, the country's emphasis on environmental protection is increasing, and environmental protection standards are also becoming stricter. The power industry also has a clear regulation on the emission of flue gas pollutants, and the concentration limit of SO2 emission standards is also decreasing. Currently, most domestic desulfurization projects adopt limestone gypsum wet desulfurization technology, resulting in zero discharge of desulfurization wastewater. Although traditional desulfurization wastewater treatment processes have certain treatment capabilities for certain pollutants in wastewater, they cannot remove chlorine from the wastewater. Ions and salts. With the increasingly strict technical standards for desulfurization wastewater discharge, the issue of zero discharge of desulfurization wastewater has become an inevitable trend of development and change.
Water quality characteristics and influencing factors of zero discharge desulfurization wastewater
The harmful substances in desulfurization wastewater pose a great threat to the environment and water, therefore, the treatment of desulfurization wastewater should be taken seriously. To achieve zero discharge of desulfurization wastewater, it is first necessary to understand the water quality characteristics and influencing factors of desulfurization wastewater.
1. Water quality characteristics of desulfurization wastewater
The composition and concentration of desulfurization wastewater have a significant impact on the operational cost management capability of the treatment information system, and are key factors affecting the selection of treatment technology equipment and corrosion. Desulfurization wastewater generally has the following characteristics.
(1) The water quality is weakly acidic: the pH value in foreign countries is 5.0-6.5, while the pH value in China is 4.0-6.0
(2) High concentration suspended solids, up to tens of thousands of mg/L.
(3) COD, fluoride, and heavy metals exceed the standard, including Class 1 pollutants such as As, Hg, and Pb.
(4) High salt content, containing a large amount of SO42 SO32 Cl? Plasma, as well as the mass fraction of Cl? Approximately 0.04
2. Factors affecting the water quality of desulfurization wastewater
The quality and quantity of desulfurization wastewater treatment are mainly influenced by factors such as the quality of coal combustion, the quality of limestone, the design and operation of desulfurization technology systems, the control and management equipment for pollutants in front of desulfurization towers, and dehydration equipment. Figure 1 shows the relationship between the main factors affecting the quality of desulfurization wastewater.
Coal is the main source of pollutants in desulfurization wastewater. Different types of coal can affect the discharge of desulfurization wastewater: the combustion of high sulfur coal will produce more problematic sulfur dioxide, which will increase the amount of sulfur dioxide used as a desulfurizer and increase the discharge of desulfurization process wastewater from enterprises; The combustion of high chlorine coal will increase the chlorine content in the flue gas, which can in turn increase the chlorine content in China's desulfurization slurry. In order to prevent corrosion of the desulfurization system and maintain a certain level of chloride ion concentration in the desulfurization slurry, the removal rate of the desulfurization slurry will be increased to enable desulfurization. The amount of wastewater discharge has increased.
The conventional desulfurization wastewater treatment process can no longer meet the current environmental protection situation and market demand of enterprises, and zero discharge of desulfurization wastewater has become a trend of social development and change;
The zero emission steam evaporation technology for desulfurization wastewater occupies a large area, has high investment and operation management costs, and is difficult to widely promote and apply in the market;
The zero emission flue gas evaporation process management system for desulfurization wastewater can be simple, with high investment and operating time costs, and will become the mainstream media technology for enterprises in the future zero emission desulfurization wastewater market.
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