Research on the killing effect of chlorine dioxide disinfectant on bacteria and viruses and its application in poultry breeding

Abstract:

As an internationally recognized fourth-generation bactericidal disinfectant, chlorine dioxide has the advantages of high efficiency, broad spectrum and safety, and is widely used in disinfection, sterilization and deodorization in drinking water treatment, environment, medical and health care, food processing, aquaculture, aquaculture and planting industries. Chlorine dioxide can not only kill all kinds of bacteria, fungi, viruses and even protozoa, but also has a strong oxidation effect, which can effectively eliminate toxic gases and odors such as ammonia and hydrogen sulfide produced by the accumulation of manure in the chicken house through redox reaction. In this paper, the killing effect of chlorine dioxide disinfectant on bacteria, viruses and other microorganisms and its application in poultry breeding are reviewed, and the application prospect of chlorine dioxide as a new generation of environmentally friendly disinfectant is prospected.

Keywords: chlorine dioxide; Sterilization; antiviral; application prospects;

With the increase of the intensification of poultry farming, the density of poultry breeding is increasing, and the harmful gases such as ammonia and hydrogen sulfide produced by the accumulation of manure in poultry houses are increasing, which makes the air quality of poultry houses worse, and poultry live in this environment for a long time, resulting in the frequent occurrence of various diseases, especially respiratory diseases ^[1]., which in turn leads to an increase in drug costs, drug residues, environmental pollution and a series of problems, to a certain extent, restricts the steady development of the poultry industry. In the process of poultry breeding, it is a direction to improve the level of poultry breeding to reduce the concentration of harmful gases in the air to reduce the harm caused by respiratory diseases to poultry. Chlorine dioxide disinfectant can effectively eliminate toxic gases and odors such as ammonia and hydrogen sulfide produced by the accumulation of feces in the chicken house through redox reaction, and does not produce other harmful components, and is classified as an A1 disinfectant by the World Health Organization, with the characteristics of broad-spectrum, high efficiency and safety ^[2]. In this paper, the killing effect of chlorine dioxide in poultry breeding and the application prospect of related bacteria, viruses and other microorganisms in poultry breeding are discussed, in order to help the majority of breeding enterprises to prevent and reduce the occurrence of poultry diseases, and have certain practical significance for promoting the healthy and rapid development of the poultry industry.

At room temperature, chlorine dioxide is a yellow gas with a pungent odor; The molecular formula is_ClO2, its molecular weight is 67.46, its melting point is -59.5 °C, its boiling point is 11 °C, and its density is 3.01 g/L (11 °C). These physicochemical properties make_ClO2 an ideal disinfectant that can act as a gaseous molecule or in an aqueous solution. Cl_O2 is known for its high bactericidal efficiency and strong oxidation, 2.0 mg/L Cl_O2 can kill 100% of microorganisms after 30 s. The disinfection effect is better than that of other disinfectants, and the practical concentration of_ClO2 disinfection is very low ^[3,4,5].

Chlorine dioxide has a significant disinfection effect in hospitals, with a killing rate of 100% for 1 min at a concentration of 50 mg/L and other common bacteria such as Staphylococcus epidermidis ^[6]. Chen et al^{. [7]} used a 50 mg/L chlorine dioxide disinfectant to treat Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa in the suspension for 5 min, and the logarithmic values were all greater than 5.00. Zeng Jiahui et al^{. [8]} conducted a test at 18~22°C to observe the bactericidal effect of stable chlorine dioxide, and the results confirmed that 15 mg/L chlorine dioxide had an effect on Escherichia coli for 5 min, 50 mg/L chlorine dioxide had an effect on Candida albicans for 3 min, and 200 mg/L chlorine dioxide solution had a killing rate of 100% for 10 min on the spores of Bacillus subtilis black variety. At sublethal concentrations, chlorine dioxide induces different behaviors in bacteria. Studies have shown that Bacillus subtilis forms biofilms upon exposure to lethal levels of chlorine dioxide ^[9], and that biofilm formation is a defense response that helps protect cells from the toxic effects of fungicides. Young et al. ^[10] examined the efficacy and potential mechanism of action of a stable chlorine dioxide solution on Bacillus subtilis spores and compared it with a hypochlorite solution, and the results showed that there was no difference in the bactericidal effects of hypochlorite and chlorine dioxide, and that the mechanism of action of chlorine dioxide did not harm DNA, but may damage the inner membrane of the spores.

Under normal circumstances, ClO2 undergoes redox reactions with substances with reducing properties such as cyanide, sulfide, phenol, and organic matter through oxidation to kill bacteria, viruses, protists, algae, fungi, and various spores and spore-formed bacteria [^11], and this reaction is safe and residue-free, and does not produce carcinogenic, teratogenic, and mutagenic organochlorides, achieving sustainable disinfection ^[12]. Chlorine dioxide has gradually replaced chlorine, chlorine ammonia, sodium hypochlorite, calcium hypochlorite, etc., and has become an ideal disinfectant.

Chlorine dioxide is the most commonly used disinfectant in different environments and is effective against both enveloped and non-enveloped viruses ^[13]. Carducci et al. ^[14] reported that the SARS-CoV virus in domestic sewage can be completely inactivated by treatment with chlorine dioxide at a concentration of 20 mg/L for 30 minutes. The concentration of chlorine dioxide is between 0.5~1.0 mg/L, which can reduce the concentration of influenza virus by 99.9% within 5 minutes ^[15]. Ju et al. ^[16] conducted an influenza virus inactivation test, and the results showed that 5 mg/L chlorine dioxide for 30 minutes and 20 mg/L chlorine dioxide for 5 minutes could completely inactivate the influenza virus.

Zhang et al. ^[17] used immunofluorescence and suspension quantitative killing test to determine the inactivation rate of chlorine dioxide solution against Thiveral strain swine fever virus at different concentrations with different action times (3 min and 5 min), and compared the effect with the chlorine dioxide powder used in the market. The results showed that the chlorine dioxide solution at a concentration of 25 mg/L had an effect on the Thiveral strain swine fever virus for 3 min, and the inactivation rate was 100%, and the inactivation rate of the chlorine dioxide powder solution at the same concentration had an effect on the Thiveral strain swine fever virus for 3 min, indicating that both the chlorine dioxide solution and the chlorine dioxide powder had a good killing effect on the Thivalal strain swine fever virus.

In the disinfection of the new crown epidemic, chlorine dioxide can be used for spraying, wiping and soaking disinfection, acting on the surface of environmental objects, floors, walls, etc., as well as ultra-low volume spraying and disinfection of indoor air. Therefore, chlorine dioxide can also be used for daily feeding management and disinfection of poultry houses. A large amount of manure and urine will be produced in the process of chicken breeding, and if measures are not taken to deal with it in time, it will breed pathogenic microorganisms such as bacteria, resulting in unexplained disease in chickens. Moreover, the harmful gases produced not only cause harm to the growth of chickens, but also make farmers feel uncomfortable and affect physical and mental health. Therefore, it is necessary to comprehensively treat the ground and air of poultry farms, disinfect and sterilize, and reduce odors. Wang et al. ^[18] observed the killing effect of chlorine dioxide gas on bacteria on the surface of objects and studied its influencing factors, under the conditions of room temperature and humidity (temperature 20°C, humidity 60%), the chlorine dioxide gas at a concentration of 240 mg/^m3 was fumigated for 60 min, and the logarithmic values of Staphylococcus aureus and Escherichia coli on different carriers were cloth carrier> stainless steel sheet carrier > glass carrier. It was confirmed that chlorine dioxide had different effects on bacteria on different carriers, and that the smoother the surface of the carrier, the more difficult it was to kill bacteria.

The company entrusted the Comprehensive Testing Center of the Chinese Academy of Inspection and Quarantine to carry out the disinfection on-site identification test, disinfected the air in the unmanned room with a content of 50 mg/L chlorine dioxide solution, sprayed for 30 min, and after three repeated tests, the death rate of natural bacteria was > 90% each time, proving that the disinfection was qualified; When the recommended spray amount is 150~200 m L/m³ and the concentration of chlorine dioxide solution is 20 mg/L, the air in the poultry house is disinfected for 20 min, and the sterilization rate is 93.44%, which is higher than that of the control disinfectant (0.25% peracetic acid disinfection for 20 min). In addition, according to years of practical experience, when the concentration of chlorine dioxide is 20~40 mg/L, the deodorization effect of ground spraying disinfection is good.

The issue of drinking water security is often neglected. Generally, the farm stores well water or tap water in water towers and tanks, and supplies water to poultry through water pipes and terminal drinking water devices. In terms of water sources, the qualified rate of tap water is higher than that of deep well water; The pass rate of microbial indicators is higher than that of waterline water, and the pollution of waterline is more serious ^[19]. The main reason for the problem of water quality reduction and drinking water pollution in poultry farms is the long waterline, and the addition of nutrients such as multivitamins through the drinking water system to fight stress, and the addition of vaccines or water-soluble drugs to prevent or treat diseases. Functional substances such as multivitamins and sugars in drugs provide nutrients for bacteria such as E. coli, and after remaining in the waterline, they promote the formation of biofilms, and the accumulation of these biofilms leads to secondary contamination of poultry drinking water ^[20]. Water pipes and water towers are not cleaned and disinfected for a long time, resulting in moss on the inner wall of the waterline and silt accumulation at the bottom, resulting in poor water quality. In addition, the waterline of the chicken coop is basically opaque, and the pollution of the waterline is often not detected in time ^[21]. Many chicken farms often have outbreaks of E. coli, which is good when the drug is used and the drug is stopped, and the problem is very likely to be on the waterline. Therefore, regular cleaning of the waterline must be taken into account. However, chlorine dioxide disinfectant has a significant effect on soaking at high concentrations to remove biofilm, which can be removed by soaking at 50~80 mg/L for 2~4 h, and then rinsed with running water without peculiar smell ^[22]. The so-called disease enters from the mouth, and the water quality problem is the top priority, and ensuring the health of drinking water will curb the occurrence of a variety of diseases from the root. Therefore, keeping drinking water clean and hygienic is a very critical aspect of disease prevention.

A large number of tests have shown that chlorine dioxide disinfectant has a good killing effect on bacteria, viruses and other microorganisms, and has almost no effect on humans and animals due to the extremely low concentration of conventional use. Since 1983, the United States has approved chlorine dioxide for disinfection of hospitals, laboratories and other environments, as well as equipment corrosion. Subsequently, it gradually expanded to the disinfection of food, agricultural products and animal feed, and was used to treat meat products, poultry processing and control microorganisms, kill molds, etc. Chlorine dioxide sterilization and disinfection has been widely used in various fields such as health and epidemic prevention, animal husbandry, and aquaculture. With the in-depth study of chlorine dioxide, China has gradually expanded the use of chlorine dioxide.

Song Hongan et al. ^[23] conducted many investigations and applications on soil disinfection technology, and confirmed that chlorine dioxide disinfectant can effectively prevent the occurrence of downy mildew, wilt and other diseases in fruits and vegetables. When sprayed with 50 mg/L Cl_O2, it can effectively kill celery leaf spot and spot blight. Soil sterilization with 15 mg/L Cl_O2 can effectively prevent root rot and anthracnose of pepper and green pepper. The use of_ClO2 to control the heavy crop disease of cotton, spraying with 10 mg/L, 70~80 mg/L root irrigation or 15 mg/L irrigation can increase the cotton yield by 50%~60%. With the expansion of the test and application range, chlorine dioxide disinfectant has achieved good results in soil disinfection, and has a broad application prospect in agriculture.

Liang et al. ^[24] showed that chlorine dioxide could effectively remove odor from phenol-containing sewage and conventional sewage. And the deodorization effect is much stronger than that of chlorine. Xu Guolong ^[25] found that chlorine dioxide has a good deodorization effect on the odor of garbage dumps, and can oxidize and decompose odorous substances (hydrogen sulfide, ammonia, etc.) through the oxidation of chlorine dioxide, so as to achieve the deodorization effect. Chlorine dioxide has played a significant role in the treatment of sewage and the deodorization of garbage, providing a good reference for the sewage and garbage treatment of poultry farms.

Chlorine dioxide is non-toxic, and the scope of use of chlorine dioxide is very broad in various countries. However, due to the extremely strong oxidizing capacity of chlorine dioxide, it should be avoided in high concentrations in confined spaces. However, chlorine dioxide disinfection is usually mostly used as a spray, and the concentration is usually 20~40 mg/L, and it rarely involves high concentrations. Therefore, chlorine dioxide is also internationally recognized as a safe, non-toxic green disinfectant. Chlorine dioxide is more and more widely used in disinfection of public places and farms, especially in recent years, the prevention and control of the new crown epidemic, indoor and outdoor spraying, spray disinfection is convenient to use, the effect has been continuously confirmed, and the application prospect is broad.

Chlorine dioxide has a good development prospect as a recognized fourth-generation disinfectant, especially in the case of the new crown epidemic, and has a good effect on the disinfection of the environment, waste water and waste in hospitals. In addition, it is also one of the best choices for the prevention of infectious diseases in the breeding industry, as well as the usual sterilization and disinfection, and environmental control, and has also been well used in agricultural pest control and fruit and vegetable preservative. With the continuous improvement of people's living standards in China and the gradual increase of people's attention to green livestock and poultry breeding, livestock and poultry breeding is now changing to a green and healthy type ^[26]. It is particularly urgent to accelerate the development of green chlorine dioxide products and occupy the commanding heights of science and technology in this field, effectively serve the aquaculture industry and enhance the competitiveness of the international market, and it also has far-reaching economic and social significance.