ASTM D5864, ASTM D6731 Lubricant Biodegradation Test (ISO/IEC 17025:2017 Accredited)

ASTM D5864 and ASTM D6731 are two standard biodegradation test methods for determining aerobic aquatic biodegradability of lubricants or their components.

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CONCEPT

ASTM D5864 and D6731 are two ASTM methods specifically designed for the biodegradation test of lubricants or their components. ASTM D5864 measures the CO₂ evolution, which is equivalent to the OECD 301B method. ASTM D6731 measures the oxygen consumption, which is equivalent to the OECD 301F.

ASTM6731 is our preferred method for lubricant test due to its simple system setup and high applicability.

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ASTM D5864

Similar to the OECD 301B CO₂ Evolution Test, ASTM D5864 measures the CO₂ evolution to reflect the biodegradation of fully formulated lubricants or their components, based on the exposure to activated sludge from municipal wastewater treatment plant as the inoculum under laboratory conditions.

This method is designed for all lubricants that are not volatile and are not inhibitory to the inoculum at the test concentration. It is intended to specifically address the issues associated with insoluble substances and complex mixtures that are commonly found in lubricants.

It can handle materials that are soluble, insoluble and/or absorbing. Good dispersion with continuous mixing is usually required for better performance.

Test substances that achieve high levels of biodegradation are assumed to be easily biodegradable in most aerobic aquatic environments.

ASTM D6731 (highly recommended)

Similar to the OECD 301F Closed Respirometer Test, ASTM D6731 measures oxygen consumption to reflect the biodegradation of fully formulated lubricants or their components, based on the exposure to activated sludge from municipal wastewater treatment plant as the inoculum under laboratory conditions.

It has the highest applicability among all other methods and can handle materials that are highly soluble, poorly soluble, insoluble, volatile, involatile, and/or adsorbing. Good dispersion with continuous mixing is usually required for better performance.

Test substances that achieve high levels of biodegradation are assumed to be easily biodegradable in most aerobic aquatic environments.

ASTM D6731 is our second recommended method (following OECD 301F ) due to its simple experimental setup and high applicability.

Requirement and Applicability

Different testing methods are applicable for materials with different properties. Below is a summary of the applicability of ASTM D5864 and D6731. Please check our Method Selection Guide to select the most appropriate method for your materials. You can also find the applicability for many other methods on Aropha Resource Center
.

Test	Analytical method	Sample info required *	Poorly soluble	Volatile	Adsorbing
ASTM D5864 (CO₂ evolution test)	CO₂ evolution	Organic carbon content *	+	-	+
ASTM D6731 (Closed respirometer test)	Oxygen consumption	ThOD or COD *	+	+/-	+

*"Sample info required" is the information needed to calculate the biodegradation percentages. This must be available for a selected method.
*"Organic carbon content" is the ratio of the organic carbon weight to the weight of the sample. It can be calculated by the sample formula (e.g., acetic acid C₂H₄O₂, carbon content is 12*2/(12*2+1*4+16*2)=40%). Try our Online C% Calculator. If the formula is unknown, we can send the sample out to a third party lab for you for analysis (normally $110 with a 10-day turnaround time).
*"ThOD" can be easily calculated based on the formula of the sample. Try our Online ThOD Calculator.
*"COD" can be used as an alternative to ThOD if the formula of the material is unknown. We provide COD analysis at Aropha.

Aropha Resource Center

To learn more about different types of biodegradation tests, their applicability, biodegradation mechanisms, and many other information such as case studies, publications, and blogs, please check our Aropha Resource Center
.