Ozone is used in the treatment of municipal sewage, which has remarkable effects in sterilization, bleaching, decolorization, deodorization, odor removal and so on. The oxidation capacity, decomposition characteristics and corrosiveness of ozone are introduced, and a complete ozone treatment system is described. Ozone oxidation process does not produce secondary pollution, easy to operate, can be prepared by air on the spot. With the improvement of effluent water quality requirements in sewage treatment plants, using ozone as a deep treatment process for municipal sewage treatment can give full play to the characteristics of ozone strong oxidant and strong catalyst, and achieve remarkable results in sterilization, bleaching, decolorization, deodorization, odor removal and so on. (Qingdao large ozone generator, ozone equipment, ozone generator price)
1, the basic properties of ozone
1.1 Oxidation capacity of ozone
Ozone has a strong oxidizing capacity and is one of the strongest oxidants known. As can be seen from Table 1, ozone is the most oxidizing in water treatment.
The free radicals HO₂ and HO formed by the reaction have strong oxidation capacity and have oxidation capacity with other impurities in sewage.
1.2 Decomposition of ozone
The chemical properties of ozone are extremely active, and it is easy to decompose into oxygen at room temperature and release heat.
2O₃ - 3O₂+△H, △H = 284KJ/mol
The rate of ozone decomposition in the air is related to ozone concentration and temperature. When the concentration is below 1%, the decomposition rate is shown in Figure 1. It can be seen that the higher the temperature, the faster the decomposition, and the higher the concentration, the faster the decomposition.
The half-life of ozone decomposition in water is related to temperature and pH. With the increase of temperature, the decomposition speed is accelerated, and the decomposition is very violent when the temperature exceeds 100 ° C. And the higher the pH, the faster the decomposition. The decomposition half-life of ozone in water is shown in Table 2.
1.3 Corrosion
Ozone is a strong oxidizing agent, and ozonated air is corrosive to almost all metals except gold and platinum. But chromite alloy is basically protected from ozone corrosion. Based on this, chromium ferroalloy (stainless steel) containing 25% Cr is often used in production to manufacture components in direct contact with ozone in ozone generating equipment and filling equipment.
Ozone also has a strong corrosive effect on non-metallic materials. In ozone generation equipment and metering equipment, ordinary rubber cannot be used as sealing materials, and silicone or acid-resistant rubber with strong corrosion resistance must be used.
2, ozone process sewage treatment process
Ozone is often used as an operating unit after conventional wastewater treatment processes or as recycled water after effluent quality has been improved. The main flow of sewage treatment by ozone process is shown in Figure 2.
A complete ozone system, including the following components: ① power supply; ② Preparation facilities for batching gas; (3) Ozone generation facilities; ④ Contact equipment between ozone and treated liquid; ⑤ exhaust gas damage facilities.
2.1 Energy Requirements
The main requirement for electricity is to provide energy for the conversion of oxygen into ozone. Other areas that require electricity include preparation of batching gas, exposure to ozone, destruction of remaining ozone, and control, instrumentation, and monitoring facilities. Table 3 shows the energy requirements for the main components
2.2 Preparation of proportioning gas
Ozone is produced by air, oxygen-rich air, or high-purity oxygen. If ozone occurs in the use of air, moisture, particulate matter, and oil mist must be removed before it is directed to the ozone generator. If these impurities are not removed, they will cause harm to the ozone generation process. The design indicators of the raw material system that can meet the normal operation of the ozone generation system are as follows:
① Temperature: below 30℃; ② Particles: 100% removal of solid particles above 0.3μm; 95% removal of solid particles above 0.1μm. (3) Oil and other hydrocarbons: maximum 4 ~ 5 mg/l; ④ Dew point: atmospheric dew point of -65℃ ~ 100℃.
Air improvement includes at least the following steps: ① Compress the air; Cooling and drying the air; ③ Air filtration. If pure oxygen is used, no improvement steps are required.
2.3 Ozone generation
Because ozone is chemically unstable and quickly breaks down into oxygen after it occurs, it must occur in situ. The most effective method of producing ozone today is the electric discharge method. In an electric field region formed by a high voltage electrode and a low voltage electrode, when dry oxygen or air flow through this dielectric chamber formed by the electrode and the blocking dielectric, at high voltage/high density
Under the action of degree current, oxygen molecules form oxygen atoms under electron bombardment, and oxygen atoms and oxygen molecules combine to form ozone. Typical ozone discharge units and synthesis processes are shown in Figures 3 and 4.
2.4 Ozone exposure
The ozone produced by the ozone generator requires an ozone contact reaction system to put ozone into the sewage and make it carry out chemical reactions and disinfection biochemical reactions with organic matter, bacteria, metal ions and so on in the sewage. A countercurrent baffle contactor is traditionally used, as shown in Figure 5, where ozone is exposed in a one - to three-compartment capped contact cell. Ozone is introduced from the bottom of the first chamber with a porous diffuser or syringe. A rapid ozone reaction occurs in the first chamber, and then a mixture of sewage and ozone enters the second chamber for a slower reaction. A third reaction chamber is used to complete the slow reaction and to decompose the ozone.
2.5 Exhaust gas damage
Because ozone is a particularly irritating and toxic gas. Exhaust gas from the contactor should be collected and all residual ozone resolved.
The use of ozone method to treat municipal sewage in depth has remarkable sterilization and decolorization effects, and has a certain COD removal rate, and has obvious effect on improving the quality of effluent and reuse water in sewage treatment plants.
Qingdao Aikang Environmental Protection Technology Co., Ltd. is a 15-year focus on ozone generator R & D, manufacturing and application of professional companies, the company has been to serve customers as the purpose, to technology as the guide, independent development of ozone generator manufacturing and application technology, obtained zhuanli dozens, has a sincere cooperation generator manufacturing and application team.
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