North Canal Water Main Carbon Source Pollution Simulation Study To Determine The Impact Of Its Denitrification Simultaneous Nitrification

This article took the Beiyun River in Beijing river basin (from Shahe Reservoir to Yangwa Dam) as the study area, monitored the water quality of Beiyun River, recognised the basic types of pollution, and analyzed the principal basic index of pollution. Then the spatial and temporal distribution characteristics of the Beiyun River COD component were analyzed, so was three-dimensional fluorescence spectra of DOM in water. Finally, according to the concentration of COD components Ss and Xs and the type of DOM, carbon sources of different concentrations and different types were added to indoor experiment of simultaneous nitrification and denitrification process. The main conclusion is as follows:(1) According to the "surface water environment quality standard", all of the annual average index exceeded the standard of grade V, only DO met the standard of grade IV. Compared with the index in recent years (2009-2011), situation of water pollution in the Beiyun River was more serious in2013, and pollution types were more diverse too.(2) From the point of time, the Beiyun River COD components had different trends, and each three periods might be influenced by the content change of each period of microbial activity, flow rate and temperature effects. From the point of space, the biodegradability of Beiyun River water was generally not good, the distribution of types and concentration distribution of COD components along the river were not uniform, showing a significant point source pollution emissions; the Beiyun River had multiple cutoff, and there was no contact between each section, hydrological characteristics and the discharge amount of pollution source of each section could also influence the component percentage of each sample.(3) Two main types of characteristic DOM fluorescence peak were found in Beiyun River water:tryptophan fluorescence peaks and visible humic fluorescence peak. Compared with other city river, Beiyun River had fewer types of fluorescence peak. At the point of Fluorescence intensity, visible humic fluorescence peaks was stronger in most samples along the river, and there was no obvious variation trend. TN and Ss in the water had significant correlation with fluorescence intensity and the total fluorescence peak. The source of Beiyun River DOM was mainly water biological or microorganisms and their interaction products, supplemented by terrigenous DOM. (4) Enough organic carbon source is a necessary condition for nitrification denitrification. The removal rate of total nitrogen increased with the increasing of COD/N, when the adding carbon source was ethanol, nitrogen removal efficiency was better when COD/N was10; in the same range of time, adding starch as carbon source, nitrogen removal efficiency was better when COD/N was16. Investment and nitrification efficiency was both high when the carbon source was easy biodegradation and DOM carbon source, while the speed of nitrification of DOM carbon source was faster, so it had more promoting effect on nitrification. The efficiency of easy biodegradation carbon source of TN removal was the best. It can be suspected that the DOM carbon sources play a certain role in the water the process of nitrogen fixation, leading to elevation of TN.