With the rapid development of China's economy, the traditional model of extensive and labor-intensive economic development has brought about a series of environmental problems. Among them, water pollution is especially serious.
The present situation of water resources in China
Our country is a country poor in water resources, water resources is about 2.8 x 1012 m3, the sixth in the world, per capita water resources is 2310.4 m3, ranks 110th in the world, only equivalent to 1/5 of the us, Canada's 1/50, therefore, our country is listed as one of the world's 13 PinShuiGuo. Statistics released by the national bureau of statistics show that China's per capita water use has increased year by year in recent years, from 412.9m3 in 2003 to 450.2m3 in 2010. The water department predicts that by 2030, China's population will reach 1.6 billion, and the per capita water resources will be reduced to 17,60m3, which will reach the world's recognized water shortage warning line. The total water supply will be 4.0 x 1010 ~ 5.0 x 1010m3. China's water distribution is unevenly distributed, and more than 80% of total water resources are concentrated in the Yangtze river and its south region. In terms of per capita water resources, the southern highest and the northern lowest areas are tens of times, and the west is 500 ~ 600 times higher than the east. According to statistics, at present the country's 669 cities, 400 cities perennial water supply shortage, there are 110 cities severe water shortages, years of 6.0 x 109 m3 of water deficit every year due to water shortage of the country's economic loss of 200 billion yuan of above.
The current sewage situation in China
According to the 2010 China environmental bulletin and the 2010 national bureau of statistics, China's waste water emissions have increased by an average of 4% per year during the eleventh five-year plan period. In 2010, the total amount of waste water discharged in China was 61.73 billion tons, and the amount of chemical oxygen demand was 1238.10 million tons, while ammonia nitrogen emissions were 120.30 million tons. Overall for mild seven main river pollution, 204 rivers 409 surface water by the monitoring cross section, Ⅰ ~ Ⅲ, Ⅳ ~ Ⅴ and substandard Ⅴ class water quality of cross section ratio are 59.9%, 23.7% and 59.9% respectively; Lake water pollution is serious, control key lakes (reservoirs) in 26 countries, Ⅱ ~ Ⅲ class accounted for only 23% of water, Ⅳ class accounted for 15.4%, Ⅴ class accounted for 23.1%, worse Ⅴ accounted for 38.5%; The groundwater quality status is not optimistic, water quality monitoring stations to excellent, good, good totaled 1759, accounting for 42.8% of all monitoring point, 2351 of monitoring water quality is poor, very poor level, accounting for 57.2% of the total monitoring.
The state of technical development of wastewater treatment industry in China
As early as 1921, China's first sewage treatment plant, Shanghai north district sewage treatment plant, was completed and put into production, but large-scale sewage treatment started late in China. In the early 1960s and the late 1960s, China was mainly promoting sewage and agricultural irrigation, and there were only 10 sewage treatment plants in the country (including 3 built before liberation). The sewage treatment scale began to expand in the 1970s, and by 1978, 37 municipal wastewater treatment plants had been completed in China, with a capacity of 63.53 million tons/d. Since the reform and opening up, China's urban sewage treatment technology has been divided into three stages:
First stage: late 1970s and late 1980s. In China began to enter the period of taking economic construction as the center, sewage and other environmental issues more prominent, the project construction department of municipal sewage reuse on the special "purpose of" science and technology plan, work began to do research in urban sewage recycling. Then, in view of the northern part of the city in the economic development needs to solve the water shortage, China during the period of "seventh" on the "study of urban wastewater reuse" major scientific research projects, get a series of sewage treatment and utilization of important technical achievements. In 1984, the largest sewage treatment plant in China - tianjin ji zhuangzi sewage treatment plant was completed and put into operation, which filled the gap in the construction of large sewage treatment facilities in China. By 1988, 78 sewage treatment plants were built in China. At that time, the technology and capital needed for this construction depended mainly on the domestic, and the development speed was restricted by many conditions.
Phase two: the late 1980s and the late 1990s. "Five-year" period, our country completed the major scientific research project "research on urban wastewater reuse", the research developed a complete set technology, suitable for parts of the city sewage treatment to solve the problem such as water quality indexes and the approach, and established a series of demonstration project. In 1996, the state science and technology commission, the ministry of construction was carried out by the national key scientific research projects of the ninth five-year plan "sewage treatment and water industry key technology research", aims to solve the problem of water pollution prevention and control of the major key. With the deepening of reform and opening up, some advanced and efficient sewage treatment equipment has entered the market of sewage treatment industry in China. Due to the capital source and the operation management nature of the wastewater treatment industry, the development speed of sewage treatment is still not satisfactory. By the late 1990s, the number of secondary sewage treatment plants in China had increased to 200, concentrated in large and medium-sized cities.
Stage 3:2000-present. Since the 21st century, China's sewage treatment industry has entered a rapid development stage. During the tenth five-year plan, the state began to put environmental protection as an important means of macroeconomic regulation and control, and adopted a series of major policies and measures to eliminate a batch of high consumption, high pollution of backward production capacity, good results have been achieved. In 2006, the central proposed (now) "national medium and long-term science and technology development plan outline (2006 ~ 2020)", the first to water pollution control and governance and large aircraft, develop manned spacecraft and explore the moon project on 16 major r&d projects, such as the measures to vigorously promote the development of the sewage treatment technology. During the eleventh five-year plan period, China's urban sewage treatment capacity reached 100 million tons per day, and the urban sewage treatment rate increased from 52 percent in 2005 to 72 percent. The chemical oxygen demand decreased by 12.45% and exceeded the target; The state-controlled section water quality is better than the national surface water increased to 51.9% of the total Ⅲ class. State environmental protection in the "twelfth five-year" plan to ammonia nitrogen emissions as targets for the first time, puts forward new daily sewage treatment capacity of 42 million tons by 2015, a basic implementation of all county and key town sewage treatment ability; The load rate of sewage treatment facilities increased to more than 80%, and the urban sewage treatment rate reached 85%. Dianchi, chaohu, taihu and other key watersheds and coastal areas must raise the level of nitrogen removal and phosphorus removal.