Fang Xianjin
(Beijing Municipal Engineering Science and Technology Research Institute, No.26 Dagang Hutong, Xicheng District, Beijing, 100035, China)
China is a water-poor country, with per capita water resources possession of only 2200m3, which is only 1/4 of the world's average, and 88th out of the 153 countries with continuous statistics by the World Bank. At the same time, China's water resources in time and regional distribution is very unbalanced, more in the south and less in the north, and most of the northern region per capita water resources ownership is lower than the United Nations Commission on Sustainable Development to determine the line of 1750m3 water stress, of which 9 areas are lower than the line of 500m3 of severe water shortage. The shortage of water resources has become an important factor restricting China's economic and social development.
1 Problems Facing the Sustainable Utilization of Water Resources
1.1 Total Water Resources Scarcity
Over the past 50 years, the total water consumption of the whole country has increased from more than 100 billion m3 in 1949 to 556.6 billion m3 in 1997, with 75.3% of water consumption in agriculture, 20.2% in industry, and 4.5% in urban living, and the comprehensive annual water consumption per capita has increased from less than 200 m3 to more than 1,000,000,000,000 m3. At present, the national annual water shortage is nearly 40 billion m3, of which 30 billion m3 are in agriculture, with an average annual reduction of more than 20 billion kilograms of grain due to drought; 6 billion m3 are in urban and industrial water shortage, affecting the industrial output value of more than 230 billion yuan, and more than 400 of the country's 668 cities have a shortage of water, with 110 cities suffering from a serious water shortage. Especially since 1999, China's northern region continued to drought, to industrial and agricultural production caused a greater impact, but also to urban and rural residents living in water caused great difficulties. 2001, the most serious drought in the first half of June, the national drought area once reached 420 million mu (1 mu = 100m2), due to the persistent drought, the lack of water, resulting in urban and rural people's living in water stress, there are 21.98 million urban population and 33 million rural people living in water. As a result of the persistent drought and insufficient water sources, the urban and rural people's living water supply was strained, and 21.98 million urban and 33 million rural people and 14.5 million large livestock had difficulties in drinking water. Large and medium-sized cities such as Tianjin, Changchun, Dalian, Qingdao, Tangshan and Yantai have been seriously threatened by water shortages, and many reservoirs and rivers have been cut off and dried up as never before. In the future, with the growth of the population, the improvement of living standards, accelerated urbanization, the contradiction between the supply and demand of water resources will be more prominent, it is predicted that China's water consumption will peak around 2030, 2030 China's population will reach 1.6 billion people, the total food production needs to reach 700 million t, the total amount of water consumption of 700 billion to 800 billion m3, the country's annual water shortages will be in the 70 billion m3 or so.
Climate change has also had a negative impact on the availability of water resources in China. According to the 1950 ~ 1997 precipitation and temperature data analysis, China in the past 20 years, showing the situation of northern drought and flooding in the south. 1980s North China continued to drought, Beijing and Tianjin, Hailuan River Basin, the Shandong Peninsula 10 years of average precipitation is less than 10% to 15%. In the 1990s, the upper and middle reaches of the Yellow River, the Han River basin, the upper reaches of the Huaihe River, the Sichuan Basin, the eight-year average precipitation is about 5% to 10% less, the Yellow River garden mouth of the preliminary estimate of the amount of natural water is less than about 20%, the Hailuan River and the Huaihe River's annual runoff are also significantly less. The emergence of sustained dry years in the northern water-scarce areas, as well as the Yellow River, Huaihe River, Haihe River and Hanjiang River at the same time suffered from dry years and other unfavorable factors, exacerbated the contradiction of the imbalance between supply and demand of water resources in the northern part of the country. According to the relevant research, the next 50 years due to human activities generated by the greenhouse effect, the global average annual temperature may rise, the temperature will rise will make the surface evaporation increased, the amount of water resources will be reduced accordingly.
1.2 Uneven distribution of water resources
China's water resources in time and space distribution is very unbalanced. The Yangtze River Basin and its south area only accounts for 36.5% of the country's land area, its water resources accounted for 81% of the country; Huanghuaihai Basin population, food production and GDP accounted for about 1/3 of the country, but its average multi-year water resources accounted for only 7.2% of the country. Influenced by the monsoon climate, the intra-annual distribution of precipitation is extremely uneven across the region, with the four months of the annual flood season accounting for about 70% of the total annual precipitation in most areas, making it easy to form spring droughts and summer floods. Unbalanced distribution of water resources in time and space to the full utilization of water resources has brought some difficulty.
1.3 Serious waste of water resources
China's water resources on the one hand, a serious shortage of water resources, but on the other hand, a serious waste. For a long time, the non-sustainable utilization of water resources "based on demand" is the man-made reason for the shortage of water resources. Blind development of primary and secondary industries, especially the one-sided pursuit of increased food production and the development of heavy industry, resulting in an irrational industrial structure, water resources utilization efficiency is low, so that the already scarce water resources more serious problems.
Currently, China's farmland irrigation area of canal irrigation area accounted for about 75%, while the canal loss of about 50%, farmland evaporation loss of about 17%, the actual utilization of only about 33%. Due to the traditional irrigation pattern adopted in most places, the actual irrigation volume per mu reaches 450-500m3, which is more than about one times of the actual water demand, and the waste is extremely serious. China mainly rely on precipitation of dry cultivated land area of about 1.2 billion mu, 70% of which is distributed in the precipitation of 250 to 600mm in the northern region, due to water storage and water conservation and other infrastructure is insufficient, the utilization rate of natural precipitation on the farmland is only about 56%. According to the latest statistical estimates, the utilization rate of irrigation water in China's farmland is only 1.0kg/m3, and the water utilization efficiency of dry cultivated land is 0.60-0.75kg/m3, the average efficiency of agricultural water use in the country is 0.8kg/m3, and the comprehensive economic benefit is 0.2 USD/m3, while Israel has exceeded 1 USD/m3, the gap is very obvious. At this stage, China's agricultural water resources utilization does not meet the requirements of sustainable use of water resources.
China's overall level of industrial water efficiency is still low, in 2001, China's 10,000 yuan of industrial output value of water withdrawal of 90m3, about 3 to 7 times the developed countries; industrial water reuse rate of about 52%, far lower than the level of 80% of the developed countries. 2000 urban per capita water consumption of living in the country amounted to 220.2L/d, far higher than the per capita water consumption of living in the developed countries. The community's awareness of water worries is not strong, and the phenomenon of wasting water resources is still serious, which indicates that water conservation measures have not yet been effectively implemented, and the technology and management level of water conservation is not high. Over the past decade, China's economic restructuring in accordance with the strategy of sustainable economic development, although it has begun to bear fruit, but the pattern of water consumption and utilization has not yet undergone substantial changes.
1.4 water pollution situation is grim
Currently, China's sewage treatment rate is still relatively low, a large number of urban and domestic sewage is directly discharged into the rivers and lakes and reservoirs without treatment of water, most of the country's waters and nearly 50% of the key towns and cities of the centralized drinking water sources are contaminated to varying degrees, of which 98 cities and towns of the water pollution is more serious, mainly in the three rivers and three lakes basin. As a result of water pollution, some water sources have been forced to stop using them and look for new sources, thus exacerbating water shortages in cities. Water pollution also affects the quality of the water supply and jeopardizes the health of residents. At present, the national soil erosion area of 356km2, accounting for 37% of the national territory. The national groundwater has been over-exploited by an average of 7.4 billion over the years, and 164 groundwater over-exploitation zones have been formed, with ground subsidence and seawater intrusion occurring in some areas. Many important rivers and lakes are seriously polluted, and water conflicts caused by pollution are increasing. Water pollution seriously affects the sustainable use of water resources in China, affecting the sustainable development of China's economy and society.
2 realize the sustainable use of China's water resources should take measures
China's government attaches great importance to the sustainable use of water resources, clearly pointed out that: the sustainable use of water resources is the strategic issue of China's economic and social development. Over the years, in view of the characteristics of China's water resources and water resources utilization problems, a series of measures to ensure the sustainable use of water resources.
2.1 rational use of water resources
China's sustainable use of water resources is the fundamental way out in adhering to the strategy of sustainable development, change the "demand-determined supply" of the traditional mode of development for the "amount of water, water-determined" model of sustainable use of water resources. The way out lies in adhering to the sustainable development strategy. Based on the protection and rational use of available water resources, the economic and social development structure should be determined in accordance with the carrying capacity of water resources, ensuring the sustainable use of all kinds of waters, making strategic adjustments to the economic structure, and adopting different economic structures in areas with abundant and scarce water resources. Vigorously develop water-saving, energy-saving, high value-added high-tech industries and services. According to the spatial and temporal distribution characteristics of China's water resources rational development of agriculture, take the necessary return of farmland to forests, so that the ecosystem can be improved to ensure the balance between supply and demand of water resources.
2.2 Reasonable allocation of water resources
According to the uneven distribution of precipitation within the year in our country, a large number of water storage facilities should be constructed to make full use of water resources. At present, the country*** has built 85,000 reservoirs, which has greatly increased the annual water supply capacity. Water storage facilities can, on the one hand, store excess precipitation during the rainy season for use during the dry season. On the other hand, they can reduce flood disasters and ensure economic development. Geographically, China's water resources are more in the south and less in the north, with abundant water resources in the south and a serious shortage of water resources in the north. The South-to-North Water Transfer Project is a major strategic project to solve the contradiction of water shortage in the northern part of China and realize the rational allocation of water resources. The east, middle and west lines of the South-to-North Water Diversion Project will be interconnected with the Yangtze River, the Yellow River and the Haihe River to form an overall pattern of rational allocation of water resources, and to achieve the goal of water resources allocation in the north and south, and in the east and west. Three water transfer lines annual total water transfer 38 billion to 48 billion m3, can basically change China's Huanghuaihai region of the serious shortage of water resources, to ensure that China's water resources in general sustainable use.
2.3 Great efforts to carry out water conservation
China has always attached importance to water conservation, more than 20 years ago, the state put forward the implementation of the policy of equal importance to the open source and the flow of water, and seriously carry out the work of water conservation, and formulated a series of water conservation regulations and standards, the establishment of the management system of water conservation, but also the formation of a relatively sound management system, the work of urban water conservation Certain achievements have been made, and by 2000, the cities in the country had saved more than 30 billion m3 of water, making the total water consumption of the cities basically no growth in the past five years, and changing the trend of synchronized growth of water consumption of the cities with the economic development. However, at present, China's agricultural water utilization rate is still low, industrial water consumption of 10,000 yuan output value and the average daily water consumption of urban residents are still high, and the potential for water conservation is still large. In agriculture, agricultural water-saving technologies should be developed and popularized to reduce the amount of deep seepage and surface loss from farmland, reduce the amount of water used per unit area, reduce evaporation and transpiration in the field and in the process of water transmission, improve the water utilization efficiency of irrigation and precipitation, and continuously improve the yield and efficiency of water resources per unit. In terms of industrial water conservation, the structure of industrial production should be adjusted while improving the production process, increasing the water repetition rate, and reducing the water consumption of ten thousand Yuan of industrial output value. In order to ensure water conservation, it is necessary to formulate and improve relevant policies and regulations, establish a set of institutions and mechanisms in line with the principles of the market economy, reform the existing low price of water, establish a macro-control of water resources and micro-quotas system, the formation of total control and quota management combined with the management of water resources management system.
2.4 Greatly develop sewage treatment and recycling reuse work
Water pollution has exacerbated the situation of water scarcity in China, a direct threat to the safety of drinking water and people's health, affecting industrial and agricultural production and crop safety, resulting in economic losses of about 1.5% to 3% of the gross national product. Water pollution has become no less than floods, droughts and even more serious disasters. Water pollution as early as the 1970s has been revealed, but did not attract enough attention, the measures taken are not appropriate enough strong, so today's serious situation. If we do not take timely and effective countermeasures, will seriously affect the sustainable use of China's water resources. Long-used industrial pollution control strategy based on end-of-pipe treatment and emission standards has been proved by domestic and foreign experience to be costly, ineffective and inconsistent with the strategy of sustainable development. Pollution prevention strategies represented by cleaner production should be vigorously pursued, products and processes with high material and energy consumption, high water consumption and outdated technology should be eliminated, the utilization rate of water resources should be improved in the industrial production process, and pollution emissions should be cut. For point-source pollution caused by industrial and urban drainage, sewage treatment projects should be vigorously developed so that China's sewage treatment rate can be further improved on the basis of the 34.3% rate in 2000. For surface sources of pollution including all kinds of unorganized, large-area emissions, such as farmland runoff containing chemical fertilizers and pesticides, and wastewater and waste discharged by livestock and poultry farming, their control should be combined with the construction of eco-agriculture and eco-ruralism, so as to reduce surface pollution to a minimum through the rational use of chemical fertilizers and pesticides, as well as by making full use of all kinds of waste and wastewater from livestock and poultry farming in rural areas. Effluent resource reuse should be actively carried out to improve the rate of sewage reclamation and reuse.
3 Sewage reclamation and reuse is an effective way to realize the sustainable use of water resources
Sewage reclamation and reuse is an economic and reliable open source and flow reduction measures, compared with the cross-basin transfer of water, seawater desalination, rainwater storage and other open source measures, sewage reclamation and reuse has the economy and reliability. The water used by human beings only accounts for about 0.1% of the polluted impurities, much less than the 3.5% of seawater, and most of the rest of the water is reusable fresh water. Inter-basin water transfer and rainwater storage project investment is large, and need to invest a lot of money to control further pollution of water bodies, inter-basin water transfer will also have an impact on the existing ecosystem. Under the existing economic conditions in China, inter-basin water transfer and rainwater storage can only be carried out gradually. The essence of sewage reclamation and reuse is the implementation of recycled water and water quality, the sewage will be regenerated and reused for users with lower water quality requirements. With the accelerated development of industrialization, people's living standards continue to improve, the scope of water pollution is also expanding, deepening the degree of pollution, socio-economic development and environmental pollution to form a pair of sharp contradictions. The development of sewage reclamation and reuse, reduce wastewater discharge is the most powerful measures to solve environmental problems. In addition, in order to meet the needs of users, recycled water must meet the appropriate water quality standards, for this reason, the need for secondary effluent from the sewage treatment plant to carry out in-depth treatment, thereby reducing the total amount of pollutants, reducing the pressure on the environment of wastewater.
Sewage reclamation reuse should be strictly according to the reuse object and purpose of controlling the quality of reuse water to ensure the safety of reuse water. To this end, China has developed a series of relevant reuse standards. Such as domestic sewage after secondary treatment can reach the "comprehensive sewage discharge standards", but can not be used as miscellaneous water or industrial and agricultural water; if you consider reuse, must be further processed. When the sewage is reused for agricultural irrigation, water quality indicators should meet the "agricultural irrigation water quality standards"; when the sewage is reused in urban landscapes, water quality indicators should meet the "reclaimed water reused in landscape water quality standards"; when the sewage is reused for urban life miscellaneous water, water quality indicators should reach the "life miscellaneous water quality standards"; industrial wastewater reuse water quality indicators should meet the corresponding industrial water standards.
80% of the city's water supply into sewage discharged into the city sewers, collected and regeneration treatment, 70% can be safely reused; the two together, about 56% of the city's water supply can be converted into reclaimed water, back to the city water quality requirements of the user, replace the same amount of clean water, accordingly, increase the city's water supply by more than half. Wastewater is a very valuable resource, tapping the huge potential. China's national sewage discharge in 2000 was 620m3, which is a large renewable water resources. Sewage reclamation and reuse based on their own water resources to increase urban water supply, is to realize the sustainable use of water resources and effective measures. Sewage reclamation and reuse can effectively alleviate the shortage of urban water resources.
In order to ensure the sustainable use of water resources to support the sustainable development of the economy, in view of China's water resources problems, in the past decade or so, through the national scientific and technological research, as well as water-scarce cities in order to solve the problem of water pollution and water shortages to make efforts, the country has built a number of different processes, different reuse of the object of the urban sewage reuse demonstration projects. Table 1 lists the statistical results of some urban wastewater reuse projects in North China. At present, China's sewage reuse projects are mainly reused for the internal water of sewage treatment plants, municipal miscellaneous use, river recharge, greening, industrial water, etc., and have not been reused for underground recharge and drinking water sources. Beijing in 2001 completed the Gaobeidian sewage treatment plant effluent reuse project is China's largest sewage reuse project. A large number of sewage reuse project practice shows that: sewage reclamation and reuse is an effective way to solve the sustainable use of water resources.
Table 1 Some cities in northern China sewage reuse Unit: 10,000m3/d
4 China's largest sewage reclamation and reuse project
4.1 Overview of the project
Gaobeidian wastewater treatment plant reuse project is the largest sewage reclamation and reuse project in China, which completed the preliminary study of the project from March to August 1999, and completed the feasibility study. The feasibility study was completed in October 1999, the project was completed and approval; in January 2000, the preliminary design and approval of the project was completed, the construction plan design was completed in February, the construction began in April of the same year, the construction was completed in May 2001, the commissioning and commissioning was completed in June 2001, and the water supply began in July 2001, the project is now the largest sewage reuse project in China.
Gaobeidian wastewater treatment plant is currently China's largest wastewater treatment plant, with a treatment capacity of 1 million m3/d. The plant's wastewater system has a watershed area of 96km2 and serves a population of 2.4 million people, gathering most of the domestic sewage from the southern part of the urban area of Beijing, as well as all of the wastewater from the industrial area in the eastern suburb of the city, the embassy area and the chemical industry road. The plant adopts an anoxic section activated sludge process, i.e., an anoxic section is set up before the push-flow aeration tank, which aims to improve sludge properties and prevent sludge expansion. The water quality and quantity of the effluent from the plant is stable, and its secondary effluent is close to the relevant water quality standards for reuse. However, before the operation of this reuse project, the secondary effluent of Gaobeidian WWTP was directly discharged into the lower reaches of Tonghui River, and in addition to about 55 million m3 used for agricultural irrigation every year, the remaining effluent was not utilized for more than 300 million m3 per year, which is a great waste of water resources. In order to alleviate the contradiction between urban development and available water resources faced by Beijing in the 21st century, to realize the sustainable use of water resources in Beijing and to support the strategy of sustainable development of the national economy, the Beijing Municipal Government has decided to develop the wastewater resources of the plant. The Gaobeidian Wastewater Treatment Plant Reuse Project uses reused water in an area of 141km2, with reused water users involved in industry, park greening, road spraying and flushing, and river and lake replenishment.
4.2 Project scale and technical program
The recent scale of this project is 300,000m3/d, and the long-term scale is 470,000m3/d. Existing facilities are utilized as much as possible in the determination of the reuse engineering technology program in order to reduce the project investment. Specific design program is as follows: Gaobeidian wastewater treatment plant two sedimentation tank effluent by the new pumping station (size 470,000m3 / d) after upgrading the two pipelines were transported to the Gaobeidian Lake (size of 300,000m3 / d) and the water source of the six plants (size of 170,000m3 / d). The treated water sent to Gaobeidian Lake is further treated through the existing deep treatment facilities of the First Thermal Power Plant for the cooling water of the plant; the treated water sent to the Sixth Water Source Plant is treated in depth at the plant, and part of it is supplied to the Dongjiao Industrial Zone and the Coking Plant through the existing water supply system of the Sixth Water Source Plant; and part of it is transported to Xibianmen and Dongbianmen through the newly built pipeline. In the existing water supply pipeline and new pipeline along the water source plant six set up water intake, and new water reuse branch line, for municipal miscellaneous water intake.
4.3 Technical safeguards for reuse water quality
Because of the construction of the Gaobeidian wastewater treatment plant, the state of the municipal wastewater treatment plant effluent requirements in the absence of nitrogen and phosphorus index control, so the current plant effluent nitrogen and phosphorus content is higher, which will have a direct impact on the quality of reuse water, it is necessary to carry out technological renovation of the plant, and further improve the quality of effluent from the plant. The scale of transformation is 500,000m3/d, that is, the first phase of the Gaobeidian Wastewater Treatment Plant (500,000m3/d) to carry out the transformation. The renovation project is carried out in two steps. The first step after the transformation so that the effluent water quality is better than the current first thermal power plant cooling water intake source Lake Gaobeidian water quality, effluent BOD, COD, total phosphorus and ammonia nitrogen reached 10mg / L, 40mg / L, 1mg / L and 10mg / L. The second step of the transformation to make the plant 500,000m3 / d to meet the Lake Gaobeidian Ⅳ class water quality requirements. The first step of the main renovation workload includes the renovation of the aeration tank and the renovation of the sludge treatment system. The original aeration tank for 1/12 for the anaerobic zone, the rest for the aerobic zone, after the transformation of the original tank 2/9 for anoxic zone and anaerobic zone (hydraulic retention time *** for 2h), which is divided into a water intake end of the retention time of 15min to strengthen the adsorption area. The rest is still aerobic zone (hydraulic retention time 7.25h). The remaining sludge in the original sludge system is pumped into the primary sedimentation tank, and the mixed sludge is then thickened into the sludge thickening tank and digested and dewatered, because the thickened sludge tank has a longer retention time and is in an anaerobic state, and the phosphorus is released, and returned to the sewage through the supernatant, so it does not achieve the purpose of removing phosphorus. After the renovation, the original concentration pool is changed to concentration acidification pool, and the supernatant of the concentration acidification pool is discharged into the water treatment system as a carbon source; the supernatant of the digestion pool and the filtrate of the dewatering machine and the rinse water are collected for the chemical phosphorus removal.
Gaobeidian wastewater treatment plant secondary effluent quality and quantity of water is stable, to meet the design requirements, but can not meet the municipal miscellaneous water standards, and green water and road spraying and other municipal miscellaneous water quality on human health and the urban environment will have an impact on the municipal miscellaneous water must be reused before the depth of the treatment, in order to meet the appropriate standards. In the design of the depth treatment will be selected in the water source six plant. Water source plant six existing daily capacity of 170,000 m3 / d depth treatment facilities, mainly using mechanical acceleration of clarification, sand filtration and disinfection and other technological treatment processes, its effluent can meet the corresponding user requirements. Due to the adjustment of Beijing's industrial structure, the plant's average actual water supply is less than 50,000m3/d, and there is still 120,000m3/d of treatment capacity not being utilized. In addition, the water source six plant from the municipal miscellaneous water users closer to the municipal miscellaneous water depth treatment in the water source six plant to take advantage of its remaining capacity to meet the municipal miscellaneous water in the near and far future scale needs, the plant in the depth of the water quality can meet the municipal miscellaneous water quality requirements.
4.4 The main reuse object
According to the planning requirements, the project for the near future for the Beijing No. 1 Thermal Power Plant cooling circulating water 200,000 m3 / d, for the long term for the Beijing No. 1 Thermal Power Plant cooling circulating water 300,000 m3 / d. The near future through the Beijing City water source plant for the eastern suburbs of the industrial zone and coking plant 50,000 m3 / d, for the city's greening, road spraying and flushing, urban river landscape water and other municipal miscellaneous water***. Miscellaneous municipal water *** 50,000m3/d. In the long term, the amount of water supplied to industry and municipal miscellaneous water through the water source six plants will be expanded to 170,000m3/d.
4.5 Main project content and investment
The total investment of this project is 360 million yuan, of which land acquisition and relocation cost is about 100 million yuan, and the engineering cost is 218 million yuan, and the main contents of the project are as follows:
(1) (1) The Gaobeidian Wastewater Treatment Plant is located at the center of the city of Gaobeidian, which is located at the center of the city of Gaobeidian. ) A pumping station of 470,000m3/d in Gaobeidian sewage treatment plant.
(2) Gaobeidian sewage treatment plant renovation.
(3) Gaobeidian Sewage Treatment Plant to Gaobeidian Lake Water Transmission Pipeline: DN1800mm, 1,480m long.
(4) Gaobeidian Sewage Treatment Plant to Water Source Six Pipeline: DN1400mm, 4,766m long.
(5) Municipal Miscellaneous Water Distribution Pipeline: DN1200mm, 6,791m long;DN1000mm, 1,431m long;DN1000mm, 1,431m long. 1431m; DN800mm, length 4615m; DN600mm, length 2845m; D=500mm, length 2880m.
(6) water source of the six plant renovation: including the depth of the treatment facilities renovation, cistern desilting and masonry, sludge pond expansion, water supply pumping station renovation, inlet and outlet renovation, increase automatic control and electrical equipment.
(7) garden water supply branch pipeline.
4.6 Engineering Benefits
The project can save 166.73 million m3 of clean water resources per year, saving 36.5 million m3/a of tap water, which is equivalent to saving 400 million yuan of investment in the construction of a 100,000 m3/d tap water plant. The project achieves the purpose of open-source and cut down on expenses, creates conditions for the expansion of Beijing's urban greening area and road spraying and dust suppression, and has a greater effect on the comprehensive management of the environment, and the improvement of the environment will also bring about an increase in the value of the land in the surrounding areas. To a certain extent, the project has alleviated the contradiction of water shortage in Beijing. The huge economic and environmental benefits of the project have promoted water conservation and sewage reuse in Beijing. At present, Beijing has completed the sewage reclamation and reuse planning, and seven sewage reuse projects are under construction or doing preliminary work. Beijing's sewage reclamation and reuse practice shows that: sewage reclamation and reuse in line with environmental protection and sustainable use of water resources strategy, is an effective way to solve the sustainable use of water resources.
5 Conclusion
China is a country with poor water resources, with the accelerated progress of economic development and urbanization, the contradiction of water scarcity has become the sustainable use of water resources and management of China's water resources need to be resolved. The sustainable use of China's water resources is faced with the problem of insufficient total water resources, uneven distribution, low water utilization and water pollution, etc. The way out to realize the sustainable use of China's water resources lies in adhering to the strategy of sustainable development. According to the characteristics of China's water resources, water resources should be rationally utilized and allocated, and the traditional development mode of "supply according to demand" should be changed to the mode of sustainable utilization of water resources, which is based on the carrying capacity of water resources, and the economic structure should be strategically adjusted; at the same time, we should continue to develop water-saving technologies, reduce the waste of water resources in the production process, and vigorously develop sewage treatment and regeneration of water resources. At the same time, it should continue to develop water conservation technology, reduce the waste of water resources in the production process, vigorously develop sewage treatment and recycling reuse work, and improve the sewage treatment rate and treatment effect. Sewage recycling and reuse can reduce the total amount of pollutants and increase the water supply capacity, which is an economic and reliable open-source and flow-saving measure. Over the past few years, the practice of sewage reclamation and reuse shows that: sewage reclamation and reuse can effectively alleviate the shortage of urban water resources, is to realize the sustainable use of water resources is an effective way.