What are the methods for cleaning diaphragms?

　　The cleaning methods for membranes are mainly divided into two major categories: physical cleaning and chemical cleaning. The specific method to be used should be selected based on the type of contaminant, membrane material, and operating conditions.

　　Physical cleaning method

　　Isobaric flushing

　　For hollow-fiber membrane modules, using co-current water flow to scour and remove contaminants is suitable for initial-stage contamination.

　　Backwash

　　By reversing the flow of the permeate under low-pressure conditions of 0.1 MPa, the filter cake layer is removed. This technique is commonly used with flat-sheet membranes and tubular membranes.

　　Mechanical scraping

　　Use soft tools (such as sponges) to physically remove organic contaminants like gel layers; this method is suitable for tubular membrane modules.

　　Intermittent Operation + Backwashing Combination

　　Maintaining membrane flux by periodically shutting down equipment and performing backwashing is commonly seen in MBR processes.

　　Chemical cleaning method

　　Alkaline cleaning

　　Use a sodium hydroxide or phosphate solution (concentration 1%-5%) to decompose organic pollutants such as proteins and fats.

　　Acid cleaning

　　Use sulfuric acid, hydrochloric acid, or citric acid (at concentrations of 0.5%–2%) to remove inorganic scale such as calcium carbonate and calcium sulfate.

　　Enzyme-based cleaning

　　For targeted degradation of polysaccharide and protein contaminants, the reaction temperature must be controlled between 30℃ and 45℃. This method is particularly suitable for situations with severe biological contamination.

　　Surfactant cleaning

　　By reducing interfacial tension, colloidal substances can be stripped off; this method is often used in combination with acid/alkali cleaning agents.

　　Disinfectant cleaning

　　Use sodium hypochlorite or hydrogen peroxide (at concentrations of 0.01%–0.1%) to kill microorganisms and disrupt biofilm structures.