Carbon, Nitrogen And Phosphorus Metabolism In Industrial Parks

Being hives of intensive industrial activities, industrial parks become the focus of water pollution control. Industrial metabolism, especially for phosphorus and nitrogen, can present insights for improving water use efficiency and reducing water pollution.Based on substance flow analysis (SFA), this paper established a hierarchical substance metabolism framework for industrial parks, and presented the flows of carbon, nitrogen and phosphorus in Yixing Economic Development Zone. The empirical results are as follows:1.In 2008, the input of carbon to Yixing Economic Development Zone was 2761.2 Kt, mainly in energy; the input of nitrogen was 1164.7 Kt, mainly from air; the input of phosphorus was 12.2 Kt, mainly in chemicals. The output of carbon was mainly in carbon oxides; the output of nitrogen and phosphorus were mainly in chemicals.2.Domestic sewage accounted for 14%, 34% and 35% in the carbon, nitrogen and phosphorus loads in water bodies, respectively. Also, domestic sewage had lower carbon, nitrogen, and phosphorus removal ratio (72%, 58%, 62%) than industrial wastewater (96%, 92%, 88%). And, a lot of domestic sewage went into water bodies after simple treatment. So, domestic sewage is important in water pollution control of Yixing Economic Development Zone.3.The main pollutants emission industries have more complete treatment system. Food processing, printing and dyeing and chemical industry were major water carbon-emission industries. However, the carbon removal ratios of these industries were 99.4%, 93.5%, and 92.6%, respectively. Nitrogen fertilizer production, printing and dyeing and food processing were major water nitrogen-emission industries, the nitrogen removal ratios of these industries were 93.4%, 85.5%, and 94.1%, respectively. Printing and dyeing, food processing and machinery (phosphating) were major water phosphorus-emission industries, the phosphorus removal ratios of these industries were 90.4%, 91.8%, and 81.5%, respectively.4.In Yixing economic development zone, phosphorus has the lowest removal ratio (74.5%), compared to carbon (94.1%) and nitrogen (84.5%) in wastewater, and also the treatment approach was not as efficient as carbon and nitrogen, but phosphorus is the exceeding contamination of the wastewater treatment plant's effluent, and the key element of eutrophication of water bodies. So, much attention should be payed on the phosphorus control.5.The pre-processing facilities of enterprises play an important role in the wastewater treatment system of Yixing Economic Development Zone. They removed 87% of the carbon, 74% of the nitrogen and 54% of the phosphorus in wastewater, and reduced the load for wastewater plants. But in Yixing Economic Development Zone, most enterprises still only have simple pre-processing facilities.