Trend Of Environment Nitrogen Load And Source Of Nitrogen In Urban Sewage

With the global development of urbanization a large numbers of people are gather in city. The material and the energy of urban ecosystem require 10 to 100 times that of other ecosystems, while urban residents dependence on nitrogen that is increaseing,affecting the global nitrogen cycle. Activated of nitrogen increase in the total amount of nitrogen on the air, water and land. Environmental issues arising have been threated to human health and life safety, more and more people think it is the third largest global environmental issues after global warming and loss of biodiversity. Urban ecosystem metabolism heavily dependent on most material and energy. Urban ecosystem nitrogen input makes the city become the world’s hot spots of nitrogen.Sewage is the product of the city of human activity, the output sewage of nitrogen accounts for a large proportion. The wastewater treatment system is removing system in urban ecosystem and is an artificial control technology. It helps to reduce the pollution in water cycle conducted. Besides, it is a key to prevent the water from pollutanted.But the process of construction and operation of sewage treatment plants will consume large amounts of physical product and energy at the same time, like the exhausted gas into the environment, the treated water and sludge.N₂ O emissions will lead to global warming or human-induced respiratory diseases. Even though the treated water to reach the control standards of emissions, high work load making some incomplete residual chemical composition in treated sewage. It may still exceed the self-purification capacity of receiving water bodies and increased water environmental load. The remaining nitrogen in sludge disposed in landfills which is absence of anti-seepage project conditions may induce secondary pollution.Increasing the nitrogen content of the treated water、rivers and groundwater will lead to greatly increasing the risk of nitrogen contanmination.These output products to some extent undermined the environmental benefits of water treatment. How to find the exact source of sewage nitrogen, then the reasonable control will be the key to solving the surface water environmental threats.Beijing is the political and cultural center in recent years, rapid economic development, good living conditions of urban residents, the new residential buildings is increasing rapidly. Rapid population growth brought the rapid increase in domestic wastewater emissions and sewage treatment plants often in overloaded.Selected study area in Haidian District which are Beijing important scientific and cultural center, many colleges and universities gathered area, showing a rapid growth in recent years. We selects representative of the modern Haidian District sewage treatment plant as sewage output and input of research points.Fixed-point dynamic sampling and analysis methods, focusing on preliminary exploration nitrogen from the sewage output mechanism. And the use of stable isotope methods to explore the potential source of urban sewage, in order to provide a reference for other nitrogen output of urban sewage. The main conclusions are as follows:（1） 2014--2015 in Beijing Haidian District, nitrogen concentration of untreated urban sewage and treated urban sewage having a more significant seasonal variation, the higher the concentration of untreated sewage TN, which ranged from 34.975 59.987 mg.L-1 spring and summer were significantly higher than in autumn and winter. NH₄ ⁺-N is a major presence in the untreated of sewage. The nitrogen concentration fluctuated within a year showing the highest values appear in the autumn. NO₃--N as the main of treated urban nitrogen pollution, TN concentration peak in winter.（2） Municipal wastewater but also has a significant date change characteristics and features which present differences seasons character. Overall, TN in two period of 11: 00-13: 00 and ¹⁸: 00-21: 00 is higher, indicating that the daily patterns of life residents have a certain impact on urban sewage nitrogen output.（3） For the urban sewage nitrogen environment load, treated sewage produced most nitrogen environment load while the surrounding water environment was greatly affected. In Haidian the per capita environmental impact of sewage nitrogen presented high values in autumn and winter and low values in spring and summer.（4） The environmental impact of urban sewage nitrogen emission rates with significant seasonal variation was higher in winter. It is indicated that most costs in removing nitrogen contaminate for this season. At the same time, more advanced sewage treatment process helped to reduce the environmental influence of nitrogen. Winter is the key time for prevention the nitrogen from pollutanted.It should be popularize the update technology.（5） The stable nitrogen isotope tracer method shows that the urban sewage δ¹⁵N and δ¹⁸O values have significant seasonal differences. δ¹⁵N values was highest in autumn and winter, followed by spring and summer minimum. Municipal sewage in autumn was mainly from manure and produced by human activities. While in spring and winter its source not only come from the manure but also rainfall runoff and industrial wastewater. The δ¹⁸O values present the seasons differences. It has widest range of sources which may nitrification and nitrate deposition while the source in other season were nitrification which is mainly the biosynthesis of nitrogen fertilizer and manure.（6）Based on Iso-source software to calculate the contribution of urban sewage showing that fecal contribution ratio up to 61.46%, followed by rainfall was 35.54%, industrial wastewater contribution ratio was 0.033%. This area of the urban sewage nitrogen mainly affected by human activities, such as residents’ daily lifestyle.（7） According to urban sewage nitrogen loads in Haidian, the city proposed control measures and proposals from the guiding role of macro-government regulations and policies to reduce the pollution in nitrogen and to improve urban sewage treatment technology. The city water recycling should we work together governments, companies, residents and promote a healthy lifestyle with low nitrogen.