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Application of sodium hypochlorite in wastewater treatment of thermal power plants

Sep19,24

In thermal power plants, water is an essential medium. Raw water is treated into a boiler and converted into steam into a turbine. The thermal energy of the steam is converted into mechanical energy, and the turbine drives a generator, which in turn converts the mechanical energy into electrical energy. Most of the wastewater discharged in the production process of thermal power plants contains harmful or toxic pollutants with different characteristics, which may cause different degrees of environmental pollution hazards if discharged directly into the natural water system. In the total water consumption of thermal power plants, the cooling water of condenser accounts for the vast majority, followed by hydraulic flushing (slag) ash water, chemical wastewater, desulfurization water from coal field, etc.

The circulating water effluent comes from the sewage of the circulating cooling water system, which is the high salt content wastewater discharged in order to control the content of salt impurities in the cooling water during the operation of the system. In order to recover and reuse the circulating water sewage, the main process of treatment is to first stand the precipitated sewage for a period of time, then pour it into the clear tank, use the pump to transport it to the fiber filter and the ultrafiltration system, and then perform reverse osmosis treatment again. After desalting treatment, it can be used as a fresh water source for replenishing circulating water. This technology can effectively improve the problem of high salt content of circulating water in industrial enterprises, and the water resource utilization efficiency of industrial enterprises will also be significantly improved.

Desulphurization wastewater is the industrial wastewater produced by the desulphurization process using wet limestone and gypsum in power plants. Compared with other types of wastewater in power plants, the content of pollutants in the water is higher, containing various inorganic salts and heavy metals, and causing greater damage to the environment. At present, the main desulphurization wastewater treatment process has played a certain role in the treatment of desulphurization wastewater. However, the potential pollution caused by desulphurization wastewater is still unresolved. Due to poor water quality, desulfurization wastewater is not considered for reuse, and is generally discharged after treatment. There are many items in desulfurization wastewater that exceed discharge standards, including COD, pH, heavy metal ions, F- and so on. The sodium hypochlorite solution produced by BLUEWAV sodium hypochlorite generator can effectively solve the problem of excessive emissions.

CI content is one of the key factors affecting the treatment and reuse of desulphurization wastewater. If the Cl content in desulphurization wastewater can be reduced, the recycling ratio of wastewater can be increased, and the waste water can be reduced, which is of great significance for realizing zero discharge of waste water in the whole plant. As a clean, convenient, low cost, high chlorine wastewater treatment technology with high water quality fluctuation resistance and no secondary pollution, electrolysis method has inherent advantages in industrialization due to its relatively mature process, and its electrolytic product effective chlorine solution can be used as a fungicide in circulating cooling water system, indirectly inhibiting carbon steel corrosion and realizing the recycling of resources. By adding sodium hypochlorite solution to its circulating water system, it can inhibit the growth of microorganisms, keep the heat exchanger or condenser system, cooling tower and other systems clean, ensure the flow section of the water intake channel, and ensure the safe operation of the water system. Thermal power plants need a lot of cooling water, in order to save fresh water resources, usually use electrolytic seawater to produce NaClO solution as a bactericide, this process is mature, and the advantages of being near the sea, easy to use, and its production cost is low.

For the deamination treatment of desulphurization wastewater, sodium hypochlorite solution can be used to further oxidize residual ammonia nitrogen, so that it can finally meet the discharge standard. Adding 10% sodium hypo can effectively improve the removal effect of ammonia nitrogen in desulfurization wastewater, and the greater the dosage, the better the effect. With the increase of chlorination dosage, the remaining ammonia nitrogen in the wastewater decreases continuously. When the dosage is 12 g/L, the ammonia nitrogen in the desulfurization wastewater is completely removed, and the removal rate reaches 100%. In practical application, as long as ammonia nitrogen is less than 15 mg/L, the standard discharge can be reached. Therefore, the optimal dosage of sodium hypo is determined to be 7.5g/L, and the ammonia nitrogen of the treated desulfurization wastewater can meet the requirements of the first-level discharge standard.

In thermal power plants, domestic sewage is a special kind of wastewater, mainly from the canteen, bathroom, office building, living area drainage, generally with a special drainage system. Its water quality is different from other industrial wastewater, with odor, color, organic matter, suspended matter, bacteria, oil, detergent and other components, and the salt content is slightly higher than tap water. Most power plants are equipped with domestic sewage treatment devices, which are discharged after treatment to meet the standards. The bactericidal tank (contact tank) kills bacteria in the water by adding sodium hypochlorite bactericide to prevent harmful bacteria from being discharged to other bodies of water. Out of the pool, collect and store the treated water, discharge or return to the circulating water system.
It is wise to choose BLUEWAV for wastewater treatment. We are a professional manufacturer of sodium hypo machine , we have good experience on small plants and big plants up to 30 tons/day 12% HYPO. Our company, BLUEWAV are specialized on disinfection & water treatment technology since year 2001, we research & develop & manufacture.
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