1、Designation: D 5988 03Standard Test Method forDetermining Aerobic Biodegradation in Soil of PlasticMaterials or Residual Plastic Materials After Composting1This standard is issued under the fixed designation D 5988; the number immediately following the designation indicates the year oforiginal adopt
2、ion 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. Scope*1.1 This test method covers determination of the degree andrate of aerobic
3、biodegradation of synthetic plastic materials(including formulation additives that may be biodegradable) incontact with soil, or a mixture of soil and mature compost,under laboratory conditions.1.2 This test method is designed to rate the biodegradabilityof plastic materials relative to a standard i
4、n an aerobicenvironment.1.3 This test method is designed to be applicable to allplastic materials that are not inhibitory to the bacteria and fungipresent in soil and compost.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 thes
5、afety 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. A specific hazardstatement is given in Section 8.1.6 This ASTM test met
6、hod is equivalent to ISO17556:2003.2. Referenced Documents2.1 ASTM Standards:2D 425 Test Method for Centrifuge Moisture Equivalent ofSoilsD 618 Practice for Conditioning Plastics and ElectricalInsulating Materials for TestingD 883 Terminology Relating to PlasticsD 1193 Specification for Reagent Wate
7、rD 1293 Test Methods for pH of WaterD 1898 Practice for Sampling of PlasticsD 2980 Test Method for Volume Weights, Water-HoldingCapacity, and Air Capacity of Water-Saturated Peat Mate-rialsD 2989 Test Method for Acidity-Alkalinity of HalogenatedOrganic Solvents and Their AdmixturesD 4129 Test Method
8、 for Total and Organic Carbon in Waterby High-Temperature Oxidation and Coulometric Detec-tionD 4972 Test Method for pH of SoilsD 5338 Test Method for Determining Aerobic Biodegrada-tion of Plastic Materials Under Controlled CompostingConditionsD 5511 Test Method for Determining Anaerobic Biodegra-d
9、ation of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions2.2 APHA-AWWA-WPCF Standards:32540 D Total Suspended Solids Dried at 103105C2540 G Total, Fixed, and Volatile Solids in Solids andSemi-Solid Samples2.3 ISO Standard:ISO 17556:2003 PlasticsDetermination of the UltimateAerobic
10、Biodegradability of Plastic Materials in Soil byMeasuring the Oxygen Demand in a Respirometer or theAmount of Carbon Dioxide Evolved3. Terminology3.1 DefinitionsDefinitions of terms applicable to this testmethod appear in Terminology D 883.4. Summary of Test Method4.1 The test method described consi
11、sts of the selection ofplastic material or compost containing residual plastic materialafter composting for the determination of aerobic biodegrad-ability, obtaining soil as a matrix and source of inoculum,exposing the plastic materials or the compost containingresidual plastic material to the soil,
12、 measuring the carbondioxide evolved by the microorganisms as a function of time,and assessing the degree of biodegradability.4.2 The CO2production measured for a material, expressedas a fraction of the measured or calculated carbon content, is1This test method is under the jurisdiction of ASTM Comm
13、ittee D20 on Plasticsand is the direct responsibility of Subcommittee D20.96 on EnvironmentallyDegradable Plastics.Current edition approved November 1, 2003. Published January 2004. Originallyapproved in 1996. Last previous edition approved in 1996 as D 5988 - 96.2For referenced ASTM standards, visi
14、t the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Standard Methods for the Examination of Water and Wastewater, 17th Edition,1989, American Public
15、 Health Association (APHA), 1015 Fifteenth Street NW,Washington, DC 20005.1*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.reported with respect to time, from which the
16、 degree ofbiodegradability is assessed.4.3 Alternatively, the consumption of oxygen, or biochemi-cal oxygen demand (BOD), can be determined, for example, bymeasuring the amount of oxygen required to maintain aconstant gas volume in the respirometer flask, or by measuringthe change in volume or press
17、ure (or a combination of the two)either automatically or manually. The level of biodegradationexpressed in percent is determined by comparing the BOD withthe theoretical oxygen demand (ThOD). The influence ofpossible nitrification processes on the BOD has to be consid-ered.5. Significance and Use5.1
18、 The degree and rate of aerobic biodegradability of aplastic material in the environment determines the extent towhich and time period over which plastic may be mineralized.Disposal is becoming a major issue with the increasing use ofplastics, and the results of this test method may permit anestimat
19、ion of the degree of biodegradability and the timeperiod over which plastics will remain in an aerobic soilenvironment. This test method determines the degree ofaerobic biodegradation by measuring evolved carbon dioxideas a function of time that the plastic is exposed to soil.5.2 Soil is an extremel
20、y species-rich source of inoculum forevaluation of the biodegradability of plastics in the environ-ment. When maintained appropriately with regard to moisturecontent and oxygen availability, the biological activity is quiteconsiderable, although lower than other biologically activeenvironments, such
21、 as activated sewage-sludge or compost.Soil is also the application target for composted materials, andtherefore the biodegradability of such materials should beevaluated in the soil environment after the materials have beencomposted. A mixture of soil and mature compost containingcomposted plastic
22、material (as obtained after performing TestMethod D 5338) is therefore also an appropriate matrix forevaluation of the biodegradability of plastics.6. Apparatus6.1 Soil-Contact Incubation Apparatus (see Fig. 1; biom-eter flasks are also appropriate):6.1.1 Vessels, a set of approximately 2 to 4-L int
23、ernalvolume that can be sealed air-tight, such as 150-mm desicca-tors. For testing a plastic material in soil: three vessels for soilonly controls, three for a positive control material, and threeper test material. For testing a compost containing residualplastic material: three for soil only contro
24、ls, three for a positivecontrol material in soil, three for the compost-soil control, andthree per compost containing test material (optional: three forthe compost containing the positive reference from the previ-ous composting test). In either case, three vessels may also beincluded as technical co
25、ntrols, containing only the absorbingsolution and no soil.6.1.2 Beakers, sets of 150 and 100-mL, equal in number tothe soil incubation vessels.6.1.3 Perforated Plates or Other Support, a set to hold thebeakers above the soil inside each vessel.6.1.4 Darkened Chamber or Cabinet, in which the tempera-
26、ture is maintained at 21 6 2C.6.2 Analytical Equipment:6.2.1 Analytical Equipment, to measure the total carboncontent of the test specimen.6.2.2 Analytical Balance, to weigh the test specimen.6.2.3 Burette, 100 mL.6.2.4 Bench-Top Centrifuge, for moisture-holding capacity(MHC) determination.6.2.5 Ove
27、n, set to 104 6 1C for moisture determinations.6.2.6 Muffle Furnace, set to 550C for ash determinations.6.2.7 pH Meter.6.3 Alternatively, a flow-through apparatus or manometricapparatus as described in ISO 17566 may be used.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall
28、 beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provided it is first ascertained that the reagent i
29、s of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Ammonium phosphate, (NH4)2HPO4), 4.72 g/L.7.3 Barium Hydroxide Solution (0.025 N), prepared bydissolving 4.0 g anhydrous Ba(OH)2/L of distilled water. Filterfree of solid material, confirm normality
30、 by titration withstandard acid, and store sealed as a clear solution to preventabsorption of CO2from the air. It is recommended that 5 to 20L be prepared at a time when running a series of tests. Whenusing Ba(OH)2, however, care must be taken that a film ofBaCO3does not form on the surface of the s
31、olution in thebeaker, which would inhibit CO2diffusion into the absorbingmedium. Alternatively, potassium hydroxide solution (KOH,0.5 N) could be used and is prepared by dissolving 28 g of4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For sugg
32、estions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.NOTE 1(1) Barium hydroxide so
33、lution or potassium hydroxide solu-tion, (2) soil, (3) water, and (4) perforated plate.FIG. 1 Soil-Contact Incubation ApparatusD5988032anhydrous KOH/L of distilled water and proceeding in thesame way as for the KOH.7.4 Hydrochloric acid, 0.05 N HCl when using 0.025 NBa(OH)2, or 0.25 N HCl when using
34、 0.5 N KOH.8. Hazards8.1 This test method includes the use of hazardous chemi-cals. Avoid contact with chemicals and follow the manufactur-ers instructions and material safety data sheets.9. Soil9.1 The soil can be a laboratory mixture of equal parts (byweight) of sand, topsoil, and composted manure
35、 or a naturalsoil sample. The soil should not be handled in any way thatwould inhibit the activity of the soil microorganisms. In thecase of a natural soil, it is advisable to avoid soils that havebeen exposed to pollutants that may cause a significantperturbation of the microbial population. The so
36、urce of the soilmust be reported (see 14.1.1). The test soil may also be amixture of a natural soil and a mature compost, as obtained atthe end of Test Method D 5338. A ratio of 1 g compost to 25g soil corresponds to a typical application of approximately120 tons of compost per hectare of agricultur
37、al land, assuming20 cm of soil depth and a bulk density of 1.5 Mg m3.9.2 The soil is sieved to less than 2-mm particle size, andobvious plant material, stones, or other inert materials shouldbe removed. The soil is then stored in a sealed container at 4 61C for a maximum of one month.9.3 The soil is
38、 analyzed for MHC by Test Method D 425,Test Method D 2980, or another analogous test method forMHC or field capacity.9.4 The pH of the soil is determined on a 5:1 (distilledwater:soil) slurry using a glass combination electrode cali-brated with standard buffers, following the guidelines given inTest
39、 Methods D 1293. The pH must fall between 6.0 and 8.0.(Soil with a pH above 8.0 may retain more of the CO2evolvedby the microorganisms than a neutral soil, and soil with a pHbelow 6.0 may have an atypical microbial population.) Alter-natively, the soil pH may be determined by Test MethodD 4972.9.5 T
40、he moisture (total solidsdry solids) and ash (totalsolidsvolatile solids) contents of the soil are determined inaccordance with APHA-AWWA-WPCF 2540 D and G, respec-tively.10. Test Specimen10.1 Test specimens should be of known weight and havesufficient carbon content to yield carbon dioxide that can
41、 bemeasured accurately by the trapping procedure described inthis test method (see 11.1 and 11.4). The carbon content of thetest material may be determined by calculation or elementalanalysis, according to Test Method D 4129.10.2 Test specimens may be in the form of films, pieces,fragments, powders,
42、 or formed articles, or in aqueous solution,and they should be in accordance with Practice D 618. Any testspecimens in the form of powders should be characterized as toparticle size distribution by sieve analysis.10.3 Test specimens can be added directly to the soil matrixor, alternatively, after be
43、ing submitted to a composting test(Test Method D 5338). In the latter case, a homogenous andrepresentative sample of the compost containing the residualplastics is used.11. Procedure11.1 Place between 100 and 500 g of soil in the bottom ofthe vessel.11.2 Amend the soil with nitrogen to give a C:N of
44、 between10:1 and 20:1 (by weight) to the added carbon in the testspecimen by adding the appropriate volume of ammoniumphosphate solution. Add the same amount of nitrogen to thesoil blanks as to those that will receive a test material orpositive control material.11.3 Add distilled water, prepared in
45、accordance with Speci-fication D 1193, to bring the moisture content to 80 to 100 %of the MHC of the soil (if the MHC is determined inaccordance with Test Method D 425; if in accordance with TestMethod D 2989, then 50 to 70 % MHC is appropriate).11.4 Add the test specimen or positive control to the
46、soil(approximately 200 mg to 1000 mg carbon for 500 g soil), andmix the soil thoroughly. In the case of compost with plasticmaterials coming from Test Method D 5338 or Test MethodD 5511, the amount of compost should be 20 to 50 g added to500 g of soil.11.5 Record the weight of the vessel and lid (wi
47、th thenecessary amount of stopcock grease to seal air-tight) withamended soil.11.6 Place 100 mL of 0.025 N barium hydroxide solution ina 150-mL beaker (or 20 mL of 0.5 N KOH in a 100-mL beaker)and 50 mL of distilled water in a 100-mL beaker on theperforated plate inside the vessel; seal the vessel a
48、nd place it inthe dark chamber or cabinet at 21 6 2C.11.7 Carbon Dioxide Analysis:11.7.1 The carbon dioxide produced in each vessel reactswith Ba(OH)2and is precipitated as barium carbonate(BaCO3). The amount of carbon dioxide produced is deter-mined by titrating the remaining barium hydroxide with
49、0.05 Nhydrochloric acid to a phenolphthalein end-point or by auto-matic titrator. Because of the static incubation, the bariumcarbonate builds up on the surface of the liquid and must bebroken up periodically by shaking the vessel gently to ensurecontinued absorption of the evolved carbon dioxide. (Thisproblem can be avoided by using KOH instead of Ba(OH)2,which does not form a precipitate.)11.7.2 The barium hydroxide traps must be removed andtitrated before their capacity is exceeded. Considering that a150-mm desiccator vessel provides approximately 2000 cm3headspace,
