ASTM D5526-94(2002)
(Test Method)Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under Accelerated Landfill Conditions
Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under Accelerated Landfill Conditions
SIGNIFICANCE AND USE
Decomposition of a plastic within a landfill involves biological processes that will affect the decomposition of other materials enclosed by, or in close proximity to, the plastic. Rapid degradation of the plastic may increase the economic feasibility of landfill-gas recovery, minimize the duration of after-care of the landfill, and make possible the recovery of the volume reduction of the waste due to biodegradation during the active life of the landfill. This procedure has been developed to permit determination of the anaerobic biodegradability of plastic products when placed in biologically active environments simulating landfill conditions.
The decomposition of plastic materials in a landfill is of limited importance, as few landfills are operated so as to be biologically active. However, as degradation occurs inevitably in a landfill, it is of immediate concern that the plastic materials do not produce toxic metabolites or end products under the various conditions that may occur in a landfill. The mixtures remaining after completion of the test method, containing fully or partially degraded plastic materials or extracts, can be submitted subsequently to ecotoxicity testing in order to assess the environmental hazards posed by the breakdown of plastics to varying degrees in landfills. This test method has been designed to assess biodegradation under optimum and less-than-optimum conditions.
Limitations—Because a wide variation exists in the construction and operation of landfills, and because regulatory requirements for landfills vary greatly, this procedure is not intended to simulate the environment of all landfills. However, it is expected to closely resemble the environment of a biologically active landfill. More specifically, the procedure is intended to create a standard laboratory environment that permits rapid and reproducible determination of the anaerobic biodegradability under accelerated landfill conditions, while at the same time producing repro...
SCOPE
1.1 This test method covers determination of the degree and rate of anaerobic biodegradation of plastic materials in an accelerated-landfill test environment. This test method is also designed to produce mixtures of household waste and plastic materials after different degrees of decomposition under conditions that resemble landfill conditions. The test materials are mixed with pretreated household waste and exposed to a methanogenic inoculum derived from anaerobic digesters operating only on pretreated household waste. The anaerobic decomposition occurs under dry (more than 30 % total solids) and static nonmixed conditions. The mixtures obtained after this test method can be used to assess the environmental and health risks of plastic materials that are degraded in a landfill.
1.2 This test method is designed to yield a percentage of conversion of carbon in the sample to carbon in the gaseous form under conditions that resemble landfill conditions. This test method may not simulate all conditions found in landfills, especially biologically inactive landfills. This test method more closely resembles those types of landfills in which the gas generated is recovered or even actively promoted, or both, for example, by inoculation (codeposition of anaerobic sewage sludge and anaerobic leachate recirculation), moisture control in the landfill (leachate recirculation), and temperature control (short-term injection of oxygen and heating of recirculated leachate) (1-7).
1.3 This test method is designed to produce partially degraded mixtures of municipal solid waste and plastics that can be used to assess the ecotoxicological risks associated with the anaerobic degradation of plastics after various stages of anaerobic biodegradation in a landfill.
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...
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Designation: D5526 – 94 (Reapproved 2002)
Standard Test Method for
Determining Anaerobic Biodegradation of Plastic Materials
Under Accelerated Landfill Conditions
This standard is issued under the fixed designation D5526; 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 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 Thistestmethodcoversdeterminationofthedegreeand
responsibility of the user of this standard to establish appro-
rate of anaerobic biodegradation of plastic materials in an
priate safety and health practices and determine the applica-
accelerated-landfill test environment. This test method is also
bility of regulatory limitations prior to use. Specific hazards
designed to produce mixtures of household waste and plastic
statements are given in Section 8.
materials after different degrees of decomposition under con-
ditions that resemble landfill conditions. The test materials are
NOTE 1—There is no similar or equivalent ISO standard.
mixed with pretreated household waste and exposed to a
2. Referenced Documents
methanogenic inoculum derived from anaerobic digesters op-
erating only on pretreated household waste. The anaerobic
2.1 ASTM Standards:
decomposition occurs under dry (more than 30% total solids)
D618 Practice for Conditioning Plastics for Testing
and static nonmixed conditions. The mixtures obtained after
D883 Terminology Relating to Plastics
this test method can be used to assess the environmental and
D1293 Test Methods for pH of Water
health risks of plastic materials that are degraded in a landfill.
D1888 Test Methods for Particulate and Dissolved Matter,
1.2 This test method is designed to yield a percentage of
Solids, or Residue in Water
conversion of carbon in the sample to carbon in the gaseous
D2908 Practice for Measuring Volatile Organic Matter in
form under conditions that resemble landfill conditions. This
Water by Aqueous-Injection Gas Chromatography
test method may not simulate all conditions found in landfills,
D3590 Test Methods for Total Kjeldahl Nitrogen in Water
especiallybiologicallyinactivelandfills.Thistestmethodmore
D4129 Test Method for Total and Organic Carbon in Water
closely resembles those types of landfills in which the gas
by High Temperature Oxidation and by Coulometric De-
generated is recovered or even actively promoted, or both, for
tection
example, by inoculation (codeposition of anaerobic sewage
E260 Practice for Packed Column Gas Chromatography
sludge and anaerobic leachate recirculation), moisture control
E355 Practice for Gas Chromatography Terms and Rela-
in the landfill (leachate recirculation), and temperature control
tionships
(short-term injection of oxygen and heating of recirculated
2.2 APHA-AWWA-WPCF Standards:
leachate) (1-7).
2540D Total Suspended Solids Dried at 103°–105°C
1.3 This test method is designed to produce partially de-
2540E Fixed and Volatile Solids Ignited at 550°C
graded mixtures of municipal solid waste and plastics that can
212 Nitrogen Ammonia
be used to assess the ecotoxicological risks associated with the
3. Terminology
anaerobic degradation of plastics after various stages of
anaerobic biodegradation in a landfill.
3.1 Definitions—For definitions of terms used in this test
1.4 The values stated in SI units are to be regarded as the method see Terminology D883.
standard.
3.2 Definitions of Terms Specific to This Standard:
1 3
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and is the direct responsibility of Subcommittee D20.96 on Environmentally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Degradable Plastics. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved March 15, 1994. Published May 1994. DOI: 10.1520/ the ASTM website.
D5526-94R02. Standard Methods for the Examination of Water and Wastewater, 17th ed.,
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof 1989, available from American Public Health Association, 1740 Broadway, New
this standard. York, NY 10018.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5526 – 94 (2002)
3.2.1 methanogenic inoculum—anaerobically digested or- partially decomposed household waste with plastic materials
ganic waste containing a high concentration of anaerobic for ecotoxicological assessment.
methane-producing microorganisms.
6. Apparatus
4. Summary of Test Method
6.1 Pressure-Resistant Glass Vessels—Twenty-seven, each
with a volume of 4 to 6 L, which can be closed airtight and
4.1 Thistestmethoddescribedconsistsofthefollowing:(1)
capable of withstanding an overpressure of two atmospheres.
selecting and analyzing material for testing; (2) obtaining a
The lids of the reactors are equipped with an overpressure
pretreated municipal-solid-waste fraction and a concentrated
valve (to prevent the overpressure from becoming higher than
anaerobic inoculum from an anaerobic digester; (3) exposing
2 bars), a manometer that provides a rough indication of the
the material to an anaerobic static batch fermentation at more
overpressure,aseptumthatallowsonetotakegassamplesand
than 30% solids; (4) measuring total carbon in the gas (CO
measure the exact overpressure, and, finally, a valve to release
and CH ) evolved as a function of time; (5) removing the
the overpressure (Fig. 1).
specimens for cleaning (optional), conditioning, testing, and
6.2 Incubators, sufficient to store the vessels in the dark at
reporting; (6) assessing the degree of biodegradability; and (7)
35 6 2°C for the duration of the test.
assessing the degree of biodegradability under less than opti-
6.3 Pressure Transducer, connected to a syringe needle to
mum conditions.
measure the headspace pressure in the test vessel.
4.2 The percentage of biodegradability is obtained by de-
6.4 Gas Chromatograph, or other apparatus, equipped with
termining the percent of conversion of carbon from the test
a suitable detector and column(s) for measuring methane and
material to carbon in the gaseous phase (CH and CO ). This
4 2
carbon dioxide concentrations in the evolved gases.
percentage of biodegradability will not include the amount of
6.5 pH Meter, precision balance (60.1 g), analytical bal-
carbonfromthetestsubstancethatisconvertedtocellbiomass
ance (60.1 mg), thermometer, and barometer.
and that is not, in turn, metabolized to CO and CH .
2 4
6.6 Suitable Devices, for determining volatile fatty acids by
aqueous-injection chromatography, total Kjeldahl nitrogen,
5. Significance and Use
ammonia nitrogen, dry solids (105°C), and volatile solids
5.1 Decomposition of a plastic within a landfill involves
(550°C) concentrations.
biologicalprocessesthatwillaffectthedecompositionofother
materials enclosed by, or in close proximity to, the plastic.
Rapid degradation of the plastic may increase the economic
feasibility of landfill-gas recovery, minimize the duration of
after-careofthelandfill,andmakepossibletherecoveryofthe
volumereductionofthewasteduetobiodegradationduringthe
activelifeofthelandfill.Thisprocedurehasbeendevelopedto
permit determination of the anaerobic biodegradability of
plastic products when placed in biologically active environ-
ments simulating landfill conditions.
5.2 The decomposition of plastic materials in a landfill is of
limited importance, as few landfills are operated so as to be
biologically active. However, as degradation occurs inevitably
inalandfill,itisofimmediateconcernthattheplasticmaterials
do not produce toxic metabolites or end products under the
various conditions that may occur in a landfill. The mixtures
remainingaftercompletionofthetestmethod,containingfully
or partially degraded plastic materials or extracts, can be
submittedsubsequentlytoecotoxicitytestinginordertoassess
the environmental hazards posed by the breakdown of plastics
to varying degrees in landfills. This test method has been
designed to assess biodegradation under optimum and less-
than-optimum conditions.
5.3 Limitations—Because a wide variation exists in the
construction and operation of landfills, and because regulatory
requirements for landfills vary greatly, this procedure is not
intended to simulate the environment of all landfills. However,
it is expected to closely resemble the environment of a
1 = Digester.
biologically active landfill. More specifically, the procedure is
2 = Incubation chamber.
3 = Overpressure valve.
intended to create a standard laboratory environment that
4 = Manometer.
permits rapid and reproducible determination of the anaerobic
5 = Septum.
biodegradability under accelerated landfill conditions, while at
6 = Valve.
the same time producing reproducible mixtures of fully and FIG. 1 Setup of Accelerated Landfill
D5526 – 94 (2002)
7. Reagents and Materials dry-matter content as the digester from which it was derived.
This means that the inoculum is not fed but is allowed to
7.1 Pretreated-Household Waste, derived from mixed mu-
post-ferment anaerobically by itself. This is to ensure that
nicipal solid waste or the organic fraction thereof, after
large, easily biodegradable particles are degraded during this
homogenizing, screening over a screen with holes of a diam-
period and also to reduce the background level of degradation
eterof40to80mm,andaerobicallystabilizedoveraperiodof
of the inoculum itself.
2 to 4 weeks by blowing air into the material and maintaining
9.3 Thebiochemicalcharacteristicsoftheinoculumshallbe
a dry-matter content of 50 6 5% and a temperature of 55 6
as follows:
10°C. (Optional: the pretreated household waste can be re-
9.3.1 pH—Between 7.5 and 8.5 (in accordance with Test
placed by a similarly pretreated simulated solid waste.)
Methods D1293);
7.2 Anaerobic Inoculum, derived from a properly operating
9.3.2 Volatile Fatty Acids (VFA)—Below 1 g/kg wet weight
anaerobic digester with pretreated household waste as a sole
(in accordance with Practice D2908); and
substrate or a digester that treats predominantly household
+
9.3.3 NH -N—Between0.5and2g/kg(inaccordancewith
waste.
APHATest and Test Method D3590).
7.3 Cellulose, Analytical-Grade, for thin-layer chromatog-
9.4 Analyses are performed after dilution of the inoculum
raphy as a positive control.
with distilled water on a ratio of distilled water to inoculum of
7.4 Polyethylene (optional), as a negative control. It should
5 to 1 on a weight-over-weight basis.
be in the same form as that in which the sample is tested: film
polyethylene for film samples, pellets of polyethylene in case
10. Test Specimen
the sample is in the form of pellets, etc.
10.1 The test specimen should be of sufficient carbon
content, analyzed in accordance with Test Method D4129,to
8. Hazards
yield carbon dioxide and methane volumes that can be mea-
8.1 This procedure involves the use of inoculum and mu-
sured accurately by the trapping devices described. Add more
nicipalsolidwastecontainingbiologicallyandpossiblychemi-
testspecimenwhenlowbiodegradabilityisexpected,upto100
cally active materials known to produce a variety of diseases.
g of dry matter of the test specimen.
Avoidcontactwiththesematerialsbywearingglovesandother
10.2 Thetestspecimenmaybeintheformoffilms,powder,
appropriate protective equipment. Use good personal hygiene
pellets, or formed articles, or in the form of a dog bone and in
to minimize exposure.
accordance with Practice D618. The test setup should be
8.2 The solid-waste mixture may contain sharp objects.
capable of handling articles that are 100 by 50 by 4 mm thick.
Take extreme care when handling this mixture to avoid injury.
8.3 This test method includes the use of hazardous chemi-
11. Procedure
cals. Avoid contact with the chemicals and follow the manu-
11.1 Preparation of the Mixtures:
facturer’s instructions and material safety data sheets.
11.1.1 Determinethevolatilesolids,drysolids,andnitrogen
8.4 The methane produced during the procedure is explo-
content of the pretreated household waste and the inoculum in
sive and flammable. Upon release of the biogas from the
accordance with Test Methods D1888, D3590, andAPHAand
gas-collection system, take care in venting the biogas to the
.
outside or to a hood.
11.1.2 Determine the volatile solids, dry solids, and carbon
contentofalltestsubstancesinaccordancewithAPHAandand
9. Inoculum
Test Method D4129.
9.1 The inoculum can be derived either from a laboratory-
11.1.3 Weigh and combine the components and adjust the
scale or full-scale continuous digester or batch digester, oper-
drymattercontentofthefinalmixtureswithwatertoreachthe
ating at 35°C and functioning with an organic fraction of
desired dry-matter content for each vessel. Roughly weigh out
household waste as the predominant substrate. In case the
600gonadry-weightbasisofpretreatedhouseholdwaste,and
inoculum is derived from a continuous laboratory-scale or
mix it with 100 g on a dry-weight basis of mesophilic
full-scale digester, the digester must be operating for a period
anaerobic inoculum from a continuously operating digester or
of at least one month on the organic fraction of household
150 g on a dry-weight basis of anaerobic inoculum from a
waste, with a maximum retention time of 30 days under
batch digester. Add 60 to 100 g of dry matter of the test
mesophilic conditions (35 6 2°C). Gas production yields must
substance. Add water until the appropriate final dry matter
be at least 15 mL at standard temperature and pressure of
content is reached. (In order to reach 60% dry matter content
biogas/gramofdrysolidsinthedigesterandperdayforatleast
in the mixture, water may have to be removed prior to
7 days. In case the inoculum is derived from a batch digester,
combiningthedifferentcomponentsofthemixture.Thiscanbe
the gas production rate must have exceeded 1 L/kg waste/day,
accomplished by drying the pretreated household waste or
and the methane concentration of the biogas being produced
centrifuging the anaerobic inoculum.) Mix the required
must be above 60%.
amounts of pretreated household waste, inoculum, and test
9.2 The prepared inoculum should undergo a short meso-
substance in a small container for 2 to 3 min. Introduce the
philic post-fermentation of approximately 7 days at the same
mixtureinthevessel,weighthevesselwithallofthecontents,
and close it airtight. Prepare the pressure vessels in the
tri
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