1.1 Earth for human survival

The Earth's environment can be divided into five circles, namely the atmosphere, the hydrosphere, the lithosphere, the soil circle, and the biosphere. These five laps are the environment in which human beings depend. The sky we look up and see, the blue sky is the atmosphere. It is about 16km high, and the air is already thin at 1000km. What really affects human life is the densely populated area within a height of 16km. Various climate and meteorological changes occur here, and human life breathing metabolism also depends on the air in this area. It provides both the oxygen that humans need, and a thick gown that protects the Earth's creatures from excessive UV radiation. The hydrosphere is rich in water, which occupies 70.8% of the Earth's surface and has an average depth of 3.8 km. Among them, seawater accounts for about 97%. The water in the hydrosphere is constant, it does not increase or decrease, it is only in a constant cycle. The water on the ground, rivers, rivers, lakes and seas evaporates and turns into clouds. Under certain conditions, the clouds become rain and snow and fall to the ground, thus continuously circulating, forming a common weather change in human life. The lithosphere is the earth's crust and has a thickness of up to 100km. It contains both metallic and non-metallic minerals, which are essential for human life. The soil circle is the surface of the lithosphere, about a few meters to a few hundred meters. The soil nourishes crops, plants and animals. About one-tenth of the earth's area is cultivated or arable, about 150 million square kilometers. The biosphere is a region of human life. Biology, air, water, and soil are all part of the biosphere. Because it is most closely related to humans, it is divided into a single area.

1.2 Water shortage and pollution

For a long time, people have thought that water is inexhaustible. Among the 617 cities in China, 300 have water shortages and more than 50 cities are seriously short of water. About one-third of the industrial wastewater and 4/5 of the domestic wastewater are discharged into rivers, rivers, lakes and seas without treatment, causing serious pollution to the water environment. According to the monitoring of the environmental protection department, at least 100 million tons of sewage per day in the towns of the country are directly discharged into the water body without treatment. In China, only coastal cities and factories directly discharge 8.6 billion tons of sewage, and the main harmful substances are 1.46 million tons. The ocean has become huge garbage.

1.3 measures

In the face of increasing water pollution, we must take certain measures. The use of water treatment agents has become especially important!