ASTM D5338-15(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5338 − 15 (Reapproved 2021)
Standard Test Method for
Determining Aerobic Biodegradation of Plastic Materials
Under Controlled Composting Conditions, Incorporating
Thermophilic Temperatures
This standard is issued under the fixed designation D5338; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This test method determines the degree and rate of
bility of regulatory limitations prior to use.
aerobic biodegradation of plastic materials on exposure to a
1.7 This test method is equivalent to ISO14855.
controlled-composting environment under laboratory
1.8 This international standard was developed in accor-
conditions, at thermophilic temperatures. This test method is
dance with internationally recognized principles on standard-
designedtoyieldreproducibleandrepeatabletestresultsunder
ization established in the Decision on Principles for the
controlled conditions that resemble composting conditions,
Development of International Standards, Guides and Recom-
where thermophilic temperatures are achieved. The test sub-
mendations issued by the World Trade Organization Technical
stances are exposed to an inoculum that is derived from
Barriers to Trade (TBT) Committee.
compost from municipal solid waste. The aerobic composting
takes place in an environment where temperature, aeration and
2. Referenced Documents
humidity are closely monitored and controlled.
2.1 ASTM Standards:
NOTE 1—During composting, thermophilic temperatures are most
D618Practice for Conditioning Plastics for Testing
readily achieved in large-scale, professionally-managed facilities.
D883Terminology Relating to Plastics
However, these temperatures may also be reached in smaller residential
composting units, frequently referred to as “backyard” or “home” com-
D1293Test Methods for pH of Water
posting.
D2908Practice for Measuring Volatile Organic Matter in
1.2 This test method is designed to yield a percentage of Water by Aqueous-Injection Gas Chromatography
conversion of carbon in the sample to carbon dioxide.The rate D3590Test Methods for Total Kjeldahl Nitrogen in Water
of biodegradation is monitored as well. D4129Test Method for Total and Organic Carbon in Water
by High Temperature Oxidation and by Coulometric
1.3 This test method is designed to be applicable to all
Detection
plastic materials, which are intended to be composted in
E260Practice for Packed Column Gas Chromatography
facilities that achieve thermophilic temperatures.
E355PracticeforGasChromatographyTermsandRelation-
1.4 The values stated in SI units are to be regarded as the
ships
standard.
2.2 APHA—AWWA—WPCF Standards:
1.5 This standard does not purport to address all of the
2540DTotal Suspended Solids Dried at 103 to 105°C
safety concerns, if any, associated with its use. It is the
2540EFixed and Volatile Solids Ignited at 550°C
responsibility of the user of this standard to establish appro-
2.3 ISO Standard:
priate safety, health, and environmental practices and deter-
ISO14855Plastics—Evaluation of the Ultimate Aerobic
mine the applicability of regulatory limitations prior to use.
Biodegradability and Disintegration Under Controlled
Specific hazard statements are given in Section 8.
Composting Conditions—Method by Analysis of Re-
1.6 This standard does not purport to address all of the
leased Carbon Dioxide
safety concerns, if any, associated with its use. It is the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics Standards volume information, refer to the standard’s Document Summary page on
and is the direct responsibility of Subcommittee D20.96 on Environmentally the ASTM website.
Degradable Plastics and Biobased Products. Standard Methods for the Examination of Water and Wastewater, 17th Edition,
Current edition approved Jan. 15, 2021. Published January 2021. Originally 1989,American Public HealthAssociation, 1740 Broadway, NewYork, NY19919.
approved in 1992. Last previous edition approved in 2015 as D5338-15. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D5338-15R21. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5338 − 15 (2021)
3. Terminology
3.1 Definitions—Definitions of terms applying to this test
method appear in Terminology D883.
4. Summary of Test Method
4.1 This test method consists of the following:
4.1.1 Selection of plastic material for the determination of
the aerobic biodegradability in a controlled-composting
system,
4.1.2 Obtaining an inoculum from composted municipal
solid waste,
4.1.3 Exposing the test substances to a controlled aerobic
composting process in conjunction with the inoculum,
FIG. 1 Set-Up Using Carbon Dioxide-Trapping Apparatus
4.1.4 Measuring carbon dioxide evolved as a function of
time, and
4.1.5 Assessing the degree of biodegradability.
4.2 The percentage of biodegradability is obtained by de- in three replicates) of 2 to 5 L of volume. For screening
purposes, depending upon the test material, a smaller volume
termining the percentage of carbon in the test substance that is
converted to CO during the duration of the test. This percent- also may be used.
6.1.2 Water Baths, or other temperature controlling means
age of biodegradability will not include the amount of carbon
capable of maintaining the temperature of the composting
converted from the test substance that is converted to cell
vessels at 58°C (62°C).
biomass and that is not, in turn, metabolized to CO during the
6.1.3 Pressurized-Air System, that provides CO -free, H O-
course of the test.
2 2
saturated air to each of the composting vessels at accurate
4.3 The disintegration of a compact test material is visually
aeration rates. If using a direct measurement of CO (see 6.4),
determined at the end of the test.Additionally, the weight loss
then normal air may be used.
of the test material may be determined.
6.1.4 Suitable devices for measuring oxygen and CO
concentrations in the exhaust air of the composting vessels,
5. Significance and Use
such as specific sensors or appropriate gas chromatographs.
5.1 Biodegradation of a plastic within a composting unit is
6.2 Carbon Dioxide-Trapping Apparatus for Each Com-
an important phenomenon because it may affect the decompo-
posting Vessel:
sition of other materials enclosed by the plastic and the
6.2.1 Atleastthree5000-mLbottlesfittedwithgassparging
resulting quality and appearance of the composted material.
and containing Ba(OH) carbon-dioxide scrubbing solution.
Biodegradation of plastics will also allow the safe disposal of
6.2.2 Flexible Tubing, nonpermeable to carbon dioxide.
these plastics through large, professionally-managed compost-
6.2.3 Stoppers, equipped with gas-sampling parts.
ing plants and well-run residential units, where thermophilic
6.3 Miscellaneous:
temperatures are achieved.This procedure has been developed
6.3.1 Analytical Balance, (61 mg) to weigh test specimen.
to permit the determination of the rate and degree of aerobic
6.3.2 100-mL Burette.
biodegradability of plastic products when placed in a con-
6.3.3 0.05 N HCl.
trolled composting process.
6.3.4 pH Meter.
5.2 Limitations—Because there is a wide variation in the
6.3.5 Suitabledevicesandanalyticalequipmentformeasur-
construction and operation of composting facilities and be-
ing dry solids (at 105°C), volatile solids (at 550°C), volatile
cause regulatory requirements for composting systems vary,
fatty acids by aqueous-injection chromatography, total Kjel-
this procedure is not intended to simulate the environment of
dahl nitrogen and carbon concentrations.
any particular composting system. However, it is expected to
6.4 Optional—The carbon dioxide-trapping apparatus and
resemble the environment of a composting process operated
titration equipment can be replaced by a gas flow meter plus a
under optimum conditions where thermophilic temperatures
gas-chromatograph, or other apparatus equipped with suitable
are achieved. More specifically, the procedure is intended to
detector and column(s), for measuring CO and O concentra-
2 2
create a standard laboratory environment that will permit a
tions in the exhaust air of each vessel. Take care to analyze
rapidandreproducibledeterminationoftheaerobicbiodegrad-
CO concentration on a sufficiently frequent basis in order to
ability under controlled composting conditions.
produce a reliable cumulative CO production over the course
of the test (for example, every 3 to 6 h).Astandard gas should
6. Apparatus
be injected to internally standardize the gas-chromatograph on
6.1 Composting Apparatus (see Fig. 1):
a continuous basis over the course of the test. Operate the gas
6.1.1 Aseriesofatleasttwelvecompostingvessels(onetest chromatograph in conformance with Practices E260 and E355
substance,oneblank,onepositiveandonenegativecontrol,all (see Fig. 2).
D5338 − 15 (2021)
9.2 The compost inoculum should be as free from larger
inert materials (glass, stones, metals, etc.) as possible. These
items should be removed manually as much as possible to
produce a homogeneous compost inoculum.
9.3 It is recommended to use compost of sufficient porosity
to enable conditions to be as aerobic as possible. Addition of
structural material, such as small wood particles, or persistent
or poorly biodegradable inert material may prevent the com-
post from sticking together and clogging during the test.
10. Test Specimen
10.1 The test specimen should have sufficient carbon to
yield carbon dioxide that can be adequately measured by the
FIG. 2 Optional Set-Up Using a Gas Chromatograph
trapping apparatus or CO measurements.
10.2 All basic composting parameters, such as C/N, oxygen
inthecompostingvessel,porosity,andmoisturecontentshould
6.5 Ensure that all glassware is cleaned thoroughly and free
be optimized so as to make a good composting process
from organic matter.
possible. The C/N ratio should preferably be between 10 and
40forboththeinoculumandtestsubstancecombined.Oxygen
7. Reagents and Materials
levels in the composting vessel should be at least 6% at all
7.1 Barium Hydroxide Solution,approximately0.024Nand
timesandnofree-standingwaternorclumpsofmaterialshould
then standardized, prepared by dissolving 4.0 g Ba(OH) per
be present.
litre of distilled water. Filter through filter paper and store
10.3 Test specimens may be in the form of films, formed
sealedasaclearsolutiontopreventabsorptionofCO fromthe
articles, dog bones, granules, powder, or other, and conform to
air.
Practice D618.
7.2 Analytical-Grade Cellulose,forthin-layerchromatogra-
phy with a particle size of less than 20 µm as positive control.
11. Procedure
7.3 Polyethylene, as a negative control. It should be in the
11.1 Preparation of the Samples:
same form as the form in which the sample is tested (polyeth-
11.1.1 Obtain an inoculum from a properly operating aero-
ylenefilmforfilmsamples,polyethylenepelletsincasesample
bic composting plant treating municipal solid waste, or the
is in the form of pellets, etc.).
organic fraction thereof. If required, further stabilize the
inoculum at the laboratory in order to obtain a low CO
8. Hazards
production (see 9.1.).
8.1 This test method requires the use of hazardous chemi-
11.1.1.1 Screen the inoculum to less than 10 mm and
cals.Avoid contact with the chemicals and follow manufactur-
manually remove and discard any large inert items (pieces of
er’s instructions and Material Safety Data Sheets.
glass, stone, wood, etc.). Determine volatile solids, dry solids
and nitrogen content according to Test Methods D3590,
8.2 The compost inoculum may contain sharp objects. Take
care when handling it. D1888, and APHA Test Methods 2540D and 2540E.
11.1.2 Determine volatile solids, dry solids and carbon
8.3 The composting vessels are not designed to withstand
content of all the test substances according to APHA Test
high pressures. The system should be operated at close to
Methods 2540D and 2540E and Test Method D4129.
ambient pressure.
11.1.3 Weigh out roughly 600 g of dry solids of inoculum
and mix with about 100 g of dry solids coming from the
9. Compost Inoculum
sample. Adjust the dry solids content of the mixture in the
9.1 Thecompost
...