Advantages of ozone generators in water treatment

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Ozone generators possess strong oxidizing properties and are used in water treatment for wastewater, purified water, domestic water, and more； What are the advantages of ozone generators in water treatment? 1. Ozone is an excellent oxidant that can kill viruses and spores with strong resistance to chlorine ； 2. Ozone disinfection is less affected by the pH value and temperature of wastewater ； 3. Ozone can remove pollutants such as color, odor, taste, and phenols and chlorines from wastewater, increase the dissolved oxygen in water, and improve water quality ； 4. Ozone can decompose biodegradable organic compounds and carcinogenic, mutagenic, and teratogenic substances, thereby improving the biodegradability of wastewater ； 5. Ozone decomposes easily in water, so it does not cause secondary pollution due to residues. Wastewater ozone treatment process: 1. In the wastewater ozone treatment process, ozone generators are used for disinfection. Pretreatment is extremely important for wastewater that is to be disinfected with ozone; insufficient pretreatment often affects the effectiveness of ozone disinfection. The degree of wastewater treatment should be determined through technical and economic considerations. It is best to disinfect wastewater by ozone treatment after secondary treatment. This can reduce the amount of ozone added, thereby lowering equipment investment and operating costs. 2. Ozone generators in the design of ozone disinfection processes and equipment selection: The design of wastewater ozone disinfection processes includes the design of pre-treatment processes, the design of ozone disinfection contact systems, as well as the selection of ozone generators and related equipment. The pretreatment process refers to the primary or secondary treatment of wastewater prior to ozone disinfection. Safety and protection of ozone generators and ozone treatment systems. Factors affecting the performance of ozone generators in water treatment. Ozone disinfection machines exhibit very high sterilization efficiency when used for drinking water disinfection; however, when applied to wastewater disinfection, a larger amount of ozone is required along with a longer contact time. The main reason is the presence of high levels of pollutants in wastewater, such as COD, NO2-N, color, and suspended solids; these substances consume ozone and reduce its disinfecting capacity. Only by subjecting the wastewater to appropriate pretreatment before ozone disinfection can this process be made more economical and effective. The mass transfer effect resulting from the contact between ozone and wastewater also influences the amount of ozone added and the disinfection efficiency. 1. The effects of water quality mainly refer to the impact of COD, NO2-N, suspended solids, and color in water on ozone disinfection. 2. Ozone dosage and residual ozone level: Residual ozone plays an important role in disinfection, just like residual chlorine. For drinking water disinfection, a residual ozone concentration of 0.4 mg/L is required, at which point E. coli levels in the drinking water meet the quality standards. In the case of wastewater disinfection, residual ozone can only exist for a short period of time; for example, in the ozone disinfection of secondary treated water, the ozone remains present for only 3–5 minutes. The residual ozone measured, in addition to a small amount of free ozone, also includes ozonides, peroxides, and other oxidants. When the water quality is good, the concentration of free ozone is high, resulting in the best disinfection effect. 3. Contact time: The contact time required for ozone disinfection is very short, but this process is also influenced by water quality factors. Additionally, studies have shown that the disinfecting effect continues during the period after exposure to ozone; ozone maintains its disinfecting effect within the first 10 minutes of contact, but no such effect is observed after 30 minutes. 4. The way ozone comes into contact with wastewater also affects the disinfection efficiency; for example, when the bubbling method is used, the smaller the bubbles, the higher the utilization rate of ozone and the better the disinfection effect. The size of the bubbles depends on factors such as the diameter of the diffusion pores, water pressure, and surface tension. Mechanical mixers, reverse spiral fixed mixers, and water jetters all provide excellent mixing of water and air, making them fully suitable for ozone disinfection of wastewater. Ozone generator selection 1. Anti-corrosion treatment of system equipment pipelines Ozone gas is highly corrosive, with its corrosivity being greatest in humid conditions. Therefore, the valves of the ‘ozone delivery pipes’ in the ozone generation equipment, as well as the contact reaction equipment, all have anti-corrosion measures in place. If carbon steel material is used, an anti-corrosion coating must be applied. It is best to use stainless steel pipes, glass fiber reinforced plastic pipes, as well as ABS, PVC, PVDF plastic pipes, etc. When reinforced concrete materials are used for contact tanks, an anti-corrosion coating should be applied. Generally, rubber is not resistant to ozone oxidation; therefore, wires and cables in ozone generation equipment must not be covered with rubber, but rather plastic wires should be used. 2. Install ventilation and exhaust equipment. Ozone is toxic; when its concentration in the air reaches 0.1 mg/m3, it can irritate the eyes, nose, throat, and respiratory tract. An odor can be detected at concentrations of 0.01–0.02 mg/m3 ； Therefore, ventilation equipment should be installed in ozone equipment rooms to allow for the prompt removal of ozone in the event of a leak. Ozone is heavier than air, so the ventilator should be installed near the ground. 3. The ozone delivery pipes and ozone equipment must be airtight to prevent leaks. Before the equipment is put into operation, it should be checked for any leaks; if a leak occurs during operation, the power to the ozone generator must be turned off immediately, and a exhaust fan should be used to remove the ozone before any repairs can be carried out. 4. The ozone generator is a high-voltage discharge device, and a grounding system must be installed; the grounding resistance should be less than 4 ohms. The operation must be carried out strictly in accordance with the equipment’s user manual and relevant electrical usage requirements. 5. An exhaust gas treatment or recovery system must be installed; the ozone-containing exhaust gases emitted after the reaction must be decomposed or recycled in order to meet the emission standards, otherwise the atmosphere will be polluted. Key points for the layout of ozone generators and ozone disinfection equipment: 1. In wastewater ozone treatment plants, an air compressor room, an ozone generator room, and an operation room should be provided. The air compressor is placed in the air compressor room, where it should be protected from vibrations and noise. Space is provided between the ozone generators for equipment maintenance. 2. In cold regions, the ozone contact tower should be installed indoors, with the treated exhaust gas being discharged outdoors through an exhaust pipe. 3. According to the requirements of the treatment process, the pump should be placed as close as possible to the treatment equipment. 4. It is essential to prevent the wastewater inside the tower from returning to the ozone generator through the ozone pipes. 5. There should be drainage channels within the equipment room to allow for the drainage of water from the air compressors; in cold regions, heating equipment is necessary. Exhaust gas treatment: 1. Ozone generated during wastewater treatment cannot always be fully absorbed and utilized by the wastewater, so some ozone remains in the exhaust gases. If these gases are released directly into the atmosphere, they will pollute the environment and harm human health. The remaining ozone should be made use of as much as possible, for example by regularly introducing it into the raw wastewater. If it truly cannot be utilized, it must be disposed of. Methods for exhaust gas treatment include combustion, activated carbon adsorption, chemical absorption, and catalytic decomposition. The ozone content in the treated exhaust gas should be less than 0.1 mg/l. Currently, recycling, thermal decomposition, and Hogaratt catalyst-assisted decomposition methods are commonly used.