1、Designation: D6731 01 (Reapproved 2011)D6731 18Standard Test Method forDetermining the Aerobic, Aquatic Biodegradability ofLubricants or Lubricant Components in a ClosedRespirometer1This standard is issued under the fixed designation D6731; the number immediately following the designation indicates
2、the year oforiginal adoption or, in the case 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. Scope Scope*1.1 This test method covers a procedure for d
3、etermining the degree of biodegradability of lubricants or their components in anaerobic aqueous medium on exposure to an inoculum under controlled laboratory conditions. This test method is an ultimatebiodegradation test that measures oxygen demand in a closed respirometer.1.2 This test method is s
4、uitable for evaluating the biodegradation of volatile as well as nonvolatile lubricants or lubricantcomponents.1.3 This test method is applicable to lubricants and lubricant components which are not toxic and not inhibitory to the testmicroorganisms at the test concentration.1.4 The values stated in
5、 SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety
6、, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. Specific hazards are given in Section 10.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Deci
7、sion on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1293 Tes
8、t Methods for pH of WaterD4175 Terminology Relating to Petroleum Products, Liquid Fuels, and LubricantsD4447 Guide for Disposal of Laboratory Chemicals and SamplesD6384 Terminology Relating to Biodegradability and Ecotoxicity of LubricantsE943 Terminology Relating to Biological Effects and Environme
9、ntal Fate2.2 ISO Standards:3ISO 4259:1992(E)42591,2 Petroleum ProductsDeterminationproductsDetermination andApplicationapplication of PrecisionDataprecision data in Relationrelation to Methodsmethods of TesttestISO 6107-2:19976107-2 Water QualityVocabularyPartqualityVocabularyPart 2ISO 8192:19868192
10、 Water QualityTestqualityTest for Inhibitioninhibition of Oxygen Consumption by Activated Sludgeoxy-gen consumption by activated sludge for carbonaceous and ammonium oxidationISO 9408:19999408 Water QualityEvaluation of Ultimate Aerobic Biodegradability of Organic Compounds in Aqueous1 This test met
11、hod is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of SubcommitteeD02.12 on Environmental Standards for Lubricants.Current edition approved May 1, 2011Oct. 1, 2018. Published May 2011October 2018. Originally approved
12、 in 2001. Last previous edition approved in 20052011 asD6731D6731 01 (2011).01 (2005). DOI: 10.1520/D6731-01R11.10.1520/D6731-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume informatio
13、n, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an i
14、ndication of what changes have been made to the previous version. Becauseit 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 versionof the standard as published by ASTM is to b
15、e considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Medium by Determination of Oxygen Demand in a Closed RespirometerqualityEvaluation of
16、ultimate aerobic biodegrad-ability of organic compounds in aqueous medium by determination of oxygen demand in a closed respirometer2.3 OECD Standards:4OECD 301F:1992301F Ready Biodegradability-Manometric Respirometry2.4 APHA Standards:52540B Total Solids Dried at 103-105C9215 Heterotrophic Plate Co
17、unt3. Terminology3.1 Definitions:3.1.1 Definitions of terms applicable to this test method appear in the Compilation of ASTM Standard Definitions and thefollowing terminology standards: D1129, D4175, D6384, E943, and ISO 6107-2:1997.6107-2.3.1.2 activated sludge, nthe precipitated solid matter, cons
18、isting mainly of bacteria and other aquatic microorganisms, that isproduced at a domestic wastewater treatment plant and is used primarily in secondary sewage treatment to microbially oxidizedissolved organic matter in the effluent.3.1.3 aerobic, adj(a) taking place in the presence of oxygen; (b) li
19、ving or active in the presence of oxygen.3.1.4 biochemical oxygen demand (BOD), nthe mass concentration of dissolved oxygen consumed under specified conditionsby the biological oxidation of organic or inorganic matter, or both.3.1.4.1 DiscussionBOD determination is performed using empirical tests em
20、ploying standardized laboratory procedures. These tests measure oxygenutilization during a specified incubation period for the biochemical degradation of organic material (carbonaceous demand) inwater.3.1.5 biodegradation, nthe process of chemical breakdown or transformation of a test material cause
21、d by microorganisms ortheir enzymes.3.1.5.1 DiscussionBiodegradation is only one mechanism by which materials are removed, transformed, or both, in the environment.3.1.6 lag phase, nthe period of diminished physiological activity and cell division following the addition of microorganismsto a new cul
22、ture medium.3.1.7 log phase, nthe period of growth of microorganisms during which cells divide at a positive constant rate.3.1.8 pre-adaptation, nthe incubation of an inoculum in the presence of the test material which is done prior to the initiationof the test and under conditions similar to the te
23、st conditions.3.1.8.1 DiscussionThe aim of pre-adaptation is to improve the precision of the test method by decreasing variability in the rate of biodegradationproduced by the inoculum. Pre-adaptation may mimic the natural processes which cause changes in the microbial population ofthe inoculum lead
24、ing to more rapid biodegradation of the test material but is not expected to change the overall extent ofbiodegradation of the test material.3.1.9 pre-condition, nthe pre-incubation of an inoculum under the conditions of the test in the absence of the test material.3.1.10 sludge, na water-formed sed
25、imentary deposit.3.1.11 suspended solids (of an activated sludge or other inoculum samples), nsolids present in activated sludge or otherinoculum samples that are not removed by settling under specified conditions.4. Summary of Test Method4.1 Biodegradation of a lubricant or the component(s) of a lu
26、bricant is determined by measuring the oxygen consumed whenthe lubricant or component is exposed to microorganisms under controlled aerobic aquatic conditions. This value is then comparedto the theoretical amount of oxygen (ThO2) which is required to oxidize all of the elements (that is, carbon, hyd
27、rogen, nitrogen,4 Available from Organisation for Economic Cooperation and Development (OECD), 2 rue Andr Pascal, F-75775, Paris Cedex 16, France, http:/www.oecd.org.5 From Standard Methods for the Examination of Water and Wastewater, latest edition.Available from theAmerican Public HealthAssoc., 10
28、15 18th St., NW, Washington,DC 20036.D6731 182and so forth) in the test material. This test method mixes the test material (lubricant or component) with aerobic microorganismsin a closed respirometer containing a defined aquatic medium and measures the biodegradation of the test material by followin
29、gthe decrease in oxygen in the respirometer.4.2 The test material is the sole source of carbon and energy in the medium. A reference material known to biodegrade, suchas low erucic acid rapeseed oil (LEAR or canola oil) is run alongside the test material to confirm that the inoculum is viable andcap
30、able of biodegrading suitable materials under the test conditions. The test material or reference material concentration isnormally 5050 mgL to 100100 mg mg/L, L, providing a theoretical oxygen demand of at least 50 mg 50 mg O2/L but no morethan 200 mg O2/L. The ThO2 of the test and reference materi
31、als will be determined from measured elemental compositionalanalysis and will be calculated as in 13.1.4.3 The inoculated medium is stirred in a closed flask and the consumption of oxygen is determined either by measuring theamount of oxygen required to maintain a constant gas volume in the respirom
32、eter flask, or by measuring the change in volume orpressure (or a combination of the two) in the apparatus.4.4 Evolved CO2 (carbon dioxide) is absorbed in an alkaline trap solution (for example, 10 10 M NaOH or KOH) or otherCO2-absorbing system suspended within the test vessel, typically in the head
33、space of the test vessel.4.5 Biodegradation is followed over a specified period by determining the consumption of oxygen. The amount of oxygenutilized in oxidation of the test and reference material is corrected for oxygen uptake by the inoculum in the blank controls andis expressed as a percentage
34、of the theoretical oxygen demand (ThO2) calculated from the empirical formula of the material.Evaluation of the biodegradability of the test material is made on the basis of these data. Normally the test duration is 28 days;however, the test may be terminated if oxygen consumption has plateaued. The
35、 test may be extended as long as the systemsintegrity is maintained and the inoculum in the blank systems is viable. The duration of the test will be dependent on the lengthof time required for the rate of test material biodegradation to achieve a plateau. A graphical illustration of the test result
36、s for abiodegradable material is presented in Fig. 1.5. Significance and Use5.1 Results from this test method suggest the degree of aerobic, aquatic biodegradation of a lubricant or lubricant component.The rate and extent of oxygen consumption is measured upon exposure of the test material to an ino
37、culum within the confines ofa controlled laboratory setting. Test materials which achieve a high degree of biodegradation in this test may be assumed to easilybiodegrade in many aerobic aquatic environments.5.2 Because of the stringency of this test method, low results do not necessarily mean that t
38、he test material is not biodegradableunder environmental conditions, but indicate that further testing is necessary to establish biodegradability.5.3 If the pH value at the end of the test is outside the range from 6 to 8 and if the percentage degradation of the test materialis less than 50 %, it is
39、 advisable to repeat the test with a lower concentration of the test material or a higher concentration of thebuffer solution, or both.5.4 A reference or control material known to biodegrade under the conditions of this test method is necessary in order to verifythe activity of the inoculum. The tes
40、t must be regarded as invalid and shall be repeated using a fresh inoculum if the referencematerial does not demonstrate biodegradation to the extent of 60 % of the ThO2 within 28 days.FIG. 1 Respirometric TestBiodegradationTestBiodegradation CurveD6731 1835.5 Information on the toxicity of the test
41、 material to the inoculum may be useful in the interpretation of low biodegradationresults. Toxicity of the test material to the inoculum may be evaluated by testing the test material in combination with the referencematerial in inhibition control systems. If an inhibition control is included, the t
42、est material is assumed to be inhibiting if thedegradation percentage of the reference material is lower than 40 % (ISO 8192:1986).8192). In this case, it is advisable to repeatthe test with lower concentrations of the test material.5.6 Total oxygen utilization in the blank at the end of the test ex
43、ceeding 60 mg O2/L invalidates the test.5.7 The water solubility or dispersibility of the lubricant or component may influence the results obtained and hence comparisonof test results may be limited to lubricants or components with similar solubilities.5.8 The behaviors of complex mixtures are not a
44、lways consistent with the individual properties of the components. Test resultsfor individual lubricant components may be suggestive of whether a mixture containing these components (that is, fully formulatedlubricants) is biodegradable, but such information should be used judiciously.6. Apparatus6.
45、1 Closed Respirometer:6.1.1 The principle of a closed respirometer is given in Fig. 2. When testing volatile compounds, the apparatus used shall beappropriate or adapted to this particular purpose in accordance with the manufacturers instructions. Exercise care that the closedrespirometer apparatus
46、is well sealed to prevent any loss (for example, leakage) of volatile compounds from the system or ofoxygen into the system.6.1.2 The test mixture is stirred by a magnetic stirrer in the test flask, which is filled with sufficient volume to minimizeheadspace and prevent delay of O2 and CO2 diffusion
47、 through the air-water phases. This volume is dependent on the selected flasksize, and is normally specified by the manufacturer of the respirometer. If biodegradation takes place, the microorganisms consumeoxygen and produce carbon dioxide. Oxygen from the headspace is then dissolved in the liquid
48、to reestablish chemical equilibrium.The carbon dioxide produced by the microorganisms diffuses into the headspace where it is trapped in an absorbent solution ormaterial and the total pressure in the flask then decreases.6.1.3 This pressure drop is detected by a manometer, which produces a signal th
49、at results in the electrolytic generation ofoxygen. When the original pressure is re-established, the signal is stopped and the quantity of electricity used is measured. Theamount of electricity used is proportional to the amount of consumed oxygen. This is indicated on a plotter or a printer, or the dataare collected using an appropriate software program.6.2 Water-Bath or Constant Temperature Room, to comply with 11.2.FIG. 2 Principle of a Closed RespirometerD6731 1846.3 Centrifuge.6.4 pH-meter.6.5 Analytical Balance, capable of weighing to
