1、Designation: D5526 12Standard Test Method forDetermining Anaerobic Biodegradation of Plastic MaterialsUnder Accelerated Landfill Conditions1This standard is issued under the fixed designation D5526; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the degree andrate of anaerobic biodegradation of
3、 plastic materials in anaccelerated-landfill test environment. This test method is alsodesigned to produce mixtures of household waste and plasticmaterials after different degrees of decomposition under con-ditions that resemble landfill conditions. The test materials aremixed with pretreated househ
4、old waste and exposed to amethanogenic inoculum derived from anaerobic digesters op-erating only on pretreated household waste. The anaerobicdecomposition occurs under dry (more than 30 % total solids)and static nonmixed conditions. The mixtures obtained afterthis test method can be used to assess t
5、he environmental andhealth risks of plastic materials that are degraded in a landfill.1.2 This test method is designed to yield a percentage ofconversion of carbon in the sample to carbon in the gaseousform under conditions that resemble landfill conditions. It ispossible that this test method will
6、not simulate all conditionsfound in landfills, especially biologically inactive landfills.This test method more closely resembles those types oflandfills in which the gas generated is recovered or evenactively promoted, or both, for example, by inoculation (code-position of anaerobic sewage sludge a
7、nd anaerobic leachaterecirculation), moisture control in the landfill (leachate recir-culation), and temperature control (short-term injection ofoxygen and heating of recirculated leachate) (1-7).21.3 This test method is designed to produce partially de-graded mixtures of municipal solid waste and p
8、lastics that canbe used to assess the ecotoxicological risks associated with theanaerobic degradation of plastics after various stages of an-aerobic biodegradation in a landfill.1.4 Claims of performance shall be limited to the numericalresult obtained in the test and not be used for unqualified“bio
9、degradable” claims. Reports shall clearly state the percent-age of net gaseous carbon generation for both the test andreference samples at the completion of the test. Furthermore,results shall not be extrapolated past the actual duration of thetest.1.5 The values stated in SI units are to be regarde
10、d as thestandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to us
11、e. Specific hazardsstatements are given in Section 8.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:3D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1293 Test Methods for pH of WaterD1888 Methods Of Test for
12、Particulate and DissolvedMatter in Water4D2908 Practice for Measuring Volatile Organic Matter inWater by Aqueous-Injection Gas ChromatographyD3590 Test Methods for Total Kjeldahl Nitrogen in WaterD4129 Test Method for Total and Organic Carbon in Waterby High Temperature Oxidation and by Coulometric
13、De-tectionE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Rela-tionships2.2 APHA-AWWA-WPCF Standards:52540D Total Suspended Solids Dried at 103105C2540E Fixed and Volatile Solids Ignited at 550C1This test method is under the jurisdiction ofASTM Commit
14、tee D20 on Plasticsand is the direct responsibility of Subcommittee D20.96 on EnvironmentallyDegradable Plastics and Biobased Products.Current edition approved May 1, 2012. Published June 2012. Originallyapproved in 1994. Last previous edition approved in 2011 as D5526 94(2011)1.DOI: 10.1520/D5526-1
15、2.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Docu
16、ment Summary page onthe ASTM website.4Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.5Standard Methods for the Examination of Water and Wastewater,20thed.,1999, available from American Public Health Association, 800 I Street, NW,Washington, D.C. 20001-3
17、710, or http:/www.standardmethods.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.212 Nitrogen Ammonia3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod see Terminology D883.3.2 Definitions of Terms Spe
18、cific to This Standard:3.2.1 methanogenic inoculumanaerobically digested or-ganic waste containing a high concentration of anaerobicmethane-producing microorganisms.4. Summary of Test Method4.1 This test method described consists of the following: (1)selecting and analyzing material for testing; (2)
19、 obtaining apretreated municipal-solid-waste fraction and a concentratedanaerobic inoculum from an anaerobic digester; (3) exposingthe material to an anaerobic static batch fermentation at morethan 30 % solids; (4) measuring total carbon in the gas (CO2and CH4) evolved as a function of time; (5) rem
20、oving thespecimens for cleaning (optional), conditioning, testing, andreporting; (6) assessing the degree of biodegradability; and (7)assessing the degree of biodegradability under less than opti-mum conditions.4.2 The percentage of biodegradability is obtained by de-termining the percent of convers
21、ion of carbon from the testmaterial to carbon in the gaseous phase (CH4and CO2). Thispercentage of biodegradability will not include the amount ofcarbon from the test substance that is converted to cell biomassand that is not, in turn, metabolized to CO2and CH4.5. Significance and Use5.1 Decompositi
22、on of a plastic within a landfill involvesbiological processes that will affect the decomposition of othermaterials enclosed by, or in close proximity to, the plastic.Rapid degradation of the plastic has the ability to increase theeconomic feasibility of landfill-gas recovery, minimize theduration o
23、f after-care of the landfill, and make possible therecovery of the volume reduction of the waste due to biodeg-radation during the active life of the landfill. This procedurehas been developed to permit determination of the anaerobicbiodegradability of plastic products when placed in biologi-cally a
24、ctive environments simulating landfill conditions.5.2 As degradation occurs inevitably in a landfill, it is ofimmediate concern that the plastic materials do not producetoxic metabolites or end products under the various conditionsthat have the potential to occur in a landfill. The mixturesremaining
25、 after completion of the test method, containing fullyor partially degraded plastic materials or extracts, can besubmitted subsequently to ecotoxicity testing in order to assessthe environmental hazards posed by the breakdown of plasticsto varying degrees in landfills. This test method has beendesig
26、ned to assess biodegradation under optimum and less-than-optimum conditions.5.3 LimitationsBecause a wide variation exists in theconstruction and operation of landfills, and because regulatoryrequirements for landfills vary greatly, this procedure is notintended to simulate the environment of all la
27、ndfills. However,it is expected to closely resemble the environment of abiologically active landfill. More specifically, the procedure isintended to create a standard laboratory environment thatpermits rapid and reproducible determination of the anaerobicbiodegradability under accelerated landfill c
28、onditions, while atthe same time producing reproducible mixtures of fully andpartially decomposed household waste with plastic materialsfor ecotoxicological assessment.6. Apparatus6.1 Pressure-Resistant Glass VesselsTwenty-seven, eachwith a volume of 4 to 6 L, which can be closed airtight andcapable
29、 of withstanding an overpressure of two atmospheres.The lids of the reactors are equipped with an overpressurevalve (to prevent the overpressure from becoming higher than2 bars), a manometer that provides a rough indication of theoverpressure, a septum that allows one to take gas samples andmeasure
30、the exact overpressure, and, finally, a valve to releasethe overpressure (Fig. 1).6.2 Incubators, sufficient to store the vessels in the dark at35 6 2C for the duration of the test.6.3 Pressure Transducer, connected to a syringe needle tomeasure the headspace pressure in the test vessel.6.4 Gas Chro
31、matograph, or other apparatus, equipped witha suitable detector and column(s) for measuring methane andcarbon dioxide concentrations in the evolved gases.6.5 pH Meter, precision balance (60.1 g), analytical bal-ance (60.1 mg), thermometer, and barometer.1 = Digester.2 = Incubation chamber.3 = Overpr
32、essure valve.4 = Manometer.5 = Septum.6 = Valve.FIG. 1 Setup of Accelerated LandfillD5526 1226.6 Suitable Devices, for determining volatile fatty acids byaqueous-injection chromatography, total Kjeldahl nitrogen,ammonia nitrogen, dry solids (105C), and volatile solids(550C) concentrations.7. Reagent
33、s and Materials7.1 Pretreated-Household Waste, derived from mixed mu-nicipal solid waste or the organic fraction thereof, afterhomogenizing, screening over a screen with holes of a diam-eter of 40 to 80 mm, and aerobically stabilized over a period of2 to 4 weeks by blowing air into the material and
34、maintaininga dry-matter content of 50 6 5 % and a temperature of 55 610C. (Optional: the pretreated household waste can be re-placed by a similarly pretreated simulated solid waste.)7.2 Anaerobic Inoculum, derived from a properly operatinganaerobic digester with pretreated household waste as a soles
35、ubstrate or a digester that treats predominantly householdwaste.7.3 Cellulose, Analytical-Grade, for thin-layer chromatog-raphy as a positive control.67.4 Polyethylene (optional), as a negative control. It needsto be in the same form as that in which the sample is tested:film polyethylene for film s
36、amples, pellets of polyethylene incase the sample is in the form of pellets, etc.8. Hazards8.1 This procedure involves the use of inoculum and mu-nicipal solid waste containing biologically and possibly chemi-cally active materials known to produce a variety of diseases.Avoid contact with these mate
37、rials by wearing gloves and otherappropriate protective equipment. Use good personal hygieneto minimize exposure.8.2 It is possible that the solid waste mixture will containsharp objects. Take extreme care when handling this mixture toavoid injury.8.3 This test method includes the use of hazardous c
38、hemi-cals. Avoid contact with the chemicals and follow the manu-facturers instructions and material safety data sheets.8.4 The methane produced during the procedure is explo-sive and flammable. Upon release of the biogas from thegas-collection system, take care in venting the biogas to theoutside or
39、 to a hood.9. Inoculum9.1 The inoculum can be derived either from a laboratory-scale or full-scale continuous digester or batch digester, oper-ating at 35C and functioning with an organic fraction ofhousehold waste as the predominant substrate. In case theinoculum is derived from a continuous labora
40、tory-scale orfull-scale digester, the digester must be operating for a periodof at least one month on the organic fraction of householdwaste, with a maximum retention time of 30 days undermesophilic conditions (35 6 2C). Gas production yields mustbe at least 15 mL at standard temperature and pressur
41、e ofbiogas/gram of dry solids in the digester and per day for at least7 days. In case the inoculum is derived from a batch digester,the gas production rate must have exceeded 1 L/kg waste/day,and the methane concentration of the biogas being producedmust be above 60 %.9.2 The prepared inoculum needs
42、 to undergo a short meso-philic post-fermentation of approximately 7 days at the samedry-matter content as the digester from which it was derived.This means that the inoculum is not fed but is allowed topost-ferment anaerobically by itself. This is to ensure thatlarge, easily biodegradable particles
43、 are degraded during thisperiod and also to reduce the background level of degradationof the inoculum itself.9.3 The biochemical characteristics of the inoculum shall beas follows:9.3.1 pHBetween 7.5 and 8.5 (in accordance with TestMethods D1293);9.3.2 Volatile Fatty Acids (VFA)Below 1 g/kg wet weig
44、ht(in accordance with Practice D2908); and9.3.3 NH+4-NBetween 0.5 and 2 g/kg (in accordance withAPHA Test 212 and Test Method D3590).9.4 Analyses are performed after dilution of the inoculumwith distilled water on a ratio of distilled water to inoculum of5 to 1 on a weight-over-weight basis.10. Test
45、 Specimen10.1 The test specimen needs to be of sufficient carboncontent, analyzed in accordance with Test Method D4129,toyield carbon dioxide and methane volumes that can be mea-sured accurately by the trapping devices described. Add moretest specimen when low biodegradability is expected, up to 100
46、g of dry matter of the test specimen.10.2 It is acceptable for the test specimen to be in the formof films, powder, pellets, or formed articles, or in the form ofa dog bone and in accordance with Practice D618. The testsetup needs to be capable of handling articles that are 100 by50 by 4 mm thick.11
47、. Procedure11.1 Preparation of the Mixtures:11.1.1 Determine the volatile solids, dry solids, and nitrogencontent of the pretreated household waste and the inoculum inaccordance with Test Methods D1888, D3590, and APHA2540D and 2540E.11.1.2 Determine the volatile solids, dry solids, and carbonconten
48、t of all test substances in accordance withAPHA2540Dand 2540E and Test Method D4129.11.1.3 Weigh and combine the components and adjust thedry matter content of the final mixtures with water to reach thedesired dry-matter content for each vessel. Roughly weigh out600 g on a dry-weight basis of pretre
49、ated household waste, andmix it with 100 g on a dry-weight basis of mesophilicanaerobic inoculum from a continuously operating digester or150 g on a dry-weight basis of anaerobic inoculum from abatch digester. Add 60 to 100 g of dry matter of the testsubstance. Add water until the appropriate final dry mattercontent is reached. (In order to reach 60 % dry matter contentin the mixture, it is necessary, in some cases, to have waterremoved prior to combining the different components of themixture. This can be accomplished by drying the pretreated6Avicelt, available
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