A large amount of cutting fluid is used for lubrication and cooling in the mechanical processing and metal cold rolling industries. After long-term use, the cutting fluid will deteriorate and fail due to high temperature and microbial effects, resulting in high concentration cutting fluid wastewater and low concentration cutting fluid wastewater generated in the workpiece cleaning section. The discharge of cutting fluid wastewater causes serious environmental pollution. In China's national hazardous waste regulations, it is clearly stipulated that cutting fluid is an emulsion and belongs to hazardous waste. Therefore, cutting fluid wastewater must be strictly treated to meet national discharge standards.

At present, the commonly used emulsion treatment processes in China include: (1) the combination of physical and chemical methods and biochemical methods. This method is suitable for places with low emulsion concentration and large water volume. The operating cost of this process is low, the effluent effect is good, but there are disadvantages such as high investment, relatively complex operation management, and high requirements for operators; (2) The combination of physical-chemical method and adsorption method has strong applicability and easy operation, but the active filter material needs to be replaced after adsorption saturation, resulting in increased operating costs. (3) The combination of physical-chemical method and membrane filtration results in good effluent quality and convenient management of wastewater treated by this process, but there are difficulties in treating concentrated solution and backwash water, and membrane pores are prone to blockage. (4) The treatment process is complex and the operating cost of sewage is high. Inorganic ceramic membranes are increasingly being used in the treatment of waste emulsions due to their advantages of good chemical stability and high mechanical strength.