Domestic sewage is the waste water discharged from the daily life of residents, mainly from residential buildings and public buildings, such as houses, institutions, schools, hospitals, shops, public places, and industrial enterprise toilets. The pollutants contained in domestic sewage are mainly organic matter (such as protein, carbohydrate, fat, urea, ammonia nitrogen, etc.) and a large number of pathogenic microorganisms (such as parasitic eggs and intestinal infection viruses, etc.). The organic matter present in domestic sewage is extremely unstable, and it is easy to decay and produce malodor. Bacteria and pathogens multiply in large quantities by the organic matter in domestic sewage, which can lead to the spread of infectious diseases. Therefore, domestic sewage must be treated before being discharged.

Sewage treatment

The development of my country's sewage treatment industry is relatively late. Since the founding of the People's Republic of China and before the reform and opening up, my country's sewage treatment demand has been mainly based on the cutting-edge use of industry and defense. After the reform and opening up, the rapid development of the national economy and the marked improvement in people's living standards have driven the demand for sewage treatment. After entering the 1990s, my country's sewage treatment industry has entered a period of rapid development, and the growth rate of sewage treatment demand is far higher than the global level.

Since 1990, the global average consumption of sewage treatment has increased at an average annual rate of 6%. During the decade of the 1990s, the annual average growth rate of China’s apparent consumption of sewage treatment reached 17.73%, which is the world’s average annual growth rate. 2.9 times. In the 21st century, my country's sewage treatment industry has grown rapidly. From 2000 to 2004, my country's sewage treatment consumption increased from 1.88 million tons to 4.47 million tons, an increase of 2.3 times, with an average annual growth rate of more than 27%. Among them, in 2001, my country's apparent consumption of sewage treatment reached 2.25 million tons, surpassing the United States as the world's largest consumer of sewage treatment. At the same time, sewage treatment imports have also increased significantly. In 1998, my country imported 1 million tons of sewage treatment, thus becoming the world's largest importer of sewage treatment. Compared with 1998, the annual growth rate of sewage treatment imports reached 27.14%. It is estimated that in 2005, China's apparent consumption of sewage treatment will reach 5 million tons, and imports will remain at around 3 million tons.

With the rapid development of the sewage treatment market, my country's sewage treatment output has ended its long-term lingering situation and achieved rapid growth. my country's sewage treatment output increased from 460,000 tons in 2000 to 2.36 million tons in 2004, with an average annual growth rate of 82.6%, and its share of domestic market demand also increased from 24.47% in 2000 to 52.80% in 2004. In the same period, the world's sewage treatment output increased only at a rate of about 6%.

Since the late 1990s, China's Taigang, Baosteel, Baoxin, Zhangpu and other state-owned and joint-venture enterprises have successively built a series of sewage treatment production lines through the introduction and technical transformation. The sewage treatment process technology equipment has reached the international advanced level. Production is beginning to take shape. The structure of sewage treatment products has also undergone positive changes, and the quality of sewage treatment products has rapidly improved. In particular, the domestic sewage treatment cold-rolled plate has grown rapidly. In 2003, the domestic cold-rolled plate output reached 1.7 million tons, which exceeded imports for the first time, and the self-sufficiency rate reached 66%. In 2004, the domestic cold-rolled plate output reached 2 million tons, the self-sufficiency rate Over 70%. From the end of 2004 to the end of 2005, the domestic cold rolling sewage treatment capacity will increase by about 1.5 million tons, basically meeting the domestic market demand. By 2007, my country will become a net exporter of sewage treatment.

On the whole, China's sewage treatment is undergoing a profound transformation from small scale, low level, single variety, serious inability to meet demand to a considerable scale and level, significant improvement in variety quality, and preliminary meeting the requirements of national economic development. Gradually achieve self-sufficiency.