Nongfu Spring, Yibao, Master Kong, Jingtian Baisui Mountain, Evergrande Ice Spring, and Evian.

Pure water, also known as deionized water, refers to water that meets the sanitary standards for drinking water as raw water, and is produced through electrodialyzer method, ion exchanger method, reverse osmosis method, distillation method and other appropriate methods. Processing method, the water produced is sealed in a container, does not contain any additives, is colorless and transparent, and can be directly drank. It can also be called pure water (chemically). It is often used in experiments, and because it is It is produced by distillation and other methods, so it is also called distilled water. The space water and distilled water sold in the market are all pure water; but it is better to drink less pure water because it does not contain many minerals needed by the human body. Pure water does not conduct electricity easily and is an insulator. Use pure water when replenishing lead-acid batteries.

Water refers to H2O without impurities. From an academic point of view, pure water, also known as high-purity water, refers to water with extremely high chemical purity. It is mainly used in the fields of biology, chemistry, metallurgy, aerospace, electric power, etc. However, its requirements for water purity are quite high, so it is generally used in the most The most common one is the electronics industry. For example, pure water used in power systems is required to have low impurity content reaching the "microgram/liter" level. In the production of pure water, various indicators stipulated in water quality standards should be determined according to the production process of electronic (microelectronics) components (or materials) (for example, it is generally believed that the size of particulate matter that causes damage to circuit performance is its line width. 1/5-1/10), but due to the complexity of microelectronics technology and the many factors that affect product quality, there is still no complete water quality standard suitable for certain circuit production obtained from process testing. With the continuous revision of electronic grade water standards, many breakthroughs and developments in the field of high-purity water analysis, the continuous application of new instruments and new analysis methods have created conditions for the development of pure water production processes.

Pollution factors

1 Factors causing microbial contamination of pure water There are many factors that cause microbial contamination of pure water, but there are mainly three factors.

1.1 The enterprise does not pay attention to food hygiene. Although relevant operating procedures and systems have been formulated, the supervision is not strong enough. During the production process, various procedures and systems have not been implemented and implemented. We are investigating It was found that some factories have modern factories, advanced foreign production machines and complete air purification and disinfection equipment, but the purified water they produce sometimes turns out to have zero bacterial colonies per milliliter, and sometimes several or even dozens are detected. An in-depth investigation revealed that the batch number in which the bacteria was detected was caused by the failure to strictly follow the regulations when production was restarted after two days of suspension. The existence of such a phenomenon often results in unstable product quality. Li Hong et al. [1] reported that the water treatment terminal filter and the hands of filling workers are the key contamination links of microorganisms in the production process of bottled mineral water. In the pure water production process, every link may be contaminated by microorganisms. The key depends on the hygiene awareness of production personnel and the strict implementation of various operating procedures.

1.2 Unreasonable production processes and imperfect facilities are also one of the main factors causing excessive microbial standards. Different water sources lead to different processes for producing different types of purified water. The general principle is that on the premise of achieving purification, the simpler the process, the better. The shorter the process, the easier it is to control the hygienic quality of the product. At present, the technological process of pure water is basically water source → filtration → purification treatment → ozone mixing and disinfection → filling → inspection → storage. The advantage of this process is that ozone still remains in the purified filling water. If a small amount of microorganisms are introduced from the air in the bottle or cap and the filling room, it can be killed and the product can be kept sterile. We have learned that some manufacturers have imperfect equipment or do not fill the pure water directly after it has been mixed and sterilized with ozone. Instead, they hold the water in a water storage tank for a certain period of time before filling. As a result, the presence of bacteria was found through inspection. Xu Rongnian et al. [2] reported that if the water stays for 0.5 to 2 hours before filling into the bottle, the ozone has passed approximately 2 to 8 lifespans, and the ozone concentration in the water has greatly decreased. Even if the treated water itself is sterile, it will not be filled into the bottle before it is filled into the bottle. It is impossible to kill the remaining bacteria that are reintroduced by the packaging or the air in the filling room. From the above theory, it is believed that in this process, the bottle, cap and filling room must be sterile, otherwise there must be microorganisms in the product, but it is difficult to achieve in actual work.

1.3 Low technical level and vague understanding of the performance of various equipment are also another factors leading to microbial contamination.

During our on-site investigation, we found that technicians from some manufacturers have only a superficial understanding of ozone generators that can effectively kill microorganisms and facilities that control microorganisms, even though they have installed ozone generators and air purification equipment that are currently considered to have the best effect in purified water disinfection. , but cannot apply its effective performance or play its most effective role in production, and microorganisms are often detected in products. The current basic principle of using ozone to treat pure water is to mix ozone with water and make its final concentration in the water reach 0.5 mg/L to meet the sterilization requirements. Based on this parameter, companies should calculate the ozone generator based on the actual usage during production. The amount of ozone that should be produced. In addition, the actual operable output of the equipment during actual production must also be considered. If the performance of the equipment declines after long-term use, it should be adjusted appropriately and passed effective measurement; whether the mixing of ozone and water is complete, and whether the dosage required for sterilization can ultimately be achieved; and The time it can be maintained is the most basic factor in whether it can achieve killing intensity. The same is true for air purification equipment. Some manufacturers cannot use and maintain it correctly to ensure the normal operation of the purification equipment and the best purification effect. It is always believed that if air purification equipment is installed, the purified air will be sterile, and the product will definitely be qualified. There is no regular testing of the degree of air purification. The above phenomenon reflects that the technical level of technicians directly affects the hygienic quality of the product.

2 Measures to control microbial contamination: Purified water is a special product. Once contaminated by a small number of microorganisms, it may exceed the standard and even cause flocculent precipitation and other consequences. Therefore, controlling microbial contamination is a very important task for production companies. The above analysis shows that measures to control microbial contamination of pure water should be comprehensive and should not overemphasize one aspect and ignore other aspects, because contamination in any link in the production process will affect the quality of the product.

2.1 Strengthen own hygiene management, strengthen food hygiene and quality awareness, designate a leader to be responsible for hygiene work, set up a full-time hygiene inspection agency, strengthen the testing of water sources, packaging, filling room air and products, and formulate a follow-up Hygiene management system for all aspects of water source management, sterilization, filling, packaging and personal hygiene, and designate dedicated personnel to supervise the implementation, strengthen training and learning of food hygiene knowledge, focus on mastering disinfection methods and identify key links that are prone to microbial contamination.

2.2 Based on the characteristics of the water source, design the production process reasonably and scientifically, equip with necessary water treatment and production equipment, and select a sterilization system that is suitable for water disinfection. At present, mineral water and purified water in my country mostly use ultraviolet rays, ultrafiltration and ozone as sterilization and disinfection facilities. However, many years of experience have proven that the first two have poor reliability and are the main factors causing product failure, and ozone sterilization is considered to be the best method at present.

2.3 Regularly strengthen the cleaning and disinfection of pipelines, containers, filters and other related facilities throughout the production process, and do a good job in disinfecting bottles, caps and filling rooms. It is understood that most manufacturers use chlorine dioxide (ClO2) for disinfection of pipelines and packaging. This drug has strong oxidation and disinfection effects, but the quality monitoring of disinfection drugs must be strengthened to ensure its disinfection effect.