Problems Existing in Chemical Wastewater Treatment Technology

1. Physical method The physical method mainly uses physical principles and means to realize wastewater treatment. Its operation is simple. The common treatment technologies are: (1) Filtration method, which refers to the use of filter layers to intercept pollutants. This method is mainly used to reduce large amounts of pollutants in water. The content of molecular suspended matter. (2) Precipitation method refers to the process of sedimentation and separation of pollutants under the action of gravity. (3) The air flotation method refers to the method of using the generated air bubbles to bring suspended pollutants out of the water. However, these methods cannot handle water-soluble components and have great limitations. 2. Chemical method Chemical method is to oxidize, decompose and precipitate impurities in sewage through various chemical reactions, so as to achieve the purpose of reducing toxic substances. There are three common chemical wastewater treatment methods: (1) Chemical oxidation method, which refers to the use of oxidants such as ozone and chlorine to oxidize the pollutants in wastewater to convert them into easily degradable substances. This method has better processing effect, but the cost is high. (2) Coagulation-sedimentation method, which refers to adding chemical coagulants to accumulate and precipitate pollutants in wastewater. However, this method is affected by factors such as pH value and temperature, and its scope of application is limited. (3) Micro-electrolysis technology refers to the use of electrolysis to electrochemically act on the pollutants in wastewater, so that the pollutants undergo chemical reactions and are transformed into easily degradable molecules. However, the current micro-electrolysis technology can only treat specific industrial wastewater and cannot be widely promoted. 3. Biological method Biological method refers to the use of microbial metabolism to transform and degrade organic pollutants in wastewater. There are two main types of biological wastewater treatment: aerobic treatment and anaerobic treatment. Aerobic treatment methods include activated sludge and biofilm. Activated sludge is a flocculent organism composed of aerobic microorganisms and their metabolized and adsorbed organic and inorganic substances. It has the function of adsorbing pollutants and can reduce the content of pollutants in wastewater. The biofilm method is to use the adsorption and oxidation of the biofilm to treat the organic matter in the wastewater. Anaerobic treatment refers to the process of decomposing and converting organic pollutants in wastewater into non-toxic substances under the action of anaerobic microorganisms. The biological wastewater treatment method has the advantages of low cost and simple operation, but microorganisms have certain requirements for the living environment, and it is difficult to survive in the highly toxic chemical wastewater, which leads to various situations in the actual application stage of the biological method. 4. Technology combining physics and chemistry There are various types of pollutants in wastewater, and the ideal treatment effect cannot be achieved by using only one technology. Therefore, wastewater treatment technology often combines the above three principles. It mainly includes the following three types: (1) Ion exchange method, which refers to the method of using ion exchangers to exchange the ions of substances in wastewater to remove pollutants. This method is often used in water softening and organic wastewater treatment. (2) Extraction method, the extraction agent is immiscible with water or has a low solubility, but it can greatly dissolve pollutants. Using this feature, the extraction agent can separate pollutants from water to achieve the purpose of purifying wastewater. (3) Membrane separation method refers to the process of using a semi-permeable membrane to separate and infiltrate solutes from water. Since this technology permeates anions and cations under the action of an electric current, it is also called electrodialysis. . This method is simple and convenient, but the cost is high and re-pollution is prone to occur.