853 do not necessarily correspond to the optimum conditions for the maximum degree of biodegradation to occur. The test calls for exposure of the test material to sludge for a period of up to 90 d, which is longer than the normal sludge retention time (25 to 30 d) in anaerobic digesters, although digesters at industrial sites can have much longer retention times. The method applies to the following materials: - natural and/or synthetic polymers, copolymers or mixtures thereof; - plastic materials which contain additives such as plasticizers, colorants or other compounds; - water-soluble polymers; - materials which, under the test conditions, do not inhibit the microorganisms present in the inoculum. Inhibitory effects can be determined using an inhibition control or by another appropriate method (see e.g. ISO 13641). If the test material is inhibitory to the inoculum, a lower test concentration, another inoculum or a pre-exposed inoculum can be used.
Plastiques — Évaluation de la biodégradabilité anaérobie ultime des matériaux plastiques en milieu aqueux — Méthode par détermination de la production de biogaz
L'ISO 14853:2016 spécifie une méthode pour la détermination de la biodégradabilité anaérobie ultime des plastiques par des micro-organismes anaérobies. Les conditions décrites dans l'ISO 14853:2016 ne correspondent pas nécessairement aux conditions optimales permettant d'obtenir le taux maximal de biodégradation. L'essai exige que le matériau d'essai soit exposé aux boues pendant une période allant jusqu'à 90 j, ce qui est plus long que le temps de rétention normal de la boue (25 j à 30 j) dans les digesteurs anaérobies, bien que les digesteurs sur les sites industriels puissent avoir des temps de rétention beaucoup plus longs. La présente méthode s'applique aux matériaux suivants: - polymères naturels et/ou synthétiques, copolymères ou mélanges de ceux-ci; - matériaux plastiques contenant des additifs, tels que plastifiants, colorants ou autres composés; - polymères hydrosolubles; - matériaux qui, dans les conditions d'essai, n'ont pas d'effet inhibiteur sur les micro-organismes présents dans l'inoculum. Les effets inhibiteurs peuvent être déterminés en utilisant une substance de contrôle de l'effet inhibiteur ou par toute autre méthode appropriée (voir, par exemple, l'ISO 13641). Si le matériau d'essai a un effet inhibiteur vis-à-vis de l'inoculum, il est possible d'utiliser une plus faible concentration, un autre inoculum ou un inoculum pré-exposé.
General Information
Relations
Buy Standard
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 14853
Second edition
2016-07-15
Plastics — Determination of the
ultimate anaerobic biodegradation of
plastic materials in an aqueous system
— Method by measurement of biogas
production
Plastiques — Évaluation de la biodégradabilité anaérobie ultime des
matériaux plastiques en milieu aqueux — Méthode par détermination
de la production de biogaz
Reference number
ISO 14853:2016(E)
©
ISO 2016
---------------------- Page: 1 ----------------------
ISO 14853:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14853:2016(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Reagents and materials . 3
6 Apparatus . 5
6.1 Laboratory equipment . 5
6.2 Apparatus for use when biogas is measured by a manometric method . 6
6.3 Apparatus for use when biogas is measured by a volumetric method . 6
7 Procedure. 6
7.1 General . 6
7.2 Digested sludge . 6
7.3 Preparation of the inoculum . 7
7.4 Preparation of test suspensions and controls . 7
7.5 Incubation and gas measurement . 8
7.6 Test duration . 9
7.7 Measurement of inorganic carbon . 9
7.8 Specific analyses . 9
8 Calculation and expression of results . 9
8.1 Amount of carbon in headspace . 9
8.2 Calculation of amount of carbon in headspace when manometric measurement
method is used .10
8.3 Calculation of amount of carbon in headspace when volumetric measurement
method is used .11
8.4 Amount of inorganic carbon in the liquid .11
8.5 Total amount of carbon converted to gas .11
8.6 Amount of carbon in test material .12
8.7 Calculation of percentage biodegradation .12
9 Validity of results .12
9.1 Maintenance of anaerobic conditions .12
9.2 Inhibition of degradation .12
9.3 Validity of the test .12
10 Test report .13
Annex A (informative) Example of apparatus for determining the amount of biogas
produced by measuring the increase in gas pressure .14
Annex B (informative) Example of apparatus for determining volumetrically the amount of
biogas produced .15
Annex C (informative) Example of a biodegradation curve .17
Annex D (informative) Examples of data sheets for anaerobic biodegradability tests .18
Annex E (informative) Table of water vapour pressures at various temperatures .21
Annex F (informative) Calculation of theoretical carbon dioxide (ThCO ) and theoretical
2
methane (ThCH ) production .22
4
Annex G (informative) Example of determination of recovery rate .23
Annex H (informative) Example of a workflow scheme .26
© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 14853:2016(E)
Bibliography .28
iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 14853:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This second edition cancels and replaces the first edition (ISO 14853:2005), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 14853:2005/Cor.1:2009.
© ISO 2016 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 14853:2016(E)
Introduction
With the increasing use of plastics, their recovery and disposal have become a major issue. As a first
priority, recovery should be promoted. For example, plastic litter, which originates mainly from
consumers, is difficult to recover completely. Additional examples of materials difficult to recover
are found in the disposal of fishing tackle, agricultural mulch films and water-soluble polymers.
These plastic materials tend to leak from closed waste management infrastructures into natural
environments. Biodegradable plastics are now emerging as one of the available options to solve such
environmental issues. Plastic materials, such as products or packaging, which are sent to anaerobic
treatment facilities should be potentially biodegradable. Therefore, it is very important to determine
the potential biodegradability of such materials and to obtain a quantitative measure of their
biodegradability in anaerobic environments.
vi © ISO 2016 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 14853:2016(E)
Plastics — Determination of the ultimate anaerobic
biodegradation of plastic materials in an aqueous system
— Method by measurement of biogas production
WARNING — Sewage and activated sludge may contain potentially pathogenic organisms.
Therefore, appropriate precautions should be taken when handling them. Digesting sewage
sludge produces flammable gases which present fire and explosion risks. Care should be taken
when transporting and storing quantities of digesting sludge. Toxic test chemicals and those
whose properties are not known should be handled with care and in accordance with safety
instructions. The pressure meter and microsyringes should be handled carefully to avoid needle
stick injuries. Contaminated syringe needles should be disposed of in a safe manner.
1 Scope
This International Standard specifies a method for the determination of the ultimate anaerobic
biodegradability of plastics by anaerobic microorganisms. The conditions described in this
International Standard do not necessarily correspond to the optimum conditions for the maximum
degree of biodegradation to occur. The test calls for exposure of the test material to sludge for a period
of up to 90 d, which is longer than the normal sludge retention time (25 to 30 d) in anaerobic digesters,
although digesters at industrial sites can have much longer retention times.
The method applies to the following materials:
— natural and/or synthetic polymers, copolymers or mixtures thereof;
— plastic materials which contain additives such as plasticizers, colorants or other compounds;
— water-soluble polymers;
— materials which, under the test conditions, do not inhibit the microorganisms present in the inoculum.
Inhibitory effects can be determined using an inhibition control or by another appropriate method
(see e.g. ISO 13641). If the test material is inhibitory to the inoculum, a lower test concentration,
another inoculum or a pre-exposed inoculum can be used.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
ultimate anaerobic biodegradation
breakdown of an organic compound by microorganisms in the absence of oxygen to carbon dioxide,
methane, water and mineral salts of any other elements present (mineralization) plus new biomass
3.2
primary anaerobic biodegradation
structural change (transformation) of a chemical compound by microorganisms, resulting in the loss of
a specific property
© ISO 2016 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 14853:2016(E)
3.3
digested sludge
mixture of settled sewage and activated sludge which have been incubated in an anaerobic digester at
about 35 °C to reduce the biomass and odour and to improve the dewaterability of the sludge
Note 1 to entry: Digested sludge contains an association of anaerobic fermentative and methanogenic bacteria
producing carbon dioxide and methane.
3.4
concentration of suspended solids in digested sludge
amount of solids obtained by filtration or centrifugation of a known volume of activated sludge and
drying at about 105 °C to constant mass
3.5
dissolved organic carbon
DOC
organic carbon in the water phase which cannot be removed by specified phase separation, for example,
–2
by centrifugation at 40 000 m⋅s for 15 min or by membrane filtration using membranes with pores of
0,2 µm to 0,45 µm diameter
3.6
inorganic carbon
IC
inorganic carbon which is dissolved or dispersed in the aqueous phase of a liquid and is recoverable
from the supernatant liquid after the sludge has been allowed to settle
3.7
total dry solids
amount of solids obtained by taking a known volume of test material or inoculum and drying at about
105 °C to constant mass
3.8
theoretical amount of evolved biogas
Thbiogas
maximum theoretical amount of biogas (CH + CO ) evolved after complete biodegradation of an
4 2
organic material under anaerobic conditions, calculated from the molecular formula and expressed as
millilitres of biogas evolved per milligram of test material under standard conditions
3.9
theoretical amount of evolved carbon dioxide
ThCO
2
maximum theoretical amount of carbon dioxide evolved after complete oxidation of an organic material,
calculated from the molecular formula and expressed as milligrams of carbon dioxide per milligram of
test material
3.10
theoretical amount of evolved methane
ThCH
4
maximum theoretical amount of methane evolved after complete reduction of an organic material,
calculated from the molecular formula and expressed as milligrams of methane evolved per milligram
of test material
3.11
lag phase
lag period
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
2 © ISO 2016 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 14853:2016(E)
3.12
plateau phase
time, measured in days, from the end of the biodegradation phase until the end of the test
3.13
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
3.14
maximum level of biodegradation
degree of biodegradation, measured in percent, of a chemical compound or organic matter in a test,
above which no further biodegradation takes place during the test
4 Principle
The biodegradability of a plastic material is determined using anaerobic conditions in an aqueous
system. Test material with a concentration of 20 mg/l to 200 mg/l organic carbon (OC) is incubated
at (35 ± 2) °C in sealed vessels together with digested sludge for a period normally not exceeding 90 d.
Before use, the digested sludge is washed so that it contains very low amounts of inorganic carbon
(IC) and diluted to 1 g/l to 3 g/l total solids concentration. The increase in headspace pressure or the
volumetric increase (depending on the method used for measuring biogas evolution) in the test vessels
resulting from the production of carbon dioxide (CO ) and methane (CH ) is measured. A considerable
2 4
amount of CO will be dissolved in water or transformed to bicarbonate or carbonate under the
2
conditions of the test. This inorganic carbon (IC) is measured at the end of the test. The amount of
microbiologically produced biogas carbon is calculated from the net biogas production and the net IC
formation in excess of blank values. The percentage biodegradation is calculated from the total amount
of carbon transformed to biogas and IC and the measured or calculated amount of carbon added as
test material. The course of biodegradation can be followed by making intermediate measurements
of biogas production. As additional information, the primary biodegradability can be determined by
specific analyses at the beginning and end of the test.
This test method is designed to determine the biodegradability of plastic materials under anaerobic
conditions. Optionally, the assessment of the recovery rate may also be of interest (see Annex G).
5 Reagents and materials
5.1 Distilled or deionized water, free of toxic substances, containing less than 2 mg/l of DOC.
5.2 Test medium, prepared using only reagents of recognized analytical grade.
Prepare the test medium to contain the following constituents in the stated amounts:
Anhydrous potassium dihydrogen phosphate KH PO 0,27 g
2 4
Disodium hydrogen phosphate dodecahydrate Na HPO ⋅12H O 1,12 g
2 4 2
Ammonium chloride NH Cl 0,53 g
4
Calcium chloride dihydrate CaCl ⋅2H O 0,075 g
2 2
Magnesium chloride hexahydrate MgCl ⋅6H O 0,10 g
2 2
Iron (II) chloride tetrahydrate FeCl ⋅4H O 0,02 g
2 2
Resazurin (oxygen indicator) 0,001 g
a
Disodium sulfide nonahydrate Na S⋅9H O 0,1 g
2 2
Stock solution of trace elements (optional) 10 ml
Stock solutions of vitamins (optional) Vitamin solution No. 1 0,5 ml
© ISO 2016 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 14853:2016(E)
Anhydrous potassium dihydrogen phosphate KH PO 0,27 g
2 4
Vitamin solution No. 2 0,5 ml
Add water (5.1) (oxygen-free) to 1 l
a
Use freshly prepared sodium sulfide, or wash and dry it before use, to ensure sufficient reductive capacity.
In order to ensure strictly anaerobic conditions, it is recommended that a small amount of sodium dithionite be
added to the medium after it has been prepared until it becomes colourless. Do not use more than 10 mg/l because
higher concentrations may produce inhibitory effects.
Adjust the pH of the medium with dilute mineral acid or alkali, if necessary, to 7 ± 0,2.
To ensure oxygen-free conditions, purge the water with nitrogen for about 20 min immediately before use.
5.3 Trace-element solution (optional).
It is recommended that the test medium be supplemented with the following trace elements to improve
the anaerobic degradation process, especially if low inoculum concentrations are used:
Manganese chloride tetrahydrate MnCl ⋅4H O 0,05 g
2 2
Boric acid H BO 0,005 g
3 3
Zinc chloride ZnCl 0,005 g
2
Copper (II) chloride CuCl 0,003 g
2
Disodium molybdate dihydrate Na MoO ⋅2H O 0,001 g
2 4 2
Cobalt chloride hexahydrate CoCl ⋅6H O 0,1 g
2 2
Nickel chloride hexahydrate NiCl ⋅6H O 0,01 g
2 2
Disodium selenite Na SeO 0,005 g
2 3
Disodium tungstate dihydrate Na WO ⋅2H O 0,002 g
2 4 2
Add water (5.1) (oxygen free) to 1 l
Use 10 ml of trace-element solution per litre of test medium.
5.4 Vitamin solutions (optional).
5.4.1 Vitamin solution No. 1
4-Aminobenzoic acid 40 mg
d-Biotin 10 mg
Dissolve in hot water (5.1) 500 ml
Allow to cool and add:
d-Pantothenic acid, calcium salt 50 mg
Pyridoxamine dihydrochloride 150 mg
Thiamine dichloride 100 mg
Filter the solution through a membrane filter (pore size 0,45 µm) that neither adsorbs nor releases
organic carbon in significant amounts, and store in the dark at 4 °C.
Use 0,5 ml of vitamin solution per litre of test medium.
5.4.2 Vitamin solution No. 2
Cyanocobalamin (vitamin B12) 10 mg
Dissolve in water (5.1) 100 ml
4 © ISO 2016 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 14853:2016(E)
Filter the solution through a membrane filter (pore size 0,45 µm) that neither adsorbs nor releases
organic carbon in significant amounts, and store in the dark at 4 °C.
Use 0,5 ml of vitamin solution per litre of test medium.
5.5 Barrier solution.
NaCl 200 g
Dissolve in water (5.1) 1 000 ml
Acidify with citric acid 5 g
Add a pH indicator such as bromophenol blue or methyl orange in order to be able to verify that the
solution remains acid during the test.
5.6 Test material.
The test material is usually added directly as solid to give a concentration of 20 mg/l to 200 mg/l
organic carbon. The test material (plastic) should be used in powdered form, if possible.
The test material should preferably be used in powder form, but it may also be introduced as films,
pieces, fragments or shaped articles. The form and shape of the test material may influence its
biodegradability. Similar shapes should preferably be used if different kinds of plastic material are
to be compared. If the test material is used in the form of a powder, particles of known, narrow size
distribution should be used. A particle-size distribution with the maximum at 250 µm diameter is
recommended. Also, the size of the test equipment used may depend on the form of the test material.
The biodegradability of plastic materials which are not inhibitory to microorganisms can be determined
using concentrations higher than 200 mg/l organic carbon. In this case, ensure that the buffer capacity
and mineral-salt content of the medium are sufficient.
5.7 Reference material.
Use a well-defined anaerobically biodegradable polymer, e.g. poly-β-hydroxybutyrate, cellulose or
poly(ethylene glycol) 400 as a reference material. If possible, the form, size, solubility and concentration
of the reference material should be comparable with that of the test material.
Prepare the reference material in the same way as the test material.
5.8 Inhibition control (optional).
Add both the test material and the reference material to a vessel containing test medium (5.2) to give
the concentrations specified in 5.6 and 5.7, respectively.
6 Apparatus
6.1 Laboratory equipment
Required is usual laboratory equipment, plus the following:
6.1.1 Incubator or water or sand bath, thermostatically controlled at (35 ± 2) °C.
6.1.2 Carbon analyser (optional), suitable for the direct determination of inorganic carbon in the
range 1 mg/l to 200 mg/l IC. Alternatively, the IC in the supernatant may be determined indirectly by
release of the dissolved IC as carbon dioxide that can be measured in the headspace, as described in 7.7.
© ISO 2016 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO 14853:2016(E)
6.2 Apparatus for use when biogas is measured by a manometric method
6.2.1 Pressure-resistant glass test vessels, nominal size 0,1 l to 1 l, each fitted with a gastight septum
capable of withstanding about 2 000 hPa (for an example, see Annex A). The headspace volume shall be
about 10 % to 30 % of the total volume. If gas is released at regular intervals, about 10 % headspace
volume is adequate, but if gas is released only at the end of the test, 30 % is more appropriate.
From a practical point of view, the use of serum bottles sealed with butyl rubber serum caps and
crimped aluminium rings is recommended.
6.2.2 Pressure-measuring device, e.g. a manometer connected to a suitable syringe needle, with
a gastight three-way valve to facilitate the release of excess pressure. Use and calibrate the device in
accordance with the manufacturer’s instructions.
It is necessary to keep the internal volume of the tubing and the valve as low as possible so that errors
introduced by neglecting the volume of the device are not significant.
6.3 Apparatus for use when biogas is measured by a volumetric method
6.3.1 Glass test vessels (e.g. conical flasks or bottles), nominal size 0,1 l to 1 l, preferably 300 ml for
every 250 ml of medium. If foaming is not expected to occur, a headspace volume of 10 % to 20 % is
recommended. The vessels shall be equipped with a septum for gas sampling (see Annex B) and shall be
connected via gastight tubing to a graduated glass gas-collection tube which is filled with acidified salt
solution (barrier solution 5.5). This graduated glass tube shall be connected to an expansion tank which
can be moved up and down to bring the surface of the acidified solution in the expansion tank to the
same level as that in the gas-collection tube.
7 Procedure
7.1 General
Carry out the following initial operations using techniques which will ensure that the digested sludge
comes into contact with oxygen as little as practicable, e.g. work in a glove-box in an atmosphere of
nitrogen or purge the test vessels with nitrogen.
7.2 Digested sludge
Collect digested sludge from a digester at a sewage treatment plant treating predominantly domestic
sewage. Be sure to collect active sludge. Use wide-necked bottles made of high-density polyethylene or
a similar material which can expand. Glass is not recommended for safety reasons. Fill the bottles to
within 1 cm of the top and seal. After transport to the laboratory, use directly or place in a laboratory-
scale digester. Release excess biogas.
Alternatively, use a laboratory-grown anaerobic sludge as a source of the inoculum.
Consider pre-incubation of the sludge to reduce background gas production and to decrease the
influence of the blanks. Allow the sludge to digest, without the addition of any nutrients or substrates,
at (35 ± 2) °C for up to 7 d.
It has been shown that pre-incubation for about 5 d gives an optimum decrease in gas production by the
blank without an unacceptable increase in either lag period or incubation period during the test. For
test materials which are expected to be poorly biodegradable, consider pre-incubating the sludge with
the test material to get a better adapted inoculum. In such a case, add test material with a concentration
of 5 mg/l to 20 mg/l OC to the digested sludge. Wash the pre-incubated sludge carefully before use.
Indicate in the test report that pre-incubation was carried out.
6 © ISO 2016 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 14853:2016(E)
7.3 Preparation of the inoculum
Wash the sludge just prior to use to reduce the IC content to less than 20 mg/l in the final test suspension.
If the IC has not been sufficiently
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 14853
ISO/TC 61/SC 5
Plastics — Determination of the
Secretariat: DIN
ultimate anaerobic biodegradation of
Voting begins on:
201604-12 plastic materials in an aqueous system
— Method by measurement of biogas
Voting terminates on:
201606-12
production
Plastiques — Évaluation de la biodégradabilité anaérobie ultime des
matériaux plastiques en milieu aqueux — Méthode par détermination
de la production de biogaz
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 14853:2016(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2016
---------------------- Page: 1 ----------------------
ISO/FDIS 14853:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 14853:2016(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Reagents and materials . 3
6 Apparatus . 5
6.1 Laboratory equipment . 5
6.2 Apparatus for use when biogas is measured by a manometric method . 6
6.3 Apparatus for use when biogas is measured by a volumetric method . 6
7 Procedure. 6
7.1 General . 6
7.2 Digested sludge . 6
7.3 Preparation of the inoculum . 7
7.4 Preparation of test suspensions and controls . 7
7.5 Incubation and gas measurement . 8
7.6 Test duration . 9
7.7 Measurement of inorganic carbon . 9
7.8 Specific analyses .10
8 Calculation and expression of results .10
8.1 Amount of carbon in headspace .10
8.2 Calculation of amount of carbon in headspace when manometric measurement
method is used .10
8.3 Calculation of amount of carbon in headspace when volumetric measurement
method is used .11
8.4 Amount of inorganic carbon in the liquid .12
8.5 Total amount of carbon converted to gas .12
8.6 Amount of carbon in test material .12
8.7 Calculation of percentage biodegradation .13
9 Validity of results .13
9.1 Maintenance of anaerobic conditions .13
9.2 Inhibition of degradation .13
9.3 Validity of the test .13
10 Test report .13
Annex A (informative) Example of apparatus for determining the amount of biogas
produced by measuring the increase in gas pressure .15
Annex B (informative) Example of apparatus for determining volumetrically the amount of
biogas produced .16
Annex C (informative) Example of a biodegradation curve .18
Annex D (informative) Examples of data sheets for anaerobic biodegradability tests .19
Annex E (informative) Table of water vapour pressures at various temperatures .22
Annex F (informative) Calculation of theoretical carbon dioxide (ThCO ) and theoretical
2
methane (ThCH ) production .23
4
Annex G (informative) Example of determination of recovery rate .24
Annex H (informative) Example of a workflow scheme .27
© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 14853:2016(E)
Bibliography .29
iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 14853:2016(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 nongovernmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This second edition cancels and replaces the first edition (ISO 14853:2005), which has been technically
revised.
It also incorporates the Technical Corrigendum ISO 14853:2005/Cor 1:2009.
© ISO 2016 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/FDIS 14853:2016(E)
Introduction
With the increasing use of plastics, their recovery and disposal have become a major issue. As a first
priority, recovery should be promoted. For example, plastic litter, which originates mainly from
consumers, is difficult to recover completely. Additional examples of materials difficult to recover
are found in the disposal of fishing tackle, agricultural mulch films and water-soluble polymers.
These plastic materials tend to leak from closed waste management infrastructures into natural
environments. Biodegradable plastics are now emerging as one of the available options to solve such
environmental issues. Plastic materials, such as products or packaging, which are sent to anaerobic
treatment facilities should be potentially biodegradable. Therefore, it is very important to determine
the potential biodegradability of such materials and to obtain a quantitative measure of their
biodegradability in anaerobic environments.
vi © ISO 2016 – All rights reserved
---------------------- Page: 6 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 14853:2016(E)
Plastics — Determination of the ultimate anaerobic
biodegradation of plastic materials in an aqueous system
— Method by measurement of biogas production
WARNING — Sewage and activated sludge may contain potentially pathogenic organisms.
Therefore, appropriate precautions should be taken when handling them. Digesting sewage
sludge produces flammable gases which present fire and explosion risks. Care should be taken
when transporting and storing quantities of digesting sludge. Toxic test chemicals and those
whose properties are not known should be handled with care and in accordance with safety
instructions. The pressure meter and microsyringes should be handled carefully to avoid needle
stick injuries. Contaminated syringe needles should be disposed of in a safe manner.
1 Scope
This International Standard specifies a method for the determination of the ultimate anaerobic
biodegradability of plastics by anaerobic microorganisms. The conditions described in this
International Standard do not necessarily correspond to the optimum conditions for the maximum
degree of biodegradation to occur. The test calls for exposure of the test material to sludge for a period
of up to 90 d, which is longer than the normal sludge retention time (25 to 30 d) in anaerobic digesters,
although digesters at industrial sites can have much longer retention times.
The method applies to the following materials:
— natural and/or synthetic polymers, copolymers or mixtures thereof;
— plastic materials which contain additives such as plasticizers, colorants or other compounds;
— water-soluble polymers;
— materials which, under the test conditions, do not inhibit the microorganisms present in the inoculum.
Inhibitory effects can be determined using an inhibition control or by another appropriate method
(see e.g. ISO 13641). If the test material is inhibitory to the inoculum, a lower test concentration,
another inoculum or a preexposed inoculum can be used.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
ultimate anaerobic biodegradation
breakdown of an organic compound by microorganisms in the absence of oxygen to carbon dioxide,
methane, water and mineral salts of any other elements present (mineralization) plus new biomass
3.2
primary anaerobic biodegradation
structural change (transformation) of a chemical compound by microorganisms, resulting in the loss of
a specific property
© ISO 2016 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/FDIS 14853:2016(E)
3.3
digested sludge
mixture of settled sewage and activated sludge which have been incubated in an anaerobic digester at
about 35 °C to reduce the biomass and odour and to improve the dewaterability of the sludge
Note 1 to entry: Digested sludge contains an association of anaerobic fermentative and methanogenic bacteria
producing carbon dioxide and methane.
3.4
concentration of suspended solids in digested sludge
amount of solids obtained by filtration or centrifugation of a known volume of activated sludge and
drying at about 105 °C to constant mass
3.5
dissolved organic carbon
DOC
organic carbon in the water phase which cannot be removed by specified phase separation, for example,
–2
by centrifugation at 40 000 m⋅s for 15 min or by membrane filtration using membranes with pores of
0,2 µm to 0,45 µm diameter
3.6
inorganic carbon
IC
inorganic carbon which is dissolved or dispersed in the aqueous phase of a liquid and is recoverable
from the supernatant liquid after the sludge has been allowed to settle
3.7
total dry solids
amount of solids obtained by taking a known volume of test material or inoculum and drying at about
105 °C to constant mass
3.8
theoretical amount of evolved biogas
Thbiogas
maximum theoretical amount of biogas (CH + CO ) evolved after complete biodegradation of an
4 2
organic material under anaerobic conditions, calculated from the molecular formula and expressed as
millilitres of biogas evolved per milligram of test material under standard conditions
3.9
theoretical amount of evolved carbon dioxide
ThCO
2
maximum theoretical amount of carbon dioxide evolved after complete oxidation of an organic material,
calculated from the molecular formula and expressed as milligrams of carbon dioxide per milligram of
test material
3.10
theoretical amount of evolved methane
ThCH
4
maximum theoretical amount of methane evolved after complete reduction of an organic material,
calculated from the molecular formula and expressed as milligrams of methane evolved per milligram
of test material
3.11
lag phase
lag period
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
2 © ISO 2016 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/FDIS 14853:2016(E)
3.12
plateau phase
time, measured in days, from the end of the biodegradation phase until the end of the test
3.13
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
3.14
maximum level of biodegradation
degree of biodegradation, measured in percent, of a chemical compound or organic matter in a test,
above which no further biodegradation takes place during the test
4 Principle
The biodegradability of a plastic material is determined using anaerobic conditions in an aqueous
system. Test material with a concentration of 20 mg/l to 200 mg/l organic carbon (OC) is incubated
at (35 ± 2) °C in sealed vessels together with digested sludge for a period normally not exceeding 90 d.
Before use, the digested sludge is washed so that it contains very low amounts of inorganic carbon
(IC) and diluted to 1 g/l to 3 g/l total solids concentration. The increase in headspace pressure or the
volumetric increase (depending on the method used for measuring biogas evolution) in the test vessels
resulting from the production of carbon dioxide (CO ) and methane (CH ) is measured. A considerable
2 4
amount of CO will be dissolved in water or transformed to bicarbonate or carbonate under the
2
conditions of the test. This inorganic carbon (IC) is measured at the end of the test. The amount of
microbiologically produced biogas carbon is calculated from the net biogas production and the net IC
formation in excess of blank values. The percentage biodegradation is calculated from the total amount
of carbon transformed to biogas and IC and the measured or calculated amount of carbon added as
test material. The course of biodegradation can be followed by making intermediate measurements
of biogas production. As additional information, the primary biodegradability can be determined by
specific analyses at the beginning and end of the test.
This test method is designed to determine the biodegradability of plastic materials under anaerobic
conditions. Optionally, the assessment of the recovery rate may also be of interest (see Annex G).
5 Reagents and materials
5.1 Distilled or deionized water, free of toxic substances, containing less than 2 mg/l of DOC.
5.2 Test medium, prepared using only reagents of recognized analytical grade.
Prepare the test medium to contain the following constituents in the stated amounts:
Anhydrous potassium dihydrogen phosphate KH PO 0,27 g
2 4
Disodium hydrogen phosphate dodecahydrate Na HPO ⋅12H O 1,12 g
2 4 2
Ammonium chloride NH Cl 0,53 g
4
Calcium chloride dihydrate CaCl ⋅2H O 0,075 g
2 2
Magnesium chloride hexahydrate MgCl ⋅6H O 0,10 g
2 2
Iron (II) chloride tetrahydrate FeCl ⋅4H O 0,02 g
2 2
Resazurin (oxygen indicator) 0,001 g
a
Disodium sulfide nonahydrate Na S⋅9H O 0,1 g
2 2
Stock solution of trace elements (optional) 10 ml
Stock solutions of vitamins (optional) Vitamin solution No. 1 0,5 ml
© ISO 2016 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO/FDIS 14853:2016(E)
Anhydrous potassium dihydrogen phosphate KH PO 0,27 g
2 4
Vitamin solution No. 2 0,5 ml
Add water (5.1) (oxygen-free) to 1 l
a
Use freshly prepared sodium sulfide, or wash and dry it before use, to ensure sufficient reductive capacity.
In order to ensure strictly anaerobic conditions, it is recommended that a small amount of sodium dithionite be
added to the medium after it has been prepared until it becomes colourless. Do not use more than 10 mg/l because
higher concentrations may produce inhibitory effects.
Adjust the pH of the medium with dilute mineral acid or alkali, if necessary, to 7 ± 0,2.
To ensure oxygen-free conditions, purge the water with nitrogen for about 20 min immediately before use.
5.3 Trace-element solution (optional).
It is recommended that the test medium be supplemented with the following trace elements to improve
the anaerobic degradation process, especially if low inoculum concentrations are used:
Manganese chloride tetrahydrate MnCl ⋅4H O 0,05 g
2 2
Boric acid H BO 0,005 g
3 3
Zinc chloride ZnCl 0,005 g
2
Copper (II) chloride CuCl 0,003 g
2
Disodium molybdate dihydrate Na MoO ⋅2H O 0,001 g
2 4 2
Cobalt chloride hexahydrate CoCl ⋅6H O 0,1 g
2 2
Nickel chloride hexahydrate NiCl ⋅6H O 0,01 g
2 2
Disodium selenite Na SeO 0,005 g
2 3
Disodium tungstate dihydrate Na WO ⋅2H O 0,002 g
2 4 2
Add water (5.1) (oxygen free) to 1 l
Use 10 ml of traceelement solution per litre of test medium.
5.4 Vitamin solutions (optional).
5.4.1 Vitamin solution No. 1
4Aminobenzoic acid 40 mg
dBiotin 10 mg
Dissolve in hot water (5.1) 500 ml
Allow to cool and add:
dPantothenic acid, calcium salt 50 mg
Pyridoxamine dihydrochloride 150 mg
Thiamine dichloride 100 mg
Filter the solution through a membrane filter (pore size 0,45 µm) that neither adsorbs nor releases
organic carbon in significant amounts, and store in the dark at 4 °C.
Use 0,5 ml of vitamin solution per litre of test medium.
5.4.2 Vitamin solution No. 2
Cyanocobalamin (vitamin B12) 10 mg
Dissolve in water (5.1) 100 ml
4 © ISO 2016 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/FDIS 14853:2016(E)
Filter the solution through a membrane filter (pore size 0,45 µm) that neither adsorbs nor releases
organic carbon in significant amounts, and store in the dark at 4 °C.
Use 0,5 ml of vitamin solution per litre of test medium.
5.5 Barrier solution.
NaCl 200 g
Dissolve in water (5.1) 1 000 ml
Acidify with citric acid 5 g
Add a pH indicator such as bromophenol blue or methyl orange in order to be able to verify that the
solution remains acid during the test.
5.6 Test material.
The test material is usually added directly as solid to give a concentration of 20 mg/l to 200 mg/l
organic carbon. The test material (plastic) should be used in powdered form, if possible.
The test material should preferably be used in powder form, but it may also be introduced as films,
pieces, fragments or shaped articles. The form and shape of the test material may influence its
biodegradability. Similar shapes should preferably be used if different kinds of plastic material are
to be compared. If the test material is used in the form of a powder, particles of known, narrow size
distribution should be used. A particlesize distribution with the maximum at 250 µm diameter is
recommended. Also, the size of the test equipment used may depend on the form of the test material.
The biodegradability of plastic materials which are not inhibitory to microorganisms can be determined
using concentrations higher than 200 mg/l organic carbon. In this case, ensure that the buffer capacity
and mineral-salt content of the medium are sufficient.
5.7 Reference material.
Use a well-defined anaerobically biodegradable polymer, e.g. poly-β-hydroxybutyrate, cellulose or
poly(ethylene glycol) 400 as a reference material. If possible, the form, size, solubility and concentration
of the reference material should be comparable with that of the test material.
Prepare the reference material in the same way as the test material.
5.8 Inhibition control (optional).
Add both the test material and the reference material to a vessel containing test medium (5.2) to give
the concentrations specified in 5.6 and 5.7, respectively.
6 Apparatus
6.1 Laboratory equipment
Required is usual laboratory equipment, plus the following:
6.1.1 Incubator or water or sand bath, thermostatically controlled at (35 ± 2) °C.
6.1.2 Carbon analyser (optional), suitable for the direct determination of inorganic carbon in the
range 1 mg/l to 200 mg/l IC. Alternatively, the IC in the supernatant may be determined indirectly by
release of the dissolved IC as carbon dioxide that can be measured in the headspace, as described in 7.7.
© ISO 2016 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO/FDIS 14853:2016(E)
6.2 Apparatus for use when biogas is measured by a manometric method
6.2.1 Pressure-resistant glass test vessels, nominal size 0,1 l to 1 l, each fitted with a gastight septum
capable of withstanding about 2 000 hPa (for an example, see Annex A). The headspace volume shall be
about 10 % to 30 % of the total volume. If gas is released at regular intervals, about 10 % headspace
volume is adequate, but if gas is released only at the end of the test, 30 % is more appropriate.
From a practical point of view, the use of serum bottles sealed with butyl rubber serum caps and
crimped aluminium rings is recommended.
6.2.2 Pressure-measuring device, e.g. a manometer connected to a suitable syringe needle, with
a gastight three-way valve to facilitate the release of excess pressure. Use and calibrate the device in
accordance with the manufacturer’s instructions.
It is necessary to keep the internal volume of the tubing and the valve as low as possible so that errors
introduced by neglecting the volume of the device are not significant.
6.3 Apparatus for use when biogas is measured by a volumetric method
6.3.1 Glass test vessels (e.g. conical flasks or bottles), nominal size 0,1 l to 1 l, preferably 300 ml for
every 250 ml of medium. If foaming is not expected to occur, a headspace volume of 10 % to 20 % is
recommended. The vessels shall be equipped with a septum for gas sampling (see Annex B) and shall be
connected via gastight tubing to a graduated glass gas-collection tube which is filled with acidified salt
solution (barrier solution 5.5). This graduated glass tube shall be connected to an expansion tank which
can be moved up and down to bring the surface of the acidified solution in the expansion tank to the
same level as that in the gascollection tube.
7 Procedure
7.1 General
Carry out the following initial operations using techniques which will ensure that the digested sludge
comes into contact with oxygen as little as practicable, e.g. work in a glove-box in an atmosphere of
nitrogen or purge the test vessels with nitrogen.
7.2 Digested sludge
Collect digested sludge from a digester at a sewage treatment plant treating predominantly domestic
sewage. Be sure to collect active sludge. Use wide-necked bottles made of high-density polyethylene or
a similar material which can expand. Glass is not recommended for safety reasons. Fill the bottles to
within 1 cm of the top and seal. After transport to the laboratory, use directly or place in a laboratory-
scale digester. Release excess biogas.
Alternatively, use a laboratory-grown anaerobic sludge as a source of the inoculum.
Consider preincubation of the sludge to reduce background gas production and to decrease the
influence of the blanks. Allow the sludge to digest, without the addition of any nutrients or substrates,
at (35 ± 2) °C for up to 7 d.
It has been shown that pre-incubation for about 5 d gives an optimum decrease in gas production by the
blank without an unacceptable increase in either lag period or incubation period during the test. For
test materials which are expected to be po
...
NORME ISO
INTERNATIONALE 14853
Deuxième édition
2016-07-15
Plastiques — Évaluation de la
biodégradabilité anaérobie ultime
des matériaux plastiques en milieu
aqueux — Méthode par détermination
de la production de biogaz
Plastics — Determination of the ultimate anaerobic biodegradation
of plastic materials in an aqueous system — Method by measurement
of biogas production
Numéro de référence
ISO 14853:2016(F)
©
ISO 2016
---------------------- Page: 1 ----------------------
ISO 14853:2016(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2016, Publié en Suisse
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée
sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur
l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à
l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 14853:2016(F)
Sommaire Page
Avant-propos .v
Introduction .vi
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Principe . 3
5 Réactifs et matériaux . 3
6 Appareillage . 6
6.1 Matériel de laboratoire . 6
6.2 Appareillage à utiliser lorsque le biogaz est mesuré par une méthode manométrique. 6
6.3 Appareillage à utiliser lorsque le biogaz est mesuré par une méthode volumétrique . 7
7 Mode opératoire. 7
7.1 Généralités . 7
7.2 Boue digérée . 7
7.3 Préparation de l’inoculum . 7
7.4 Préparation des suspensions d’essai et des substances de contrôle. 7
7.5 Incubation et mesurage du gaz . 8
7.6 Durée de l’essai . 9
7.7 Mesurage du carbone inorganique .10
7.8 Analyses spécifiques .10
8 Calcul et expression des résultats .10
8.1 Quantité de carbone dans l’espace de tête .10
8.2 Calcul de la quantité de carbone dans l’espace de tête avec une méthode de
mesure manométrique . .11
8.3 Calcul de la quantité de carbone dans l’espace de tête avec une méthode de
mesure volumétrique .11
8.4 Quantité de carbone inorganique dans le liquide .12
8.5 Quantité totale de carbone converti en gaz .12
8.6 Quantité de carbone dans le matériau d’essai .13
8.7 Calcul du pourcentage de biodégradation.13
9 Validité des résultats .13
9.1 Maintien des conditions anaérobies.13
9.2 Inhibition de la dégradation .13
9.3 Validité de l’essai .13
10 Rapport d’essai .14
Annexe A (informative) Exemple d’appareillage pour déterminer la quantité de biogaz
produit en mesurant l’augmentation de la pression du gaz .15
Annexe B (informative) Exemple d’appareillage pour déterminer de manière volumétrique
la quantité de biogaz produit .16
Annexe C (informative) Exemple de courbe de biodégradation .18
Annexe D (informative) Exemples de fiches techniques pour les essais de
biodégradabilité anaérobie .19
Annexe E (informative) Table des pressions de vapeur d’eau à différentes températures .24
Annexe F (informative) Calcul de la production théorique de dioxyde de carbone (ThCO )
2
et de méthane (ThCH ) .25
4
Annexe G (informative) Exemple de détermination du taux de récupération .26
© ISO 2016 – Tous droits réservés iii
---------------------- Page: 3 ----------------------
ISO 14853:2016(F)
Annexe H (informative) Exemple de diagramme de flux .29
Bibliographie .31
iv © ISO 2016 – Tous droits réservés
---------------------- Page: 4 ----------------------
ISO 14853:2016(F)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www.
iso.org/directives).
L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www.iso.org/brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la signification des termes et expressions spécifiques de l’ISO liés à l’évaluation
de la conformité, ou pour toute information au sujet de l’adhésion de l’ISO aux principes de l’Organisation
mondiale du commerce (OMC) concernant les obstacles techniques au commerce (OTC), voir le lien
suivant: http ://www.iso.org/iso/fr/foreword.html.
Le comité chargé de l’élaboration du présent document est l’ISO/TC 61, Plastiques, sous-comité SC 5,
Propriétés physicochimiques.
Cette deuxième édition annule et remplace la première édition (ISO 14853:2005), qui a fait l’objet d’une
révision technique. Elle intègre également le Corrigendum technique ISO 14853:2005/Cor.1:2009.
© ISO 2016 – Tous droits réservés v
---------------------- Page: 5 ----------------------
ISO 14853:2016(F)
Introduction
Les plastiques étant de plus en plus utilisés, leur valorisation et leur élimination sont devenues un enjeu
majeur. Il convient de favoriser en priorité leur valorisation. Par exemple, un déchet plastique, venant
principalement des consommateurs, est difficile à valoriser complètement. Autres exemples de produits
difficiles à valoriser: les articles de pêche, les paillages agricoles et les polymères hydrosolubles. Ces
matériaux plastiques tendent à migrer des infrastructures fermées de gestion des déchets vers le milieu
naturel. Désormais, les plastiques biodégradables apparaissent comme l’une des options possibles
pour résoudre ce genre de problème environnemental. Il convient que les matériaux plastiques, sous
forme de produits ou d’emballages, qui sont envoyés dans les installations de traitement anaérobie
soient potentiellement biodégradables. Il est donc très important de déterminer la biodégradabilité
potentielle de ce type de matériaux et d’obtenir une mesure quantitative de leur biodégradabilité en
milieu anaérobie.
vi © ISO 2016 – Tous droits réservés
---------------------- Page: 6 ----------------------
NORME INTERNATIONALE ISO 14853:2016(F)
Plastiques — Évaluation de la biodégradabilité anaérobie
ultime des matériaux plastiques en milieu aqueux —
Méthode par détermination de la production de biogaz
AVERTISSEMENT — Les eaux usées et les boues activées peuvent contenir des organismes
potentiellement pathogènes. Il convient donc de prendre les précautions appropriées pour les
manipuler. Les boues d’eaux usées digérées produisent des gaz inflammables qui présentent des
risques d’incendie et d’explosion. Il convient de prendre des précautions lors du transport et
du stockage de grandes quantités de boues digérées. Il convient de manipuler avec précaution
et en respectant les instructions de sécurité les produits chimiques toxiques et ceux dont les
propriétés sont inconnues. Il convient de manipuler avec précaution le pressiomètre et les
microseringues pour éviter les piqûres d’aiguilles. Il convient d’éliminer de manière appropriée
les aiguilles de seringues contaminées.
1 Domaine d’application
La présente Norme internationale spécifie une méthode pour la détermination de la biodégradabilité
anaérobie ultime des plastiques par des micro-organismes anaérobies. Les conditions décrites dans
la présente Norme internationale ne correspondent pas nécessairement aux conditions optimales
permettant d’obtenir le taux maximal de biodégradation. L’essai exige que le matériau d’essai soit exposé
aux boues pendant une période allant jusqu’à 90 j, ce qui est plus long que le temps de rétention normal
de la boue (25 j à 30 j) dans les digesteurs anaérobies, bien que les digesteurs sur les sites industriels
puissent avoir des temps de rétention beaucoup plus longs.
La présente méthode s’applique aux matériaux suivants:
— polymères naturels et/ou synthétiques, copolymères ou mélanges de ceux-ci;
— matériaux plastiques contenant des additifs, tels que plastifiants, colorants ou autres composés;
— polymères hydrosolubles;
— matériaux qui, dans les conditions d’essai, n’ont pas d’effet inhibiteur sur les micro-organismes
présents dans l’inoculum. Les effets inhibiteurs peuvent être déterminés en utilisant une substance
de contrôle de l’effet inhibiteur ou par toute autre méthode appropriée (voir, par exemple, l’ISO 13641).
Si le matériau d’essai a un effet inhibiteur vis-à-vis de l’inoculum, il est possible d’utiliser une plus
faible concentration, un autre inoculum ou un inoculum pré-exposé.
2 Références normatives
Il n’y a pas de références normatives dans le présent document.
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions suivants s’appliquent.
3.1
biodégradation anaérobie ultime
décomposition d’un composé organique par des micro-organismes en l’absence d’oxygène, en dioxyde
de carbone, méthane, eau et sels minéraux de tous les autres éléments présents (minéralisation) et
production d’une nouvelle biomasse
© ISO 2016 – Tous droits réservés 1
---------------------- Page: 7 ----------------------
ISO 14853:2016(F)
3.2
biodégradation anaérobie primaire
modification structurelle (transformation) d’un composé chimique par des micro-organismes, résultant
en la perte d’une propriété spécifique
3.3
boue digérée
mélange d’eaux usées décantées et de boues activées qui ont été incubées dans un digesteur anaérobie à
environ 35 °C pour réduire la biomasse et l’odeur et pour améliorer la déshydratation de la boue
Note 1 à l’article: Les boues digérées contiennent un ensemble de bactéries fermentatives et méthanogènes
anaérobies qui produisent du dioxyde de carbone et du méthane.
3.4
concentration de la boue digérée en matières solides en suspension
quantité de matières solides obtenue par filtration ou centrifugation d’un volume connu de boue activée
et séchage à environ 105 °C jusqu’à l’obtention d’une masse constante
3.5
carbone organique dissous
COD
carbone organique contenu dans la phase aqueuse, qui ne peut pas être éliminé par une séparation de
–2
phase spécifique, par exemple par centrifugation à 40 000 m⋅s pendant 15 min ou par filtration sur
des membranes ayant des pores de 0,2 µm à 0,45 µm de diamètre
3.6
carbone inorganique
CI
carbone inorganique qui est dissous ou dispersé dans la phase aqueuse d’un liquide et qui est
récupérable dans le liquide surnageant une fois que la boue a décanté
3.7
matières sèches totales
quantité de matières solides obtenue par prélèvement d’un volume connu de matériau d’essai ou
d’inoculum et séchage à environ 105 °C jusqu’à l’obtention d’une masse constante
3.8
quantité théorique de biogaz libéré
Thbiogaz
quantité théorique maximale de biogaz (CH + CO ) libéré après la biodégradation complète d’une
4 2
matière organique dans des conditions anaérobies, calculée d’après la formule moléculaire et exprimée
en millilitres de biogaz libéré par milligramme de matériau d’essai dans les conditions normales
3.9
quantité théorique de dioxyde de carbone libéré
ThCO
2
quantité théorique maximale de dioxyde de carbone libéré après oxydation complète d’une matière
organique, calculée d’après la formule moléculaire et exprimée en milligrammes de dioxyde de carbone
par milligramme de matériau d’essai
3.10
quantité théorique de méthane libéré
ThCH
4
quantité théorique maximale de méthane libéré après réduction complète d’une matière organique,
calculée d’après la formule moléculaire et exprimée en milligrammes de méthane libéré par
milligramme de matériau d’essai
2 © ISO 2016 – Tous droits réservés
---------------------- Page: 8 ----------------------
ISO 14853:2016(F)
3.11
phase de latence
période de latence
durée, mesurée en jours, écoulée à partir du début de l’essai jusqu’à l’obtention de l’adaptation
et/ou de la sélection des micro-organismes qui provoquent la dégradation, et jusqu’à ce que le taux de
biodégradation du composé chimique ou de la matière organique ait atteint environ 10 % du niveau
maximal de biodégradation
3.12
phase stationnaire
durée, mesurée en jours, écoulée entre la fin de la phase de biodégradation et la fin de l’essai
3.13
phase de biodégradation
durée, mesurée en jours, depuis la fin de la phase de latence de l’essai jusqu’à ce que l’on ait obtenu
environ 90 % du niveau maximal de biodégradation
3.14
niveau maximal de biodégradation
taux de biodégradation, mesuré en pourcentage, d’un composé chimique ou d’une matière organique
lors d’un essai, au-dessus duquel la biodégradation ne se poursuit pas
4 Principe
La biodégradabilité d’un matériau plastique est déterminée dans des conditions anaérobies en milieu
aqueux. Le matériau d’essai d’une concentration de 20 mg/l à 200 mg/l de carbone organique (CO) est
incubé à (35 ± 2) °C dans des récipients fermés avec la boue digérée pendant une durée ne dépassant
normalement pas 90 j. Avant utilisation, la boue digérée est lavée afin qu’elle contienne de très petites
quantités de carbone inorganique (CI) et elle est diluée à une concentration comprise entre 1 g/l et
3 g/l de matières solides totales. L’augmentation de pression dans l’espace de tête ou l’augmentation
volumétrique (en fonction de la méthode utilisée pour mesurer la libération de biogaz) dans les
récipients d’essai, résultant de la production de dioxyde de carbone (CO ) et de méthane (CH ), est
2 4
mesurée. Une quantité considérable de CO sera dissoute dans l’eau ou transformée en bicarbonate ou
2
en carbonate dans les conditions de l’essai. Ce carbone inorganique (CI) est mesuré à la fin de l’essai.
La quantité de carbone de biogaz produit de manière microbiologique est calculée à partir de la
production nette de biogaz et de la formation nette de CI dépassant les valeurs du blanc. Le pourcentage
de biodégradation est calculé à partir de la quantité totale de carbone transformé en biogaz et en CI
et de la quantité mesurée ou calculée de carbone ajouté en tant que matériau d’essai. L’évolution de la
biodégradation peut être suivie en réalisant des mesurages intermédiaires de la production de biogaz.
À titre d’informations complémentaires, la biodégradabilité primaire peut être déterminée par des
analyses spécifiques réalisées au début et à la fin de l’essai.
La présente méthode d’essai est conçue pour déterminer la biodégradabilité des matériaux plastiques
dans des conditions anaérobies. À titre facultatif, l’évaluation du taux de récupération peut également
présenter un intérêt (voir l’Annexe G).
5 Réactifs et matériaux
5.1 Eau distillée ou déionisée, exempte de substances toxiques et contenant moins de 2 mg/l de COD.
5.2 Milieu d’essai, préparé uniquement avec des réactifs de qualité analytique reconnue.
Préparer le milieu d’essai en utilisant les constituants suivants dans les quantités indiquées:
© ISO 2016 – Tous droits réservés 3
---------------------- Page: 9 ----------------------
ISO 14853:2016(F)
Dihydrogénophosphate de potassium anhydre KH PO 0,27 g
2 4
Hydrogénophosphate disodique Na HPO ⋅12H O 1,12 g
2 4 2
dodécahydraté
Chlorure d’ammonium NH Cl 0,53 g
4
Chlorure de calcium dihydraté CaCl ⋅2H O 0,075 g
2 2
Chlorure de magnésium hexahydraté MgCl ⋅6H O 0,10 g
2 2
Chlorure de fer(II) tétrahydraté FeCl ⋅4H O 0,02 g
2 2
Résazurine (indicateur d’oxygène) 0,001 g
a
Sulfure disodique nonahydraté Na S⋅9H O 0,1 g
2 2
Solution mère d’éléments traces (facultative) 10 ml
Solutions mères de vitamines (facultatives) Solution de vitamines n° 1 0,5 ml
Solution de vitamines n° 2 0,5 ml
Ajouter de l’eau (5.1) (exempte d’oxygène) 1 l
a
Utiliser du sulfure de sodium fraichement préparé ou le laver et le sécher avant utilisation pour
garantir une capacité réductrice suffisante. Pour garantir des conditions strictement anaérobies, il
est recommandé d’ajouter une petite quantité de dithionite de sodium dans le milieu préparé, jusqu’à
ce qu’il devienne incolore. Ne pas utiliser plus de 10 mg/l car des concentrations plus élevées peuvent
produire des effets inhibiteurs.
Ajuster le pH du milieu avec de l’acide ou de la base minéral(e) dilué(e), si nécessaire, à pH 7 ± 0,2.
Pour garantir des conditions exemptes d’oxygène, purger l’eau avec de l’azote pendant environ 20 min
juste avant utilisation.
5.3 Solution d’éléments traces (facultative).
Il est recommandé d’ajouter les éléments traces suivants dans le milieu d’essai pour améliorer le
processus de dégradation anaérobie, en particulier si de faibles concentrations d’inoculum sont
utilisées:
Chlorure de manganèse tétrahydraté MnCl ⋅4H O 0,05 g
2 2
Acide borique H BO 0,005 g
3 3
Chlorure de zinc ZnCl 0,005 g
2
Chlorure de cuivre(II) CuCl 0,003 g
2
Molybdate disodique dihydraté Na MoO ⋅2H O 0,001 g
2 4 2
Chlorure de cobalt hexahydraté CoCl ⋅6H O 0,1 g
2 2
Chlorure de nickel hexahydraté NiCl ⋅6H O 0,01 g
2 2
Sélénite disodique Na SeO 0,005 g
2 3
Tungstate disodique dihydraté Na WO ⋅2H O 0,002 g
2 4 2
Ajouter de l’eau (5.1) (exempte d’oxygène) 1 l
4 © ISO 2016 – Tous droits réservés
---------------------- Page: 10 ----------------------
ISO 14853:2016(F)
Utiliser 10 ml de solution d’éléments traces par litre de milieu d’essai.
5.4 Solutions de vitamines (facultatives).
5.4.1 Solution de vitamines n° 1
Acide 4-aminobenzoïque 40 mg
d-biotine 10 mg
Dissoudre dans de l’eau chaude (5.1) 500 ml
Laisser refroidir et ajouter:
Acide d-pantothénique, sel de calcium 50 mg
Dihydrochlorure de pyridoxamine 150 mg
Dichlorure de thiamine 100 mg
Filtrer la solution sur une membrane (ouverture de pore de 0,45 µm) qui n’adsorbe pas et ne libère pas
de carbone organique en quantités significatives, et la conserver dans l’obscurité à 4 °C.
Utiliser 0,5 ml de solution de vitamines par litre de milieu d’essai.
5.4.2 Solution de vitamines n° 2
Cyanocobalamine (vitamine B12) 10 mg
Dissoudre dans de l’eau (5.1) 100 ml
Filtrer la solution sur une membrane (ouverture de pore de 0,45 µm) qui n’adsorbe pas et ne libère pas
de carbone organique en quantités significatives, et la conserver dans l’obscurité à 4 °C.
Utiliser 0,5 ml de solution de vitamines par litre de milieu d’essai.
5.5 Solution barrière.
NaCl 200 g
Dissoudre dans de l’eau (5.1) 1 000 ml
Acidifier avec de l’acide citrique 5 g
Ajouter un indicateur de pH, par exemple du bleu de bromophénol ou de l’orange de méthyle, pour
pouvoir vérifier que la solution reste acide lors de l’essai.
5.6 Matériau d’essai.
Le matériau d’essai est généralement ajouté directement sous forme solide pour donner une
concentration de 20 mg/l à 200 mg/l de carbone organique. Il convient que le matériau d’essai
(plastique) soit utilisé sous forme de poudre, dans la mesure du possible.
Il convient d’utiliser le matériau d’essai de préférence sous forme de poudre; toutefois, ce dernier peut
également être employé sous forme de film, de morceaux, de fragments ou d’articles façonnés. La
consistance et la forme du matériau d’essai peuvent influer sur sa biodégradabilité. Il convient d’utiliser,
de préférence, des formes similaires si l’on doit comparer différents types de matériaux plastiques. Si
le matériau d’essai est utilisé sous forme de poudre, il est recommandé d’utiliser des particules ayant
une distribution granulométrique étroite connue. Une distribution granulométrique avec un diamètre
© ISO 2016 – Tous droits réservés 5
---------------------- Page: 11 ----------------------
ISO 14853:2016(F)
maximal de 250 µm est recommandée. D’autre part, la forme du matériau d’essai peut également avoir
une influence sur la taille du dispositif d’essai utilisé.
La biodégradabilité des matériaux plastiques qui ne sont pas inhibiteurs de micro-organismes peut
être déterminée à l’aide de concentrations supérieures à 200 mg/l de carbone organique. Dans ce cas,
s’assurer que le pouvoir tampon et la teneur en sels minéraux du milieu sont suffisants.
5.7 Matériau de référence.
Utiliser un polymère biodégradable anaérobie bien défini, par exemple du poly-β-hydroxybutyrate, de
la cellulose ou du poly(éthylène glycol) 400 comme matériau de référence. Si possible, il convient que la
forme, la taille, la solubilité et la concentration du matériau de référence soient comparables à celles du
matériau d’essai.
Préparer le matériau de référence de la même façon que le matériau d’essai.
5.8 Substance de contrôle de l’effet inhibiteur (facultative).
Ajouter à la fois le matériau d’essai et le matériau de référence dans un récipient contenant le milieu
d’essai (5.2) pour obtenir les concentrations spécifiées en 5.6 et 5.7, respectivement.
6 Appareillage
6.1 Matériel de laboratoire
Est nécessaire le matériel courant de laboratoire, et ce qui suit:
6.1.1 Incubateur, bain-marie ou bain de sable, thermostaté à (35 ± 2) °C.
6.1.2 Analyseur de carbone (facultatif), adapté pour la détermination directe du carbone inorganique
dans la plage de 1 mg/l à 200 mg/l de CI. Autrement, le CI présent dans le liquide surnageant peut être
déterminé indirectement par la libération de CI dissous sous forme de dioxyde de carbone qui peut être
mesurée dans l’espace de tête, comme décrit en 7.7.
6.2 Appareillage à utiliser lorsque le biogaz est mesuré par une méthode
manométrique
6.2.1 Récipients d’essai en verre résistants à la pression, d’une taille nominale de 0,1 l à 1 l, munis
d’un septum étanche au gaz capable de résister à environ 2 000 hPa (pour un exemple, voir l’Annexe A).
Le volume de l’espace de tête doit représenter environ 10 % à 30 % du volume total. Si du gaz est libéré
à intervalles réguliers, un volume d’espace de tête d’environ 10 % est adéquat, mais si le gaz est libéré
uniquement à la fin de l’essai, une valeur de 30 % est plus appropriée.
D’un point de vue pratique, l’utilisation de flacons à sérum fermés par des bouchons en caoutchouc
butyle et des anneaux sertis en aluminium est recommandée.
6.2.2 Dispositif de mesure de la pression, par exemple un manomètre raccordé à une aiguille de
seringue adaptée, avec un robinet à trois voies étanche au gaz pour faciliter la libération de la pression en
excès. Utiliser et étalonner ce dispositif conformément aux instructions du fabricant.
Il est nécessaire de faire en sorte que le volume interne du tube et du robinet soit le plus petit possible
pour éviter que les erreurs introduites du fait que le volume du dispositif a été ignoré ne soient pas
significatives.
6 © ISO 2016 – Tous droits réservés
---------------------- Page: 12 ----------------------
ISO 14853:2016(F)
6.3 Appareillage à utiliser lorsq
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.