The treatment processes used in biological treatment are: oxidation pond method: Carrousel, alternating method and Orbal. Phostrip method, Phoredox method, SBR method, AB method, biological fluidized bed method, ICEAS method, DAT-IAT method, CASS(CAST, CASP) method, UNITANK method, MSBR method, A/O method, A2/O method, A3/O method, UCT method, VIP method, UASB method and integrated biochemical method.
Chemical enhanced biological phosphorus removal wastewater treatment process
In the process of sewage treatment, major rivers and lakes in China are seriously eutrophic due to phosphorus pollution. In order to control phosphorus pollution, the State Environmental Protection Agency has formulated stricter phosphorus emission standards. Chemical enhanced biological phosphorus removal wastewater treatment process is mainly to remove organic pollutants and various forms of phosphorus in wastewater. This wastewater treatment process integrates chemical dephosphorization and biological dephosphorization. Volatile organic acids are produced by anaerobic digestion of activated sludge in biological system, which are used as substrates or nutrients for the growth of phosphorus-accumulating bacteria, so that phosphorus-accumulating bacteria can selectively proliferate in activated sludge and return to the biological system, so that the biological wastewater treatment system can work in a high-efficiency dephosphorization state. At the same time, phosphorus released by sludge under anaerobic conditions is eliminated by chemical phosphorus removal. This is an efficient urban sewage treatment technology, which meets the requirements of further phosphorus removal on the basis of conventional secondary sewage treatment, so as to solve the problem of eutrophication of water bodies in China at present.
Circulating intermittent aeration sewage treatment process
The level of economic development in China varies greatly, so it is impossible for a city with backward economic development to spend a lot of money on sewage treatment. Therefore, how to use limited funds to reduce environmental pollution is a problem faced by many city governments. In terms of sewage treatment, until recently, some cities still adopted primary or primary enhanced treatment technology, and the effluent could not meet the requirements of national secondary discharge standards for removing organic pollutants. The cyclic intermittent aeration process makes full use of the high treatment efficiency of high-load oxidation ditch and the good effluent of sequencing batch activated sludge wastewater treatment process, which ensures that the effluent of the system meets the requirements of the first-class national sewage discharge standard in terms of removing organic pollutants. Compared with the two-stage biological sewage treatment system that usually removes organic pollutants, the investment and operation cost are reduced by about 30%, which is a suitable technology for sewage treatment in China at present.
Rotating contact oxidation sewage treatment process
Rotating contact oxidation wastewater treatment technology is a new generation of aerobic biofilm treatment technology based on biological turntable technology and combining the advantages of biological contact oxidation technology. Rotating contact oxidation sewage treatment technology and complete sets of equipment provide a simple and reliable sewage treatment method. The rotating shaft is the only rotating part in the whole sewage treatment system. Once the machine breaks down, the general mechanic can repair it. The biomass of the system will be automatically compensated according to the change of organic load. Microorganisms attached to the turntable are alive. When organic matter in sewage increases, microorganisms increase. On the contrary, the organic matter in sewage is reduced and the microorganisms are reduced. Therefore, the working effect of this sewage treatment system is not easily affected by the sudden change of flow and load and power failure. The operation cost is low, which is only 1/8 ~ 1/3 of other aerated sewage treatment systems. The occupied area is only half that of the traditional activated sludge process. Because there are many kinds of microorganisms growing in the biological system, it can effectively treat all kinds of refractory industrial sewage.
Process of continuous circulating aeration system
Continuous circulating aeration system is a SBR aeration system with continuous water inflow. CCAS is an improved sewage treatment process based on SBR (sequencing batch reactor). CCAS sewage treatment process has low requirements for sewage pretreatment, and only mechanical grid and grit chamber are set with the spacing of15 mm.. The core of biological treatment is CCAS reaction tank, and the functions of phosphorus removal, nitrogen removal and degradation of organic matter and suspended matter are all completed, and the effluent can meet the standard.
The unique advantages of CCAS in sewage treatment;
(1) When aerated, the sewage and sludge of CCAS sewage treatment are in a completely ideal mixed state, which ensures the removal rate of BOD and COD, with the removal rate as high as 95%.
(2) The repeated operation modes of "aerobic-anoxic" and "aerobic-anaerobic" strengthen phosphorus absorption and nitrification-denitrification, so that the removal rate of nitrogen and phosphorus reaches over 80% and the effluent index is qualified.
(3) During precipitation, the whole CCAS reaction tank is in a completely ideal precipitation state, and the effluent suspended solids are extremely low, which also ensures the phosphorus removal effect.
The disadvantage of CCAS wastewater treatment process is that each tank runs intermittently at the same time, and manual control is almost impossible. It depends entirely on computer control, which requires high quality of management personnel in the treatment plant and strict requirements on design, training, installation and debugging.
Domestic sewage treatment process of biological aerated filter
Brief introduction of sewage treatment process: The biological aerated filter (BAF) is to set packing in the biological filter treatment device, and make a large number of microorganisms grow on the packing through artificial oxygen supply. The sewage treatment process flow device consists of a filter bed, a gas distribution device, a water distribution device and a drainage device. The aeration device adopts a special aeration head, and the generated small and medium bubbles are repeatedly cut by the filler to achieve the effect of micro-control aeration. Due to the high sludge concentration and compact treatment facilities in the reaction tank, the floor space can be greatly saved and the reaction time can be shortened.
Phosphorus removal process of urban sewage spring water
Brief introduction of sewage treatment technology: The main reason of water eutrophication is that human beings discharge a lot of ammonia nitrogen and phosphorus into water, and phosphorus is the most important factor of water eutrophication. In the whole process of domestic sewage treatment, phosphorus removal technology has always been a difficult problem that puzzles the operation of sewage treatment plants. The traditional physical and chemical phosphorus removal technology needs a lot of chemical agents, which has the disadvantages of high operating cost and large sludge output. Pre-anaerobic biological phosphorus removal process has the advantage of low operating cost, but it is difficult to meet the requirements of national sewage treatment process because it depends entirely on the uptake and release of phosphorus by microorganisms. It is more difficult to meet the requirements when considering the reuse of reclaimed water.
A/O biofilter wastewater treatment process
Brief introduction of sewage treatment technology: Due to the scattered residential areas in small towns in China, the distribution points of sewage sources are becoming less and less, and the scale of town-level sewage treatment plants is mostly less than 10000 tons/day. At present, the traditional activated sludge process, A2/O, SBR, oxidation ditch and so on are mostly used in sewage treatment plants in large and medium-sized cities in China. If these technologies are used to build sewage treatment plants in small towns, it will not be able to run continuously because of the high operating cost. According to the characteristics of small towns, technologies with low investment, low operation cost, stable and reliable technology and relatively simple operation and management must be adopted.
MBFB membrane biological fluidized bed process
MBFB process is used for advanced sewage treatment. On the basis of raw sewage discharge reaching the standard, COD, NH-N, turbidity and other indicators are further reduced by biological fluidized bed and ceramic membrane separation system. On the one hand, it can be directly reused, on the other hand, it can also be used as pretreatment process of RO desalination treatment to replace the original lengthy filtration processes such as sand filtration, security filtration and ultrafiltration. At the same time, due to the decrease of organic matter content, the service life of RO membrane is greatly prolonged. To reduce the cost of reuse water treatment, the inorganic ceramic membrane separation system is the first set of inorganic membrane separation system dedicated to sewage treatment in the world. Compared with other organic and inorganic membranes, it has the advantages of large membrane flux, recoil and automatic operation.
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Foreign sewage treatment technology
European urban sewage treatment technology-sustainable biological phosphorus and nitrogen removal process
Nitrogen and phosphorus removal for the purpose of controlling eutrophication has become the main goal of all countries. Undoubtedly, in order to meet the increasingly stringent emission standards, the above shortcomings will make the traditional process worse. In this case, it is imperative to develop a sustainable sewage treatment process. The so-called sustainable sewage treatment process is to strive for the minimum oxidation of COD, the minimum release of CO2, the minimum output of excess sludge, and the realization of phosphorus recovery and treatment water reuse. Therefore, the problem of sewage treatment must be comprehensively solved, that is, sewage treatment should not only meet the single water quality improvement, but also consider the recycling and energy utilization of sewage and pollutants. The adopted technology must be based on low energy consumption (avoiding pollution transfer) and less resource loss.
The development of new wastewater biological treatment process depends on the new discovery or new understanding of microbiology and biochemistry. Dutch researcher Mulder discovered anaerobic ammonia (nitrogen) oxidation 10 years ago. At the same time, scientists in South Africa, the Netherlands, Japan and other countries have re-recognized the metabolic mechanism of biological phosphorus uptake/release, and determined a new way of denitrifying phosphorus removal. The research and application of these two new technologies are of epoch-making significance for promoting the development of sustainable wastewater biological treatment process. Based on anaerobic ammonium oxidation and denitrification phosphorus removal technology, their technical principles, process flow and application in Europe are introduced in detail. On this basis, the recommended process of biological phosphorus and nitrogen removal technology for sustainable urban sewage is put forward, which aims at converting organic energy (methane), recovering phosphorus compounds (struvite) and reusing treated water (non-drinking purpose).
In the practice of biological phosphorus removal from sewage, researchers at the University of Cape Town (UCT) in South Africa first found that it is not only obligate aerobic bacteria that have an influence on biological phosphorus uptake/release, but also facultative denitrifying bacteria have a strong biological phosphorus uptake/release phenomenon. The biological uptake/release of phosphorus by denitrifying bacteria was confirmed by the cooperative research of researchers from Tudelford University of Technology in the Netherlands and UT University in Japan, and it was named denitrifyingdephosphatation. In the process of biological uptake/release of phosphorus, denitrifying phosphorus removal bacteria use nitrogen nitrate instead of oxygen as electron acceptor, which means that denitrifying phosphorus removal bacteria can combine denitrifying nitrogen removal and biological phosphorus removal that were originally thought to be independent. Obviously, in the process of combined phosphorus and nitrogen removal, the consumption of COD and oxygen can be saved accordingly. Compared with the traditional aerobic phosphorus removal process, denitrifying phosphorus removal bacteria can save about 50% and 30% of COD and oxygen consumption, respectively, and correspondingly reduce the amount of excess sludge by 50%. In the process of nitrogen and phosphorus removal, the demand for COD is greatly reduced, so excess COD can be separated and methanated, thus avoiding the single oxidation stability of COD (CO2). Due to the reduction of aeration energy and the generation of energy after methanation of excess COD, this comprehensive energy saving will eventually lead to a significant reduction in the amount of CO2 released into the atmosphere. Therefore, the treatment system enriched by denitrifying phosphorus removal bacteria can be regarded as a sustainable treatment process. Traditionally, nitrification (NH+4→NO3-) and denitrification (NO3→N2) have been used for biological denitrification in sewage treatment. This traditional biological nitrogen removal method is not the best from the perspective of sustainability, because the complete oxidation of ammonia nitrogen to nitrate nitrogen first consumes a lot of energy (due to aeration); Secondly, there needs to be enough carbon source (COD) to reduce nitrate nitrogen to nitrogen. The improvement of this traditional denitrification route can be realized by ——SHARON, a medium-temperature nitrosation technology recently developed by TUDelft Company in the Netherlands. Nitrogen nitrite is the only intermediate form in the process of nitrosation/denitrification. This method can minimize oxidation (NH+4→NO2-) and reduction (NO2-→N2), which means double saving of O2 and COD consumption. Obviously, nitrosation/denitrification can be a sustainable nitrogen removal technology.
In addition, researchers in TUDelft, the Netherlands, also confirmed a new transformation pathway of ammonia nitrogen almost at the same time, which made it possible to directly oxidize ammonia nitrogen into nitrogen with nitrogen nitrite as electron acceptor. The combination of ammonia nitrogen oxidation under anaerobic conditions and nitrosation process (such as SHARON process) can realize the shortest path transformation of ammonia nitrogen in engineering, which means that it is completely possible to minimize the energy and resource consumption in the process of biological nitrogen removal. Figure 1 lists all possible transformation paths of nitrogen during sewage treatment. Compared with the traditional nitrogen removal process, it is obvious that the complete autotrophic transformation mode of nitrogen combined with anaerobic ammonium oxidation and nitrosation process is the most sustainable nitrogen removal way.
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Present situation and future of sewage treatment in China
general situation
The development and progress of sewage treatment industry in China is relatively late. From the founding of the People's Republic of China to the reform and opening up, China's demand for sewage treatment is mainly based on cutting-edge industrial and national defense uses. After the reform and opening up, the rapid development of the national economy and the remarkable improvement of people's living standards have stimulated the demand for sewage treatment. After entering the 1990s, China's sewage treatment industry has entered a period of rapid development, and the growth rate of sewage treatment demand is much higher than the global level.
Since 1990, the global apparent consumption of sewage treatment has increased by 6% annually, while in the decade of 1990s, the average annual growth rate of China's apparent consumption of sewage treatment reached 17.73%, which is 2.9 times of the world's average annual growth rate. In the 2 1 century, the sewage treatment industry in China has developed rapidly. From 2000 to 2004, the consumption of sewage treatment in China increased from 6.5438+0.88 million tons to 4.47 million tons, an increase of 2.3 times, with an average annual growth rate of over 27%. Among them, in 200 1 year, the apparent consumption of sewage treatment in China reached 2.25 million tons, surpassing the United States to become the largest consumer of sewage treatment in the world. At the same time, the import of sewage treatment has also increased significantly. 1998, China imported1100,000 tons of sewage treatment, becoming the largest sewage treatment importer in the world. Compared with 1998 in 2004, the annual growth rate of sewage treatment imports reached 27. 14%. It is estimated that the apparent consumption of sewage treatment in China will reach 5 million tons in 2005, and the import volume will remain at around 3 million tons.
With the rapid development of sewage treatment market, China's sewage treatment output has also ended the long-term wandering situation and achieved rapid growth. The output of sewage treatment in China increased from 460,000 tons in 2000 to 2.36 million tons in 2004, with an average annual increase of 82.6%, and the proportion of domestic market demand also increased from 24.47% in 2000 to 52.80% in 2004. In the same period, the world sewage treatment output only increased at a rate of about 6%.
Since the end of 1990s, China Taigang, Baosteel, Baoxin, Zhang Pu and other state-owned and joint ventures have successively built a series of sewage treatment production lines through introduction and technological transformation. Sewage treatment technology and equipment have reached the international advanced level, and sewage treatment production has begun to take shape. The variety structure of sewage treatment has also undergone positive changes, and the quality of sewage treatment products has improved rapidly. In particular, the cold-rolled sheet for domestic sewage treatment has grown rapidly. In 2003, the domestic cold-rolled plate output reached 6.5438+0.7 million tons, surpassing imports for the first time, and the self-sufficiency rate reached 66%. In 2004, the domestic cold-rolled plate output reached 2 million tons, and the self-sufficiency rate reached over 70%. From the end of 2004 to the end of 2005, the domestic cold rolling wastewater treatment capacity will increase by about 65438+500,000 tons, basically meeting the domestic market demand. By 2007, China will become a net exporter of sewage treatment.
Generally speaking, sewage treatment in China is undergoing a profound transformation from small scale, low level, single variety, which can't meet the demand seriously to a considerable scale and level. The quality of varieties has been significantly improved, which initially meets the requirements of national economic development, and the sewage treatment demand will gradually realize self-sufficiency.
Sources of funds for urban sewage treatment in China
(Question 1) With the increase of population, there is more and more sewage.
In China, with the increase of urban population and the development of industrial and agricultural production, sewage discharge is increasing day by day, and water pollution is quite serious, almost all over the country. By the end of 2000, 3 10 of the 663 cities in China had sewage treatment facilities and 427 sewage treatment plants, with an annual sewage treatment capacity of 1 1.36 billion cubic meters, and the sewage treatment rate was only 34.23%.
(2) To speed up development, funds are urgently needed.
Under the condition of socialist market economy, sewage treatment begins with a certain amount of capital investment. The scale of sewage treatment funds determines the scale of sewage treatment. The development speed of sewage treatment fund itself determines the development speed of sewage treatment and the progress speed of sewage treatment technology. In the actual sewage treatment, the decision-making scheme with advanced technology and low treatment cost is usually the scheme with a large amount of prepaid funds. In this sense, the faster the capital itself develops, the faster the progress and application of sewage treatment technology, and the faster the sewage treatment.
(3) Difficulties in handling funds and sources.
1, the source of funds for urban sewage treatment in China is difficult.
For a long time, China's urban sewage treatment facilities have adopted the policy of free use. Not only the expansion of reproduction can be completed by financial investment, but also the simple reproduction needs financial allocation, so financial allocation has become the only source of investment for the maintenance and construction of sewage treatment facilities. Only in different periods, the names of the sources are different, but they are all financial-centered capital cycles. The reform of economic system denies the traditional centralized financial model of our country, denies the identity of the country as a producer and operator, denies the unity of the owner of the means of production and the exerciser of political power, and requires the separation of government and enterprise, and the separation of government and capital. Accordingly, under the premise of unified finance with the state as the main body, China's finance is divided into two parts: public finance and state-owned assets management. Public finance is a country that appears as the executor of political power. Raise funds mainly in the form of taxes, solve problems that cannot be solved by market allocation of resources, and meet the needs of public finance. Urban sewage treatment is a public welfare undertaking, and the financial allocation of sewage treatment funds should be public expenditure. Because the reform of China's socialist market economic system is still deepening, the proportion of public finance revenue to GDP and the proportion of central public finance revenue to public finance revenue are not reasonable enough, so it is difficult for most urban sewage treatment funds to come from financial allocations or loans like developed countries such as the United States.
2. Difficulties in sewage treatment loans.
The demand for urban sewage treatment funds is huge, and bank loans are an important source of sewage treatment funds. Bank loans are divided into commercial bank loans and China Development Bank loans. The source of funds for commercial banks is the deposits of residents and enterprises, mostly short-term funds. Although it can also be used as part of medium and long-term loans, the proportion should not be too large. The use of funds in commercial banks requires the unity of safety, liquidity and profitability, while the use and return of sewage treatment funds are difficult to match the "three characteristics" of the use of funds in commercial banks. Therefore, it is difficult for commercial banks to make loans for sewage treatment projects.
Solve the problem of capital source of urban sewage treatment in China
(1) Increase the financial allocation.
Under the condition of socialist market economy, due to various reasons, part of urban sewage treatment funds must be given necessary subsidies by the government. The main point is: 1. The price demand elasticity and government's "monopoly" operation generally exist in sewage treatment, and the affordability of residents must be considered in the formulation of its charges, rather than relying on competitive prices to completely solve the problems of facility construction and enterprise development. 2. The services provided by sewage treatment are public, and the use of many facilities is difficult to calculate, so that service charges can not directly enter the market for equivalent exchange, but can only become a part of public consumption. 3. The services provided by sewage treatment have extensive sociality and external economy. When measuring its investment benefit, social benefit is the first.
The national financial allocation for urban sewage treatment in China mainly includes capital construction investment, special allocation from the central government and local financial allocation. Investment in capital construction arrangements is divided into two types: national budget and local self-financing. The amount of capital construction investment in the national budget shall be determined by the central government and handed over to the State Planning Commission by the Ministry of Finance for unified arrangement. Local self-raised capital construction investment is an investment arranged by local self-raised funds within the limits stipulated by the state. Central and local financial allocations, one is to allocate a certain amount of funds as special funds for sewage treatment every year according to needs; The other is to subsidize according to the project quota. When the project is completed, the subsidy will stop.
(crack method 2) increase the intensity of self-promotion by enterprises.
Under the condition of market economy, the reproduction of sewage treatment can only be realized by transforming its value into repeated capital return in its construction and business activities. According to the requirements of the law of value, it is an objective requirement to rationalize the input and output of sewage treatment and bring it into the new market economy order. Sewage treatment fee should not be a temporary financing measure, but a market-oriented way to realize the compensation of sewage treatment funds, and it is also an economic means to adjust the rational utilization of sewage treatment facilities.
Self-raised sewage treatment funds, under the conditions of socialist market economy, should be based on the law of value to develop sewage treatment charges, and in accordance with state regulations from operating income to extract production development funds, fixed assets depreciation funds and major repair funds. Sewage treatment units should not only rely on their own strength to complete simple reproduction and expand reproduction, but also pay taxes and fees to the state. Therefore, reasonable sewage treatment charges must be based on reasonable cost and reasonable profit rate.
The reasonable cost of sewage treatment fee should generally include production cost, operating cost, depreciation of fixed assets, major repair fund, loan interest, etc. Among them, the depreciation of fixed assets should have a suitable depreciation rate, change the current practice of long depreciation period and low depreciation rate, and avoid the company's profits and losses. Reasonable profit rate of sewage treatment fee means that the approval of profit rate should not only consider the reasonable welfare and necessary accumulation of enterprises, but also consider the characteristics of low demand elasticity and strong social service of sewage treatment fee to prevent the use of its monopoly position to pursue excess profits. In order to prevent monopoly from bringing burdens to users, the government can restrict operators through administrative and economic means so that their possible profits do not exceed the average profits of the whole society.
(Cracking Method 3) Trial Priority Stock Issuance
The experience of market economy countries shows that issuing preferred shares to absorb domestic and foreign private capital for urban sewage treatment can not only meet the huge capital demand of sewage treatment, but also won't lose the government's control over sewage treatment projects. Preferred stock is relative to common stock. The advantages of investing in common stock include higher investment income than other similar securities, strong liquidity in the securities trading market, fair trading and so on.
Preferred stock is a stock that has a certain priority over common stock, mainly the right to get dividends and the remaining property of the company first. The biggest advantage of preferred stock is its stable income and low risk compared with common stock. However, when the operating performance of the joint-stock company is outstanding and the operating profit surges, the income enjoyed by the preferred stock will not increase, while the income of the common stock can increase with the improvement of the company's operating efficiency. From this perspective, preferred stocks are less developed and less enterprising than common stocks.
According to China's current practice, stocks are divided into state shares, legal person shares, individual shares and foreign-funded shares according to the identity of investors, and there is no distinction between preferred shares and common shares. There is no concept of preferred stock in China's company law, and there is no corresponding provision. This is because the joint-stock enterprises in China are all transformed from enterprises under the planned economy system, so they have all kinds of historical traces and become historical problems to be further explored and solved in the reform. From the reality of urban sewage treatment, we can discuss the problem of sewage treatment stock. It is necessary to reform the existing sewage treatment enterprises into stock system, issue some preferred shares to domestic and foreign private capital, or transfer some state-owned shares to private capital in the form of preferred shares, and the raised funds will be used by sewage treatment enterprises for sewage treatment. This method is based on the development performance of existing enterprises, and the performance of transformed enterprises continues to grow, so it is easier to succeed in financing.
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Development of sewage treatment industry in China
Although 70.8% of the earth is covered by water, the fresh water resources are extremely limited. What humans can really use is a part of rivers, lakes and groundwater, which accounts for only 0.26% of the total water volume of the earth and is unevenly distributed.
After 1950s, the global population grew rapidly and the industry developed rapidly. The global water resources situation is deteriorating rapidly, and the "water crisis" is getting worse. On the one hand, human demand for water resources is expanding at an alarming rate; On the other hand, the increasingly serious water pollution consumes a lot of water resources available for consumption.
Around the world, about 200 tons of garbage are dumped into rivers, lakes and streams every day, and every liter of wastewater will pollute 8 liters of fresh water; All the rivers flowing through Asian cities are polluted; 40% of the water resources basins in the United States are polluted by processed food waste, metals, fertilizers and pesticides; Only five of the 55 rivers in Europe have poor water quality. In the 20th century, the world population tripled, while human water consumption increased fivefold. Many countries in the world are facing water crisis: 65.438+0.2 billion people lack water and 3 billion people lack water sanitation facilities.
China's per capita water resources are small and the spatial distribution is uneven. With the acceleration of urbanization and industrialization in China, the demand gap of water resources is increasing. In this context, the sewage treatment industry has become a new industry, which is currently in the same important position as the tap water production, water supply, drainage and reclaimed water reuse industries.
By the end of 2005, 792 sewage treatment plants had been built in 383 cities out of 66/kloc-0 cities nationwide, and the sewage treatment rate increased from 34% in 2000 to 52%, forming a sewage treatment technical route and management mechanism suitable for the national conditions. Among them, 135 urban sewage treatment rate reaches or approaches 70%, and the treatment scale of a single plant reaches 1 10,000 cubic meters/day.
In 2007, China's investment in water pollution control reached 338.76 billion yuan, an increase of 32% over the previous year, accounting for 1.36% of GDP in that year. The quality of China's water environment has remained generally stable. In 2007, * * * banned 942 sewage outlets in the first-class water source protection zone, stopped the construction projects that may cause pollution in the second-class water source protection zone 1294, and treated 93 1 within a time limit.
By the end of September 20 10, 263/kloc-0 sewage treatment plants have been built in cities, counties and some key towns (hereinafter referred to as "towns"), and the sewage treatment capacity has reached1.200 million cubic meters/day. There are 849 urban sewage treatment projects under construction in China/KLOC-0, with a total design capacity of about 46.6 million cubic meters per day. Among the cities in China, 593 cities have built sewage treatment plants, accounting for 90.7% of the total number of cities; Accumulated sewage treatment plants 1623, forming sewage treatment capacity1040,000 cubic meters/day; Among them, 376 sewage treatment plants have been built in 36 large and medium-sized cities (municipalities directly under the central government, provincial capitals and cities with separate plans), with a treatment capacity of 43.68 million cubic meters per day. In counties, townships and towns, 933 counties (including regimental units of Xinjiang Production and Construction Corps) have built sewage treatment plants, accounting for 52.1%of the total number of counties; There are sewage treatment plants in counties, townships and towns 1008, with a daily treatment capacity of18.26 million cubic meters.
Although the government and governments at all levels pay more attention to environmental protection, China's sewage treatment industry has developed rapidly, the total amount of sewage treatment has increased year by year, and the urban sewage treatment rate has been continuously improved. However, the sewage treatment industry in China is still in the initial stage of development.
On the one hand, China's current sewage treatment capacity cannot keep up with the rapid expansion of water consumption, and the construction of supporting facilities such as pipe network and sludge treatment is seriously lagging behind. On the other hand, compared with developed countries, there is still a significant gap in sewage treatment rate in China, and the load rate of treatment facilities is low.
Therefore, China should improve the policies and regulations of sewage treatment, establish a supervision system, establish a reasonable sewage treatment charging system, cultivate the development of domestic environmental protection industry, and promote the industrialization and marketization of sewage treatment industry. Sewage treatment industry is a sunrise industry with a very broad development prospect. China will invest 300 billion yuan to promote the treatment and utilization of urban sewage during the Eleventh Five-Year Plan period, and China's sewage treatment industry will usher in a period of rapid development.