ASTM D5338-98(2003)
(Test Method)Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions
Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions
SIGNIFICANCE AND USE
Biodegradation of a plastic within a composting unit is an important phenomenon because it will affect the decomposition of other materials enclosed by the plastic and the resulting quality and appearance of the composted material. Biodegradation of plastics will also allow the safe disposal of these plastics through solid-waste composting plants. This procedure has been developed to permit the determination of the rate and degree of aerobic biodegradability of plastic products when placed in a controlled composting process.
Limitations—Because there is a wide variation in the construction and operation of composting systems and because regulatory requirements for composting systems vary, this procedure is not intended to simulate the environment of any particular composting system. However, it is expected to resemble the environment of a composting process operated under optimum conditions. More specifically, the procedure is intended to create a standard laboratory environment that will permit a rapid and reproducible determination of the aerobic biodegradability under controlled composting conditions.
SCOPE
1.1 This test method determines the degree and rate of aerobic biodegradation of plastic materials on exposure to a controlled-composting environment under laboratory conditions. This test method is designed to yield reproducible and repeatable test results under controlled conditions that resemble composting conditions. The test substances are exposed to an inoculum that is derived from compost from municipal solid waste. The aerobic composting takes place in an environment where temperature, aeration and humidity are closely monitored and controlled.
1.2 This test method is designed to yield a percentage of conversion of carbon in the sample to carbon dioxide. The rate of biodegradation is monitored as well.
1.3 This test method is designed to be applicable to all plastic materials that are not inhibitory to the microorganisms present in aerobic composting piles.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8.
1.6 This test method is equivalent to ISO 14852.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D5338–98 (Reapproved 2003)
Standard Test Method for
Determining Aerobic Biodegradation of Plastic Materials
Under Controlled Composting Conditions
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 D1888 Test Methods for Particulate and Dissolved Matter,
Solids, or Residue in Water
1.1 This test method determines the degree and rate of
D2908 Practice for Measuring Volatile Organic Matter in
aerobic biodegradation of plastic materials on exposure to a
Water by Aqueous-Injection Gas Chromatography
controlled-composting environment under laboratory condi-
D3590 Test Methods for Total Kjeldahl Nitrogen in Water
tions. This test method is designed to yield reproducible and
D4129 Test Method for Total and Organic Carbon in Water
repeatable test results under controlled conditions that re-
by High Temperature Oxidation and by Coulometric De-
semblecompostingconditions.Thetestsubstancesareexposed
tection
to an inoculum that is derived from compost from municipal
E260 Practice for Packed Column Gas Chromatography
solid waste. The aerobic composting takes place in an envi-
E355 Practice for Gas Chromatography Terms and Rela-
ronment where temperature, aeration and humidity are closely
tionships
monitored and controlled.
2.2 APHA—AWWA—WPCF Standards:
1.2 This test method is designed to yield a percentage of
2540D Total Suspended Solids Dried at 103 to 105°C
conversion of carbon in the sample to carbon dioxide.The rate
2540E Fixed and Volatile Solids Ignited at 550°C
of biodegradation is monitored as well.
2.3 ISO Standard:
1.3 This test method is designed to be applicable to all
ISO14855 Plastics—Evaluation of the Ultimate Aerobic
plastic materials that are not inhibitory to the microorganisms
Biodegradability and Disintegration Under Controlled
present in aerobic composting piles.
Composting Conditions—Method by Analysis of Re-
1.4 The values stated in SI units are to be regarded as the
leased Carbon Dioxide
standard.
1.5 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions—Definitions of terms applying to this test
responsibility of the user of this standard to establish appro-
method appear in Terminology D883.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific hazard
4. Summary of Test Method
statements are given in Section 8.
4.1 This test method consists of the following:
1.6 This test method is equivalent to ISO14855.
4.1.1 Selection of plastic material for the determination of
2. Referenced Documents the aerobic biodegradability in a controlled-composting sys-
2 tem,
2.1 ASTM Standards:
4.1.2 Obtaining an inoculum from composted municipal
D618 Practice for Conditioning Plastics for Testing
solid waste,
D883 Terminology Relating to Plastics
4.1.3 Exposing the test substances to a controlled aerobic
D1293 Test Methods for pH of Water
composting process in conjunction with the inoculum,
4.1.4 Measuring carbon dioxide evolved as a function of
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
time, and
and is the direct responsibility of Subcommittee D20.96 on Environmentally
4.1.5 Assessing the degree of biodegradability.
Degradable Plastics and Biobased Products.
Current edition approved Dec. 1, 2003. Published January 2004. Originally
´1
approved in 1992. Last previous edition approved in 1998 as D5338-98 . DOI:
10.1520/D5338-98R03. Discontinued.
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Standard Methods for the Examination of Water and Wastewater, 17th Edition,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 1989,American Public HealthAssociation, 1740 Broadway, NewYork, NY19919.
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5338–98 (2003)
4.2 The percentage of biodegradability is obtained by de- 6.1.3 Pressurized-Air System, that provides CO -free, H O-
2 2
termining the percentage of carbon in the test substance that is saturated air to each of the composting vessels at accurate
converted to CO during the duration of the test. This percent- aeration rates. If using a direct measurement of CO (see 6.4),
2 2
age of biodegradability will not include the amount of carbon then normal air may be used.
converted from the test substance that is converted to cell
6.1.4 Suitable devices for measuring oxygen and CO
biomass and that is not, in turn, metabolized to CO during the concentrations in the exhaust air of the composting vessels,
course of the test.
such as specific sensors or appropriate gas chromatographs.
4.3 The disintegration of a compact test material is visually
6.2 Carbon Dioxide-Trapping Apparatus for Each Com-
determined at the end of the test.Additionally, the weight loss
posting Vessel:
of the test material may be determined.
6.2.1 Atleastthree5000-mLbottlesfittedwithgassparging
and containing Ba(OH) carbon-dioxide scrubbing solution.
5. Significance and Use
6.2.2 Flexible Tubing, nonpermeable to carbon dioxide.
5.1 Biodegradation of a plastic within a composting unit is
6.2.3 Stoppers, equipped with gas-sampling parts.
an important phenomenon because it will affect the decompo-
6.3 Miscellaneous:
sition of other materials enclosed by the plastic and the
6.3.1 Analytical Balance,(60.1 mg) to weigh test speci-
resulting quality and appearance of the composted material.
men.
Biodegradation of plastics will also allow the safe disposal of
6.3.2 100-mL Burette.
these plastics through solid-waste composting plants. This
6.3.3 0.05 N HCl.
procedure has been developed to permit the determination of
6.3.4 pH Meter.
the rate and degree of aerobic biodegradability of plastic
6.3.5 Suitabledevicesandanalyticalequipmentformeasur-
products when placed in a controlled composting process.
ing dry solids (at 105°C), volatile solids (at 550°C), volatile
5.2 Limitations—Because there is a wide variation in the
fatty acids by aqueous-injection chromatography, total
constructionandoperationofcompostingsystemsandbecause
Kjeldahl nitrogen and carbon concentrations.
regulatory requirements for composting systems vary, this
6.4 Optional—The carbon dioxide-trapping apparatus and
procedure is not intended to simulate the environment of any
titration equipment can be replaced by a gas flow meter plus a
particular composting system. However, it is expected to
gas-chromatograph, or other apparatus equipped with suitable
resemble the environment of a composting process operated
detector and column(s), for measuring CO and O concentra-
2 2
under optimum conditions. More specifically, the procedure is
tions in the exhaust air of each vessel. Take care to analyze
intended to create a standard laboratory environment that will
CO concentration on a sufficiently frequent basis in order to
permit a rapid and reproducible determination of the aerobic
produce a reliable cumulative CO production over the course
biodegradability under controlled composting conditions.
of the test (for example, every 3 to 6 h).Astandard gas should
be injected to internally standardize the gas-chromatograph on
6. Apparatus
a continuous basis over the course of the test. Operate the gas
6.1 Composting Apparatus (see Fig. 1):
chromatograph in conformance with Practices E260 and E355
6.1.1 Aseriesofatleasttwelvecompostingvessels(onetest
(see Fig. 2).
substance,oneblank,onepositiveandonenegativecontrol,all
6.5 Ensure that all glassware is cleaned thoroughly and free
in three replicates) of 2 to 5 L of volume. For screening
from organic matter.
purposes, depending upon the test material, a smaller volume
also may be used.
7. Reagents and Materials
6.1.2 Water Baths, or other temperature controlling means
7.1 Barium Hydroxide Solution,approximately0.024Nand
capable of maintaining the temperature of the composting
then standardized, prepared by dissolving 4.0 g Ba(OH) per
vessels at 58°C (62°C). 2
FIG. 1 Set-Up Using Carbon Dioxide-Trapping Apparatus FIG. 2 Optional Set-Up Using a Gas Chromatograph
D5338–98 (2003)
litre of distilled water. Filter through filter paper and store 11. Procedure
sealedasaclearsolutiontopreventabsorptionofCO fromthe
11.1 Preparation of the Samples:
air.
11.1.1 Obtain an inoculum from a properly operating aero-
7.2 Analytical-Grade Cellulose,forthin-layerchromatogra-
bic composting plant treating municipal solid waste, or the
phy with a particle size of less than 20 µm as positive control.
organic fraction thereof. If required, further stabilize the
7.3 Polyethylene, as a negative control. It should be in the
inoculum at the laboratory in order to obtain a low CO
same form as the form in which the sample is tested (polyeth-
production (see 9.1.).
ylenefilmforfilmsamples,polyethylenepelletsincasesample
is in the form of pellets, etc.).
11.1.1.1 Screen the inoculum to less than 10 mm and
manually remove and discard any large inert items (pieces of
8. Hazards
glass, stone, wood, etc.). Determine volatile solids, dry solids
8.1 This test method requires the use of hazardous chemi-
and nitrogen content according to Test Methods D3590,
cals.Avoid contact with the chemicals and follow manufactur-
D1888, and APHATest Methods 2540D and 2540E.
er’s instructions and Material Safety Data Sheets.
11.1.2 Determine volatile solids, dry solids and carbon
8.2 The compost inoculum may contain sharp objects. Take
content of all the test substances according to APHA Test
care when handling it.
Methods 2540D and 2540E and Test Method D4129.
8.3 The composting vessels are not designed to withstand
high pressures. The system should be operated at close to 11.1.3 Weigh out roughly 600 g of dry solids of inoculum
ambient pressure. and mix with about 100 g of dry solids coming from the
sample. Adjust the dry solids content of the mixture in the
9. Compost Inoculum
vessel to approximately 50% with distilled water.Add ammo-
9.1 Thecompostinoculumshouldbetwotofourmonthsold
nium chloride if the C/N ratio is more than 40. Weigh vessels
well-aerated compost coming from the organic fraction of
with all of the contents immediately before initiation of the
municipal solid waste and sieved on a screen of <10 mm. If
composting process.
such a compost is not available, compost from plants, treating
11.1.4 The blank consists of the inoculum only, containing
green,oryardwaste,ormixturesofgreenwasteandmunicipal
about 600 g of dry solids. As references, use thin-layer
solid waste may be used. It is recommended that the compost
chromatography cellulose as a positive control and polyethyl-
inoculumproducesbetween50and150mgofCO pergramof
ene as a negative control.
volatile solids over the first ten days of the test, and has an ash
contentoflessthan70%andapHbetween7and8.2.Totaldry 11.1.5 Thetestmaterialmaybeintheformoffilms,formed
solids should be between 50 and 55%.
articlessuchasdogbones,granules,orpowder.Themaximum
9.2 The compost inoculum should be as free from larger
surface area of a compact test material used should be about 2
inert materials (glass, stones, metals, etc.) as possible. These
by 2 cm. In case the original test material is larger, reduce it in
items should be removed manually as much as possible to
particle size.
produce a homogeneous compost inoculum.
11.1.6 No more than about ⁄4 of the volume of the test
9.3 It is recommended to use compost of sufficient porosity
vessel should be filled with test mixture. Sufficient headspace
to enable conditions to be as aerobic as possible. Addition of
is required in order to provide enough space for manual
structural material, such as small wood particles, or persistent
shaking of the test mixture.
or poorly biodegradable inert material may prevent the com-
11.2 Start-Up Procedure—Initiate aeration of the compost-
post from sticking together and clogging during the test.
ing vessels with air-flow rates that are sufficiently high to
10. Test Specimen
ensurethatoxygenlevelsdonotdropbelow6%intheexhaust
10.1 The test specimen should have sufficient carbon to air. Oxygen levels should be closely controlled during the first
yield carbon dioxide that can be adequately measured by the
weekandmeasuredatleasttwicedaily.Adjustair-flowratesas
trapping apparatus or CO measurements. needed.
10.2 All basic composting parameters, such as C/N, oxygen
11.3 Operating Procedure:
inthecompostingvessel,porosity,andmoisturecontentshould
11.3.1 The composting vessels are incubated in the dark or
be optimized so as to make a good composting process
in diffuse light for a period of 45 days in an enclosure that is
possible. The C/N ratio should preferably be between 10 and
free from vapors toxic to microorganisms. The temperature is
40forboththeinoculumandtestsubstancecombined.Oxygen
maintained at 58°C (62°C). In special cases, for example,
levels in the composting vessel should be at least 6% at all
when the melting point of the test material is low, another
timesandnofree-standingwaternorclumpsofmaterialshould
temperature may be chosen. This temperature should be
be present.
constant during the test and kept in a range of 62°C. The
10.3 Test specimens may be in the form of films, formed
change of temperature should be justified and clearly indicated
articles, dog bones, granules, powder, or other, and conform to
in the test report.
Practice D618.
11.3.2 CheckCO andO concentrationsintheoutgoingair
2 2
6 atleastdailywithaminimumtimeintervalof6hafterthefirst
For development of this test method, Avicel, available from EM Chemicals,
Inc., Hawthorne, New York, was used. week for the remainder of the test.
D5338–98 (2003)
11.3.3 Check air flow daily before the composting vessels 12.2.1 Determine the amount of CO produced by the
and at the outlets, ensuring that no leaks are present in the difference, in millilitres of titrant, between the test substance
complete system. Adjust air flow to maintain a CO concen- and blank Ba(OH) traps. Perform the titration with 0.05 N
2 2
tration of at least 2% volume over volume to allow accurate HCl.
determination of CO level in the exhaust air. 12.2.1
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