Ultrafiltration
Ultrafiltration is similar to reverse osmosis. It also uses a semi-permeable membrane, but it cannot control the removal of ions because the membrane has a larger pore size, about 10-200A. Can only exclude bacteria, viruses, pyrogens and particles, etc., can not filter water-soluble ions. The main function of the ultrafiltration method is to act as a pretreatment of the reverse osmosis method to prevent the reverse osmosis membrane from being contaminated by bacteria. It can also be used as a final step in water treatment to prevent upstream water from being contaminated with bacteria in the pipeline. Generally, the difference between the inlet water pressure and the outlet water pressure is used to determine whether the ultrafiltration membrane is effective. Similar to activated carbon, usually the backwash method is used to remove impurities attached to it.
Distillation
Distillation is an ancient but effective water treatment method. It can remove any non-volatile impurities, but it cannot exclude volatile pollutants. It requires a large water tank to store it. This water tank and conveying pipe are An important cause of contamination. At present, hemodialysis water is not treated in this way.
Ultraviolet disinfection method
Ultraviolet disinfection is one of the commonly used methods. Its sterilization mechanism is to destroy the biological genetic material of bacterial nucleic acid and prevent it from reproducing. The most important reaction is that the pyrimidine base in the nucleic acid molecule becomes a dimer. . Generally, it uses artificial 253.7nm ultraviolet energy with low-pressure mercury discharge lamp (sterilization lamp). The principle of the ultraviolet germicidal lamp is the same as that of the fluorescent lamp, except that the inside of the lamp tube is not coated with fluorescent substances, and the material of the lamp tube is quartz glass with high ultraviolet transmission rate. General ultraviolet devices are divided into irradiation type, immersion type and running type according to the application.
Water treatment UV germicidal lamp used in the hemodialysis dilution water is used in the pipeline between the water storage tank and the dialysis machine, that is, all dialysis water must be exposed to ultraviolet radiation before use to achieve complete sterilization effect. Pseudomonas aeruginosa and coliforms are the most sensitive to ultraviolet light. Conversely, the more tolerant are the bacillus subtilis. Because the UV disinfection method is safe, economical, less selective to bacteria, and the water quality will not change, this method has been widely used in recent years. For example, drinking water on ships often uses this disinfection method. The water kills all the bacteria, including Bacillus, Salmonella and so on. It can dive into the water center for 360 degrees of sterilization, and its efficiency is three times that of the surface germicidal lamp. It can eliminate algae in the water, with significant effects and convenient use. The UV germicidal lamp is suitable for: filtration of various sizes of fishing grounds, water treatment, large and small pools, swimming pools, hot springs. The sterilization efficiency can reach 99% -99.99%.
Biochemical method
Biochemical water treatment method uses various bacterial microorganisms existing in the natural world to decompose and convert organic matter in the waste water into harmless substances, so that the waste water can be purified. Biochemical water treatment methods can be divided into activated sludge method, biofilm method, biological oxidation tower, land treatment system, and anaerobic biological water treatment method.
