A development and construction project in Wenshan Prefecture, the building covers an area of about 22,000 m2, the total construction area of the project is about 120,000 m2, and the project's greening and roads each cover about 12,000 m2. There is no centralized municipal wastewater treatment facility in the area where the project is located. According to "Surface Water Environmental Functional Zoning of Yunnan Province (Review)", the environmental category of the affected surface water near the project is Class III, and the Class III standard in "Surface Water Environmental Quality Standard" (GB3838-2002) is implemented.
2 The necessity of setting up water reuse system in the project
2.1 Requirements of local regulations According to Article 15 of the Regulations on Urban Building Management of Yunnan Province (2006 Amendment), "The following projects shall be newly constructed, reconstructed and expanded within the urban planning area: hotels, restaurants with a floor area of more than 20,000 m2, shopping malls, comprehensive service buildings, high-rise residential buildings, shopping centers, shopping malls, comprehensive service buildings, high-rise residential buildings, etc. The project is expected to be completed by the end of this year, Shopping malls, comprehensive service buildings, high-rise residential; building area of 30,000m2 or more of the institutions, scientific research units, colleges and universities and large-scale integrated cultural and sports facilities; building area of 50,000m2 or more of the residential area and centralized construction areas.
Recyclable water in more than 150m3 / d of the construction project; other projects should be supported by the construction of recycled water facilities: construction units should be supported by the construction of recycled water facilities at the same time, recycled water facilities should be designed at the same time as the main project, the same time as the construction, the same time the delivery of the use of the fund should be included in the main project's total investment budget estimates are not included in the same period of construction, the relevant departments shall not handle the relevant approval procedures of the construction project." According to its requirements, the example project is classified as a centralized construction area with a floor area of more than 50,000m2, which meets the relevant requirements in the "Regulations on the Management of Urban Buildings in Yunnan Province" (2006 Amendment), and it is necessary to propose the setup of water reuse system in the process of environmental impact assessment of the construction project.
2.2 Imperfect factors of sewage collection and treatment facilities in small towns There are more imperfect factors of sewage collection and treatment facilities in small towns. Small towns in the past, the residential population is small, the amount of domestic sewage produced is small, coupled with economic constraints, lack of environmental awareness, small towns in the planning and construction of centralized collection and treatment of domestic sewage facilities, domestic sewage is directly discharged into the surface water body after pre-treatment of septic tanks.
This not only has a certain impact on the surface water environment, but also in the dry season, due to the inability to get diluted in a timely manner, the sewage emits a foul odor on the atmospheric environment also has a certain impact. Later, with the development of the economy, environmental protection awareness and requirements of the improvement of some small towns centralized collection of domestic sewage and treatment facilities, but in the construction process, due to the lack of regional development planning considerations, the existence of urban development unforeseen, etc., the small town sewage collection and treatment facilities there are more drawbacks, such as small town sewage treatment plant capacity is small, can not accommodate the treatment of urban areas to deal with the new domestic sewage; small town sewage collection and treatment facilities there are more drawbacks, such as smaller capacity, can not accommodate the treatment of urban areas to deal with the new domestic Sewage; small town sewage collection trunk pipe diameter is small, can not meet the collection of new sewage in urban areas, resulting in small towns within the development and construction projects generated by the domestic sewage can not be centralized collection and further treatment.
Example project construction area is currently no centralized municipal sewage treatment facilities, and the project area of the affected surface water category for Class III water bodies, the project generated by the domestic sewage such as septic tanks only pre-treatment of discharges, can not meet the "Comprehensive Sewage Discharge Standards" (GB8978-1996) in the first level of the standard requirements. The project must construct sewage treatment facilities to treat domestic sewage. Coupled with the large green area and road area set up by the project and the fact that the water supply project of the market town in which the project is located is not yet perfect, it is necessary to propose the setting up of a water reuse system for the construction project in the process of environmental impact assessment of the construction project.
2.3 Total emission reduction of environmental protection requirements of small town construction projects during the operation period of the wastewater is mainly domestic sewage, wastewater in the total control indicators are COD and ammonia nitrogen. According to the National Environmental Protection "Twelfth Five-Year Plan", by 2015, the total amount of chemical oxygen demand should be reduced by 8% on the basis of 2010, and the total amount of ammonia nitrogen emission should be reduced by 10%. Urban pollution sources are one of the main factors affecting the total amount of chemical oxygen demand and ammonia nitrogen. In small towns where sewage collection and treatment facilities are imperfect but rapidly developed and built, it is a measure to achieve the total emission reduction and environmental protection requirement to establish a water reuse system in the project area, so that sewage can be collected, treated and reused in the vicinity.
2.4 The benefits of water reuse are analyzed using the building base of the example project as a parameter. Example project building area of about 120,000m2, the project's operating period of sewage generated by about 360m3 / d, the project to establish a treatment capacity of 360m3 / d of water reuse system. In consideration of the rainy season watering water reuse less water, the actual amount of available water according to 80% of the water, according to the construction budget, the unit construction area of the cost of construction and safety according to 1500 yuan / m2, the cost of building water reuse system according to the total cost of the 1.0% of the consideration, according to the relevant information, water reuse system maintenance according to the cost of 10% of the water reuse system, water reuse system operating costs (including depreciation and maintenance, labor, electricity, water reuse system, water reuse system, water reuse system) and maintenance, labor, electricity, pharmaceuticals, etc.) at 0.7 yuan / m3, calculated that the project to establish and maintain the total investment in water reuse system for (1500 × 12 × 1.0% × (1 + 10%)) = 1.98 million yuan. At present, the price of water in the project area is 2.0 yuan/m3, then the project can save (2.0-0.7)=1.3 yuan/m3 by using water, and the annual saving is (1.3×360×(1-20%)×365)=136,700 yuan, which is the direct benefit of the water reuse system. In addition, the establishment of the water reuse system can save the construction and operation costs of drainage facilities in the towns of the project area, and can save the construction and operation costs of long-distance water diversion and water purification projects in the towns of the project area. In short, the water reuse system as a systematic project, construction projects to establish water reuse system, the benefits are not only reflected in the project itself, but also reflected in the regional water supply and drainage facilities to establish and operate.
3 water reuse system set up constraints
3.1 management mechanism is not sound in China in the late 1970s only began to water reuse related research, although Beijing, Shanghai, and Dalian and other major cities in the water reuse facilities have been effective, but in general, the building of water reuse in our country is still in its infancy. Relevant national policies, regulations and technical specifications are not sound, has not formed a supporting industrial policy and regulatory system, the lack of local constraints on the laws and regulations, the lack of supervision and regulatory standards and requirements, which makes the EIA, small towns, building projects in the water reuse system set up only as an indispensable sewage prevention and control measures appeared in the text, but the practical applicability of the poorer.
3.2 Construction projects involving departments disconnected from each other at present, most of the preliminary design of the building development projects mentioned in the description of the water reuse system set up, but in the construction project specific water supply and drainage design, the design department only do the water supply and drainage network design, did not do the water reuse system part of the design. EIA units in the process of environmental impact assessment of construction projects, although according to the environmental requirements of sewage discharge standards, local regulations, etc., put forward the construction project to set up a water reuse system requirements, but due to the design department, the EIA department and the environmental protection engineering design departments, such as the disconnect, the water reuse system of the pipeline network of the construction project does not get a specific design of the drainage, in the process of the actual construction of the construction project in the water reuse system construction is not implemented. In the actual construction process, the construction of building projects in the water reuse system is not implemented.
3.3 technical force and operation management is not in place because of China's water reuse technology in the construction of the late start of the research, making this aspect has not yet formed a market mechanism, in the actual implementation of the process, because of the weak technical force, lack of experience in the design, there are often projects put into use can not run normally, the water quality does not meet the standards or operating costs and other issues. In addition, due to the operation and management is not in place, water reuse system operation process of sludge, odor and other secondary pollutants can not be properly treated and disposed of, so that some of the completed water reuse system is in a semi-paralyzed state, which brings a certain negative impact on the small town building water reuse system set up.
3.4 economic and other constraints in the water reuse system one-time investment is large. As roughly estimated, the initial investment in the water reuse system of the example project is about 1.98 million yuan, which is a large amount of environmental protection investment in the development and construction of small town building projects. Investors and builders are reluctant to consider part of their environmental investment in the total investment in the project, and the cost of water in the initial operation of the water reuse system is significantly higher than the price of tap water, which makes the economic factors become one of the constraints on the setup of the water reuse system in small town buildings.
In addition, the small town building development and construction process, due to regional terrain and geomorphological constraints and in order to reduce the project "three passes and one leveling" construction costs, the general construction project based on the topography of the layout, resulting in construction projects between the blocks of the terrain height difference is relatively high, which is reasonable for water reuse system set up is another constraint: if a centralized system is set up within the project area, the water reuse system can be used in the construction of the building. If the project scope to set up a centralized water reuse system, in the operation process due to the use of sewage pumps or water transfer pumps, etc. will increase the operating costs; if the construction of a number of water reuse system, not only the initial construction of a larger investment will increase the cost of sewage treatment unit, and difficult to unify the management of the operation period.
4 Recommendations
Small town building development and construction process, water reuse system set up a certain necessity, there are more factors constraining the setup and implementation of water reuse system, thus reducing the environmental impact assessment work put forward to set up water reuse system operability. In order to solve the above contradictions, the following suggestions are made:
(1) Improve the national and local policies, regulations and technical specifications, from top to bottom to form a supporting industrial policy and regulatory system.
(2) the rapid development of small towns should first improve the centralized sewage collection and treatment of municipal engineering, so that the development and construction projects can be generated during the operation of fecal waste water after septic tank pretreatment discharged to the municipal sewage treatment facilities for treatment to meet the relevant environmental requirements. The development and construction of building water reuse system can be high-quality miscellaneous drainage water (bathing, washing, etc.) as raw water, after treatment, to meet the development and construction projects themselves for toilet flushing, landscaping, road flushing and other water requirements, thereby reducing the water reuse system investment.
(3) environmental management departments, environmental design departments, engineering design departments and other departments should strengthen coordination, the formation of the system's market operation mechanism, so that the water reuse system source of raw water, collection, treatment and water supply engineering facilities constitute an organic integration.
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