China has water resources reserves of 2.80 billion yuan / m3, but per capita is only 2,300m3. Compared with the world's per capita water resources, it only accounts for 1/4. It is one of the countries with the most per capita water resources in the world. At the same time, China's water pollution situation is particularly serious. The discharge of industrial sewage, domestic sewage and other sewage has increased with the development of the economy and the continuous increase of the population. A large amount of untreated wastewater is directly discharged into the water body, causing the amount of various pollutants to exceed the self-cleaning capacity of the water body environment. The deterioration of the water environment. According to statistics from the Ministry of Environmental Protection of China, from 2001 to 2013, the total amount of wastewater discharged has increased year by year, and the amount of domestic wastewater discharged has exceeded the industrial wastewater, showing an increasing trend. In domestic sewage, human excreta, detergents and waste foods contain a large amount of phosphorus. Among them, the main source of phosphorus in water is synthetic detergent, which accounts for about 50% of the total TP (Total Phosphorus) pollution load. Volelwneide, a world-famous lake science, believes that a total phosphorus content of more than 0.002 mg / L is eutrophic. Skamaotol's research on Shuicheng, Japan found that TP amount of 0.01 ～ 0.09mg / L is eutrophication; the US Environmental Protection Agency (EPA) surveyed 812 lakes and reservoirs in the United States and proposed that the eutrophication TP standard is> 0.02 ～ 0.025mg / L. Chinese researchers believe that only when the mass concentration of phosphorus in the water body is less than 0.02mg / L will it not cause eutrophication pollution in the water body. According to statistics, in China, eutrophic lakes caused by nitrogen and phosphorus pollution account for more than half of the statistical lakes. In 2013, the total amount of wastewater discharged from key river basins (Songhua River, Liaohe River, Haihe River, middle and upper reaches of the Yellow River, Huaihe River, middle and lower reaches of the Yangtze River, Taihu Lake, Chaohu Lake, Dianchi Lake, Three Gorges Reservoir, and Danjiangkou Reservoir) totaled 46.37 billion tons. It accounted for 66.7% of the country's total wastewater discharge.
At present, water pollution caused by nitrogen and phosphorus has become increasingly serious. Nitrogen and phosphorus pollution mainly refers to the direct discharge of untreated domestic wastewater and industrial wastewater containing large amounts of nitrogen and phosphorus nutrients under the influence of human activities. In addition, its nutrients exceed the self-purification ability of water bodies, which directly leads to eutrophic pollution of water bodies. In 2014, China ’s State of the Environment bulletin statistics showed that among the 61 lakes (reservoirs) that were being monitored for nutrition, 10, 36, and 30 were poor, moderate, and moderately eutrophic, respectively. 13 and 2. Moreover, according to the survey, about 92% of the 25 large and medium-sized lakes in China tend to be eutrophic, and phosphorus and nitrogen-restricted lakes account for 65% and 28%, and the remaining limiting factors account for 7%. Therefore, strict restrictions on nitrogen and phosphorus in water bodies and effective management are essential.