Application of chlorine dioxide in library environmental disinfection

In dairy production, the microbial control of raw materials has been highly effective, fully meeting product hygiene requirements. However, significant gaps remain in the microbial control of production equipment, environment, tools, and personnel. For pipeline and storage tank disinfection, traditional hot water or steam sterilization is safe, efficient, and residue-free, but it cannot kill all microorganisms, including heat-resistant bacterial spores and heat-resistant enzymes of low-temperature bacteria. These bacteria and enzymes still pose a certain degree of harm to the product. Furthermore, the cost of using hot water or steam is high. Currently, chlorine-based disinfectants are commonly used for disinfecting production equipment, tools, and personnel. Their advantages are ease of use and low cost. The disadvantages are that the disinfectant itself has a certain degree of toxicity, and the disinfection process can produce carcinogenic, teratogenic , and mutagenic substances, leaving residues, odors, and causing damage to equipment and personnel. The current overall trend in microbial control in the domestic and international dairy industry is that heat sterilization is gradually being replaced by cold sterilization, and chlorine-based disinfectants are gradually being replaced by chlorine dioxide.

(1) Sterilization of Pipeline Systems The cleaning and sterilization of pipelines is a crucial step in dairy production. Currently, pipeline sterilization largely utilizes the CIP system, which involves first removing milk residue with acid, then neutralizing the residual acid with alkali, and finally sterilizing the pipeline with hot or clean water. This sterilization method is safe, efficient, and residue-free, but its high operating costs and the increased ambient temperature due to system heat dissipation make it more difficult to control environmental microorganisms. Furthermore, the pipeline system, including storage tanks, requires cooling, further increasing operating costs. Currently, the CIP system is gradually being replaced by single-use chlorine dioxide solution sterilization. Well-known domestic dairy companies are using chlorine dioxide as their cleaning and sterilization method.

Chlorine dioxide offers several advantages over CIP (Clean-In-Place) disinfection: ① It has superior sterilization effects, killing all microorganisms, including heat-resistant microorganisms that are difficult to kill at high temperatures and heat-resistant enzymes in low-temperature bacteria. This is unmatched by other disinfection methods. ② It has low operating costs, equivalent to only the cost of the cleaning water consumed by CIP, a fact proven in production practice. ③ The disinfectant solution is recyclable and can be reused for one day after each preparation. ④ It does not cause an increase in the operating environment temperature, reducing the difficulty of controlling microorganisms in the production environment. ⑤ The piping system and its storage tanks do not require ice water cooling, reducing production costs, shortening cleaning time, and improving production efficiency.

(2) Sterilization of tools, containers and equipment: Sterilization and disinfection of tools, containers and equipment are crucial steps in dairy processing. Currently, most methods use sodium hypochlorite and dichloroisocyanurate for sterilization and disinfection. The advantages are ease of use and low cost. The disadvantages are that these materials are toxic, produce carcinogenic, mutagenic, and teratogenic substances during disinfection, leave residues, have an odor, corrode equipment, and can harm users.

Replacing chlorine-based disinfectants with chlorine dioxide has the following advantages: ① Excellent bactericidal effect, 5-10 times stronger than chlorine-based disinfectants. ② Good safety, being non-toxic and not producing carcinogenic, mutagenic, or teratogenic substances such as organochlorides and chloroform during disinfection. ③ Stable bactericidal effect, easy control of disinfection concentration, and less affected by environmental conditions such as pH, temperature, and organic matter. ④ No harmful residues and easy rinsing. ⑤ Minimal corrosion to equipment and no skin irritation.

(3) Disinfection of air, floors, and walls in the production environment. Currently, the common methods for disinfecting the production environment are ultraviolet lamps or lactic acid, peracetic acid, etc. The advantage of ultraviolet lamp disinfection is its convenience, but the disadvantages are its limited bactericidal effect and poor penetration. Since ultraviolet light is invisible to the naked eye and can harm the human body, ultraviolet lamp sterilization can only be used as pre-disinfection in the production process. Chlorine dioxide disinfectant can be applied to the environment for disinfection by spraying or fumigation.

Compared with ultraviolet disinfection, it has the following advantages: ① Good sterilization effect, with a sterilization rate of over 80% in a single application. ② Short sterilization time; for example, production can resume immediately after disinfection by spraying the environment. ③ No harm to the human body.

Compared with lactic acid and peracetic acid, chlorine dioxide has the following advantages: ① Better bactericidal effect, 2-3 times stronger than lactic acid. ② Lower cost, 25%-50% of the cost of lactic acid and peracetic acid. ③ Does not pollute the production environment or corrode equipment during use. ④ Convenient to use, requiring no heating.

(4) Sterilization and disinfection in other production processes: In dairy production, chlorine-based disinfectants such as bleaching powder, sodium hypochlorite, and dichloroisocyanurate are commonly used to disinfect the hands, clothing, fabrics, milk carts, and boot troughs of operators . Chlorine dioxide can significantly improve the shortcomings of chlorine-based disinfectants: ① It has a good and stable sterilization effect, and its sterilization effect is 5 to 8 times that of chlorine-based disinfectants. ② It is non-irritating to the skin and non-corrosive to clothing and other fabrics. ③ It leaves no harmful residues and has no odor after disinfection.