What are the main methods of river sewage treatment 14?

There are many kinds of sewage treatment technologies, but in a nutshell, they can be divided into three categories:

1. Physical sewage treatment technology: Physical methods can be subdivided into many small categories.

1 Grille and screen: Like screen, the process of separating large physical solids from sewage by mechanical isolation.

2. Homogenization and water quantity regulation: the sewage discharged from the same unit at different times has different water quality and water quantity. Therefore, these sewage should be homogenized and enter the sewage treatment system at a unified speed.

3. Precipitation: Some tiny solid particles cannot be ground. It is a good method to separate precipitation with screen.

4. Coagulation: Turbidity impurities in water vary greatly, and fine suspended impurities settle slowly, even close to no settlement. Colloidal particles are still dispersed in water and cannot be precipitated. After the coagulation process, turbid fine suspended impurities, unstable colloidal particles and reagent reactants in the water adhere to each other to form flocs with large size, visible to the naked eye and easy to settle and filter. Coagulation sewage treatment includes physical methods and chemical methods.

5. Clarification: A sewage treatment method, similar to precipitation but different. Based on the principle of contact coagulation, it suspends the generated flocculant in a pool to form a suspended sludge layer (contact coagulation zone), in which the concentration of suspended solids is about 3-10g/L. When raw water containing coagulant passes through it, the newly generated micro-flocculant in water is quickly adsorbed on the suspended sludge, thus achieving good removal effect. The efficiency of the purification tank depends on the activity and stability of the sludge suspension layer. Therefore, it is the common requirement of all cleaning tanks to keep the sludge in suspension, with uniform concentration and stable activity.

6. Air floatation: Solid particles suspended in water and water-insoluble liquid are wrapped by tiny bubbles and float to the surface for separation.

7. Filtration: It is similar to the principle of grid and screen, but it deals with tiny impurities in water.

8. Extraction method: the process of extracting pollutants with solvents that are insoluble in water but can dissolve impurities and pollutants contained in some sewage.

Two. Chemical wastewater treatment technology:

1 redox: using the principle of redox, the chemical substances dissolved in water are treated to form stable chemical raw materials.

2. Neutralization: Acidic or alkaline sewage is treated into neutral sewage through acid-base neutralization, which is convenient for other links.

3. Chemical precipitation method: It mainly deals with soluble salts in water. Some chemicals are put into sewage, and the water-soluble chemicals are changed into water-insoluble substances through chemical reaction, and then further separated through precipitation.

4. Adsorption method: the solute moves from water to the surface of solid particles and is adsorbed, which is the result of the interaction between water, solute and solid glume. The reasons for adsorption are the hydrophobicity of solute to water, the hydrophobicity of solute to water and the high affinity of solute to solid glume. The solubility of solute is an important factor to determine the first reason. The greater the solubility of solute, the less likely it is to move to the surface. On the contrary, the greater the hydrophobicity of the solute, the greater the possibility of moving to the adsorption interface.

5. Ion exchange method: Ion exchange method is a method of exchanging ions on ion exchanger with ions in water to remove harmful ions in water. In industrial wastewater treatment, it is mainly used to recover precious metal ions, and also used to treat radioactive wastewater and organic wastewater.

Three, sewage biological treatment technology:

1 microbial decomposition method: it is mainly the process of decomposing organic matter in water by microorganisms, including anaerobic bacteria, aerobic bacteria and facultative bacteria.

2. Biofilm method: Biofilm method mainly relies on microbial membrane fixed on the surface of carrier to purify organic matter.

3. Wetland ecological improvement method: artificially create wetland environment, plant lotus root, water hyacinth and other plants with strong adaptability in sewage treatment system, and improve wastewater through plant absorption and filtration. It is a sewage treatment technology widely used in large-scale urban sewage treatment.

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