Machinery Lubrication

Machinery Lubrication March April 2014

Machinery Lubrication magazine published by Noria Corporation

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Page 26 of 83

22 March - April 2014 | By dr. MartiN Völt z INdUstrY FoCUs New test Method for lubricant Biodegradability F Following criticism of the Coordinating European Council's well-known biodegradability test (CEC-L-33-A-93) for its use of hazardous solvents, and with alternative tests not designed for testing lubricants, a technical development group (TDG-L-103) was formed to establish a replacement test method. After 3½ years, a new biodegradability test procedure has been devel- oped, thoroughly tested and approved. It essentially measures the loss of oil and oil-soluble metabolites over 21 days in a nature-like aqueous environment. Before presenting the new test method, an understanding of biodegradation may be useful. Biodegradation Biodegradation of organic material (natural or synthetic hydrocarbon compounds) is actually biochemical oxidation. It is initiated and performed by the enzymes of micro-organisms such as algae and microfungi. Although similar to combustion, this biochemical process is much longer, comprising several small bio-oxidation steps via long-chain alcohols and carboxylic acids, as well as shorter chain acids down to acetic acid and carbon dioxide. This process delivers energy to the micro-organ- isms. There is also another side reaction inside these "microbugs" that uses long-chain carboxylic acids for the formation of amino acids and proteins. This reaction makes the micro-organisms grow in size and number. When oil or other organic material is spilled into natural water containing the usual micro-organisms, the initial speed of biodegradation is very slow, as not all "bugs" present will accept this material as "food." Those that do will eat and grow in number and size, thus producing a faster biodegradation speed until this food (the added substrate) is fully consumed. The resulting degradation/time curve of any organic material usually has three stages: the lag (or adaptation) phase, the degradation (or exponential) phase and the stationary phase, where the new biomass will die away if no additional food is added. This type of degradation curve is found whenever the concentration of added organic material is observed. However, -CH 2 + 1½O 2 H 2 O + CO 2 Multi-stage biochemical oxidation catalyzed by enzymes of micro-organisms Biodegradation of hydrocarbon compounds The biodegradation process

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