Transformation Characteristics Of Different Forms Of Nitrogen Nutrients In The Process Of Wastewater Treatment

Along with our country water environment quality worsen, the total nitrogen wastewater plant effluent discharge standard increasingly strict, so researchers for the sewage treatment process and system operating parameters has been a lot of research and improvement and optimization, but less research on the occurrence form of nitrogen nutrient in sewage. The aim of this study was to investigate the transformation process of different forms of nitrogen nutrients by filed measurement and stable nitrogen isotope technology in the whole city sewage treatment(A/A/O) system.The results showed that influent dissolved nitrogen and particulate nitrogen proportion were almost the same, Concentration of 39.28±0.67mg/L and 41.24±1.07mg/L, respectively. Dissolved nitrogen was mainly composed of dissolved inorganic nitrogen, which portion constituted 93.2%, but dissolved organic nitrogen concentration was very low. The particulate organic nitrogen portion constituted 96.58% of the particulate nitrogen. Dissolved nitrogen Changes was very small in the primary treatment process. Nitrogen nutrient tending towards is analyzed by stable nitrogen isotope and the results showed that slight nitrification occurred, but particulate organic nitrogen reduced by 45% in the primary treatment process, which mainly due to physical deposition.In secondary treatment, nitrogen nutrients were mainly composed of inorganic nitrogen, but more than 70% were particulate organic nitrogen in the activated sludge, at the same time the surface of the activated sludge adsorption amounts of soluble organic nitrogen. Stable nitrogen isotope technology and nitrogen balance model showed that in the anaerobic and anoxic compartments, reflux liquid dilution effect was the main reason of ammonia nitrogen decreased, at the same time because of the ammoniation would generate new ammonia nitrogen, Concentration of 1.85 mg/L and 2.26 mg/L, respectively. Most of the nitrate nitrogen in raw water and recirculation water was converted into nitrogen by denitrification in the anaerobic and anoxic compartments. DON from raw water and recirculation water was converted into ammonia nitrogen in the anaerobic and anoxic compartments, and ammoniation mainly in the anoxic compartments. Because microbial metabolism and particulate organic nitrogen hydrolysis produced new DON lead to DON increased in the the aerobic compartments. Ammonia could be transformed into nitrate nitrogen by nitrification in the anoxic compartments. Particulate organic nitrogen converted into DON by microbial hydrolysis in the entire biological pool.Secondary effluent nitrogen mainly composed of inorganic nitrogen, but dissolved organic nitrogen concentration was very low, only 1.94mg/L(about 15%), More than 90% of them were aerobic pool of organic nitrogen. With Water total nitrogen emission standards more stringent, DON will be a key factor in reducing total nitrogen effluent limitations.