1, physical cleaning: generally refers to hydraulic cleaning, such as mechanical scrubbing and backwashing. Because no chemicals are introduced in the water washing process, the water washing method is the most economical. In particular, the membrane with good heat resistance has the best washing effect at high temperature. Backwashing is the main method of hydraulic cleaning, such as water flushing and air-water recoil expansion. Backwashing refers to the method of blowing gas or liquid from the side to remove the deposits on the membrane surface. External pressurization refers to backwashing with compressed air or liquid with a pressure of 0. 1MPa, and internal suction refers to periodically sucking air or liquid outside the membrane into the membrane for backwashing. After backwashing, the intermediate difference will decrease, but after operation, the membrane filtration pressure difference will increase, and the effluent will decrease. Too much backwashing water or too high backwashing pressure may damage the membrane structure. With the development of technology, the suction cleaning method has the advantages of no new equipment, good cleaning effect and no damage to the membrane.
2. Chemical cleaning: Chemical cleaning is the most effective method to deal with all kinds of pollution. The gel layer formed by macromolecules on the membrane surface is not very effective only by physical cleaning. Organic matter, silicon dioxide and biological pollutants are easy to be cleaned under alkaline conditions, and some metal ion pollution is easy to be dissolved under acidic conditions. Surfactants and chelating agents can remove firmly attached substances, but the cost is high. In addition, some people think that surfactants should be used with caution, because improper application may change the original surface characteristics of the membrane. For different types of membranes and different types of pollution, chemicals should be carefully selected to prevent the membranes from being damaged by chemical cleaning agents. Protein pollution can be removed by dissolving and removing minerals and DNANaOH aqueous solution with acid cleaner. After protein heavily polluted the membrane, washing it with 0.0 1mol/ln NaOH solution containing 0.5% pepsin for 30min can effectively restore the water permeability. In some applications, such as removing polysaccharides, water permeability can be restored by soaking in warm water and washing. The material comes from Yun Xi Environmental Protection. I hope I can help you.