The combined disinfection method of "ozone + sodium hypochlorite" is rarely applied in the water treatment of industrial enterprises. This disinfection method combines two disinfection methods: ozone and sodium hypochlorite. Using ozone disinfection, ozone takes less time to kill pathogens, is more efficient and does not produce toxic and harmful byproducts. Ozone disinfection has the advantages of on-site occurrence, fast reaction speed, immediate decomposition of ozone after disinfection, basically eliminating the toxic effect on biota, increasing dissolved oxygen in water, and non-toxic. Combined with the advantages of air compressors in the factory area and lower electricity costs, ozone disinfection can be used. Because ozone does not have continuous disinfection capacity, a small amount of sodium hypochlorite is added at the same time to control residual chlorine in water, which can make this disinfection method have continuous disinfection capacity. According to the above analysis, the disinfection prescription of "ozone + sodium hypochlorite" takes a short time to disinfect and kill pathogens, has high efficiency, and produces fewer toxic and harmful by-products, and has continuous disinfection capacity; The combined disinfection method of "ozone + sodium hypochlorite" has high realizability in domestic sewage treatment station.
Process flow
The effluent from the valveless filter enters the ozone contact pool, and the ozone generator adds ozone disinfection by contacting the aeration plate set at the bottom of the pool, and auxiliary sodium hypochlorite disinfection. After disinfection, the effluent enters the middle pool and is raised to the water point by the middle water pumping station.
Ozone disinfection air source system
Ozone generator air source can be used dry air, liquid oxygen or on-site oxygen, this design uses air as the air source. The raw material gas required to produce ozone is oxygen or gases containing oxygen (such as air), should not contain impurities such as moisture, dust oil, hydrocarbons and hydrogen as much as possible, all of these impurities will have an adverse effect on the ozone formation process, and may cause a certain degree of damage to the equipment.
The raw material gas supplied to the ozone generator must meet at least the following standards:
1, water content: the dew point of the air source is required to be lower than -50℃;
2, oil content: the oil content is not higher than 0.01mg/m(21℃);
3, impurity particle size: impurity particles <0.1mm, preferably <0.01μm;
4, temperature: the general requirements of the temperature is not higher than 25℃, special conditions are not higher than 35℃;
5, pressure: a certain pressure is required to ensure stable work and meet the needs of ozone gas dozing.
Ozone preparation room
Ozone preparation room is equipped with ozone preparation system, this design includes two sets of ozone generation system and supporting power distribution system, automatic control system and safety exhaust system. The ozone preparation room is arranged on the ozone contact pool. Refer to "Water Supply and Drainage Design Manual" (Volume 5 Urban drainage), because the purpose of ozone injection in this project is to inactivate bacteria and control the total number of bacteria in effluent, the recommended ozone dosage is 5~15mg/L, and the contact time is 6~15min. According to the results of scientific research, the recommended value of ozone dosage is about 5mg. Therefore, 5mg/L is used as the design ozone dosing concentration in this project. This project calculates the ozone dosing concentration of 5mg/ h according to the maximum hourly water of 180m'/h, then the ozone dosing amount is 900g/h, so 2 sets of ozone generators with an ozone output of 500g/h are selected.
Ozone system configuration includes air source treatment system, ozone generator, cooling water system, ozone dosing system, tail gas destruction system. Air source treatment system: including freeze dryer and adsorption dryer. After the air is compressed by the compressor, the filter of the main pipeline removes >1um dust particles and water mist and oil mist, the shallow water is removed by the refrigerated dryer, and the dust particles of >0.01mm are removed by the high efficiency oil removal filtration and ultra-high efficiency oil removal filtration, so that the content of water mist and oil mist does not exceed 0.01mg/m3, and then enters the oxygen generator to produce high purity oxygen. Then the dust particles >0.01um are removed by the general dust removal filter and the high efficiency dust removal filter to become a qualified raw material gas source.
Ozone generator: The qualified air source enters the ozone generation chamber after reducing pressure and stabilizing pressure. In the ozone generating room, part of the oxygen is changed into ozone by medium frequency high voltage discharge, and the product gas is produced by the ozone outlet after temperature, pressure and flow monitoring and adjustment.
Cooling water system: The primary water produced in the factory is used as cooling water, the cooling water is not circulated, and the cooling equipment directly flows into the middle pool. Direct cooling water flow 5~10m '/h, water temperature 10~20℃.
Ozone dosing system: aeration dosing method is used to fully react ozone gas with water in the contact tank.
Exhaust gas destruction system: the ozone contact tank is equipped with two-way breathable safety valve and exhaust outlet. The exhaust gas in the pool is removed by the mist eliminator and enters the exhaust gas destroyer. The exhaust gas destroyer uses the method of heating and catalysis to decompose the ozone, and the control of the entire exhaust gas destroyer is controlled by the exhaust gas destruction box. The decomposed gas ozone concentration <0.1mg/m3 can be directly discharged into the atmosphere.
The ozone leakage alarm device is set in the ozone preparation room, and an alarm is issued when the concentration exceeds the set limit.
Ozone contact cell
Due to the shortage of land for the sewage treatment station, the solution adopted is to set up an ozone disinfection room on the ozone contact pool. The ozone contact cell is divided into three diffusion chambers with a partition in the middle. Microporous aerator heads are used in each diffusion chamber. Ozone is added in three stages, and microbubble aeration systems are arranged in each stage. The proportion of ozone added in the three stages is 50%, 25% and 25% respectively. In order to facilitate the mixed contact between ozone and water, improve the mass transfer effect and ozone utilization rate, and improve the operation effect, the vertical diversion partition is set up in the reaction zone of the ozone contact pool. The top and bottom of the baffle are provided with air holes and water holes. The ozone contact cell adopts a fully closed structure. The total residence time of the ozone contact cell is 30min. The ozone conveying and dosing pipe is made of 316L stainless steel pipe.、
Sodium hypochlorite dosing system
According to GB50014-2006 Outdoor drainage Design Code, the recommended amount of chlorination disinfection is 6~15mg/L, and 15mg/L sodium hypochlorite is used as the purchased solution in the design, and the concentration is 12.5%. Add to the inlet pipe of the ozone contact tank through the dosing pipe to carry out mixing auxiliary disinfection in the ozone contact tank.
After water quality analysis, the changes of total coliform groups in and out of water are shown in Table 1.
It can be seen that the combined disinfection method of "ozone + sodium hypochlorite" has achieved good results and meets the requirements of microbial indicators in reclaimed water reuse.
Conventional disinfection, such as chlorine, chlorine dioxide, ozone and ultraviolet light, is economical and effective, but has disadvantages such as harmful by-products produced in the disinfection process. Combined disinfectants can effectively inactivate pathogenic microorganisms in water, effectively control the generation of disinfection by-products, and prolong or guarantee the disinfection effect of pipe network water. The disinfection of different projects can not be confined to a single disinfection method, and the combined disinfection method of "ozone + sodium hypochlorite" in this project has achieved a good treatment effect, and provides an application example with high reference value for the water disinfection of industrial enterprises. In order to protect the environment, it is necessary to control sewage discharge to meet the standards. The two combined forms of disinfectants better integrate the advantages of ozone and sodium hypochlorite, so that the disinfection process is more diversified. BLUEWAV sodium hypochlorite generator Lower salt consumption, higher output, multiple exporting countries experience, welcome to buy!
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