Compared with conventional disinfection and sterilization methods, ozone disinfection and sterilization methods have the following characteristics:
(1) Efficiency: Ozone disinfection does not need any other auxiliary materials and additives. During disinfection, the ozone generator generates a certain amount of ozone, which spreads evenly in a relatively sealed environment with good inclusiveness and permeability, overcomes the problem of disinfection dead angle in ultraviolet disinfection, and achieves the purpose of all-round, rapid and efficient disinfection and sterilization. In addition, because of its broad bactericidal spectrum, it can not only kill bacterial propagules, spores, viruses, fungi, protozoa and other microorganisms, but also kill Botox, toxins and rickettsia, and also has a strong effect of removing mold, fishy smell and odor.
(2) High cleanliness: ozone can be naturally decomposed into oxygen in the environment, which is the unique advantage of ozone as a disinfectant. Ozone is produced by oxygen in the air. In the process of disinfection and oxidation, excess oxygen atoms (O) combine to form molecular oxygen (O2) after 30 minutes, and there is no residue, which solves the problem of secondary pollution of residues during disinfection of disinfectants and saves cleaning after disinfection.
(3) Convenience: Ozone sterilization equipment is generally installed in indoor or central air conditioning systems, air purification systems, or sterilization equipment (such as ozone sterilization cabinets, transmission windows, etc. ). According to the concentration and time required for sterilization, the timing control of ozone sterilization equipment can be automatically set, which is convenient to operate and use. However, formaldehyde and epoxyacetic acid fumigation disinfection takes a long time, while ozone disinfection can be started regularly every day.
(4) Economy: Compared with other methods, ozone disinfection has great economic and social benefits through the application of ozone disinfection in GMP in many pharmaceutical industries and the comparison of operation in medical and health units.
2. Application fields of ozone disinfection
(1) water disinfection: due to the instability of ozone in water, hydroxyl (OH) and monoatomic oxygen with strong oxidation ability (stronger than monoatomic oxygen) are generated after decomposition, which can effectively kill various bacteria and viruses in water. Ozone is considered as the most ideal water disinfection and purification agent abroad. Many large waterworks generally use ozone to treat drinking water, and domestic Kunming Water Supply Company, Deepwater Group and Shanghai Water Supply Company also use ozone to purify and disinfect water.
Chlorine-containing disinfection water can produce carcinogenic poison chloroform. If the dosage of chlorine agent increases, the dosage of chloroform will also increase. With the in-depth study of carcinogen toxicity, the World Water Quality Association and the World Health Organization have stopped advocating the use of chlorine agents for disinfection of drinking water. Ozone used for disinfection of drinking water has the following advantages:
Strong oxidation ability, high sterilization efficiency and fast sterilization speed. Ozone can kill microorganisms in water 600-3000 times more efficiently than chlorine, and it can kill all bacteria, viruses, spores and sporozoites in water, as well as algae.
After ozone acts in water, the product is non-toxic and harmless oxygen, and ozone itself has no permanent residue, which can also increase dissolved oxygen in water; It has the function of decoloring and deodorizing, reducing the turbidity of water; It can oxidize and decompose iron, manganese, silver, cobalt, suspended particles, organic pesticides and detergents in water, greatly improving water quality.
The dosage of ozone in water treatment should be designed according to the physical and chemical properties of water, pollution degree and contact time. For disinfection of domestic water and drinking water, 0. 1- 1 mg/L is enough. In general, the amount of ozone added to water is 0.5- 1.5mg/L, the contact time is 5- 10 min, and the residual ozone concentration in water is 0.1-0.5 mg/L.
Ozone is also widely used in sewage treatment. Because of the strong sterilization ability of ozone, many hospitals abroad have adopted ozone to treat sewage and achieved satisfactory results. Experiments show that when the sewage discharged from the hospital contains 106- 108 bacteria /L, the ozone concentration reaches 10-20mg/L, and the effect is 10-65438. The killing rate of bacterial propagules is 99.999%- 100%, and the killing rate of spores can reach above 99.999% when the dosage is 25-30 mg/L for 15 minutes.
When ozone is used to disinfect drinking water and sewage, it can also be made into high-concentration ozone disinfection water, which can be used to clean and disinfect vegetables, fruits, utensils, hands and other items. In Japan, using high concentration ozone to disinfect water has become the focus of disinfection field. Especially in the summer of 1996, in the outbreak of pathogenic Escherichia coli 05 17, the disinfectants such as sodium hypochlorite, ethanol and acetic acid used before, at the long-term concentration of 100-300 ppm, led to strong drug-resistant bacterial variation of Gram-negative bacteria such as Escherichia coli. In Japan's medical and health system, penicillin-resistant Staphylococcus aureus infection has also become a serious problem, and the solution of using high concentration ozone water to wash hands of medical staff and disinfect medical instruments has been paid attention to.
In the germicidal efficacy test of ozone water on related microorganisms in Japanese medical departments, microorganisms that are often contacted and also important in hospital infection are taken as test samples, such as bacteria: Escherichia coli IFO330 1, Trichomonas aeruginosa IFO3445, Staphylococcus aureus ATCC43300, Staphylococcus epidermidis IFO12993; ; Viruses: herpesvirus RF, adenovirus type 3, coxsackie virus B5FAULKNER, echovirus WALLACE type 7, influenza virus PR8, etc. Compared with chlorine-containing disinfection water, all the tested bacteria can be killed after the ozone water concentration is 4mg/L 10 second, while the control group still has more than 103mg/L after 30 seconds. For the virus, the result is expressed by the infection amount (TCID50) of half of the virus tissue culture, and the TCID50 is reduced by more than 103, which can be considered as virus inactivation. After exposure to ozone water with a concentration of 4mg/L for 20 seconds, the TCID of herpes virus and influenza virus decreased by more than 50 103, and Coxsackie B5 virus and Echo 7 virus decreased by more than 50 104. It can be confirmed that ozone water has a good killing effect on infected bacteria and viruses in medical, pharmaceutical and food processing fields.
After removing the bacteria attached to the fingers of medical staff, the test bacteria were penicillin-resistant Staphylococcus aureus, while the control group was disinfected with ethanol, MK2 12. After cleaning, the sterilization effect and secondary pollution of the drainage water were identified. In the control group, the number of bacteria in the drainage fluid was 104, and the ozone water was only 10 1. It is proved that ozone water has obvious sterilization effect and will not cause secondary bacterial pollution to the outside world.
According to the basic biological test standards of medical devices and medical materials:
Cytotoxicity test: solid toxicity test for animals refers to the cytotoxicity test of human or animal cells. This time, mouse glandular cells were stained with Giemsa. The results show that ozone water has no cytotoxicity or slight toxicity.
Allergy test, skin allergy test is that people repeatedly contact with a substance, causing immune response disorder, check whether it causes allergic symptoms. The experiment was carried out at the maximum, and ozone water was injected into the skin of groundhog. The results showed that there were no allergic symptoms such as erythema and edema, and no allergic reaction.
Eye mucous membrane irritation test: 4mg/L ozone was used to drip water into eyes, and there was no irritation, no damage to conjunctiva, iris and cornea, and it was judged that there was no primary irritation to eye mucous membrane.
In the cumulative skin irritation test, ozone water was used to wipe the back skin of New Zealand mice for 14 days. During the experiment, the experimental animals were normal, with no changes in hair and excreta, and no erythema and edema on the skin. It can be considered that continuous use of ozone water has no cumulative irritation to the skin.
To sum up, it is extremely effective and safe to use ozone water for disinfection and sterilization. For ordinary bacteria, 1mg/L ozone water is enough to kill. For virus inactivation, we suggest using high concentration ozone water.
Besides bacteria and viruses used in experiments, ozone water can also be used for lipophilic viruses and hydrophilic viruses (including hepatitis A, hepatitis B, hepatitis C, hepatitis C and HIV), Pseudomonas aeruginosa, Pseudomonas fluorescens, Legionella, Flavobacterium, Alcaligenes, amoeba, human pathogenic fungi (such as Candida albicans) and so on.
Similarly, ozone water is also used as an effective treatment for diseases. 1902 J H Clarke's medical practice manual describes the successful application of ozone water in the treatment of anemia, diabetes and other diseases. 1979 Dr. George Frebort started using ozone to treat AIDS patients. Nowadays, ozone therapy has been widely used in Germany, France, Italy, Russia, Portugal and other EU countries. The application of ozone water in puerperal care and cleaning and disinfection of burn patients has also been preliminarily studied in China. When the Queen Mother of England was alive, one of the secrets of longevity was to carry a thermos bottle with her, and the other was to insist on injecting ozone water for health care.
In the field of food production, ozone water sterilization has also shown outstanding advantages instead of traditional disinfectants. The United States, the European Union and other countries have widely used ozone water in public water use and food processing. In vegetable processing, the traditional sterilization method is high temperature sterilization, which not only destroys the color, taste and quality of vegetables, but also consumes a lot of energy. Using ozone water as cold sterilization technology can avoid the damage of traditional technology to vegetable quality, improve the added value of products and reduce costs. In related experiments, compared with chlorine dioxide, the hygienic index of processed vegetables meets the aseptic requirements, and the sterilization effect is better than that of chlorine dioxide aqueous solution.
In the disinfection and purification of aquatic products (such as fish), ozone water is superior to chlorine agent in storage time, bacterial reproduction rate, taste, protoplasm and appearance. When treating shellfish with ozone seawater, the self-purification speed of shellfish is accelerated after treatment. The nine strains studied included Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium, and the number of1100-11000 was reduced compared with the control group with chlorine.
Ozone water can also be used for soaking and cleaning pipelines, production equipment and containers in pharmaceutical industry and food processing industry to achieve the purpose of disinfection and sterilization. Soak and rinse with high concentration ozone water. First, a large number of bacteria and viruses on the surfaces of pipelines, equipment and containers are cleaned and removed. Second, ozone is used to kill the bacteria and viruses remaining on the surface that have not been washed away. It is simple to use, and there will be no dead ends in drug production and food processing, thus avoiding environmental problems such as the discharge of chemical toxic substances and residual pollution caused by the use of chemical disinfectants in production.
(2) air disinfection: ozone can diffuse around all indoor objects and every corner of the space in the air, with good diffusivity, uniform concentration and no dead angle, so it has advantages over ultraviolet rays. Ultraviolet rays are sterilized by light radiation, and the sterilization effect can only be produced if the irradiated part reaches the irradiation intensity standard, and the sterilization and disinfection mechanism of ozone can effectively kill various microorganisms in the air. Ozone below the safe allowable concentration (0.2 mg /M3) has a good killing effect on general bacterial propagules. In the experiment, ozone15min with the concentration of 30 mg/M3 was used, and the killing rate of natural bacteria in the sample hospital wards was ≥ 92.7%. For Staphylococcus aureus in aerosol, ozone with the concentration of 0.12mg /M3 was used for 30min, and the killing rate was over 99.9%. Bacillus subtilis var Niger was treated with ozone with a concentration of 5.67 mg /M3 for 60 minutes.
The main advantages of gas-phase ozone disinfection are: ozone is finally decomposed into oxygen, with no residue and no pollution to the environment; There will be no residue on the sterilized articles, such as utensils, tableware, food, etc. , the physical and chemical properties of the original items will be less affected; Compared with other disinfection methods, such as ultraviolet rays and drug fumigation. , low operating cost; The scope of application is wide and there are no special restrictions.
In the gas phase, the effect of ozone on killing microorganisms depends on these main factors: the threshold concentration of ozone, that is, when the ozone air concentration reaches this concentration requirement, it can have the ability to kill microorganisms; Microbial species; Processing time; Distribution pattern of ozone; Temperature and humidity conditions of the space; Restoration effect of indoor walls, ceilings, floors and other decorative materials.
Under the condition of gas phase, the killing effect of ozone on microorganisms is different. Experiments show that ozone has a strong bactericidal effect on human and animal pathogens and viruses.
Temperature and humidity are the main environmental factors that affect the sterilization effect of gaseous ozone. In general, the killing effect is good at low temperature and high humidity, especially when the relative humidity is less than or equal to 45%. Ozone has almost no killing effect on suspended microorganisms in the air, and only when the relative humidity is greater than 70% does it really show the killing effect. This is due to the increase of relative humidity, which can make the cells swell and the cell wall thinner, and it is more vulnerable to the penetration and dissolution of ozone.
Table 3 Reference concentration of ozone in air (unit: ppm)
use
kind
concentrate
Application mode
disinfect
cold store
Food workshop
Ward, operating room
Disinfection of work clothes
Air in SARS polluted area
6- 10
1.0- 1.5
1.5-5
10-20
≥ 15
According to the storage capacity and pollution degree.
Turn on the machine to send ozone gas after work every day.
Turn on the machine when disinfection is needed, and check the total number of bacteria according to the standard.
The relative temperature is about 90, and the clothes rack is hanging.
Mouldproof and fresh-keeping
General place
Eggs (of hens)
banana
apple
Vegetables with less chlorophyll content
Fish cheese
1-2
2-2.5
2.5-3.5
2.0
1.5- 1
0.5- 1
Turn on the machine regularly.
Supply ozone gas intermittently, and start the machine 2-3 times a day.
Supply ozone gas intermittently, and start the machine 2-3 times a day.
Deodorization and purification
mortuary
Fish processing plant
Slaughtering workshop
Fatty acid factory
rubber tree
Garbage disposal site
Sewage treatment plant
three
three
2-3
10
3- 10
10
1-2
If there is an odor, start the machine to deodorize.
The pipeline is treated by pumping polluted gas, and ozone gas is added to the pipeline for oxidation and deodorization. If the odor in the workshop is serious, ozone gas should be added to the air inlet of the workshop until the ozone smell is not smelled.
Based on the above factors, we suggest using ozone generator for air disinfection:
Install ozone generator for air disinfection. Separated or moving in a separate space, it is usually placed in a high place, because ozone is easy to fall because of its heavy proportion in the air, and the purpose of placing it in a high place is mainly conducive to the diffusion of ozone; In a sterile room with relatively closed space, such as air self-circulation, it is suggested to install an ozone generator in the closed air circulation system, such as assembling it in an air conditioning unit and installing it in a main air supply duct or a main return air duct. After reaching the set disinfection time, the air can be disinfected by activated carbon adsorption or catalyst reduction, which can not only achieve the purpose of air disinfection, but also keep the staff from leaving the working environment. At present, the application of this technology in the aseptic room of pharmaceutical industry has been very extensive and mature, and the main workflow is as follows: air compressor-oxygen generator-ozone generator-main air supply pipeline of air conditioner-disinfection and purification area.
Selection and calculation of ozone generator for air disinfection. Ozone disinfection needs to reach at least the threshold concentration. If the generated concentration is lower than the threshold concentration, the sterilization effect will not be achieved, while if the concentration is too high, the operation cost will be increased. Therefore, it is necessary to calculate and select an ozone generator with a suitable concentration range. According to the Technical Specification for Disinfection and the actual application data, the ozone concentration in the clean area of GMP pharmaceutical workshop should be kept at n = 5 mg/m3, 100000 times n = 10 mg/m3,100000 times n = 30 mg/m3,100000 times n = 40 mg. The calculation formula of total ozone consumption is: w = NV/( 1-s), where w- total ozone consumption (mg/m3); S- ozone attenuation rate s = 40%; V- total volume (m3); N- ozone concentration (mg /M3) to be maintained during disinfection in clean areas. Where v = v 1+v2+v3, v 1- total volume of clean area; V2- air conditioning duct volume; V3- effective volume of ozone loss caused by fresh air supply (V3 = total air supply × 20% × replacement rate of conventional fresh air × 10% (positive pressure of fresh air supply in clean area) × 60% = total air supply × 1.2%).
The humidity is suitable. Ozone has the best sterilization effect when the humidity is 70-80%, and the effect is poor when the humidity is lower than 45%. Therefore, in general use, especially in sterile rooms and wards of pharmaceutical workshops, attention should be paid to increasing the humidity in the environment appropriately.
Ozone concentration. Concentration control is the key to the use of air-type ozone generator, and different uses should be coordinated with different concentrations and time. Such as general deodorization, deodorization, etc. , the concentration is generally not more than 0.05ppm. If used for indoor sterilization, it is generally controlled at 0.1-1ppm; If it is used for food preservation or surface disinfection, the concentration is generally controlled at 1-5ppm. Of course, these concentration indicators are all related to the amount of time, referring to the diffusion concentration of the whole space, not the local concentration. The surface of the object or ward area generally needs high concentration.
Selection of ozone generator for air disinfection. Because ozone can only be generated locally, corona discharge is the most economical and technically mature ozone generation method at present. The ozone generator used for air disinfection mostly adopts high-frequency discharge of ceramic sheets, which has the advantages of simple structure, reliable performance, low operating cost and flexible adjustment.
Safety of ozone air disinfection. Safety of ozone in a wide range of animal and human experiments, the main exposure route is inhalation, and continuous and long-term inhalation tests show that ozone will not cause cancer (NTP,1995); However, it has obvious stimulating effect on the respiratory system of animals and human bodies, and can affect the respiratory function in exposed environment. Therefore, we suggest that ozone disinfection of air should be carried out in an unmanned environment, and personnel can enter after disinfection for half an hour.
Applicable fields of ozone air disinfection:
GMP verification of air disinfection in pharmaceutical industry. Sterilizing the production spaces such as central air-conditioning purification system and ozone sterilization cabinet without central air-conditioning system in clean production areas are some pharmaceutical enterprises that use ozone disinfection, such as Shenyang Jishi Pharmaceutical Co., Ltd., Dalian Zhen 'ao Pharmaceutical Co., Ltd., Shanghai Qing 'an Pharmaceutical Co., Ltd., Jilin Aodong Pharmaceutical Group Yanji Co., Ltd. and Fujian Xing 'an Pharmaceutical Co., Ltd.. As the main means of air disinfection, ozone has made important contributions to GMP verification of these enterprises.
Hospital air disinfection. Hospital wards, outpatient operating rooms, treatment rooms, etc. In Japan, 28 hospitals use ozone as air disinfection, including Sapporo Self-Defense Force Hospital and Nagoya Health University. As many as 53 units and hospitals use ozone technology to treat food and health care. There are 5/kloc-0 hospitals using ozone in Taiwan Province province, and there are Beijing Hospital and Beijing You 'an Hospital in China.
Military air disinfection. Western countries have developed military ozone air disinfection products, such as installing ozone generating devices in the cabins of space capsules, submarines, tanks and other military vehicles and ships to purify the space environment and sterilize. This product is powered by batteries or photovoltaic cells.
Household air disinfection. With the aggravation of urban environmental pollution, the market prospect of household air purifiers is broad. Transplanting the ozone generator into the air conditioner and installing an ozone catalytic decomposition adsorption device at the air outlet can not only cool and heat, but also disinfect and purify the air with indoor circulating air. The decomposed oxygen and negative ions can keep the indoor air fresh. In addition, the ozone generator used for air disinfection can also be used in hotels, restaurants, shopping malls, theaters and other public places. It should be noted that the sterilization effect k of ozone is the product of the actual concentration c of ozone and the action time t, that is, k = c× t. When the actual concentration c of ozone reaches the sterilization threshold concentration Cmin, even if the time is prolonged, there will be no sterilization effect in actual operation. Ozone used for air disinfection should be equipped with ozone generating devices with different ozone output and ozone generation concentration according to different application spaces and different sterilization purposes. Ozone generation concentration refers to the concentration meter in a fixed volume after natural diffusion for 30 minutes, and the unit is mg/m3. Ozone production is calculated by the accumulation of ozone production concentration and time, and ozone production and ozone production concentration are the most basic parameter standards. Therefore, the ozone disinfection products used for air disinfection should indicate the disinfection concentration and disinfection time. There are also two general indicators, namely ozone safety index of application space and product service life index, which also need to be explained to users.
(3) ozone disinfection surface:
Ozone also has the function of killing microorganisms on the surface of articles, and it is also widely used, such as disinfection and sterilization of tableware, toys, utensils and medical devices. At present, in ozone disinfection cabinet, ozone can be diffused around appliances for sterilization, with low power consumption and obvious sterilization effect, which makes up for the shortage of high temperature and high pressure steam, infrared and ultraviolet disinfection cabinets. For example, the work clothes in sterile rooms, clean rooms and hospitals are traditionally sterilized by high temperature and high pressure steam. After sterilization, cotton fabric will turn from white to yellow, and after repeated sterilization, clothing fibers will become brittle and fall off. It directly affects the service life of clothes and the cleanliness of aseptic room and clean room. However, the existing silk work clothes are not suitable for high-temperature and high-pressure steam sterilization, but ozone disinfection has a low degree of damage to clothes, no residue, no imprint and no odor, and the disinfection effect is the same as or slightly better than that of high-temperature and high-pressure steam sterilization. In the experiment, the tester of sterile overalls was contaminated flora, and the overall killing rate was ≥ 95%.
There is also an experimental study (Jingmen Poultry and Egg Joint Processing Factory). Compared with traditional formalin fumigation, ozone gas fumigation time is shorter, residual gas is decomposed faster, and it is economical and convenient to use. Moreover, ozone can also delay the sterilization of breeding eggs and significantly improve the hatching rate of breeding eggs.