The treatment processes used in biological treatment are:Oxidation Pond Method:Carrousel.Alternate.Orbal.Phostrip Method.Phoredox Method.SBR Method, AB Method, Biofluidized Bed Method, ICEAS Method, DAT-IAT Method, CASS ( CAST, CASP) method, UNITANK method, MSBR method, A/O method, A2/O, A3/O, UCT method, VIP method, UASB method, integrated biochemistry, integrated biochemistry and filtration method, increase the flow of carriers, deep-well aeration, biofiltration, bio-rotary disk method, biofilm tower biofilter and other municipal wastewater primary, secondary, deep treatment method.
Chemical enhanced biological phosphorus removal sewage treatment process
Sewage treatment process, China's major rivers and lakes due to phosphorus pollution, eutrophication is serious, the State Environmental Protection Administration for the control of phosphorus pollution, the phosphorus discharge has developed a more stringent standards. Chemical enhanced biological phosphorus removal sewage treatment process to remove organic pollutants and various forms of phosphorus in sewage, this sewage treatment process will be chemical phosphorus removal and biological phosphorus removal integration, through anaerobic digestion of activated sludge in the biological system to produce volatile organic acids, as a substrate for the growth of polyphosphorus bacteria or called nutrients, so that the polyphosphorus bacteria in the activated sludge to selectively proliferate, and back to the biological system, so that the biological wastewater treatment system works in the state of high efficiency phosphorus removal; at the same time, the phosphorus release produced by sludge under anaerobic conditions is eliminated by chemical phosphorus removal. This is a high-efficiency municipal wastewater treatment process technology to meet the current stage of China, in order to solve the eutrophication of water bodies, the need for further phosphorus removal on the basis of conventional secondary sewage treatment requirements.
Circulating intermittent aeration sewage treatment process
China's level of economic development varies greatly from place to place, economic development lagging behind the city has not been able to come up with a lot of money for sewage treatment, so how to utilize the limited funds to reduce environmental pollution is a lot of city governments are facing problems. In terms of sewage treatment, until recently, some cities still use a level or a level of enhanced treatment process technology, the water does not meet the national secondary emission standards for the removal of organic pollutants. Cyclic intermittent aeration process to give full play to the advantages of high-load oxidation ditch treatment efficiency, but also make full use of sequential batch activated sludge wastewater treatment process of good water characteristics, to ensure that the system effluent to meet the national sewage discharge standards in the first level of organic pollutants in addition to the requirements of the requirements. In the investment and operating costs than usually to remove organic pollutants mainly in the secondary biological sewage treatment system to reduce about 30%, is suitable for China's current stage of sewage treatment requirements of the process technology.
Rotary contact oxidation wastewater treatment process
Rotary contact oxidation wastewater treatment process technology is based on biological turntable technology, combined with the advantages of biological contact oxidation technology developed a new generation of aerobic biofilm treatment technology. The rotary contact oxidation sewage treatment process technology and complete sets of equipment provide a simple and reliable sewage treatment method. The rotating shaft is the only rotating part of the entire wastewater treatment system, and once the machine breaks down, it can be repaired by general mechanical personnel. The system biomass automatically compensates for changes in organic load. The microorganisms attached to the rotor are alive, and when the organic matter in the sewage increases, the microorganisms increase with it, and conversely, when the organic matter in the sewage decreases, the microorganisms decrease with it. So the working effect of this wastewater treatment system is not easily affected by sudden changes in flow and load and power outages. Operating costs are low, only one-eighth to one-third of the power consumption of other aeration wastewater treatment systems. The footprint is only half that of conventional activated sludge. Due to the large variety of microorganisms growing in the biological system, it is able to efficiently treat a variety of difficult to degrade industrial wastewater.
Continuous Cycle Aeration System Process
Continuous Cycle Aeration System process (Continuous Cycle Aeration System) is a continuous feed SBR aeration system. Sewage treatment process CCAS is improved on the basis of SBR (Sequencing Batch Reactor, sequencing batch treatment method).CCAS sewage treatment process does not require high sewage pre-treatment, only set up a gap of 15mm of mechanical grating and sand sedimentation tank. The core of biological treatment is CCAS reaction tank, phosphorus removal, denitrification, degradation of organic matter and suspended solids and other functions are completed in the tank, the effluent can be discharged.
Unique advantages on the sewage treatment process CCAS:
(1) Aeration, CCAS sewage treatment of sewage and sludge is in a completely ideal mixing state, to ensure that the removal rate of BOD, COD, the removal rate of up to 95%.
(2) The repeated operation mode of "aerobic-anoxic" and "aerobic-anaerobic" strengthens the absorption of phosphorus and nitrification-denitrification, so that the removal rate of nitrogen and phosphorus reaches more than 80%, which ensures that the effluent indicators are qualified.
(3)During sedimentation, the whole CCAS reaction pool is in a completely ideal state of sedimentation, so that the effluent has very low suspended solids, and the low value also ensures the removal effect of phosphorus.
The disadvantage of CCAS sewage treatment process is that the pools run intermittently at the same time, manual control is almost impossible, all rely on computer control, the quality of management personnel in the treatment plant requires high quality, design, training, installation, commissioning, and other work requirements are more stringent.
Aerated biofilter domestic sewage treatment process
Sewage treatment process introduction: aeration biofilter, that is, in the biofilter treatment device is set up in the filler, through the artificial supply of oxygen, so that a large number of microorganisms on the filler growth. This sewage treatment process flow device consists of a filter bed, gas distribution device, water distribution device, drainage device and other components. The aeration device adopts supporting special aeration head, and the small and medium bubbles produced are repeatedly cut by the packing to achieve the effect of close to micro-controlled aeration. Due to the high concentration of sludge in the reaction tank, the treatment facilities are compact, which can greatly save the floor space and reduce the reaction time.
Municipal wastewater SPR phosphorus removal process
Introduction of wastewater treatment process flow: the main reason for eutrophication of water bodies is that human beings discharged a large amount of ammonia nitrogen and phosphorus into the water body, phosphorus is the most important factor in the eutrophication of water bodies. Throughout the domestic sewage treatment process technology, phosphorus removal technology has been a problem for the operation of sewage treatment plants. The traditional physical phosphorus removal technology requires a large number of agents, with high operating costs, sludge production shortcomings; anterior anaerobic biological phosphorus removal process has the advantage of low operating costs, but due to the complete reliance on microbial phosphorus uptake, phosphorus release, it is difficult to meet the requirements of the national wastewater treatment process flow. When considering water reuse, it is more difficult to meet the requirements.
A / O biofilter sewage treatment process
Sewage treatment process introduction: due to the dispersed settlement of small towns in China, the distribution of sewage sources more than a small amount of town-level sewage treatment plant scale is less than 10,000 tons / day. At present, the domestic large and medium-sized urban sewage treatment plants often used in sewage treatment processes are traditional activated sludge, A2 / O, SBR, oxidation ditch, etc., if the construction of small towns with these technologies will result in small towns will result in sewage treatment plants due to high operating costs, can not be sustained operation. Must be used for the characteristics of small town investment, low operating costs, stable and reliable technology, operation and management of relatively simple process.
MBFB Membrane Biofluidized Bed Process
MBFB process for the deep treatment of wastewater, can be used in the original wastewater discharge on the basis of standards, after the biofluidized bed and the ceramic membrane separation system, to further reduce COD, NH-N, turbidity and other indicators, on the one hand, can be directly reused, on the other hand, can be used as a RO desalination pre-treatment process, replacing the original sand filtration, Security filtration, ultrafiltration and other lengthy filtration processes, while the reduction of organic content greatly improves the service life of the RO membrane, reducing the cost of reuse water treatment, inorganic ceramic membrane separation system, is the world's first set of sewage treatment of special inorganic membrane separation system, and other organic membranes, inorganic membranes compared to the membrane flux, backwash, fully automatic operation and other advantages.
Editorial
Foreign sewage treatment technology
European municipal wastewater treatment technology - sustainable biological phosphorus removal and denitrogenation process
Nitrogen and phosphorus removal for the purpose of controlling eutrophication has become the main goal of the countries. Undoubtedly, to cope with the increasingly stringent emission standards, the traditional process will be aggravated by the above disadvantages. Under these circumstances, the development of sustainable wastewater treatment processes has become imperative. A sustainable wastewater treatment process is one that works towards minimizing COD oxidation, minimizing CO2 release, minimizing residual sludge production, and achieving phosphorus recovery and reuse of treated water. This requires a more integrated approach to solving the problem of sewage treatment, that is, sewage treatment should not only meet a single water quality improvement, but also need to be considered together with the sewage and the pollutants contained in the problem of resource and energy, and the technology used must be low energy consumption (to avoid the phenomenon of pollution transfer), the premise of less resource loss.
The development of novel biological treatment processes for wastewater depends on new discoveries or understanding in microbiology and biochemistry. Dutch researcher Mulder discovered anaerobic ammonia (nitrogen) oxidation 10 years ago. At the same time, South Africa, the Netherlands, Japan and other countries, scientists on the biological uptake/release of phosphorus metabolism mechanism to re-understand the determination of denitrification of phosphorus removal of new ways. The research and development and application of these two new technologies have epoch-making significance in promoting the development of sustainable wastewater biological treatment process. This paper takes the anaerobic ammonia oxidation and denitrification phosphorus removal technologies as a blueprint, introduces in detail their technical principles, process flow, and application in Europe; on this basis, it proposes a recommended process for sustainable municipal wastewater biological phosphorus removal and denitrification with the goals of converting organic energy (methane), recovering phosphorus compounds (guano), and reusing the treated water (for non-drinking purposes).
In the practice of biological phosphorus removal in wastewater, the University of Cape Town, South Africa (UCT) researchers first found that specialized aerobic bacteria is not the only role of phosphorus biological uptake/release of bacterial species, parthenogenetic denitrifying bacteria also have a strong biological uptake/release of phosphorus phenomenon. The biological uptake/release of phosphorus by denitrifying bacteria was confirmed by a collaborative study between researchers at the Technical University of Delft (TUDelft) in the Netherlands and the University of Tokyo (UT) in Japan, and was named denitrifying dephosphatation (denitrifying dephosphatation). During the biological uptake/release of phosphorus, denitrifying bacteria replace oxygen with nitrate nitrogen as the electron acceptor, which means that denitrifying bacteria are able to combine denitrifying dephosphatization and biological phosphorus removal, which were thought to be independent of each other, into a single action. Obviously, in the combined phosphorus and nitrogen removal process, COD and oxygen consumption can be saved accordingly. Compared with the traditional dedicated 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 residual sludge by 50%. Due to the greatly reduced COD requirement during denitrification phosphorus removal, excess COD can therefore be separated and methanized, thus avoiding the oxidative stabilization of COD alone (to CO2). The combined energy savings attributable to the reduction in aeration energy and the generation of energy from the methanation of excess COD ultimately results in a significant reduction in the amount of CO2 released to the atmosphere. Therefore, treatment systems with enriched denitrifying phosphorus-removing bacteria can be considered as sustainable treatment processes. Traditionally, two well-recognized biological pathways, nitrification (NH+4→NO3-) and denitrification (NO3→N2) have been applied for biological nitrogen removal in wastewater treatment. This conventional biological nitrogen removal pathway is not optimal from a sustainability point of view, since sufficient oxidation of ammonia nitrogen to nitrate nitrogen firstly consumes a large amount of energy (due to aeration) and secondly, requires a sufficient carbon source (COD) to reduce nitrate nitrogen to nitrogen. Improvements to this traditional nitrogen removal pathway can be achieved with the help of SHARON, a new mesophilic nitrosation technology developed by TUDelft in the Netherlands. In the nitrosation/denitrification denitrification pathway, nitrite nitrogen is the only intermediate transition form; this pathway minimizes both oxidation (NH+4 → NO2-) and reduction (NO2- → N2), implying double savings in O2 and COD consumption. Clearly, the nitrosation/denitrification denitrification pathway can be a sustainable denitrification technology.
In addition, researchers at TUDelft in the Netherlands also experimentally confirmed a new ammonia-nitrogen conversion pathway almost at the same time, which makes it possible to oxidize ammonia nitrogen directly to nitrogen gas using nitrite nitrogen as an electron acceptor. This combination of ammonia oxidation under anaerobic conditions and nitrosation processes such as the SHARON process was engineered to achieve the shortest pathway conversion of ammonia nitrogen, which means that minimization of energy and resource consumption in biological nitrogen removal is entirely possible. All possible conversion pathways for nitrogen in wastewater treatment are listed in Figure 1.Compared to conventional nitrogen removal processes, it is clear that a fully autotrophic conversion of nitrogen by a combination of anaerobic ammonia oxidation and nitrosation processes is one of the most sustainable wastewater nitrogen removal pathways.
Editorial
China's wastewater treatment recent and future
Overview
China's wastewater treatment industry development progress late, since the founding of the country to the reform and opening up, China's demand for wastewater treatment is mainly industrial and national defense cutting-edge use. After the reform and opening up, the rapid development of the national economy, the people's living standards improved significantly, pulling the demand for sewage treatment. Into the 1990s, China's sewage treatment industry entered a period of rapid development, the growth rate of sewage treatment demand is much higher than the global level.
Since 1990, the global apparent consumption of sewage treatment at an average annual growth rate of 6%, while the decade of the nineties, China's apparent consumption of sewage treatment average annual growth rate of 17.73%, is the world's average annual growth rate of 2.9 times. Into the twenty-first century, China's sewage treatment industry is growing at a high rate. 2000-2004, China's sewage consumption grew from 1.88 million tons to 4.47 million tons, an increase of 2.3 times the average annual growth rate of 27% or more. Among them, in 2001, China's apparent consumption of sewage treatment reached 2.25 million tons, surpassing the United States to become the world's first major consumer of sewage treatment. At the same time, sewage imports also increased significantly. 1998, China's sewage imports of 1 million tons, thus becoming the world's largest importer of sewage treatment. 2004 and 1998 than, sewage imports increased at an average annual rate of 27.14%. It is expected that in 2005, China's apparent consumption of sewage treatment will reach 5 million tons, imports will remain at about 3 million tons.
Along with the rapid development of the sewage treatment market, China's sewage treatment production also ended a long period of hovering situation, to achieve a high rate of growth. China's sewage treatment production from 460,000 tons in 2000 grew to 2.36 million tons in 2004, an average annual growth rate of 82.6%, accounting for the proportion of the domestic market demand also increased from 24.47% in 2000 to 52.80% in 2004. During the same period, the world's sewage production is only about 6% growth rate.
From the late nineties, China's TISCO, Baosteel, as well as Baoxin, Zhang Pu and other state-owned and joint-venture enterprises through the introduction and technological transformation, has built a series of sewage treatment production lines, sewage treatment technology and equipment to reach the international advanced level, sewage treatment production has taken shape. Sewage treatment varieties of structure has also undergone positive changes, sewage treatment product quality has improved rapidly. In particular, the domestic sewage treatment of cold rolled plate growth, in 2003, the domestic cold rolled plate production reached 1.7 million tons, for the first time more than the amount of imports, the self-sufficiency rate of 66%; in 2004, the domestic production of cold rolled plate reached 2 million tons, the self-sufficiency rate of more than 70%. From the end of 2004 to the end of 2005, the domestic cold-rolled sewage treatment capacity will increase about 1.5 million tons, basically meet the domestic market demand. By 2007, China will become a net exporter of sewage treatment.
On the whole, China's sewage treatment is experiencing from a small scale, low level, a single variety, seriously unable to meet the demand for a considerable scale and level, variety and quality of significant improvement and initially meet the requirements of the national economic development of the profound transformation of the demand for sewage treatment will gradually realize self-sufficiency.
China's urban sewage treatment capital source of problems
(Difficulties a) population increase, sewage increase
In China, with the increase in the urban population and the development of industrial and agricultural production, sewage discharges are also increasing the amount of water pollution is quite serious, and almost all over the country. By the end of 2000, the country set up a city of 663 cities in 310 built sewage treatment facilities, the construction of sewage treatment plant 427, the annual sewage treatment volume of 11.36 billion cubic meters, sewage treatment rate of only 34.23%.
(Difficulties two) to accelerate the development of the urgent need for funds
In the socialist market economy, sewage treatment is from a certain amount of capital investment. The scale of sewage treatment funds determine the scale of sewage treatment. Sewage treatment funds itself determines the speed of development of sewage treatment and the speed of progress of sewage treatment technology. The reality of sewage treatment, technologically advanced, low treatment cost decision-making program is usually a large amount of prepaid funds program. In this sense, the faster the rate of development of the funds themselves, the faster the progress and application of sewage treatment technology can be faster, sewage treatment can also be faster.
(Difficulty three) treatment of capital, the source of the difficulty
1, China's urban sewage treatment capital source of the difficulty
For a long time, China's urban sewage treatment facilities to take the free use of the policy, not only the expansion of reproduction by the financial investment, simple reproduction also need financial allocations in order to complete the financial allocation has therefore become the sewage treatment facilities to maintain construction The financial allocation therefore became the only source of investment in the maintenance and construction of sewage treatment facilities. Just in different periods, the name of the source is different, but are centered on the financial cycle of funds. The economic system reform, denied our country's traditional unification" financial model, denied the identity of the state as a production operator, but also denied the identity of the owner of the means of production and the exercise of power unity, the requirements of the government and enterprises, the separation of government and capital. In line with this, 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 to the exercise of power in the capacity of the state, mainly in the form of taxes to raise funds to solve the market allocation of resources can not solve the problem, to meet the needs of the public ****. Urban sewage treatment is public welfare, sewage treatment funds financial allocation should be public **** financial expenditure. Because of China's socialist market economic system reform is still deepening, the proportion of public **** financial income accounted for the proportion of GDP, the central public **** financial income accounted for the proportion of public **** financial income is not reasonable, urban sewage treatment funds are difficult to like the United States and other developed countries, such as the vast majority of the vast majority of the funds from the financial allocations or loans.
2, sewage treatment borrowed funds where the difficulties
City sewage treatment funds demand is huge, bank loans is an important source of sewage treatment funds. Bank loans are divided into commercial bank loans and national development bank loans. Commercial bank funds for residents and enterprise deposits, most of the short-term funds, although some medium- and long-term loans, but the proportion should not be too large; commercial banks require security, liquidity and profitability of the "three" unity, and the use of wastewater treatment funds and back to the flow of funds is difficult to use with the commercial bank funds, "three" coincide with. Therefore, it is difficult for commercial banks to provide financial support to the sewage treatment industry. Therefore, it is difficult for commercial banks to make loans for sewage treatment projects.
China's urban sewage treatment capital source of the problem of cracking
(Cracking method a) increase the financial allocation
A part of the urban sewage treatment funds, under the conditions of socialist market economy, but also by the government to give the necessary subsidies, the reasons for a variety of things. Mainly: 1, sewage treatment is generally less price elasticity of demand and the government "monopoly" operation, its charges must take into account the affordability of the residents, and can not rely on competitive prices to completely solve the problem of facility construction and enterprise development. 2, sewage treatment services provided by the public ****, many facilities are difficult to calculate the use of the charges for its services can not be directly into the market to implement the exchange of equal prices, but can only become a public **** consumption of the public *****. Can only become part of the public **** consumption. 3, sewage treatment services provided by a wide range of social and external economy, to measure the benefits of its investment, first of all, social benefits.
National financial allocations for urban sewage treatment, in our country there are mainly capital arrangements for investment, the central financial allocation of special funds and local financial allocations. Capital construction arrangements for investment, the state budget and local self-financing two kinds. The state budget capital investment by the central government to determine the amount of the Ministry of Finance to the State Planning Commission unified arrangements. Local self-financing capital investment, is in the amount specified by the state by the local self-financing arrangements for investment. Central and local financial allocations, one is based on the need for financial allocation of a certain amount of money each year, as a special fund for sewage treatment; another is a fixed amount of subsidies according to the project, the project is completed, the subsidy stops.
(Crack method two) increase the intensity of self-financing enterprises
In the conditions of the market economy, sewage treatment only in its construction and operation of its value into the return of funds week after week, in order to realize the reproduction of sewage treatment. According to the requirements of the law of value, sewage treatment inputs and outputs rationalized to the new order of the market economy, is to accelerate China's urban sewage treatment objective requirements. Sewage treatment charges, should not be a temporary financing measures, but the realization of sewage treatment funds to compensate for the market-oriented approach, but also to regulate the rational use of sewage treatment facilities, an economic means.
Self-financing sewage treatment, in the socialist market economy, in accordance with the law of value to develop sewage charges, in accordance with national regulations from the operating income to extract the production development fund, depreciation fund of fixed assets and major repairs fund. Sewage treatment units not only rely on their own strength to complete the simple reproduction and expansion of reproduction, but also to pay taxes and fees to the state. For this reason, reasonable charges for sewage treatment must be based on reasonable costs and reasonable profit margins.
The reasonable cost of sewage charges, generally should include production costs, operating expenses, depreciation of fixed assets, overhaul base, loan interest. Among them, the depreciation of fixed assets to have the proper depreciation rate, to change the current depreciation life is too long, the depreciation rate of low practice, so as to avoid the clear profit and loss of the enterprise. Reasonable profit rate of sewage charges, means that the approved profit rate should take into account not only the reasonable welfare of the enterprise and the necessary accumulation, but also take into account the sewage charges demand elasticity is small, social service characteristics, to prevent the use of its monopoly in pursuit of excessive profits. In order to prevent the monopoly imposed on the users of the burden, the government can be administrative and economic means to limit the operator, so that the profit it may obtain does not exceed the average profit of the whole society.
(Hacking method three) Trial preferred stock issuance
Experience in market economy countries has shown that issuing preferred stock to absorb domestic and foreign private capital for municipal sewage treatment can meet the huge capital demand for sewage treatment without losing the government's control over the sewage treatment project. Preferred stock is relative to common stock. The benefits of investing in common stock also include higher investment returns than other similar securities, strong liquidity in the stock exchange market, and fair trading.
Preferred stock is a stock that has a certain priority over common stock, mainly the right to receive dividends and the company's residual property. The biggest advantage of preferred stock is that it has stable earnings and less risk than common stock. However, when the joint-stock company's business performance is outstanding and the operating profit surges, the earnings enjoyed by preferred stock will not increase, while the earnings of common stock can increase with the company's operating efficiency. From this point of view, the preferred stock is less developmental and aggressive than the common stock.
According to China's current practice, the stock is based on the identity of the investor, divided into state shares, corporate shares, individual shares and foreign shares, there is no preferred shares and common stock division. China's Company Law does not have the concept of preferred shares, nor do they make corresponding provisions. This is because China's shareholding enterprises are transformed from the enterprises under the planned economic system, and thus with all the traces of history, the historical legacy of the problem is to be further explored and resolved in the reform. From the actual starting point of urban sewage treatment, we can carry out the exploration of sewage treatment stock issuance. This will be the existing sewage treatment enterprises to carry out shareholding system transformation, to domestic and foreign private capital issued part of the preferred stock, or part of the state-owned shares in the form of preferred shares transferred to private capital, the funds raised by the sewage treatment enterprises for sewage treatment. This approach has a higher likelihood of successful capital raising because it is based on the development performance of the existing enterprise and the performance of the revamped enterprise continues to grow.
Editorial
China's sewage treatment industry development
Earth although 70.8% of the area covered by water, but the freshwater resources are extremely limited, mankind is really able to utilize is the rivers and lakes, as well as a part of the groundwater, accounting for only 0.26% of the total amount of water on earth, and the distribution is not even.
After the 1950s, the global population grew dramatically and industry developed rapidly. The global water resources situation is deteriorating rapidly, and the "water crisis" is becoming more and more serious. On the one hand, human demand for water resources is expanding at an alarming rate; on the other hand, the increasingly serious water pollution eats up a large amount of water resources available for consumption.
The world every day about 200 tons of garbage dumped into rivers, lakes and streams, every liter of wastewater will pollute 8 liters of fresh water; all rivers flowing through Asian cities are polluted; 40% of the water resources of the United States watersheds are processed food waste, metals, fertilizers and pesticides contamination; only 5 of the 55 rivers in Europe, the quality of the water is not good. 20 century, the world's population has tripled, and the water used by mankind has increased five times. In the 20th century, the world's population has tripled, while human water use has increased fivefold. Many countries around the world are facing water crises: 1.2 billion people suffer from water shortages and 3 billion people lack access to water sanitation.
China's per capita water resources are small and spatially unbalanced. As China's urbanization and industrialization accelerate, the gap in demand for water resources is growing. Against this background, the wastewater treatment industry has become an emerging industry, and is now on an equal footing with the tap water production, water supply, drainage and water reuse industries.
By the end of 2005, the country's 661 municipalities, 383 cities have built 792 sewage treatment plants, sewage treatment rate increased from 34% in 2000 to 52%, and formed a sewage treatment technology routes and management mechanisms suitable for national conditions. Among them, the sewage treatment rate of 135 cities has reached or is close to 70%, and the treatment scale of a single plant has reached 1 million cubic meters per 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 the year's GDP. The overall quality of China's water environment remained stable. in 2007, *** outlawed 942 sewage outlets in primary water source protection zones, halted 1,294 construction projects in secondary water source protection zones that could cause pollution, and fixed-term treatment for 931.
As of the end of September 2010, a total of 2,631 sewage treatment plants had been built in cities, counties and some key towns (hereinafter referred to as "cities and towns"), with a sewage treatment capacity of 122 million cubic meters per day; 1,849 sewage treatment projects are under construction in cities and towns across the country, with a total design capacity of about 46.6 million cubic meters per day. The total design capacity is about 46.6 million cubic meters/day. In the municipal cities, 593 cities have built sewage treatment plants, accounting for 90.7% of the total number of municipal cities; a total of 1,623 sewage treatment plants have been built, forming a sewage treatment capacity of 104 million cubic meters / day; of which 36 large and medium-sized cities (municipalities, provincial capitals and municipalities with separate plans) have built 376 sewage treatment plants, with a treatment capacity of 43.68 million cubic meters / day. In counties and townships, the country has 933 counties (including Xinjiang Production and Construction Corps regiment-level units) built sewage treatment plants, accounting for about 52.1% of the total number of counties; counties and townships, townships and sewage treatment plants built 1,008, with a capacity of 18.26 million cubic meters / day.
While China's sewage treatment industry is growing rapidly due to the increasing attention paid to environmental protection by the state and governments at all levels, the total amount of sewage treatment is increasing year by year, and the sewage treatment rate of cities and towns is improving. However, China's sewage treatment industry is still in the early stages of development.
On the one hand, China's current sewage treatment capacity has not been able to keep up with the rapid expansion of the scale of water use, the pipeline network, sludge treatment and other ancillary facilities construction is seriously lagging behind. On the other hand, China's sewage treatment rate compared with developed countries, there is still a significant gap, and the load rate of treatment facilities is low.
So China should improve the policies and regulations of sewage treatment, establish a regulatory system, create a reasonable sewage charging system, foster the development of domestic environmental protection industry, and promote the industrialization and marketization of sewage treatment industry. Sewage treatment industry is a sunrise industry, the development prospects are very broad. China will invest 300 billion yuan in the "Eleventh Five-Year" period to promote urban sewage treatment and utilization, China's sewage industry ushered in a period of rapid development.