Secondary treatment is mainly to remove wastewater.

Wastewater contains a lot of organic matter, which will cause serious harm to the environment and human health if it is not treated. Therefore, secondary treatment is a very important step in wastewater treatment. The main function of secondary treatment is to remove organic matter and other pollutants from wastewater, so that the wastewater can meet the national discharge standards.

1. Method of secondary treatment

The methods of secondary treatment mainly include biological treatment and physical and chemical treatment. Biological treatment is the use of microorganisms to degrade organic matter in wastewater, including aerobic and anaerobic methods. Aerobic method is to use oxygen as a necessary factor for microbial degradation of organic matter in wastewater, and treat wastewater in biological treatment tank. Anaerobic method is to degrade the organic matter in wastewater by microorganisms under anoxic or anaerobic conditions, and the by-products can be used for fermentation or as energy.

Physical and chemical treatment is the treatment of wastewater by physical or chemical methods, including adsorption, oxidation, reduction, electrolysis and so on. Among them, adsorption method is to adsorb the organic matter in wastewater by adsorbent and fix it on the surface of adsorbent to achieve the purpose of removing the organic matter. The law of oxidation is to use oxidant to oxidize organic matter into harmless substances. The principle of reduction is to reduce inorganic substances in wastewater by reducing agent and convert them into harmless substances. Electrolysis is to oxidize the organic matter in wastewater into harmless substances by electrolysis.

2. Advantages of secondary treatment

Compared with the primary treatment, the secondary treatment has a better effect, which can remove more pollutants and make the wastewater more in line with the national discharge standards. The invention has the advantages of high treatment efficiency, simple operation and low cost, and can also reduce the impact of wastewater on the environment and the harm to human health.

In a word, secondary treatment is a very important step in wastewater treatment, which can effectively remove the organic matter in wastewater and make it reach the national discharge standard. When selecting the secondary treatment method, the appropriate treatment scheme should be determined according to the characteristics and treatment requirements of wastewater to achieve the best treatment effect.