1、Designation: D 5526 94 (Reapproved 2002)Standard Test Method forDetermining Anaerobic Biodegradation of Plastic MaterialsUnder Accelerated Landfill Conditions1This standard is issued under the fixed designation D 5526; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the degree andrate of anaero
3、bic biodegradation of 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 w
4、ith pretreated household 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 ca
5、n be used to assess the 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. Thistest method may
6、not simulate all conditions found in landfills,especially biologically inactive landfills. This test method moreclosely resembles those types of landfills in which the gasgenerated is recovered or even actively promoted, or both, forexample, by inoculation (codeposition of anaerobic sewagesludge and
7、 anaerobic leachate recirculation), moisture controlin the landfill (leachate recirculation), and temperature control(short-term injection of oxygen and heating of recirculatedleachate) (1-7).21.3 This test method is designed to produce partially de-graded mixtures of municipal solid waste and plast
8、ics that canbe used to assess the ecotoxicological risks associated with theanaerobic degradation of plastics after various stages ofanaerobic biodegradation in a landfill.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafe
9、ty 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 use. Specific hazardsstatements are given in Section 8.NOTE 1There is no simila
10、r or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for Testing3D 883 Terminology Relating to Plastics3D 1293 Test Methods for pH of Water4D 1888 Test Methods for Particulate and Dissolved Matter,Solids, or Residue in Water5D 2908 Practice
11、for Measuring Volatile Organic Matter inWater by Aqueous-Injection Gas Chromatography6D 3590 Test Method for Total Kjeldahl Nitrogen in Water4D 4129 Test Method for Total and Organic Carbon in Waterby High-Temperature Oxidation and Coulometric Detec-tion6E 260 Practice for Packed Column Gas Chromato
12、graphy7E 355 Practice for Gas Chromatography Terms and Rela-tionships72.2 APHA-AWWA-WPCF Standards:82540D Total Suspended Solids Dried at 103105C2540E Fixed and Volatile Solids Ignited at 550C212 Nitrogen Ammonia3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod see Termin
13、ology D 883.3.2 Definitions of Terms Specific to This Standard:3.2.1 methanogenic inoculumanaerobically digested or-ganic waste containing a high concentration of anaerobicmethane-producing microorganisms.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct
14、responsibility of Subcommittee D20.96 on EnvironmentallyDegradable Plastics.Current edition approved March 15, 1994. Published May 1994.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3Annual Book of ASTM Standards, Vol 08.01.4Annual Book of ASTM Stand
15、ards, Vol 11.01.5DiscontinuedSee 1991 Annual Book of ASTM Standards, Vol 11.01.6Annual Book of ASTM Standards, Vol 11.02.7Annual Book of ASTM Standards, Vol 14.01.8Standard Methods for the Examination of Water and Wastewater, 17th ed.,1989, available from American Public Health Association, 1740 Bro
16、adway, NewYork, NY 10018.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 This test method described consists of the following: (1)selecting and analyzing material for testing; (2) obtaining apretreated mu
17、nicipal-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) removing thespecimens for cl
18、eaning (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 conversion of carbon from the te
19、stmaterial 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 Decomposition of a plastic within a
20、landfill involvesbiological processes that will affect the decomposition of othermaterials enclosed by, or in close proximity to, the plastic.Rapid degradation of the plastic may increase the economicfeasibility of landfill-gas recovery, minimize the duration ofafter-care of the landfill, and make p
21、ossible the recovery of thevolume reduction of the waste due to biodegradation during theactive life of the landfill. This procedure has been developed topermit determination of the anaerobic biodegradability ofplastic products when placed in biologically active environ-ments simulating landfill con
22、ditions.5.2 The decomposition of plastic materials in a landfill is oflimited importance, as few landfills are operated so as to bebiologically active. However, as degradation occurs inevitablyin a landfill, it is of immediate concern that the plastic materialsdo not produce toxic metabolites or end
23、 products under thevarious conditions that may occur in a landfill. The mixturesremaining 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
24、 the breakdown of plasticsto varying degrees in landfills. This test method has beendesigned 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 la
25、ndfills vary greatly, this procedure is notintended to simulate the environment of all landfills. 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
26、 reproducible determination of the anaerobicbiodegradability under accelerated landfill conditions, while atthe same time producing reproducible mixtures of fully andpartially decomposed household waste with plastic materialsfor ecotoxicological assessment.6. Apparatus6.1 Pressure-Resistant Glass Ve
27、sselsTwenty-seven, eachwith a volume of 4 to 6 L, which can be closed airtight andcapable 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 roug
28、h indication of theoverpressure, a septum that allows one to take gas samples andmeasure 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, conne
29、cted to a syringe needle tomeasure the headspace pressure in the test vessel.6.4 Gas Chromatograph, 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-
30、ance (60.1 mg), thermometer, and barometer.6.6 Suitable Devices, for determining volatile fatty acids byaqueous-injection chromatography, total Kjeldahl nitrogen,ammonia nitrogen, dry solids (105C), and volatile solids(550C) concentrations.7. Reagents and Materials7.1 Pretreated-Household Waste, der
31、ived from mixed mu-nicipal solid waste or the organic fraction thereof, after1 = Digester.2 = Incubation chamber.3 = Overpressure valve.4 = Manometer.5 = Septum.6 = Valve.FIG. 1 Setup of Accelerated LandfillD 5526 94 (2002)2homogenizing, screening over a screen with holes of a diam-eter of 40 to 80
32、mm, and aerobically stabilized over a period of2 to 4 weeks by blowing air into the material and 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 Inoculu
33、m, derived from a properly operatinganaerobic digester with pretreated household waste as a solesubstrate or a digester that treats predominantly householdwaste.7.3 Cellulose, Analytical-Grade, for thin-layer chromatog-raphy as a positive control.97.4 Polyethylene (optional), as a negative control.
34、It shouldbe in the same form as that in which the sample is tested: filmpolyethylene for film samples, pellets of polyethylene in casethe 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 ch
35、emi-cally active materials known to produce a variety of diseases.Avoid contact with these materials by wearing gloves and otherappropriate protective equipment. Use good personal hygieneto minimize exposure.8.2 The solid-waste mixture may contain sharp objects.Take extreme care when handling this m
36、ixture to avoid injury.8.3 This test method includes the use of hazardous chemi-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
37、 thegas-collection system, take care in venting the biogas to theoutside or 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 pre
38、dominant substrate. In case theinoculum is derived from a continuous laboratory-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
39、production yields mustbe at least 15 mL at standard temperature and pressure 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
40、the biogas being producedmust be above 60 %.9.2 The prepared inoculum should 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 anaerobical
41、ly by itself. This is to ensure thatlarge, easily biodegradable particles 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
42、 TestMethods D 1293);9.3.2 Volatile Fatty Acids (VFA)Below 1 g/kg wet weight(in accordance with Practice D 2908); and9.3.3 NH+4-NBetween 0.5 and 2 g/kg (in accordance withAPHA Test 212 and Test Method D 3590).9.4 Analyses are performed after dilution of the inoculumwith distilled water on a ratio of
43、 distilled water to inoculum of5 to 1 on a weight-over-weight basis.10. Test Specimen10.1 The test specimen should be of sufficient carboncontent, analyzed in accordance with Test Method D 4129, toyield carbon dioxide and methane volumes that can be mea-sured accurately by the trapping devices descr
44、ibed. Add moretest specimen when low biodegradability is expected, up to 100g of dry matter of the test specimen.10.2 The test specimen may be in the form of films, powder,pellets, or formed articles, or in the form of a dog bone and inaccordance with Practice D 618. The test setup should becapable
45、of handling articles that are 100 by 50 by 4 mm thick.11. 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 D 1888, D 3590, and APHA2540D and 2540E.11.1.2 D
46、etermine the volatile solids, dry solids, and carboncontent of all test substances in accordance with APHA 2540Dand 2540E and Test Method D 4129.11.1.3 Weigh and combine the components and adjust thedry matter content of the final mixtures with water to reach thedesired dry-matter content for each v
47、essel. Roughly weigh out600 g on a dry-weight basis of pretreated 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
48、 of the testsubstance. Add water until the appropriate final dry mattercontent is reached. (In order to reach 60 % dry matter contentin the mixture, water may have to be removed prior tocombining the different components of the mixture. This can beaccomplished by drying the pretreated household wast
49、e orcentrifuging the anaerobic inoculum.) Mix the requiredamounts of pretreated household waste, inoculum, and testsubstance in a small container for 2 to 3 min. Introduce themixture in the vessel, weigh the vessel with all of the contents,and close it airtight. Prepare the pressure vessels in thetriplicate at each of the following dry matter contents: 35, 45,and 60 %, so nine vessels are necessary for each sample.11.1.4 The blanks consist of 600 g dry matter of pretreatedhousehold waste and anaerobic inoculum at the respective totaldry-matter contents. As references,
