The early liberation due to industrial and agricultural production just started, the sewage pollution level was very low, and advocate the use of sewage for agricultural irrigation, especially in the northern region of the water scarcity of the use of sewage irrigation as an experience to be popularized, such as the famous Shenfu irrigation canals, etc., so there are only a few cities in the country to build nearly a dozen sewage treatment plant (also) Including 1921 ~ 1926 during the foreigners to build three sewage treatment plants), in the treatment process, some are still a level of treatment, the scale of treatment is also very small, only a few thousand cubic meters per day, the largest is only 50,000 cubic meters per day or so, resulting in sewage treatment technology and management level is in a backward state.
China's solution to the problem of urban sewage purification began in the 1970s. Some cities use the suburbs of the pits and depressions, waste rivers, swamps and other slightly renovated or dammed, built a stable pond, the city sewage purification process. According to the survey, this period in the country has been built in various types of stabilization of 38 ponds, daily treatment of urban sewage about 1.73 million cubic meters. Among them, the amount of domestic sewage accounted for half of the rest, including petroleum, chemical, paper, printing and dyeing and other industrial wastewater. This stage began to pay attention to the introduction of foreign advanced technology and equipment, to carry out technical exchanges with foreign countries, and gradually explore the engineering technology and design suitable for China's national conditions, laying the foundation for future construction.
70s and 80s: Tianjin Jizhuangzi sewage treatment plant put into operation led to dozens of new sewage treatment plants
With the continuous development of industrial and agricultural production, the people's living standards gradually improved, urban sewage million points also changed, the degree of pollution from the low to the high gradual evolution of a number of developed capitalist countries due to the contamination of sewage, so that the people's physical health threatened to the painful lessons (eg, the Japanese state). Painful lessons (for example, Japan's bone pain disease, Minamata disease), caused people's concern and our government attaches great importance to the establishment of a national environmental protection organization (State Council Office of Environmental Protection), the University also set up one after another Department of Environmental Engineering or Environmental Engineering, the State Council Office of Environmental Protection invested in the construction of a pilot plant for sewage treatment in Tianjin (Tianjin City, Ji Zhuangzi sewage treatment pilot plant), began to be constructed at the end of the 70's. Treatment scale: primary treatment of 0.1 cubic meters / s, secondary treatment of 0.025 cubic meters / s, Beijing Gaobeidian sewage treatment pilot plant has also run. National and local preparations for the construction of large-scale domestic sewage treatment plant to do preliminary work, at this moment the Tianjin Municipal Government and the Ministry of Construction and the relevant ministries and commissions took the lead in deciding to build the Tianjin Jizhuangzi sewage treatment plant, and in 1982 groundbreaking, completed and put into operation on April 28, 1984, the scale of treatment of 260,000 m3/d.
China's first large-scale municipal wastewater treatment plants treatment plant construction gaps. Driven by this successful experience, Beijing, Shanghai, Guangdong, Guangxi, Shaanxi, Shanxi, Hebei, Jiangsu, Zhejiang, Hubei, Hunan and other provinces and municipalities according to their specific conditions were built dozens of sewage treatment plants of different sizes.
"Ninth Five-Year" period: the official launch of the "three rivers", "three lakes" basin water pollution control
"Ninth Five-Year During the "Ninth Five-Year Plan" period, China officially launched the "Three Rivers" (Huaihe, Haihe and Liaohe), "Three Lakes" (Taihu Lake, Chaohu Lake, Dianchi) Basin and the "Bohai Rim" area water pollution control.
The establishment of national "Seventh Five-Year Plan", "Eighth Five-Year Plan", "Ninth Five-Year Plan" scientific and technological research projects, so that China's sewage treatment of new technologies, sludge treatment of new technologies, recycled water reuse of new technologies have been achieved. The new technology of sewage treatment, sludge treatment, recycled water reuse of new technologies have achieved promising scientific research results, some projects have reached the international advanced level. New technologies, techniques and equipments for sewage treatment from abroad have been introduced into our country. While the activated sludge process is applied, AB method, A/O method, AA/O method, CASS method, SBR method, oxidation ditch method, stabilized pond method, and land treatment method, etc., have also been applied in the construction of sewage treatment plants. By the past only have the function of removing organic matter sewage treatment process technology to develop the industry's market. Such as grating machines, submersible pumps, desanding devices, mud scrapers, aerators, blowers, sludge pumps, dewatering machines, biogas generators, biogas boilers, sludge digestion and mixing systems and other large-scale equipment.
Due to the construction of large-scale urban sewage treatment plant investment is very large, China's construction funds are limited, unable to adapt to the needs of water pollution control. For this reason, the introduction of foreign capital to build sewage treatment plant has become an important part of the construction funds, which also accelerated the construction of urban sewage treatment plants in China. A number of large-scale urban sewage treatment plants using foreign loan projects have been completed and put into operation. For example: China's largest sewage treatment scale in the 20th century for 600,000 cubic meters / d; Tianjin East Suburb Sewage Treatment Plant, Chengdu, Chengdu, three Wayao Sewage Treatment Plant, Shenyang North Sewage Treatment Plant, Zhengzhou, Wang Xinzhuang Sewage Treatment Plant treatment scale of 400,000 cubic meters / d.
According to statistics, by the end of 2000, the country has constructed municipal wastewater treatment plant 427, of which the second level of treatment plant 282 In 2000, the total investment for the construction of urban sewage treatment works was about 15 billion yuan. But the vast majority of small towns have not yet built sewage treatment facilities. Seven hard constraints on the development of urban sewage treatment
Sewage treatment experts Zhu Yanbo analysis, China's urban sewage treatment currently exists seven major problems, restricting the development of China's urban sewage treatment business.
First, the shortage of funds for the construction of sewage treatment plants
Although China has built more than 100 sewage treatment plants, but is still far from being able to meet the needs of the city's industrial and agricultural production and people's lives, the performance of a particular city itself is not a high rate of treatment, that is, the amount of sewage treatment is not enough, but also in the big cities have begun to embark on the construction of sewage treatment plants, the planning and construction of the plan Work. However, in small and medium-sized cities, especially in the northwestern part of the country, the planning and construction of sewage treatment has not been included in the urban development agenda. One of the main reasons is that there is no specialized construction funds, there are areas of water pollution is becoming increasingly serious, if you wait to have the funds to invest in the construction of sewage treatment plants, will make the environment tend to deteriorate, to the people's lives bring inconvenience to the people's physical and mental health hazards, so it is prompted to raise funds to speed up the treatment of water pollution, leaving a beautiful living environment for future generations.
Second, the sewage treatment plant operating funds can not be in place
The country has been built and put into operation sewage treatment plant *** counted more than 100, can run at full capacity of the sewage treatment plant less than 1/3 of the full capacity of the operation of the reasons: most of the operating funds can not be put in place due to the cause of the provinces and municipalities did not collect sewage treatment fees, some are only collected factories, Enterprises, do not collect residents, there are factories, enterprises, residents are collected, but the charges are set at a very low level, far from meeting the minimum cost of normal operation of sewage treatment plants, so that some sewage treatment plants have been able to get how much funding to deal with how many tons of sewage on the actual problem. This long-term neither play the construction of sewage treatment plants should be effective, but also make the instrumentation, equipment damage, but also can not play the role of professional managers of sewage treatment plants.
Third, the maintenance of imported equipment and equipment parts development
As a result of a large number of imported equipment into the sewage industry, after a few years of operation, the equipment will appear one after another the size of the damage, especially after the claim period of maintenance and normal overhaul. This requires specialized skills of technical personnel to carry out, ill invited foreign experts to repair, maintenance costs will be substantially higher is difficult to accept, or so that the imported equipment to maintain normal operation, we must cultivate imported equipment repair and maintenance of domestic professionals to enable them to master the maintenance skills to meet the maintenance standards of imported equipment. Maintenance professionals must also have sufficient spare parts, especially some of the equipment to be eliminated by the introduction of China, spare parts will not be produced abroad, the need for domestic mapping, processing and manufacturing, the only way to make the imported equipment to play its role, otherwise the damage to the equipment, the lack of spare parts will affect the normal operation of the sewage treatment plant.
Fourth, the sewage treatment process selection trend, not combined with the actual situation
Select the popular process is in the selection of sewage treatment process, the emergence of the simple pursuit of new technology, the pursuit of fashionable technology, do not take into account the region's intake of water quality, the amount of treated water, as well as the use of water, in our country has been built in a number of wastewater treatment plants, the quality of the intake of water is relatively low, but also to select the AB Method, the results can not be fully utilized, resulting in idle facilities and equipment. Some areas of treated reclaimed water directly for agricultural irrigation, but also overemphasize the removal of phosphorus and denitrogen, to take the A / A / O method, increasing the construction investment has also increased the daily operating costs, there are some individual areas in the construction of wastewater treatment plants to see what the wind at the time of the process to take what process.
Fifth, sewage treatment of reclaimed water is not fully utilized
Huge investment in the construction of sewage treatment plants, after the treatment of reclaimed water can not be fully utilized, and even some areas will be treated reclaimed water and untreated sewage mixed together with the same flow of sewage, and some areas do not have reclaimed water reuse but discharged into the sea to create a waste of freshwater resources. At present, the world's freshwater resources are extremely scarce, China's freshwater resources in the world ranked 121st, per capita freshwater possession of only 2000 cubic meters.
Sixth, the sludge did not really reach harmless, there is no final disposal of the way
Sewage after a variety of different processes, the effluent meets the national emission standards, but in the sewage treatment process, the sludge award has not been properly disposed of, but also to the environment caused by secondary pollution. Some areas of sludge is not harmless treatment, the sludge will be piled up off-site, arbitrarily taken without knowing where to go. Some areas will be drying sludge used as agricultural fertilizer, heavy metal content is up to standard consideration of very little, how much harm to crops is not enough analysis. The national environmental protection department prohibits the sludge as vegetable field, rice field fertilizer, as dry field fertilizer needs to analyze the composition of sludge, heavy metals and toxic substances do not exceed the standard can be used. Sludge as a green field fertilizer to have the garden department to recognize the monitoring department to track the analysis can be used, in short, sludge if there is no final disposal of the way, is to bring the environment to the hidden dangers of re-contamination.
Seventh, sewage treatment plants do not have deodorization devices
Sewage treatment plant intake pond, grating room, sand sedimentation tanks, primary sedimentation tanks and sludge treatment system of the sludge storage tanks, dewatering machine room (in addition to centrifuges) will produce a serious stench, not only affecting the operation of the operating personnel's health, but also to the surrounding residents living environment to bring pollution, especially some of the construction of the early past, around the past is farmland, Pools, far from the urban sewage treatment plant, is now becoming an urban area, sewage treatment plant around the cover up of residential homes, the formation of residential areas, sewage plants around the people were y hurt, should be more channels to solve the problem of deodorization devices, because the sewage treatment plant itself is the elimination of pollution and protection of the environment of the enterprise.