Causes of Sewage

　　The following is an introduction to the causes of sewage pollution:

　　Among the water pollution caused by human production activities, industrial water pollution is the most serious. For example, industrial wastewater contains many pollutants and has complex components. It is not only difficult to purify in water, but also difficult to treat. Industrial wastewater is the most important cause of water pollution caused by industrial pollution. It accounts for most of the pollutants discharged by industry. The pollutants contained in industrial wastewater vary greatly depending on the type of factory. Even for the same type of factory, the quality and quantity of pollutants contained are different due to different production processes. In addition to the direct injection of industrial wastewater into the water to cause pollution, solid waste and waste gas can also pollute the water.

　　Agricultural pollution is first caused by the loosening of the land surface due to farming or land reclamation. When the soil and terrain are not stable, it rains, and a large amount of sediment flows into the water, increasing the suspended matter in the water.

　　Another important reason is the increasing use of pesticides and fertilizers. Only a small amount of the pesticides and fertilizers used are attached or absorbed, and the vast majority of the rest remain in the soil and float in the atmosphere. Through rainfall and surface runoff, they enter the surface water and infiltrate the surface water to form pollution. Urban pollution sources are caused by the concentration of urban population, urban domestic sewage, garbage and exhaust gas causing water pollution. The pollution of water bodies by urban pollution sources is mainly domestic sewage, which is a mixture of various sewage generated in people's daily lives, including sewage discharged from kitchens, washrooms, bathrooms and toilets.