What is the water treatment system for hemodialysis？
The core component of the water treatment system is the reverse osmosis membrane, which uses the principle of reverse osmosis and uses water pressure to make the water permeate from the higher concentration to the lower concentration. At this time, all bacteria and impurities in the higher concentration Sundries, soluble solids, organic and inorganic substances that are harmful to the human body cannot penetrate the high-precision reverse osmosis membrane
1. Importance
For a long time, the water treatment system has only been regarded as an accessory product of the hemodialysis machine, without much technical content, as long as the water output is large. However, it is not difficult to find the serious casualties caused by a series of unqualified chemical agents in the water, such as aluminum pollution in Portuguese water treatment product water in 1993, chloramine pollution in Spain in 1996, and formaldehyde pollution in Ohio in the United States. How important is the safety of the treatment! 99.3% of the dialysate during the dialysis treatment is water. During dialysis, each patient will endure 15,000 to 30,000 liters of water per year. Dialysis patients are directly connected to water, and even a small mistake can harm the patient. It is worth noting that the chance of dialysis water coming into contact with the patient’s blood in hemodialysis is more than 20 times the total amount of drinking water. Compared with the total amount of impurities entering the patient's body, the latter may be 10-25 times that of the former. On the other hand, drinking water is always absorbed through the gastrointestinal tract and reaches the blood. When drinking water is absorbed from the gastrointestinal tract, the cell membrane can be selectively absorbed, thereby changing the proportion of chemical components in the water. In the process of hemodialysis, water diffuses into the blood through a non-biological membrane (artificial membrane), and the dialysis membrane cannot selectively absorb or reject certain ions. In this way, the substances contained in the dialysate can enter the blood as long as the molecular size is suitable to pass through the dialysis membrane. As a result, drinking water may be harmless, but using it as a dialysate may be toxic.
2. Principle
2.1 Principle of reverse osmosis
Reverse osmosis is a method of reversing its natural osmosis process. Permeation and reverse osmosis are accomplished through a semi-permeable membrane. When two solutions of different concentrations are separated by a semi-permeable membrane, the solvent of the dilute solution will pass through the semi-permeable membrane. When the membrane enters the solution side, this phenomenon is called osmosis. When an external pressure is applied to the concentrated solution side, the permeation rate will decrease. When the pressure increases to a certain value, the permeation process stops and the so-called permeation equilibrium is reached. The applied pressure required for the equilibrium state is called osmotic pressure. When the pressure on the side of the concentrated solution is increased continuously, that is, the applied pressure is greater than the osmotic pressure, the solvent will reverse its original permeation direction, from the side of the concentrated solution through the semi-permeable membrane into the side of the dilute solution. This phenomenon is called reverse osmosis
The reverse osmosis membrane was developed by NASA, and has been widely used in general industrial and civilian fields. It is refined with high-tech special materials. The membrane pores are as small as ten thousandths of a micron. In other words, E. coli is approximately larger than this membrane. Five thousand times. Therefore, except for water molecules and a small amount of trace ions dissolved in water for reverse osmosis, everything else is rejected from the membrane, and is instantly flushed out by the high-pressure water stream and drained by the wastewater pipeline. The water molecules condense into H20 pure water in the inner layer of the reverse osmosis membrane, which is stored in a sterile pressure water tank. Therefore, the pure water generated by reverse osmosis does not have the disadvantages of second-degree pollution and bacterial breeding grounds for general water filters. Reverse osmosis water treatment technology is the most popular and mature pure water production technology in the world today.
2.2 Working principle
The water treatment system may include a water softener, a sediment filter, a reverse osmosis device, a deionization device, a high efficiency filter, a micro filter, an activated carbon filter, an ultraviolet sterilizer, and a bucket.
Commonly used water treatment systems use reverse osmosis process principles, multi-stage pure water filtration, and the raw water undergoes four-stage pre-treatment to meet the feed water requirements of the RO membrane. The first stage: sand filter device or 10μm water filter element, which removes suspended particles and mud sand that are larger than 25μm in the water. The second stage: Dechlorination device to remove the odor and chlorine by-products in the water. The third stage: Deionization device, which removes calcium and magnesium plasma in the water through ion exchange, so that the water is softened. The fourth level: 5μm water filter element to filter out impurities in the water again. The water after the above treatment basically meets the feed water standard of the RO membrane, and the two-stage RO membrane treatment and treatment can meet or exceed the water requirement for dialysis.
2.3 Components
The product is composed of three parts: the inlet water pretreatment device, the RO reverse osmosis water treatment host, and the subsequent water supply device.
(1). Influent water pretreatment device
Including the pre-inlet water pressurization system and the pretreatment system: the first part of the configuration: the pre-pressurization system, including the pressure pump, filter, pressure gauge, pressure switch, pressure bag. The second part of the configuration: ① de-iron tank; ② sand tank; ③ filter 10 m cotton thread; ④ carbon tank; ⑤ resin tank; ⑥ filter 5μm cotton thread.
(2). RO reverse osmosis filtration system
The dual-stage reverse osmosis water treatment host, relying on microcomputers, touch screens, frequency converters, etc., uses program-controlled software to realize automatic operation of each working mode of the water treatment system, and reasonable and personalized settings for various performance parameters through the operating system.
(3). Post-processing device
The double-port pressure pack eliminates the possibility of secondary pollution, so that the water can reach the hemodialysis population in time, but if there is not too much water, it can be used immediately after production.
3.Requirements standard
For the requirements of dialysis water treatment, we can analyze it from three aspects: physical quality, chemical quality, and biological quality.
3.1 Physical quality
Including the water output of the system and the stability of its operation. Sufficient water output is mainly used to ensure sufficient water pressure to supply the ideal number of beds at the same time for hemodialysis treatment and to ensure its stability.
3.2 Chemical quality
Including the conductivity and ion removal rate of the treated water. The conductivity of the treated water should not exceed 38μS (25ppm).
3.3 Biological quality
It includes two aspects. One is the total number of bacteria contained in the treated water, which should not exceed 100 CFU/mL. Second, the bacterial endotoxin at the output of the water treatment device should not exceed 1 EU/mL; the bacterial endotoxin at the delivery point at the entrance of the hemodialysis device should not exceed 5 EU/mL.
3.4 Performance that may be caused by poor water quality
(1) Carpal tunnel syndrome, abnormal protein deposition, immune system disease, joint and bone disease in long-term hemodialysis patients are generally believed to be directly related to trace bacteria and endotoxins.
(2) Chloramine can cause blood volume, anemia, and chronic hemoglobinemia.
(3) Aluminum can cause dialysis bone disease, dialysis encephalopathy, and anemia.
(4) High calcium and magnesium ions can cause hard water syndrome, nausea, vomiting, headache, fever, and elevated blood pressure.
(5) Excessive levels of bacteria and pyrogens can cause pyrogen reactions.
(6) Undissolved particles will cause the filter of the dialysis machine to be clogged, which will increase the wear and tear of the machine and cause malfunctions.
