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ASTM OUR Standard Withdrawn

August 10, 2016

Much to My Dismay!


I am a strong advocate for the use and value of oxygen uptake rate (OUR) testing. I find this simple procedure to be so insightful when it comes to evaluating a biological treatment system. What always surprises me as I travel throughout the United States, as well as internationally, is how seldom OUR testing is performed or even known about. Nonetheless, I proceed to do my testing and present the results, with customers always showing great interest in the story the OUR tells. The fact is, no matter how much I seem to advocate on behalf of OUR testing, it just does not appear to be broadly recognized as providing valuable information. So, I guess, it should not have come as a surprise, though I was very surprised, to find that the standards organization known as ASTM International dropped their OUR standard, ASTM D5120-90 (2009). I copied the following information (though the bolding of the text is mine) from the ASTM website (


ASTM D5120-90 (2009)


Standard Test Method for Inhibition of Respiration in Microbial Cultures in the Activated Sludge Process (Withdrawn 2014)


Withdrawn Standard: ASTM D5120-90(2009) | Developed by Subcommittee: D34.03




Withdrawn Rationale:


This test method covered a batch procedure that evaluated the impact of selected wastewaters, materials, or specific compounds on the respiration rate of an aqueous microbial culture, such as activated sludge.

Formerly under the jurisdiction of Committee D34 on Waste Management, this test method was withdrawn in May 2014. This standard is being withdrawn without replacement due to its limited use by industry.


1. Scope


1.1 This test method covers a batch procedure that evaluates the impact of selected wastewaters, materials, or specific compounds on the respiration rate of an aqueous microbial culture, such as activated sludge.


1.2 Alternative procedures for measurement of microbial activity, such as adenosine 5′ triphosphate (ATP), specific substrate utilization, etc. are not within the scope of this test method.


1.3 The results obtained are based on comparisons in a specific test series that examines a range of concentrations of the potentially inhibitory test candidate using batch methods in a laboratory. Results are completed in a short time frame (a few hours).


1.4 The test results are specific to the microbial culture used. Microbial culture from different wastewater treatment plants will differ in kinds and numbers of organisms, and performance capability. Thus, there is no basis for comparing results for microbial cultures from different treatment facilities.


1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.


1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.




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