Continued from page 38
In the latter case, the inoculum varies from lab to lab and the number of micro-organisms will never be a stable and consistent size due to their competition for sustenance on the surface of the lubricant and their different growth rates.
Nevertheless, one has to keep in mind that test results on biodegradation according to EN 17181 do indicate the biodegradation level of a fully formulated product.
No information is given whether the residual content of non-degraded material is mainly non-biodegradable and/or bio-accumulative, or just not degraded.
Future work items and outlook To date, bioaccumulation is tested on single substances only. In the case of complex mixtures, test results are not significant and interpretation is difficult.
Nevertheless, bioaccumulation data already exist for chemical products which cannot be seen as pure single substances. It should therefore be possible to find an approach for testing of mixtures, with the first discussions having started in relation to WG33[8].
Even assuming a full test kit for renewable content, toxicity, biodegradation and bioaccumulation for finished lubricants, this would still probably not completely describe a bio-lubricant as a product of lowest possible harmful impact to the environment.
For this the use of a lubricant in a discrete application and comparison of a bio-lubricant to a conventional product would need to be considered.
A further factor to consider is whether the conventional lubricant would run longer in a machine than the bio-lubricant.
Naturally, a comprehensive rating would need to cover the whole life cycle of both products to finally decide if the bio-lubricant will be the one of lowest possible impact on the environment. This is another challenging item that opens the door for future work – not only in TC 19 WG33.
Conclusion
TC19 WG33 established a definition standard EN 16807, actually providing a tool kit of tests to check finished products with regard to renewable content,
40 LUBE MAGAZINE NO.160 DECEMBER 2020
[1] Mandate M/430 of EC to CEN; Brussels 2008-10-10
[2] Einführung in die Erfolgsgeschichten Umweltzeichen Blauer Engel, p.12; UBA 2008-02- 19
[3] Registered Trademark No. 74159129, Mobil Oil Copr. – registered 1992-06-30
[4] CEN/TR 16227 Liquid petroleum products - Bio-lubricants - Recommendation for termin- ology and characterisation of bio-lubricants and bio-based lubricants 2011-08
[5] EN 16807:2017 Liquid petroleum products - Bio-lubricants - Criteria and requirements of bio-lubricants and bio-based lubricants 2017-02-08
[6] EN 17181:2019 Lubricants - Determination of aerobic biological degradation of fully formulat-ed lubricants in an aqueous solution - Test method based on CO2
-production 2019-05
[7] Technical report on ILS of aerobic aquatic biodegradation of finished formulated lubricants; to be published
[8] Fraunhofer IME presentation on the 27th meeting of TC19 WG33; 2018-10-04
biodegradability, aquatic toxicity and technical performance.
A consequent use of this definition standard in the lubricant industry could stop the confusing over-use of the term “bio-“ in the market and provide greater transparency to customers, enabling them to verify for themselves if these products are bio-lubricants. More effort is needed to further improve the applicability of this standard.
Future activities in TC19 WG33 will see further development on the precision of biodegradation test methods as well as first attempts to evaluate bioaccumulation tests for finished lubricants and discussions about the life cycle of bio-lubricants.
LINK
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