ASTM_D_5120_-_90_2004.pdf

Designation:D 5120 90(Reapproved 2004)Standard Test Method forInhibition of Respiration in Microbial Cultures in theActivated Sludge Process1This standard is issued under the fixed designation D 5120;the number immediately following the designation indicates 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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers a batch procedure that evaluatesthe impact of selected wastewaters,materials,or specificcompounds on the respiration rate of an aqueous microbialculture,such as activated sludge.1.2 Alternative procedures for measurement of microbialactivity,such as adenosine 58 triphosphate(ATP),specificsubstrate utilization,etc.are not within the scope of this testmethod.1.3 The results obtained are based on comparisons in aspecific test series that examines a range of concentrations ofthe potentially inhibitory test candidate using batch methods ina laboratory.Results are completed in a short time frame(a fewhours).1.4 The test results are specific to the microbial culture used.Microbial culture from different wastewater treatment plantswill differ in kinds and numbers of organisms,and performancecapability.Thus,there is no basis for comparing results formicrobial cultures from different treatment facilities.1.5 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 use.2.Referenced Documents2.1 ASTM Standards:2D 4478 Test Methods for Oxygen Uptake3.Terminology3.1 Definitions:3.1.1 respiration ratethe quantitative consumption ofoxygen by an aqueous microbial system.The consumption isgenerally expressed as mg O2/L/h.3.1.2 EC50the concentration of the test candidate in thisprocedure(volume percent or mg/L)that results in a reductionof respiration rate to 50%of that observed for the control.4.Summary of Test Method4.1 This test method utilizes respiration rate as the indicatorof microbial activity.4.2 A batch system that contains a microbial culture(re-turned activated sludge from the process or a culture main-tained in the laboratory),selected nutrient dose,and a dilutionof a compound,substance,wastewater,etc.(test candidate)isprepared in a container in the laboratory.The batch system iscalled a“cell suspension.”4.3 The nutrient dose introduces a large excess of biode-gradable substrate thereby putting the culture at a high meta-bolic rate.Inhibition of respiration by the test candidate isobserved under these conditions.4.4 The prepared cell suspension is aerated for a 2-h period.At the end of the period,the respiration rate is determinedusing a respirometric or an oxygen uptake technique.4.5 A lower respiration rate for a cell suspension that hasreceived the test candidate compared to the respiration rate ofa control cell suspension indicates inhibition of respiration.5.Significance and Use5.1 The objectives of the respiration inhibition tests may bedefined by the interests of the user,but the test method isdesigned primarily for examination of the inhibition responsewith operating microbial systems such as an activated sludgeprocess treating domestic or industrial wastes.5.2 Different apparatus exist that facilitate continuous orcontinual measurement of respiration in microbial systems andeach may be used as the tool to observe respiration in this testmethod.5.3 Respirometry may utilize any apparatus and techniquethat will achieve the determination of respiration rate.Anumber of devices are presented in Appendix X1.Equivalencyin the experimental capability of each device is not implied.The analyst should select the respirometric approach that bestsuits his needs.1This Test Method is under the jurisdiction of ASTM Committee D34 on WasteManagement and is the direct responsibility of Subcommittee D34.07 on MunicipalSolid Waste.Current edition approved Sept.28,1990.Published November 1990.2For 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 Document Summary page onthe ASTM website.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.4 The inhibitory effect of a test candidate is identifiedmore completely by examining inhibition over a range ofconcentrations,such as determining the EC50.The use ofaerated containers permits concurrent management of a seriesof cell suspensions.A respirometer for each cell suspensionmight also be used.6.Interferences6.1 This test method is most readily applied to substanceswhich,due to water solubility and low volatility,are likely toremain in the aqueous system.6.2