Transformation of nitrogen nutrients in the urban sewage pipe network

The paper focuses on the changes of nitrogen compounds in the Pipe network. A 1.2km long urban sewage simulation network with artificial water distribution was selected as the research subject. Then we analyzed and evaluated the change characteristics of nitrogen nutrients along the pipe. The results proved that ammonium chloride as the nitrogen source matrix, which was necessary for microorganisms in the Pipe to survive and proliferate. Free amino acids, combined amino acids and nucleic acid produced by metabolism were the major nitrogenous organic compounds. Among which, amino acids accounted for dissolved organic nitrogen (DON) in the majority. The characterization results of three-dimensional fluorescence spectroscopy and size exclusion chromatography showed that the characteristic fluorescence peak of organic matter in waste water was increased, and the protein (tyrosine, tryptophan)-based fluorescence intensity gradually increased along the pipe. It was also found that small molecules of nutrients in the water were converted to complex organic molecules under the assimilation of microorganisms.