ASTM D5526-94
(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
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 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 hazards statements are given in Section 8.
Note 1—There is no similar or equivalent ISO standard.
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Standards Content (Sample)
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Designation: D 5526 – 94 An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Determining Anaerobic Biodegradation of Plastic Materials
Under Accelerated Landfill Conditions
This standard is issued under the fixed designation D 5526; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope statements are given in Section 8.
1.1 This test method covers determination of the degree and
NOTE 1—There is no similar or equivalent ISO standard.
rate of anaerobic biodegradation of plastic materials in an
2. Referenced Documents
accelerated-landfill test environment. This test method is also
designed to produce mixtures of household waste and plastic
2.1 ASTM Standards:
materials after different degrees of decomposition under con-
D 618 Practice for Conditioning Plastics and Electrical
ditions that resemble landfill conditions. The test materials are
Insulating Materials for Testing
mixed with pretreated household waste and exposed to a
D 883 Terminology Relating to Plastics
methanogenic inoculum derived from anaerobic digesters op-
D 1293 Test Methods for pH of Water
erating only on pretreated household waste. The anaerobic
D 1888 Test Methods for Particulate and Dissolved Matter,
decomposition occurs under dry (more than 30 % total solids)
Solids, or Residue in Water
and static nonmixed conditions. The mixtures obtained after
D 2908 Practice for Measuring Volatile Organic Matter in
this test method can be used to assess the environmental and
Water by Aqueous-Injection Gas Chromatography
health risks of plastic materials that are degraded in a landfill.
D 3590 Test Method for Total Kjeldahl Nitrogen in Water
1.2 This test method is designed to yield a percentage of
D 4129 Test Method for Total and Organic Carbon in Water
conversion of carbon in the sample to carbon in the gaseous
by High-Temperature Oxidation and Coulometric Detec-
form under conditions that resemble landfill conditions. This
tion
test method may not simulate all conditions found in landfills,
E 260 Practice for Packed Column Gas Chromatography
especially biologically inactive landfills. This test method more
E 355 Practice for Gas Chromatography Terms and Rela-
closely resembles those types of landfills in which the gas
tionships
generated is recovered or even actively promoted, or both, for
2.2 APHA-AWWA-WPCF Standards:
example, by inoculation (codeposition of anaerobic sewage
2540D Total Suspended Solids Dried at 103°–105°C
sludge and anaerobic leachate recirculation), moisture control
2540E Fixed and Volatile Solids Ignited at 550°C
in the landfill (leachate recirculation), and temperature control
212 Nitrogen Ammonia
(short-term injection of oxygen and heating of recirculated
3. Terminology
leachate) (1-7).
1.3 This test method is designed to produce partially de- 3.1 Definitions—For definitions of terms used in this test
graded mixtures of municipal solid waste and plastics that can
method see Terminology D 883.
be used to assess the ecotoxicological risks associated with the
3.2 Definitions of Terms Specific to This Standard:
anaerobic degradation of plastics after various stages of 3.2.1 methanogenic inoculum—anaerobically digested or-
anaerobic biodegradation in a landfill.
ganic waste containing a high concentration of anaerobic
1.4 The values stated in SI units are to be regarded as the methane-producing microorganisms.
standard.
4. Summary of Test Method
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 4.1 This test method described consists of the following: (1)
responsibility of the user of this standard to establish appro- selecting and analyzing material for testing; (2) obtaining a
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific hazards
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 11.01.
Discontinued—See 1991 Annual Book of ASTM Standards, Vol 11.01.
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics
and is the direct responsibility of Subcommittee D20.96 on Environmentally Annual Book of ASTM Standards, Vol 11.02.
Degradable Plastics. Annual Book of ASTM Standards, Vol 14.01.
Current edition approved March 15, 1994. Published May 1994. Standard Methods for the Examination of Water and Wastewater, 17th ed.,
The boldface numbers in parentheses refer to the list of references at the end of 1989, available from American Public Health Association, 1740 Broadway, New
this standard. York, NY 10018.
D 5526
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, a septum that allows one to take gas samples and
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 carbon dioxide concentrations in the evolved gases.
4 2
percentage of biodegradability will not include the amount of 6.5 pH Meter, precision balance (60.1 g), analytical bal-
carbon from the test substance that is converted to cell biomass ance (60.1 mg), thermometer, and barometer.
and that is not, in turn, metabolized to CO and CH . 6.6 Suitable Devices, for determining volatile fatty acids by
2 4
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.
biological processes that will affect the decomposition of other
7. Reagents and Materials
materials enclosed by, or in close proximity to, the plastic.
7.1 Pretreated-Household Waste, derived from mixed mu-
Rapid degradation of the plastic may increase the economic
nicipal solid waste or the organic fraction thereof, after
feasibility of landfill-gas recovery, minimize the duration of
homogenizing, screening over a screen with holes of a diam-
after-care of the landfill, and make possible the recovery of the
eter of 40 to 80 mm, and aerobically stabilized over a period of
volume reduction of the waste due to biodegradation during the
2 to 4 weeks by blowing air into the material and maintaining
active life of the landfill. This procedure has been developed to
a dry-matter content of 50 6 5 % and a temperature of 55 6
permit determination of the anaerobic biodegradability of
10°C. (Optional: the pretreated household waste can be re-
plastic products when placed in biologically active environ-
placed by a similarly pretreated simulated solid waste.)
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
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.
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
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 reproducible mixtures of fully and
partially decomposed household waste with plastic materials
for ecotoxicological assessment.
1 5 Digester.
6. Apparatus
2 5 Incubation chamber.
3 5 Overpressure valve.
6.1 Pressure-Resistant Glass Vessels—Twenty-seven, each
4 5 Manometer.
with a volume of 4 to 6 L, which can be closed airtight and
5 5 Septum.
capable of withstanding an overpressure of two atmospheres.
6 5 Valve.
The lids of the reactors are equipped with an overpressure FIG. 1 Setup of Accelerated Landfill
D 5526
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 D 2908); and
+
substrate or a digester that treats predominantly household 9.3.3 NH -N—Between 0.5 and 2 g/kg (in accordance with
waste. APHA Test 212 and Test Method D 3590).
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
10. Test Specimen
polyethylene for film samples, pellets of polyethylene in case
10.1 The test specimen should be of sufficient carbon
the sample is in the form of pellets, etc.
content, analyzed in accordance with Test Method D 4129, 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
nicipal solid waste containing biologically and possibly chemi-
test specimen when low biodegradability is expected, up to 100
cally active materials known to produce a variety of diseases.
g of dry matter of the test specimen.
Avoid contact with these materials by wearing gloves and other
10.2 The test specimen may be in the form of films, 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 D 618. 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.
11. Procedure
8.3 This test method includes the use of hazardous chemi-
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 Determine the volatile solids, dry solids, and nitrogen
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 D 1888, D 3590, and APHA
gas-collection system, take care in venting the biogas to the
2540D and 2540E.
outside or to a hood. 11.1.2 Determine the volatile solids, dry solids, and carbon
content of all test substances in accordance with APHA 2540D
9. Inoculum
and 2540E and Test Method D 4129.
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-
dry matter content of the final mixtures with water to reach the
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
600 g on a dry-weight basis of pretreated household waste, 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/gram of dry solids in the digester and per day for at least
in the mixture, water may have to be removed prior to
7 days. In case the inoculum is derived from a batch digester,
combining the different components of the mixture. This can be
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
mixture in the vessel, weigh the vessel with all of the contents,
dry-matter content as the digester from which it was derived.
and close it airtight. Prepare the pressure vessels in the
This means that the inoculum is not fed bu
...
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