Pure water, also known as deionized water, refers to the water that meets the hygienic standard for drinking water, is sealed in a container, contains no additives, is colorless and transparent, and can be directly drunk by proper treatment methods such as electrodialysis, ion exchange, reverse osmosis and distillation. It can also be called pure substance (chemically), which is widely used in experiments. Because it is made by distillation, it is also called distilled water. Space water and distilled water sold in the market are pure water; But it is better to drink less pure water, because the human body needs few minerals. Pure water is not easy to conduct electricity and is an insulator. Pure water should be used when replenishing water for lead-acid batteries.
Water refers to H2O without impurities. Academically speaking, pure water is also called high purity water, which refers to water with high chemical purity. Mainly used in biology, chemistry, metallurgy, aerospace, electric power and other fields, but the purity of water is very high, so the electronics industry is the most widely used. For example, pure water used in power system requires the content of each impurity to be as low as "microgram/liter". In the production of pure water, the indexes specified in the water quality standard should be determined according to the production process of electronic (microelectronic) components (or materials) (for example, it is generally believed that the particle size that damages the circuit performance is1/5-110), but due to the complexity of microelectronic technology and various factors affecting product quality, none of them have passed the process test so far. With the constant revision of electronic grade water standards, as well as many breakthroughs and developments in the field of high purity water analysis, the continuous application of new instruments and new analytical methods has created conditions for the development of pure water production technology.
Pollution factors
1 Factors of microbial contamination in purified water There are many factors of microbial contamination in purified water, but there are three main ones.
1. 1 Enterprises do not attach importance to food hygiene. Although the relevant operating rules and regulations have been formulated, the supervision is not enough. In the production process, various rules and regulations have not been implemented. In our investigation, we found that some factories have modern workshops, advanced foreign production machines and perfect air purification and disinfection equipment, but sometimes the total number of colonies per milliliter of purified water produced is zero, and sometimes several or even dozens are detected. The existence of this phenomenon often leads to unstable product quality. Li Hong et al. [1] reported that the filter of water treatment terminal and the hands of bottlers are the key pollution links of microorganisms in the production of bottled mineral water. In the process of pure water production, every link may pollute microorganisms, which depends on the hygiene awareness of producers and the strict implementation of various operating procedures.
The unreasonable production process and imperfect facilities of 1.2 are also one of the main factors that cause the microorganisms to exceed the standard. Different water sources are used to produce different types of purified water. The general principle is that under the premise of purification, the simpler the process, the better, and the shorter the process, the easier it is to control the sanitary quality of the products. At present, the process flow of purified water is basically water source → filtration → purification treatment → ozone mixed disinfection → filling → inspection → storage. The advantage of this process is that ozone remains in the filled pure water. If a small amount of microorganisms are brought into the air between the bottle or the lid and the filling room, the purpose of killing bacteria can be achieved and the product can be kept sterile. We know that some manufacturers don't have perfect equipment or fill pure water directly after ozone mixing disinfection, but stay in the water storage tank for a certain period of time before filling. As a result, bacteria were found through inspection. Xu Rongnian et al. [2] reported that the ozone concentration in water decreased greatly after 0.5 ~ 2 h before water was put into the bottle. Even if the treated water itself is sterile, the residual bacteria brought back by the air in the packaging or filling room cannot be killed when the water is put into the bottle. From the above theory, it is considered that bottles, lids and filling rooms must be sterile, otherwise there must be microorganisms in the products, but it is difficult to do so in practical work.
1.3' s low technical level and ignorance of the performance of various equipment is another factor leading to microbial pollution. In the field investigation, we found that the technicians of some manufacturers have a superficial understanding of ozone generators and facilities for controlling microorganisms. Although the ozone generator and air purification equipment, which are considered to be the best disinfection effect of pure water at present, are installed, they can not be used in production or play their most effective role, and microorganisms are often detected in products. At present, the basic principle of using ozone to treat pure water is that ozone is mixed with water, and its final concentration in water reaches 0.5 mg/L to meet the sterilization requirements. According to this parameter, the enterprise should calculate the ozone output of the ozone generator according to the actual consumption in the production process. In addition, the actual running output of equipment in actual production must also be considered. If the performance of the equipment declines after long-term use, it should be properly adjusted and passed effective measurement; Whether ozone is completely mixed with water, whether it can reach the required dose, and how long it can last. , is the most basic factor to achieve the killing strength. The same is true of air purification equipment, and some manufacturers can't use and maintain it correctly to ensure the normal operation of the purification equipment and the best purification effect. It is always thought that the air purified by air purification equipment is sterile, and the products must be qualified, and the degree of air purification is not regularly tested. The above phenomenon reflects that the technical level of technicians directly affects the hygienic quality of products.
2 Measures to control microbial pollution Pure water is a special product. Once contaminated by a few microorganisms, it may exceed the standard and even cause flocculent precipitation. Therefore, controlling microbial pollution is a very important work for production enterprises. The above analysis shows that the measures to control the microbial pollution of pure water should be comprehensive, and one aspect should not be overemphasized, while other aspects should be ignored, because any link in the production process will be polluted, thus affecting the quality of products.
2. 1 Strengthen its own hygiene management, strengthen the awareness of food hygiene quality, designate a leader to be responsible for hygiene work, set up a full-time hygiene inspection agency, strengthen the inspection of water source, packaging, air and products in the filling room, formulate a hygiene management system from water source management, sterilization, filling and packaging to personal hygiene, designate a special person to supervise the implementation, strengthen the training and learning of food hygiene knowledge, focus on mastering disinfection methods, and clarify the key to microbial contamination.
2.2 According to the characteristics of the water source, design the production process reasonably and scientifically, equip with necessary water treatment and production equipment, and choose a sterilization system that meets the disinfection of water quality. At present, the sterilization facilities of mineral water and purified water in China mostly use ultraviolet ray, ultrafiltration and ozone. However, years of experience have proved that the poor reliability of the first two types is the main factor that causes the unqualified products, and ozone sterilization is considered to be the best method at present.
2.3 Regularly strengthen the cleaning and disinfection of pipes, containers and filters in the whole production process, and do a good job in disinfection of bottles, lids and filling rooms. It is understood that chlorine dioxide (ClO2 _ 2) is used for disinfection of pipelines and packages of most manufacturers, and has strong oxidation and disinfection effects. However, the quality control of disinfection drugs should be strengthened to ensure its disinfection effect.
I hope the above will help you.