ASTM D5511-18

Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions

SIGNIFICANCE AND USE
5.1 Biodegradation of a plastic within a high-solids anaerobic digestion unit is an important phenomenon because it will affect the decomposition of other waste materials enclosed by the plastic and the resulting quality and appearance of the digestate after an anaerobic digestion process. Biodegradation of plastics could allow for the safe disposal of these plastics through aerobic and anaerobic solid-waste-treatment plants. This procedure has been developed to permit the determination of the rate and degree of anaerobic biodegradability of plastic products when placed in a high-solids anaerobic digester for the production of digestate from municipal solid waste.  
5.2 Limitations—Because there is a wide variation in the construction and operation of anaerobic-digestion systems and because regulatory requirements for composting systems vary, this procedure is not intended to simulate the environment of any particular high-solids anaerobic-digestion system. However, it is expected to resemble the environment of a high-solids anaerobic-digestion 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 anaerobic biodegradability under high-solids digestion conditions.
SCOPE
1.1 This test method covers the determination of the degree and rate of anaerobic biodegradation of plastic materials in high-solids anaerobic conditions. The test materials are exposed to a methanogenic inoculum derived from anaerobic digesters operating only on pretreated household waste. The anaerobic decomposition takes place under high-solids (more than 30 % total solids) and static non-mixed conditions.  
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 found in high-solids anaerobic digesters, treating municipal solid waste (1, 2, 3, 4).2 This test method may also resemble some conditions in biologically active landfills where the gas generated is recovered and biogas production is actively promoted by inoculation (for example, codeposition of anaerobic sewage sludge, anaerobic leachate recirculation), moisture control (for example, leachate recirculation), and temperature control (for example, short-term injection of oxygen, heating of recirculated leachate) (5, 6, 7).  
1.3 This test method is designed to be applicable to all plastic materials that are not inhibitory to the microorganisms present in anaerobic digesters operating on household waste.  
1.4 Claims of performance shall be limited to the numerical result obtained in the test and not be used for unqualified “biodegradable” claims. Reports shall clearly state the percentage of net gaseous carbon generation for both the test and reference samples at the completion of the test. Furthermore, results shall not be extrapolated past the actual duration of the test.  
1.5 The values given in SI units are to be regarded as the standard.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazards are given in Section 8.  
Note 1: This test method is equivalent to ISO 15985.  
1.7 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.

General Information

• Status: Published
• Publication Date: 14-Jan-2018
• ICS: 13.030.99 - Other standards related to wastes
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.96 - Environmentally Degradable Plastics and Biobased Products

Relations

• Replaces: ASTM D5511-12 - Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions
• Effective Date: 15-Jan-2018
• Refers: ASTM D2908-91(2024) - Standard Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography
• Effective Date: 01-Apr-2024
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D4129-05(2020) - Standard Test Method for Total and Organic Carbon in Water by High Temperature Oxidation and by Coulometric Detection
• Effective Date: 01-Jan-2020
• Refers: ASTM E260-96(2019) - Standard Practice for Packed Column Gas Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D2908-91(2017) - Standard Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography
• Effective Date: 15-Dec-2017
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM D3590-17 - Standard Test Methods for Total Kjeldahl Nitrogen in Water
• Effective Date: 01-Jun-2017

Overview

ASTM D5511-18 - Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions - is a key testing method developed by ASTM International. This standard establishes a laboratory procedure to determine the degree and rate at which plastic materials degrade in high-solids, anaerobic digestion environments. These conditions simulate those found in anaerobic digesters processing municipal solid waste, as well as environments found in some biologically active landfills.

With growing concerns about plastic waste management and environmental impacts, understanding how plastics behave in controlled, high-solids anaerobic conditions is critical for both material developers and waste treatment facility operators. ASTM D5511-18 provides a reproducible, standardized approach to assess whether new or existing plastics are suitable for treatment in anaerobic solid-waste facilities.

Key Topics

• Anaerobic Biodegradation: This standard measures how much and how quickly a plastic material is broken down by microorganisms in the absence of oxygen, within a high-solids environment.

• Test Conditions: The method exposes plastics to methanogenic inoculum from digesters operating on pretreated household waste, under static and non-mixed conditions with more than 30% total solids.

• Measurement Metrics: The main result is the percentage of carbon in the sample that is converted to gaseous forms (carbon dioxide and methane), indicating the degree of biodegradation.

• Reporting Requirements: The outcome must include the percentage of net gaseous carbon generation for both test and reference samples at test completion, without extrapolation beyond the actual test period.

• Scope Limitations: The procedure does not represent any specific anaerobic-digestion system or regulatory context, but provides a standardized baseline under optimal laboratory conditions. Claims of biodegradability must be based on explicit test results and not be generalized.

Applications

• Material Qualification: Manufacturers of biodegradable plastics use ASTM D5511-18 to verify claims about anaerobic biodegradability, supporting product development and marketing for packaging, bags, food service ware, and more.

• Regulatory Compliance: Organizations may use results from this test to demonstrate compliance with government and industry requirements related to waste management or biodegradable products.

• Waste Management Optimization: Facility operators and waste processors can evaluate how different plastic materials contribute to digestate quality and biogas production, optimizing system performance.

• Research & Development: Academic and commercial researchers apply this method to study plastic degradation behavior, influence of formulation changes, and environmental impact assessments.

• Landfill Management: The standard also informs landfill operators about potential methane generation from biodegradable plastics, especially where conditions promote active biogas recovery.

Related Standards

• ISO 15985: Plastics - Determination of the ultimate anaerobic biodegradability and disintegration under high-solids anaerobic-digestion conditions (method by analysis of released biogas); ASTM D5511-18 is technically equivalent.

• ASTM D5526: Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials under Accelerated Landfill Conditions.

• ASTM D6400: Specification for Labeling of Plastics Designed to be Aerobically Composted in Municipal or Industrial Facilities.

• ASTM D5338: Determining Aerobic Biodegradation of Plastics under Controlled Composting Conditions.

• ISO 13641-1: Water quality - Determination of inhibition of gas production of anaerobic bacteria.

By using ASTM D5511-18, organizations across the plastics and waste management sectors can consistently assess the anaerobic biodegradation performance of plastic materials, enabling sustainable product design and effective waste processing solutions. This standard supports the responsible development and disposal of plastics in line with global environmental and regulatory expectations.

Standards Content (Sample)

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: D5511 − 18
Standard Test Method for
Determining Anaerobic Biodegradation of Plastic Materials
Under High-Solids Anaerobic-Digestion Conditions
This standard is issued under the fixed designation D5511; 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* 1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the determination of the degree
responsibility of the user of this standard to establish appro-
and rate of anaerobic biodegradation of plastic materials in
priate safety, health, and environmental practices and deter-
high-solids anaerobic conditions. The test materials are ex-
mine the applicability of regulatory limitations prior to use.
posed to a methanogenic inoculum derived from anaerobic
Specific hazards are given in Section 8.
digesters operating only on pretreated household waste. The
anaerobic decomposition takes place under high-solids (more NOTE 1—This test method is equivalent to ISO15985.
than 30% total solids) and static non-mixed conditions.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.2 This test method is designed to yield a percentage of
ization established in the Decision on Principles for the
conversion of carbon in the sample to carbon in the gaseous
Development of International Standards, Guides and Recom-
formunderconditionsfoundinhigh-solidsanaerobicdigesters,
mendations issued by the World Trade Organization Technical
treating municipal solid waste (1, 2, 3, 4). This test method
Barriers to Trade (TBT) Committee.
may also resemble some conditions in biologically active
landfills where the gas generated is recovered and biogas
2. Referenced Documents
production is actively promoted by inoculation (for example,
2.1 ASTM Standards:
codeposition of anaerobic sewage sludge, anaerobic leachate
D618Practice for Conditioning Plastics for Testing
recirculation), moisture control (for example, leachate
recirculation), and temperature control (for example, short- D883Terminology Relating to Plastics
D1293Test Methods for pH of Water
term injection of oxygen, heating of recirculated leachate) (5,
6, 7). D1888MethodsOfTestforParticulateandDissolvedMatter
in Water (Withdrawn 1989)
1.3 This test method is designed to be applicable to all
D2908Practice for Measuring Volatile Organic Matter in
plastic materials that are not inhibitory to the microorganisms
Water by Aqueous-Injection Gas Chromatography
present in anaerobic digesters operating on household waste.
D3590Test Methods for Total Kjeldahl Nitrogen in Water
1.4 Claims of performance shall be limited to the numerical
D4129Test Method for Total and Organic Carbon in Water
result obtained in the test and not be used for unqualified
by High Temperature Oxidation and by Coulometric
“biodegradable”claims.Reportsshallclearlystatethepercent-
Detection
age of net gaseous carbon generation for both the test and
E260Practice for Packed Column Gas Chromatography
reference samples at the completion of the test. Furthermore,
E355PracticeforGasChromatographyTermsandRelation-
results shall not be extrapolated past the actual duration of the
ships
test.
2.2 APHA-AWWA-WPCF Standards:
2540D Total Suspended Solids Dried at 103°–105°C
1.5 The values given in SI units are to be regarded as the
2540E Fixed and Volatile Solids Ignited at 550°C
standard.
212Nitrogen Ammonia
1 3
This test method is under the jurisdiction of ASTM Committee of D20 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Plastics and is the direct responsibility of Subcommittee D20.96 on Environmen- contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
tally Degradable Plastics and Biobased Products. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 15, 2018. Published February 2018. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2012 as D5511–12. DOI: The last approved version of this historical standard is referenced on
10.1520/D5511-18. www.astm.org.
2 5
The boldface numbers is parentheses refer to a list of references at the end of Standard Methods for the Examination of Water and Wastewater, 17th Edition,
the text. 1989,American Public HealthAssociation, 1740 Broadway, NewYork, NY10018.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5511 − 18
2.3 ISO Standard:
ISO13641-1Water quality—Determination of inhibition of
gasproductionofanaerobicbacteria—Part1:Generaltest
ISO15985 Plastics—Determination of the ultimate anaero-
bic biodegradability and disintegration under high-solids
anaerobic-digestion conditions—Method by analysis of
released biogas
3. Terminology
3.1 Definitions—Definitions of terms applying to this test
method appear in Terminology D883.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 methanogenic inoculum—anaerobically digested or-
ganic waste containing a high concentration of anaerobic
methane-producing microorganisms.
FIG. 1 Test Setup
4. Summary of Test Method
4.1 This test method consists of selection and analysis of
material for testing, obtaining a concentrated anaerobic inocu-
6. Apparatus
lum from an anaerobic laboratory-scale digester, exposing the
6.1 Inverted Graduated Cylinder or Plastic Column, in
materialtoananaerobic-static-batchfermentationatmorethan
water or other suitable device for measuring gas volume. The
20% solids, measuring total carbon in the gas (CO and CH )
2 4
water in contact with the gas must be at a pH of less than two
evolved as a function of time, and assessing the degree of
during the whole period of the test to avoid CO loss through
biodegradability.
dissolution in the water. The gas-volume-measuring device, as
4.2 The percentage of biodegradability is obtained by de-
well as the gas tubing, shall be of sufficient quality to prevent
termining the percent of conversion of carbon from the test
gas migration and diffusion between the system and the
material to carbon in the gaseous phase (CH and CO ). This
4 2
surrounding air (see Fig. 1).
percentage of biodegradability will not include the amount of
6.2 Gas Chromatograph, (optional) or other apparatus,
carbonfromthetestsubstancethatisconvertedtocellbiomass
equipped with a suitable detector and column(s) for measuring
and that is not, in turn, metabolized to CO and CH .
2 4
methane and carbon dioxide concentration in the evolved
gases.
5. Significance and Use
6.3 Incubator, or hot-water bath capable of maintaining the
5.1 Biodegradation of a plastic within a high-solids anaero-
testbottlesat37°C(62°C)or52°C(62°C)forthedurationof
bic digestion unit is an important phenomenon because it will
the test.
affect the decomposition of other waste materials enclosed by
the plastic and the resulting quality and appearance of the
6.4 Erlenmeyer Flasks, with sufficient capacity for the
digestate after an anaerobic digestion process. Biodegradation
experiment and openings of at least 7-cm diameter, set up so
of plastics could allow for the safe disposal of these plastics
that no loss of gas occurs.
through aerobic and anaerobic solid-waste-treatment plants.
6.5 pHMeter,precisionbalance(60.1g),analyticalbalance
Thisprocedurehasbeendevelopedtopermitthedetermination
(60.1 mg), thermometer, and barometer.
of the rate and degree of anaerobic biodegradability of plastic
products when placed in a high-solids anaerobic digester for 6.6 Devices, suitable for determining volatile fatty acids by
aqueous-injection chromatography, total Kjeldahl nitrogen,
the production of digestate from municipal solid waste.
ammonia nitrogen, dry solids (105°C) and volatile-solids
5.2 Limitations—Because there is a wide variation in the
(550°C) concentrations.
construction and operation of anaerobic-digestion systems and
because regulatory requirements for composting systems vary,
7. Reagents and Materials
this procedure is not intended to simulate the environment of
7.1 Anaerboic Inoculum, derived from a properly operating
any particular high-solids anaerobic-digestion system.
anaerobic digester with pretreated household waste as a sole
However, it is expected to resemble the environment of a
substrate.
high-solids anaerobic-digestion process operated under opti-
mum conditions. More specifically, the procedure is intended 7.2 Analytical-Grade Cellulose,forthin-layerchromatogra-
to create a standard laboratory environment that will permit a
phy as a positive control.
rapid and reproducible determination of the anaerobic biode-
7.3 Polyethylene, as a negative control (optional). It is
gradability under high-solids digestion conditions.
optimal if it is in the same form as the form in which the
sample is tested (for example, film polyethylene for film
samples, pellets of polyethylene if the sample is in the form of
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. pellets, etc.).
D5511 − 18
8. Hazards 9.3 Analyses are performed after dilution of the inoculum
with distilled water on a ratio of distilled water to inoculum of
8.1 Theproceduregiveninthistestmethodinvolvestheuse
5 to 1 on a weight over weight basis.
of an inoculum composed of biologically and possibly chemi-
cally active materials known to produce a variety of diseases.
10. Test Specimen
Avoidcontactwiththesematerialsbywearingglovesandother
appropriateprotectivegarments.Usegoodpersonalhygieneto
10.1 Thetestspecimenshallbeofsufficientcarboncontent,
minimize exposure.
analyzed in accordance with Test Method D4129, to yield
carbon dioxide and methane volumes that can be accurately
8.2 Itispossiblethatthesolid-wastemixturecontainssharp
measured by the trapping devices described. Add more test
objects.Takeextremecarewhenhandlingthismixturetoavoid
specimen when low biodegradability is expected, up to 100 g
injury.
on a dry weight basis of the test specimen.
8.3 The biological reactor is not designed to withstand high
10.2 It is acceptable if the test specimen is in the form of
pressures; operate it at close to ambient pressure.
films, powder, pellets, formed articles, or in the form of a dog
8.4 This test method includes the use of hazardous chemi-
boneandconformingtoPracticeD618.Thetestset-upshallbe
cals. Avoid contact with the chemicals and follow the manu-
able to handle articles that are 100 mm by 50 mm by 4 mm
facturer’s instructions and Material Safety Data Sheets.
thick.
8.5 The methane produced during this procedure is explo-
sive and flammable. Upon release of the biogas from the
11. Procedure
gas-collection system, take care in venting the biogas to the
11.1 Inoculum Medium:
outside or to a hood.
11.1.1 Remove enough inoculum (approximately 15 kg)
from the post-fermentation vessel and mix carefully and
9. Inoculum
consistently by hand in order to obtain a homogeneous
9.1 The inoculum must be derived from a properly operat-
medium.
ing anaerobic digester functioning with a pretreated household
11.1.2 Testthreereplicateseachofablank(inoculumonly),
waste as a sole substrate.The pretreated household waste shall
positive control (thin-layer chromatography cellulose), nega-
comefromanexistingwastetreatmentfacilitytreatingmunici-
tive control (polyethylene), and the test substance being
pal solid waste, where through sorting, shredding, sieving, or
evaluated.
other means, a fairly homogeneous organic fraction is pro-
11.1.2.1 Manuallymix1000gwetweight(atleast20%dry
duced of less than 60 mm. The digester shall be operating for
solids) of inoculum in a small container for a period of 2 to 3
a period of at least four months on the organic fraction, with a
min with 15 to 100 g of volatile solids of the test substance or
retention time of a maximum of 30 days under thermophilic
the controls for each replicate. (Determine dry solids and
conditions (52 6 2°C). Gas-production yields shall be at least
volatilesolidsinaccordancewithAPHAStandards,2540,and
15mLatstandardtemperatu
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5511 − 12 D5511 − 18
Standard Test Method for
Determining Anaerobic Biodegradation of Plastic Materials
Under High-Solids Anaerobic-Digestion Conditions
This standard is issued under the fixed designation D5511; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This test method covers the determination of the degree and rate of anaerobic biodegradation of plastic materials in
high-solids anaerobic conditions. The test materials are exposed to a methanogenic inoculum derived from anaerobic digesters
operating only on pretreated household waste. The anaerobic decomposition takes place under high-solids (more than 30 % total
solids) and static non-mixed conditions.
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 found in high-solids anaerobic digesters, treating municipal solid waste (1, 2, 3, 4). This test method may also resemble
some conditions in biologically active landfills where the gas generated is recovered and biogas production is actively promoted
by inoculation (for example, codeposition of anaerobic sewage sludge, anaerobic leachate recirculation), moisture control (for
example, leachate recirculation), and temperature control (for example, short-term injection of oxygen, heating of recirculated
leachate) (5, 6, 7).
1.3 This test method is designed to be applicable to all plastic materials that are not inhibitory to the microorganisms present
in anaerobic digesters operating on household waste.
1.4 Claims of performance shall be limited to the numerical result obtained in the test and not be used for unqualified
“biodegradable” claims. Reports shall clearly state the percentage of net gaseous carbon generation for both the test and reference
samples at the completion of the test. Furthermore, results shall not be extrapolated past the actual duration of the test.
1.5 The values given in SI units are to be regarded as the standard.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific hazards are given in Section 8.
NOTE 1—This test method is equivalent to ISO 15985.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1293 Test Methods for pH of Water
D1888 Methods Of Test for Particulate and Dissolved Matter in Water (Withdrawn 1989)
D2908 Practice for Measuring Volatile Organic Matter in Water by Aqueous-Injection Gas Chromatography
D3590 Test Methods for Total Kjeldahl Nitrogen in Water
This test method is under the jurisdiction of ASTM Committee of D20 on Plastics and is the direct responsibility of Subcommittee D20.96 on Environmentally
Degradable Plastics and Biobased Products.
Current edition approved May 1, 2012Jan. 15, 2018. Published June 2012February 2018. Originally published asapproved in D5511 – 94.1994. Last previous edition
approved in 2012 as D5511 – 11.D5511 – 12. DOI: 10.1520/D5511-12.10.1520/D5511-18.
The boldface numbers is parentheses refer to a list of references at the end of the text.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5511 − 18
D4129 Test Method for Total and Organic Carbon in Water by High Temperature Oxidation and by Coulometric Detection
E260 Practice for Packed Column Gas Chromatography
E355 Practice for Gas Chromatography Terms and Relationships
2.2 APHA-AWWA-WPCF Standards:
2540 D Total Suspended Solids Dried at 103°–105°C
2540 E Fixed and Volatile Solids Ignited at 550°C
212 Nitrogen Ammonia
2.3 ISO Standard:
ISO 13641-1 Water quality—Determination of inhibition of gas production of anaerobic bacteria—Part 1: General test
ISO 15985 Plastics—Determination of the ultimate anaerobic biodegradability and disintegration under high-solids anaerobic-
digestion conditions—Method by analysis of released biogas
3. Terminology
3.1 Definitions—Definitions of terms applying to this test method appear in Terminology D883.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 methanogenic inoculum—anaerobically digested organic waste containing a high concentration of anaerobic methane-
producing microorganisms.
4. Summary of Test Method
4.1 This test method consists of selection and analysis of material for testing, obtaining a concentrated anaerobic inoculum from
an anaerobic laboratory-scale digester, exposing the material to an anaerobic-static-batch fermentation at more than 20 % solids,
measuring total carbon in the gas (CO and CH ) evolved as a function of time, and assessing the degree of biodegradability.
2 4
4.2 The percentage of biodegradability is obtained by determining the percent of conversion of carbon from the test material
to carbon in the gaseous phase (CH and CO ). This percentage of biodegradability will not include the amount of carbon from
4 2
the test substance that is converted to cell biomass and that is not, in turn, metabolized to CO and CH .
2 4
5. Significance and Use
5.1 Biodegradation of a plastic within a high-solids anaerobic digestion unit is an important phenomenon because it will affect
the decomposition of other waste materials enclosed by the plastic and the resulting quality and appearance of the digestate after
an anaerobic digestion process. Biodegradation of plastics could allow for the safe disposal of these plastics through aerobic and
anaerobic solid-waste-treatment plants. This procedure has been developed to permit the determination of the rate and degree of
anaerobic biodegradability of plastic products when placed in a high-solids anaerobic digester for the production of digestate from
municipal solid waste.
5.2 Limitations—Because there is a wide variation in the construction and operation of anaerobic-digestion systems and because
regulatory requirements for composting systems vary, this procedure is not intended to simulate the environment of any particular
high-solids anaerobic-digestion system. However, it is expected to resemble the environment of a high-solids anaerobic-digestion
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 anaerobic biodegradability under high-solids digestion
conditions.
6. Apparatus
6.1 Inverted Graduated Cylinder or Plastic Column, in water or other suitable device for measuring gas volume. The water in
contact with the gas must be at a pH of less than two during the whole period of the test to avoid CO loss through dissolution
in the water. The gas-volume-measuring device, as well as the gas tubing, shall be of sufficient quality to prevent gas migration
and diffusion between the system and the surrounding air (see Fig. 1).
6.2 Gas Chromatograph, (optional) or other apparatus, equipped with a suitable detector and column(s) for measuring methane
and carbon dioxide concentration in the evolved gases.
6.3 Incubator, or hot-water bath capable of maintaining the test bottles at 37°C (62°C) or 52°C (62°C) for the duration of the
test.
6.4 Erlenmeyer Flasks, with sufficient capacity for the experiment and openings of at least 7-cm diameter, set up so that no loss
of gas occurs.
6.5 pH Meter, precision balance (60.1 g), analytical balance (60.1 mg), thermometer, and barometer.
Standard Methods for the Examination of Water and Wastewater, 17th Edition, 1989, American Public Health Association, 1740 Broadway, New York, NY 10018.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D5511 − 18
FIG. 1 Test Setup
6.6 Devices, suitable for determining volatile fatty acids by aqueous-injection chromatography, total Kjeldahl nitrogen,
ammonia nitrogen, dry solids (105°C) and volatile-solids (550°C) concentrations.
7. Reagents and Materials
7.1 Anaerboic Inoculum, derived from a properly operating anaerobic digester with pretreated household waste as a sole
substrate.
7.2 Analytical-Grade Cellulose, for thin-layer chromatography as a positive control.
7.3 Polyethylene, as a negative control (optional). It is optimal if it is in the same form as the form in which the sample is tested
(for example, film polyethylene for film samples, pellets of polyethylene if the sample is in the form of pellets, etc.).
8. Hazards
8.1 The procedure given in this test method involves the use of an inoculum composed of biologically and possibly chemically
active materials known to produce a variety of diseases. Avoid contact with these materials by wearing gloves and other appropriate
protective garments. Use good personal hygiene to minimize exposure.
8.2 It is possible that the solid-waste mixture contains sharp objects. Take extreme care when handling this mixture to avoid
injury.
8.3 The biological reactor is not designed to withstand high pressures; operate it at close to ambient pressure.
8.4 This test method includes the use of hazardous chemicals. Avoid contact with the chemicals and follow the manufacturer’s
instructions and Material Safety Data Sheets.
8.5 The methane produced during this procedure is explosive and flammable. Upon release of the biogas from the gas-collection
system, take care in venting the biogas to the outside or to a hood.
9. Inoculum
9.1 The inoculum must be derived from a properly operating anaerobic digester functioning with a pretreated household waste
as a sole substrate. The pretreated household waste shall come from an existing waste treatment facility treating municipal solid
waste, where through sorting, shredding, sieving, or other means, a fairly homogeneous organic fraction is produced of less than
60 mm. The digester shall be operating for a period of at least four months on the organic fraction, with a retention time of a
maximum of 30 days under thermophilic conditions (52 6 2°C). Gas-production yields shall be at least 15 mL at standard
temperature and pressure of biogas per gram of dry solids in the digester and per day on the average for at least 30 days.
9.1.1 It is preferable to derive the inoculum from a digester operating under dry (>20 % total solids) conditions, but it is
acceptable to derive it from a wet fermentation whereby the anaerobically digested sludge is dewatered through centrifugation,
with a press or through drying at a maximum temperature of 55°C to a dry-solids content of at least 20 %.
9.2 The prepared inoculum shall undergo a short post-fermentation of approximately seven days at the same operating
temperature from which it was derived. This means that the inoculum is not fed but allowed to post-ferment anaerobically by itself.
This is to ensure that large easily biodegradable particles are degraded during this period and also to reduce the background level
of degradation of the inoculum itself.
9.2.1 The most important biochemical characteristics of the inoculum shall be as follows:
D5511 − 18
9.2.1.1 pH—Between 7.5 and 8.5 (in accordance with Test Methods D1293),
9.2.1.2 Volatile Fatty Acids (VFA)—Below 1 g/kg wet weight (in accordance with Practice D2908), and
+
9.2.1.3 NH -N—Between 0.5 and 2 g/kg wet weight (in accordance with APHA Test Method 212 and Test Method D3590).
9.3 Analyses are performed after dilution of the inoculum with distilled water on a ratio of distilled water to inoculum of 5 to
1 on a weight over weight basis.
10. Test Specimen
10.1 The test spec
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