Comprehensive Evaluation on the Environmental Policies of Water Pollution in Taihu Lake with Wuxi City in China
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Comprehensive evaluation on the environmental policies of water pollution in Taihu Lake with Wuxi City in China Lu Chanjun Mizunoya Takeshi Higano Youshiro Helmut Yabar University of Tsukuba In recent years, the rapid economic growth has caused serious environmental problems in Taihu Lake in China. Among the several cities around Taihu Lake Basin, Wuxi City is the main city to bring pollution to Taihu Lake. The amount of pollutants from household source of Wuxi City inflowing into Taihu Lake accounted for more than 55% of the total amount of pollutants from household source into Taihu Lake in 2007. In this research, we plan to focus on the composition of pollutants in each district of Wuxi City, which includes household, industrial and non-point source. We will introduce some new and effective technologies or facilities based on the previous policies we have introduced, in order to reduce the water pollution from Wuxi City into Taihu Lake. Then we plan to construct an evaluation model and make a simulation. We will use Lingo programming to calculate the simulation result. We would like to find the most optimal policy which could reduce water pollution in Taihu Lake but also meet the sustainable development in Wuxi City, China. Comprehensive evaluation on the environmental policies of water pollution in Taihu Lake with Wuxi City in China Lu Chanjun Mizunoya Takeshi Higano Youshiro Helmut Yabar University of Tsukuba 1. Background Taihu Lake, located in the east of China, which belongs to Jiangsu and Zhejiang province, is the third largest freshwater lake in the Yangtze Delta in China. The surface area of Taihu Lake is 2,338km2, the average depth is 2m, maximum depth is 2.66m and the mean water level is 3.11m. Taihu Lake basin is one of the most developed and densely populated places in China, it accounts for 11% of country’s GDP. In recent years, with the rapid development of economy and population growth, the water resource utilization in Taihu Lake Basin has been increasing. At the same time, a large number of sewage wastewater, industrial wastewater and farmland using water flow into Taihu Lake, which has caused serious environmental issues in Taihu Lake, especially eutrophication. This strongly affected people's life around Taihu Lake basin. While the government has taken a lot of measures to control pollution, there has been only a little progress. Wuxi City is known as "the pearl of Taihu Lake", which is located in Yangtze delta plain, south of Jiangsu Province. Yangtze river is to its north; Taihu Lake is to its south; Suzhou to the east and Changzhou to the west. Wuxi City is 128 kilometers away from Shanghai and 183 kilometers away from Nanjing. There are Seven Districts and Two Country-level Cities in Wuxi City. Chong’an District, Nanchang District, Beitang District, Xishan District, Huishan District, New District, Binhu District and Jiangyin City, and Yixing City (Figure.1). In 2012, GRP of Wuxi City reached is 756.82 billion yuan. Wuxi City is mainly based on the secondary industry and tertiary industry. There are five traditional industries in Wuxi City, including machinery, textile, chemical, electronic and metal. 2. Research objective This research aims to analyze the composition of pollutants from each district of Wuxi City inflow into Taihu Lake. Also to construct an evaluation model and analyze the computer simulation result in order to find the optimal and effective policy so as to reduce the pollutant discharge while maximizing socio-economic development. Figure.1 Location of Wuxi City (Source: CRIENGLISH, http://english.cri.cn/) 3. Method Firstly, build a framework of water pollution from Wuxi City inflow into Taihu Lake. Then find the sewage treatment scale and types in total nine districts of Wuxi City. Except for the policies proposed in previous study, some new and advanced technology will be introduced, which can help to reduce the pollutants into Taihu Lake, and finally simulation will be made to analyze the optimal policy to reduce pollution emission and maximize GRP growth in Wuxi City. 4. Current Results 4.1 The amount of pollutants by source from Wuxi City into Taihu Lake There are mainly 13 rivers from Wuxi City inflowing into Taihu Lake, including Wangyu River, Xiaoxi Port, Liangxi River, Zhihu Port, Baidu Port, Yincun Port, Shedu Port, Guandu Port, Hongxiang Port, Chendong Port, Dapu Port, Wuxi Port, Dagang River. The total amount of COD, T-N, T-P inflows into Taihu Lake was 127440.5t, 21542.16t, 1806.68t respectively in 2007. In Wuxi City, 20% of COD is from industrial source; 66% of COD is from household source and 14% of COD is from agricultural and non-point source; 12% of T-N is from industrial source; 66%t of T-N is from household source and 22% of T-N is from agricultural and non-point source; 11% of T-P is from industrial source; 67% of T-P is from household source and 22% of T-P is from agricultural and non-point source. The pollution is mainly from household source (Figure.2, Figure.3, Figure.4). Figure.2 The amount of COD by source into Taihu Lake Figure.3 The amount of T-N by source into Taihu Lake Figure.4 The amount of T-P by source into Taihu Lake 4.2 Utilization of sewage treatment plants According to the research, there were totally 70 sewage treatment plants in seven districts and two country-level cities of Wuxi City in 2012. The largest three sewage treatment plants are located in Chong’an District, Nanchang District, and Beitang District, the city center. According to the research, there are totally 17 kinds of techniques which are used in the waste water treatment, including activated sludge, A/O, A2/O, improved A2/O, reversed A2/O, SBR, MSBR, CASS, CAST, MBR, A2O+MBR, Orbal Oxidation Ditch, BAF, A2/O+BAF, BFBR, Physical Chemistry and Physics Chemistry+Physics Biology. Among these techniques, the most widely used is A2/O. There are differences for the population who use sewer in different districts in Wuxi City. The sewage treatment rate was higher in seven districts of city center compared with two country-level cities, Jiangyin City and Yixing City, especially in Chong’an District, Nanchang District and Beitang District, these three districts are located in the center of the city, sewer tubes has been almost covered all of these three districts, waste water from household are directly discharged into sewage treatment plants. 4.3 Utilization of Land area Total land area in Wuxi City is 462,745.79ha. Accoding to the source from Land and Resource Bureau of Wuxi, the biggest land area is Yixing City. The second largest is Jiangyi City. The land use can be devided into five categories, paddy field, dry field, garde:forest;grass, construction land and other land. Among these, construction land occupied the biggest area in Wuxi City. According to the calculation, Yixing City and Jiangyin City discharges the largest amount of COD, T-P and T-N in all districts in Wuxi City. 4.4 Industrial sector There are totally 18 industries in Wuxi City, including Farming, Forestry, Animal Husbandry, Fishing, Service Trade of FFAF, Manufacture of Foods, Food processing, Manufacture of Textile,Textile Wearing Apparel, Processing of Timber, Manufacture of Funiture, Manufacture of Paper and Paper products, Printing, Manufacture of Culture, Entertainment products, Processing of Petroleum, Coking, Processing of Nuclear fuel, Manufacture of Raw Chemical Materials and Chemical products, Manufacture of medicines, Manufacture of Non-metallic products, Manufacture of Metal products, Manufacture of Electrical Machinery and equipment, Production and Supply of Electric Power, Gas, Water and Utilization of Waste Resources, and other manufacturing. 5. Future Work Construct an evaluation model and make a simulation and analyze the simulation result. Find the optimal policy to reduce pollution emission and maximize the economic growth in Wuxi City..