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This post was last edited by slll611 on 2016-7-7 22:07. Metallurgical enterprises generate large amounts of oily wastewater during the steel rolling process; its sources include acidic wastewater discharged from the pickling lines； Wastewater containing salts and metal ions discharged after the activation or passivation treatment of steel surfaces ； Additionally, during steel rolling, in order to eliminate the thermal deformation caused by cold rolling, emulsions are used for cooling and lubrication (emulsions are primarily composed of 2–10% mineral oil or vegetable oil, anionic or non-ionic emulsifiers, and water), and the wastewater resulting from these cold rolling emulsions is generated as a consequence ； The cooled strip steel must be degreased with an alkaline solution before loose-coil annealing, which generates alkaline oily wastewater ； During the production of cold-rolled stainless steel, oil- and fat-containing rolling emulsion waste fluids are discharged, either continuously or intermittently, during processes such as annealing, pickling, cold rolling, grinding, polishing, leveling, and cutting ； Hot rolling and silicon steel plants also face the problem of emulsion wastewater discharge. Among these wastewater types, treating cold-rolling emulsion wastewater is the most challenging; conventional methods for treating oily wastewater, such as air flotation, adsorption, biological treatment, and chemical treatment, fail to achieve satisfactory results. Introduction to the process of using ceramic membranes for treating cold-rolling emulsion wastewater: Ceramic membranes possess outstanding advantages such as corrosion resistance, high mechanical strength, a narrow pore size distribution, and a long service life; these characteristics have attracted widespread attention both domestically and internationally, and they have been applied in many fields. Ceramic membrane treatment of oily wastewater features stable operation, high flux, good effluent quality, with an oil content of less than 10 ppm. Ceramic membrane equipment occupies a small space; it does not consume any chemical agents during normal operation nor does it generate new sludge. The quality of the recovered oil is good, and it has increasingly shown great competitiveness in the field of oily wastewater treatment. The cold-rolling emulsion wastewater enters the raw water tank; after appropriate pretreatment, it is pumped into the primary and secondary circulation tanks. From there, it is fed to the ceramic membrane modules. These modules operate using an internal and external circulation system, with the circulation pump responsible for maintaining the flow rate over the membrane surface, while the feed pump provides the pressure necessary for the system’s operation. The concentration ratio of the system is adjusted by controlling the flow rate of the feed pump. The concentrated liquid resulting from the treatment by the membrane module returns to the circulation tank, while the permeate is sent to designated locations as water for general household use. Once the solid content in the circulation tank reaches a certain level, it returns to the reservoir; the waste oil is collected by an oil skimmer, while the sediment is removed by a sludge scraper. Technical advantages: In 2001, the Ministry of Science and Technology assigned the research task of \"Developing technologies for the reuse of wastewater from steel cold-rolling emulsions\" to the Institute of Membrane Science and Technology at Nanjing University of Technology. Domestic steel companies such as Wuhan Iron and Steel Group Corporation’s Energy Plant have subsequently entered into horizontal research contracts with the Institute to utilize inorganic ceramic membrane technology for treating waste emulsions from cold rolling processes. Through more than six years of research from July 1997 to September 2003, the Membrane Science and Technology Institute of Nanjing University of Technology carried out studies and engineering design work on the pilot-scale, pilot plant-scale, and industrial application of ceramic membranes for treating cold-rolling wastewater. It resolved several key issues related to the industrial use of ceramic membranes in treating cold-rolling emulsion wastewater. As a project under the 10th Five-Year Plan, it was approved by experts in Nanjing in September 2003. To date, dozens of ceramic membrane systems utilizing this technology have been successfully put into use in China, yielding significant economic and social benefits. Technical features: High oil retention rate; the oil content in the effluent is less than 10 ppm, meeting environmental standards ； A large amount of valuable oil can be recovered after concentration ； Resistant to acids, alkalis, and oxidizing substances; resistant to microbial erosion; long service life ； It uses cross-flow filtration, is resistant to contamination, and enables high-throughput filtration ； No need to use expensive demulsifiers or flocculants, resulting in low operating costs ； The membrane cleaning cycle is long, and the recovery of cleaning flux is good and stable ； It enables automatic PLC control, reduces labor intensity, and saves on labor costs ； There are few vulnerable parts, the equipment is easy to maintain, and maintenance costs are low.