The Study Of Metalworking Fluids Biodegradability By Indirect Measurement Of Bacterial Inoculum Respiration

An apparatus for measuring biodegradability of metalworking fluids (MWFs) was constructed according to (1), based on the Zahn-Wellens test which enables a continuous determination of CO₂ production by the change in conductivity of absorption solution. Results obtained from the testing of 8 different MWFs by this modified method were compared to those obtained in standardized OECD 302 B. The comparison showed better description of bacterial inoculum activity in tested solution; lag phase was easy to indicate. Tested emulsion achieved the level of primary degradability 39.7 – 40.8 %, and semi-synthetics 19.1 – 43.5%. The samples of synthetics where the degradation level reached 43.9 - 58.6 % were identified as the most degradable metalworking fluids.