The membrane must be cleaned due to a decrease in flux due to contamination of the membrane.
1. The general principle of membrane cleaning is high flow rate, low pressure, and the permeate side valve must be closed. In general, membrane cleaning methods are generally classified into physical methods and chemical methods. The physical method refers to the use of high-flow water washing, sponge ball mechanical cleaning and the like to remove contaminants; the chemical method is to use a chemical reagent that does not damage the membrane material itself, dissolves or displaces the pollutants, and cleans the membrane.
2. The inorganic film can be cleaned by a wider cleaning method with its excellent chemical stability and high mechanical strength. The general rule of inorganic membrane chemical cleaning is: inorganic strong acid makes some insoluble substances in pollutants become soluble substances; organic acid mainly removes inorganic salt deposition; integrator can complex with inorganic ions in pollutants to form substances with high solubility, Reduce salt and adsorbed inorganic contaminants deposited on the surface of the membrane and pores. Surfactants mainly remove organic pollutants; strong oxidants and strong bases are used to remove oils and proteins, algae and other biological substances; and for cell debris and other pollution systems Mostly use enzyme cleaning agents. For membranes with very serious pollution, it is usually washed alternately with strong acid and strong alkali, and an oxidizing agent such as sodium hypochlorite and a surfactant are added. In these cleaning processes, high-speed, low-pressure operating conditions are often employed to maximize membrane flux recovery. After the chemical cleaning, rinse with water until neutral.
The selection of the chemical cleaning agent and the determination of the cleaning method depend on the experiment of the raw material liquid system.