Biodegradable fluids are hydraulic fluids that biodegrade significantly more quickly than mineral oils. Biodegradation is a chemical conversion caused by microorganisms under aerobic conditions in an environment containing water that continues as far as mineralisation (OECD screening test).
The biodegradability, the pollution hazard for the ground and water, and the freedom from hazardous substances are important criteria for the environmental aspects of a hydraulic fluid.
Figure: Comparison of biodegradable hydraulic fluids