development of human civilization, with the acceleration of industrialization and urbanization, the problem of water pollution has become increasingly serious, which has become one of the major obstacles restricting sustainable development. Sewage not only comes from industrial production and agricultural activities, but also widely exists in daily life, such as household washing wastewater. Untreated or improperly treated sewage discharged directly into the natural environment will cause irreversible harm to surface water, groundwater and even the whole ecosystem. Therefore, sewage treatment is not only an important part of environmental protection, but also a key measure to realize green development and build an ecological and civilized society.

I. Protecting water resources

The fresh water resources on the earth are very limited and unevenly distributed, and water is the source of life and plays an irreplaceable role in maintaining ecological balance. Through scientific and effective sewage treatment technology, harmful substances in water can be removed, and the sewage can be reused or safely discharged after reaching a certain standard, thus reducing the demand for fresh water and alleviating the pressure of water shortage.

Second, maintaining ecological health

Sewage contains a large number of pollutants such as organic matter, heavy metals and pathogenic microorganisms. Once these components enter nature, they will destroy soil structure and affect plant growth. At the same time, it will also lead to eutrophication of water bodies, lead to excessive algae reproduction, and form a "red tide", which threatens the life safety of fish and other aquatic organisms. Implementing efficient sewage treatment measures can effectively purify water quality and ensure the safety and stability of the ecological environment.

Iii. promoting sustainable economic and social development

Good environmental quality is an important foundation for sustained and healthy economic development. On the one hand, high-quality water resources help to improve agricultural irrigation efficiency and ensure food safety; On the other hand, clean waters can also attract tourism investment and promote local economic growth. In addition, the sludge produced during sewage treatment can be used as fertilizer after harmless treatment, which not only solves the problem of waste disposal, but also provides resource support for agricultural production.

In a word, sewage treatment is related to the improvement of people's quality of life, the restoration of ecological environment and the realization of the country's long-term development strategic goals. Facing the increasingly severe challenge of environmental pollution, we should take active actions, strengthen technological innovation, improve the system of laws and regulations, raise the awareness of environmental protection of the whole people, and jointly protect the precious water resources on this blue planet, so that green mountains and green rivers can remain in the world.