Water, UV and ozone sterilization technology
Food sterilization of industrial water, always use with chlorine-based disinfectants and heat sterilization methods, in addition, ozone treatment, ultraviolet irradiation, and membrane (UF / MF) Act and other new approaches. These methods have advantages and disadvantages of each method must be carefully studied the nature, scope and precautions, the further flexible use under specific conditions.
First, the food industry in the ozone water treatment process
The use of water must meet drinking water standards. Some limit the concentration of water quality standards must be prepared within the scope change, and even, according to the requirements necessary to use sterile water, the final product as the food industry type and size of different plants, the situation varies. If you do not consider the economics of the operation and maintenance and management issues, then, in the final stages of adoption 0.22um or 0.45um membrane filter (MF), may achieve effective sterilization.
Ozone is a strong oxidizing agent. Ozone treatment method is the use of ozone decomposition to generate a new eco-oxygen oxidation and decomposition capability. Table 1 shows the treatment process, ozone present in the function and use.
A metal ion removal: In addition to iron, and manganese, the decomposition of organic metal compounds; the removal of harmful substances: cyanide, NOx, SOx; nitrous oxide decomposition.
Changes in organic matter
A bleaching; B to reduce odor; C Support In addition to the pretreatment of organic matter; improve the Absorption of Carbon; D Biological Removal: sterilization, drug cases, the non-activated; E sludge removal, F organic synthesis, vitamin manufacturing; general medicine manufacturing
The complete oxidation of organic matter
E organics removal.
Ozone treatment, in addition to sterilization effect, there are bleaching, deodorizing, so difficult to decompose the material into easily decomposed substances, flocculation of the improvement and enhancement of purification capacity. Therefore, water and treatment plant, a wide range of applications of ozone, both can be used to handle raw water, process water, it can handle the drainage, but, as the water used to produce bacteria means, ozone treatment method of the composite role in some occasions and unpopular.
Ultraviolet radiation sterilization of water in the water is not new to join any impurities, not to be dealing with any chemical changes of water, but in a very short period of time within the memory of their equipment to complete the sterilization process. Therefore, the ultraviolet sterilization methods most suitable for the production of clean water for sterilization.
Micro-organisms in the water factory equipment control, and product quality deterioration, corruption-related bacteria are common bacteria of the genus Bacillus, wild type yeast, filamentous fungi and so on.
Two ozone sterilization
An ozone sterilization system and sterilization features: ozone decomposition and the new eco-oxygen of oxygen. This new ecological role of oxygen in the cell wall of bacteria and viruses, and cell membrane, the reaction in the lipid (lipid-based compounds do) the double bond. Carrying out this role, the membrane is destroyed, and SH enzyme is destroyed, so as to achieve the effect of sterilization. The bacillus (Bacillus) Bacterial spores, with a concentration of 0.3-0.5mg / l of ozone sterilization agents can achieve sterilization effect. Weak ozone resistance of lactic acid bacteria. According to reports, the initial plate count 2.3-5.6 × 109/ml, by ozone for 30 seconds, most bacteria die.
Ozone disinfection, due to the different microbial species are very different, due to differences in cell wall or membrane to move into the.
Ozone treatment of buds with bacterial spores of Bacillus species and yeast, take a long time, but, if the increase in ozone concentration can shorten the response time adequate. In actual use, can be identified according to species and selected concentrations of ozone contact time.
By drinking water standards for ozone sterilization method, contact reaction timing is 5-8 minutes, ozone generators, ozone exit concentration of 0.4mg / l or more (injection rate of 2-3mg / l), the majority of instances to the above conditions to run management objectives. If the same system, the ozone injection rate increased to 5mg / l, according to the experimental results, the outcome of such treatment of water, in general, bacteria can not survive.
2 water ozone sterilization method is not only a sterilization device, but as a sterilization system. In order to establish such a system should pay attention to the matter.
A selection of stable production of ozone ozone machine. In recent years, ozone machines and technology developed significantly increased. Ozone generator available on the market, all types have, such as the silent discharge tube type, with pole plate, ceramic surface discharge, etc., Mitsubishi Electric, Sumitomo Precision, Fuji Electric and other leading manufacturers products, their performance reached the international advanced level. From 15G / H minicomputers to 40KG / H mainframe, may be raw materials for ozone matching PSA oxygen to form a series of products. Recently joined the ranks of the big manufacturers of hand machinery manufacturer, launched a portable ozone machine.
B ozone refined raw material: In addition to using fluorescent lamps manufactured using ozone or cold storage of small ozone machines, ozone machines for the industrial scale, as the ozone air purification addition to management of raw materials, dust removal, dehumidification is very important, in general: machine with a silent discharge ozone concentration of ozone to the air as the raw material is 1-3%, with oxygen as the raw material for 2-6%, if the refining process is not sufficient, then there is only the production efficiency of ozone low, and impurities in raw materials intact, part of the nitrogen oxides to form ozone into the water management system.
Water for food production and ozone sterilization method, preferably using pure oxygen or a PSA oxygen concentrator to supply ozone material.
C water and ozone contact time: ozone injection rate and contact time, as bacteria according to the types of objects and targets microbial sterilization rate may be. Construction costs may be due to the relationship between
D ozone concentrations Management: In order to carry out reliable ozone sterilization process, monitoring of ozone concentration and ozone into the solubility is very important to their control in an appropriate range. Now, in addition to continuous ozone concentration of high-precision measuring device, low-cost hand-held tester has been developed, so regular testing of ozone concentration, and to take remedial measures are necessary. Sterilization process in the water, inevitably to the ozone discharged to outside the system, it must carry out pest elimination, so that the volume of discharge allowable concentration of ozone below.
Three ultraviolet radiation sterilization law
A mechanism and process characteristics of UV disinfection
UV wavelength 200-290mm, bacteria or viruses through the cell membrane to control the behavior and biological function of nucleic acid genetic (DNA) causing damage, it lost support reproductive capacity, so as to achieve the goal to sterilization.
Nucleic acid (DNA) for ultraviolet wavelength 250-260mm, there are particularly vulnerable to the tendency to absorb. That is why this wavelength ultraviolet disinfection strongest reason. To kill micro-organisms in accordance with UV exposure required to carry out to deal with bacteria, without making any changes in water quality, flash in a very short period of time of sterilization, good effect. Moreover, this treatment is in the straight flow type of device completed.
UV sterilization, the sterilization of the size of the force to deal with water when compared to UV exposure mw.s/cm2 (UV radiation intensity [mw/cm2 × time]) to represent. According to the size of the amount of ultraviolet and sterilization firing rate correlation between the size.
2 killed outside the nationality of the application of ultraviolet occasions and notes
a UV disinfection unit selected: in the choice of ozone machine, should the standard amount of ozone, and ultraviolet disinfection unit Zeyi and ultraviolet radiation treatment volume of water-related criteria for the selection. Germicidal lamp illumination, with the use of time and decay, so the selection of the required amount of ultraviolet radiation, we should end the life of standard lamps.
b need to address water characteristics: use of ultraviolet sterilization method, according to the treatment of bacteria in water by An exposure to UV irradiated, may be initially an effect. Thus, the transmittance of UV treated water is a problem. In particular, contain mixtures of water or sugar solution, must be considered as the treated water (liquid) of the UV attenuation factor, followed, and then select the required amount of ultraviolet radiation.
c UV lamp temperature characteristics: In the past, the general use of a low pressure mercury lamp, the ambient temperature conditions of 40-50, the exposure rate peak, if in the case of low water temperature, the lower the efficiency of sterilization, this must be taken into account .