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Methods for cleaning membranes: The main methods for cleaning membranes include hydraulic cleaning； Mechanical cleaning ； Chemical cleaning and electrical cleaning. The choice of cleaning method depends mainly on the membrane configuration, type of membrane, type of contaminants, resistance to chemical agents, as well as the nature of the contaminants. 1. Chemical cleaning: Chemical cleaning is the most important method for reducing membrane fouling, and a large number of patents on cleaning agent formulations have been published. There are many chemical reagents that can be used, either alone or in combination. Commonly used chemical reagents include acids (strong ones such as H3PO4, weaker ones such as lactic acid, etc.), bases (NaOH, KOH, etc.), detergents (alkaline, non-ionic), enzymes (proteases, amylases, glucose oxidase, etc.), chelating agents (EDTA, polyacrylates, sodium hexametaphosphate), and disinfectants (H2O2 and NaOCl). When making a specific choice, the cleaning agent should be selected and determined based on the type and severity of contamination, as well as the physical and chemical properties of the membrane. Examples are as follows: For cellulose acetate membranes (PH2.5–8.5, 50°C), the chemical cleaning process is as follows: rinsing with water → enzyme cleaner (P3-ultrasil 53, 1%, 60–90 minutes) → rinsing with room temperature water → acid cleaning (P3-ultrasil 75, 0.3%, 20 minutes) → rinsing with room temperature water → sterilization using peracetic acid (P3-oxonia aktiv, 0.3%, 20 minutes) → rinsing with room temperature water. For polysulfone membranes (PH1–13, 80°C), the chemical cleaning process is: rinsing with water → alkaline cleaning (P3-ultrasil 11, 0.5%–1%, 30 minutes) → rinsing with room temperature water → acid cleaning (P3-ultrasil 75, 0.5%, 20 minutes) → rinsing with room temperature water → sterilization using hypochlorous acid (P3-ultrasil 25, 1%, 20 minutes) or perchloric acid (P3-oxonia activ, 0.3%, 20 minutes) → rinsing with room temperature water. For polyacrylonitrile membranes (PH2–1, 50°C), the chemical cleaning process is: rinsing with water → mild alkaline cleaning (P3-ultrasil 30, 1%, 30 minutes or P3-ultrasil 10, 1%, 30 minutes) → rinsing with room temperature water → acid cleaning (P3-ultrasil 75, 0.5%, 20 minutes) → rinsing with room temperature water → sterilization using hypochlorous acid (P3-ultrasil 25, 1%, 20 minutes) → rinsing with room temperature water. For polyamide membranes (PH1–12, 50°C), the chemical cleaning process is: rinsing with water → mild alkaline cleaning (P3-ultrasil 30, 1%, 30 minutes or P3-ultrasil 10, 1%, 30 minutes) → rinsing with room temperature water → acid cleaning (P3-ultrasil 75, 0.5%, 20 minutes) → rinsing with room temperature water → sterilization using pyrosulfate (P3-ultrasil 200, 0.5%, soaking overnight) → rinsing with room temperature water. 2. Electrochemical cleaning: Electrochemical cleaning is a very special type of cleaning method. When an electric field is applied to a membrane, charged particles or molecules will migrate in the direction of the electric field. Particles or molecules are removed from the interface by applying an electric field over a time interval without having to interrupt the operation. The disadvantage of this method is that it requires a conductive membrane and a special membrane device equipped with electrodes, imposing high demands on both the membrane and the device