First, Beijing urgently needs to develop new water resources.
Beijing, the capital of China, is located at the northern end of North China Plain and belongs to semi-arid monsoon region. Limited natural water resources and extremely uneven distribution in time and space make Beijing a city with serious water shortage. In recent years, due to the growing scale of cities, population expansion, people's living standards have improved year by year, urban water consumption has increased day by day, and the contradiction between supply and demand has become more and more acute.
In order to alleviate the contradiction between supply and demand of water resources, relevant parties are actively seeking various ways to open up new water sources, such as water transfer in other river basins, increasing revenue and reducing expenditure, sewage reuse and other measures. However, it is difficult to divert water from other river basins to Beijing in the short term; Local open source is very limited and the cost is very high. The water-saving work is fruitful, and it is difficult to further tap the potential. However, urban sewage has the advantages of being unaffected by climate, not competing with neighboring areas for water, using local materials, being stable and reliable, and having high guarantee rate. Sewage reuse provides us with an economical and reliable new water source in a certain range of use, and can save high-quality drinking water sources.
Second, the domestic and international sewage reuse situation
At present, many countries facing serious water crisis in the world are actively using urban sewage as the second water source, and have achieved successful experience. 357 cities in the United States have realized sewage treatment and reuse; Since the 1960s, Japan has been vigorously researching and popularizing the technology of urban sewage reuse and reclaimed water, which has been widely supplied to factories, enterprises and residential areas for flushing toilets and miscellaneous use. 1986, South Africa built the world's first urban sewage "reclaimed water" plant as a supplementary source of urban tap water.
In addition, Denver, USA, has sent the treated reclaimed water into the tap water pipe network as supplementary pressure water for the urban pipe network. In addition, Israel, Russia, Britain and other Middle Eastern countries have also developed and utilized sewage reuse to make up for the increasingly scarce water resources.
Since 1980s, some demonstration projects of sewage reuse have been built in some water-deficient cities in China, which provides valuable experience for promoting the comprehensive utilization of urban sewage. At present, Dalian, Qingdao, Taiyuan and other water-deficient cities in China have built urban sewage reuse projects, which will treat urban sewage and reuse it for industry and municipal administration.
Experience at home and abroad shows that on the basis of secondary treatment, municipal domestic sewage can meet the water quality standard of "reclaimed water" whether it is treated by coagulation, sedimentation, filtration, ozone or inhibitory activated carbon. A series of specifications and requirements for sewage reuse issued at home and abroad provide us with reference.
Three. Feasibility of wastewater reuse in Beijing
1, technically feasible
Adequate sewage resources are the basis of urban reclaimed water reuse. It is predicted that the total amount of urban sewage will be 2,638,400 cubic meters per day in 2000 and 3,276,5438 cubic meters per day in 2065. At present, three secondary sewage treatment plants, Gaobeidian, Fangzhuang and Beixiaohe, have been built in Beijing, with a treatment capacity of 6.5438+0.08 million cubic meters per day, that is, 44% of Beijing's urban sewage has been treated, providing good conditions for Beijing's urban sewage reuse project.
At present, a series of specifications and requirements for wastewater reuse have been formulated at home and abroad, such as the Comprehensive Specification for Wastewater Reuse revised by the US National Environmental Protection Agency in 1992; The standard of agricultural microorganism content for wastewater reuse issued by the World Health Organization (WHO) is 65438-0989; On June 1989, China officially promulgated GJ Water Quality Standard for Domestic Miscellaneous Water 25.1-89; China Engineering Construction Standardization Association issued "Code for Design of Urban Sewage Reuse" in 1995, concerning the water quality standard of sewage reuse for industrial cooling water and landscape river water. 1987, Beijing promulgated the Trial Measures for the Construction and Management of Reclaimed Water Facilities in Beijing.
These specifications provide a reference for us to carry out sewage reuse projects. The effluent quality of Gaobeidian Sewage Treatment Plant is analyzed, and the effluent quality of Beijing No.6 Water Source Plant is regarded as the advanced treatment quality of secondary effluent, and compared with the requirements of industry, agriculture, municipal administration, river water supply and miscellaneous services, and the technical feasibility of sewage reuse in Beijing at present is analyzed. After comparative analysis, the treated urban sewage is suitable for the following aspects:
1) Industry: After further advanced treatment, the effluent from Gaobeidian Sewage Treatment Plant can meet the requirements of cooling water quality in general industries;
2) Agriculture: The secondary effluent quality of Gaobeidian Sewage Treatment Plant basically meets the requirements of agricultural irrigation water quality;
3) Water replenishment for rivers and lakes: According to the overall urban planning of Beijing, when replenishing water for "Lianhua River, Qinghe River, Liangshui River and other scenic rivers located in the upper reaches of the city", the sewage treatment level is advanced treatment; When replenishing water for "Qinghe River, Bahe River, Liangshui River, Tonghui River and other rivers located in the lower reaches of the city", the treatment level of the sewage treatment plant is secondary treatment;
4) Municipal miscellaneous use: After advanced treatment, urban sewage can meet the requirements of miscellaneous water use such as urban greening and cleaning;
5) Mixed use of reclaimed water and residential quarters: Reclaimed water projects have been widely used in Beijing since 1987 promulgated the Trial Measures for the Construction and Management of Reclaimed Water Facilities in Beijing. Judging from the normal operation of reclaimed water facilities at present, the water quality can basically meet the required reclaimed water standard.
2. Economically feasible
Through comparative analysis, the economic feasibility is mainly reflected in the following three aspects:
1) provide new water source: sewage reuse provides us with a very economical new water source, reducing the huge engineering investment brought by long-distance water transfer;
2) Reduce the investment of fresh water treatment facilities: Sewage reuse can reduce the consumption of fresh water while providing new water sources, thus reducing the investment of treatment facilities in urban water plants accordingly;
3) Reduce the cost of pollution control: With the requirements of social development and environmental protection, urban sewage must be treated before it can be discharged into water bodies, so sewage reuse can also reduce the discharge of sewage and reduce the cost of water pollution control.
Four, applicable to the consumption of recycled goods and water.
According to the feasibility analysis, combined with Beijing's specific situation, Beijing's urban sewage reuse targets are divided into five aspects: industry, agriculture, landscape river water supply, municipal miscellaneous use and reclaimed water in residential areas.
1. Industry: At present, Beijing is adjusting its industrial layout to form a relatively centralized and orderly layout. The main body of industry is concentrated in several old industrial zones that have been standardized and adjusted, planned urban fringe groups and several economic development zones and industrial communities outside suburban counties. In the near future, users with large water consumption should be given priority, and the long-term reuse targets include existing industrial areas and planned industrial marginal groups.
2. Agriculture: According to the influence of sewage irrigation on groundwater, urban sewage irrigation can only be carried out in suitable sewage irrigation areas and general sewage control irrigation areas. Combined with the planning of Beijing sewage treatment plant, the scope of urban sewage reuse for agriculture is concentrated in Chaoyang District and Fengtai District. The scope of long-term sewage reuse for agriculture can be extended to Tongzhou District and parts of Daxing.
3, landscape river water supply
Combined with the contents of sewage reuse in landscape rivers in Beijing Urban Master Plan, and considering the layout relationship between urban sewage plants and urban rivers, the urban area 12 rivers of Class IV and V are planned as sewage reuse targets.
4. Municipal miscellaneous purposes
According to the landscaping plan of Beijing urban area, the planning will focus on the green belt between the central area and the marginal group and the protective green belt at the outer edge of the urban area for sewage reuse.
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The planning takes marginal groups' residential areas and water-deficient areas as the targets of sewage reuse. The contents include water for flushing toilets in houses and miscellaneous water for greening in communities, road washing and car washing.
According to the research results, if implemented as planned. The recent available factory output is 295 million cubic meters/year, including industrial reclaimed water consumption of 65.438+006 million cubic meters/year, municipal reclaimed water consumption of 26.5438+000 million cubic meters/year, river and lake water supply of 65 million cubic meters/year, community facilities of 030,000 cubic meters/year, and agricultural irrigation water consumption of 65.438+000 million cubic meters/year, among which industrial reclaimed water consumption is 65.438+000 million cubic meters/year. Municipal reclaimed water consumption is 32 million cubic meters per year, water supply for rivers and lakes is 240 million cubic meters per year, residential facilities are 88 million cubic meters per year, and agricultural irrigation water consumption is 453 million cubic meters per year.
Verb (abbreviation of verb) has remarkable social and economic benefits.
In Beijing, where water resources are very scarce, sewage reuse provides us with a very economical new water source, reduces the social demand for fresh water resources and protects high-quality drinking water sources.
Through the reuse of sewage after treatment, the discharge of pollutants is reduced, thus reducing the impact on the water environment around the city; After treatment, sewage is used as supplementary water for urban landscape rivers, which improves the quality of urban water environment. Compared with the huge project investment of South-to-North Water Transfer Project, it has more economic and practical value and broad development prospects.
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