Disposal of Spent Coolant by Dynamic Membrane

Abstract

Coolants are used in metalworking processes to reduce friction, cooling, and chip removal. As a result of the use of coolant, spent emulsions are formed, which are more toxic than the original emulsion. The methods of purification of coolant containing wastewater, currently used at local treatment facilities of enterprises, do not provide a reduction in the concentration of basic pollutants to established standards, which causes significant environmental pollution. Currently, membrane methods are often used to separate spent emulsions. For ultrafiltration of spent emulsions, a dynamic membrane with an external polystyrene film and on a semipermeable basis of hydrophilic PTFE was obtained. According to the results of scanning electron microscopy, after applying a dynamic film, the membrane surface is coated with spherical polystyrene microparticles, in which particles with a size of 0.1 μm predominate and particles with sizes from 0.4 to 1.5 μm are found, which is confirmed by data from a study of the particle size of a polystyrene suspension. A high retention ability of the PTFE-PSd dynamic membrane for oil products was revealed: more than 94% at a specific productivity of 410 dm3/m2h and a working pressure of 7 bar, which is no worse than the performance of a commercial UPM-100 ultrafiltration membrane.