In recent years, China's modernization and industrialization processes have been accelerating, and the total amount of wastewater discharge has also shown a continuous growth trend. From 2001 to 2012, the total amount of wastewater discharge in China increased from 43.3 billion tons in 2001 to 68.5 billion tons in 2012, an increase of 25.2 billion tons over the past 12 years. On average, 2.1 billion tons of wastewater are discharged annually, with an average compound annual growth rate of about 4.3%.
The main sources of wastewater pollution in China are industrial sources, agricultural sources, urban domestic sources, and a small number of centralized pollution facility discharge sources. The increase in sewage discharge from urban domestic sources is the main reason for the increase in wastewater discharge in China.
According to statistics from the Ministry of Environmental Protection, the proportion of urban sewage discharge to total wastewater discharge in China has been increasing year by year, from 53.2% in 2001 to 67.6% in 2012. From 2001 to 2012, the average annual increase in urban domestic sewage discharge in China was 1.94 billion tons, accounting for 92.2% of the total annual increase in wastewater discharge.
Among the three types of wastewater pollution sources, industrial wastewater is characterized by relatively small discharge quantity and pollutant content, but multiple types of pollutants and high difficulty in treatment, leading to qualitative pollution of the water environment; The characteristic of rural sewage is that the discharge quantity is absolutely large, but as of 2010, the coverage rate of rural sewage treatment nationwide is less than 10%, and the development is still in the initial stage.
Compared with industrial wastewater and rural sewage, the characteristics of urban sewage are that the discharge amount and pollutant content are absolutely large, but the types of pollutants are few, the difficulty of treatment is low, the treatment process is relatively mature, and the coverage rate of urban sewage treatment has reached a certain level. The impact on the water environment belongs to quantitative pollution.
At the press conference of the State Council Information Office in February this year, Vice Minister of the Ministry of Environmental Protection Zhai Qing introduced that there are three problems in China's water pollution prevention and control: groundwater pollution has not been effectively controlled; The pollution problem of some rivers, especially in rural areas, or in ditches and bifurcations closely related to the lives of the people, is still very serious; There are still many shortcomings in the management of water environment.
The Inspection Report on the Protection of Centralized Groundwater Drinking Water Sources in the Beijing Tianjin Area shows that two-thirds of drinking water in Beijing comes from underground sources, and hundreds of thousands of people in Tianjin drink groundwater. However, there are many high-risk areas and widespread non-point source pollution hazards in North China.
Taking Beijing as an example, the 19 centralized drinking water sources designated as protected areas cover a population of about 13.2 million, accounting for about two-thirds of the city's permanent population. There are still about one-third of the population whose drinking water sources are not fully understood by the environmental protection department.
According to data previously released by the Ministry of Environmental Protection, China emits approximately 24 million tons of chemical oxygen demand and 2.45 million tons of ammonia nitrogen annually. "The emissions far exceed the environmental capacity," Zhai Qing said at the aforementioned press conference.
Meng Wei, an academician of the CAE Member and president of the Chinese Academy of Environmental Sciences, also told the reporter that the COD (chemical oxygen demand) carrying capacity of China's water environment was 7.409 million tons, but the first national survey of pollution sources found that the actual discharge of COD was 30.2896 million tons, more than four times the environmental capacity.
The Ministry of Environmental Protection estimates that these total amounts must be reduced by 30% to 50% in order for China's water environment to undergo fundamental changes.
Regarding the effectiveness of water pollution control, Zhai Qing once told reporters that as long as measures are in place, they can be effective. He showcased the effectiveness of the Songhua River governance to reporters using "peach blossom jellyfish". The Songhua River has a total length of about 1900 kilometers, flowing through provinces and regions such as Jilin, Inner Mongolia, and Heilongjiang. Its main stream is mainly in Heilongjiang Province, with a total length of about 939 kilometers, and finally joins the Sino Russian border river Heilongjiang. On November 13, 2005, an explosion occurred at the Double Benzene Plant of PetroChina Jilin Petrochemical Company, triggering a major water pollution incident.
In the following five years, the country invested a total of 7.84 billion yuan in pollution control funds. According to the Water Pollution Prevention and Control Plan for the Songhua River Basin (2006-2010), a total of 222 pollution control projects need to be arranged with a total investment of 13.4 billion yuan.
