The Migration And Transformation Of Nitrogen Of Sludge Discharged Into The River

Excess nitrogen is common problems in black smelly river. Contribution to the nitrogen pollution of water body is not only the polluted water, but also the drain-pipeline sediment and farm waste solid contaminants which discharged with sewage effluent or rainstorm runoff. Part of solid pollutants sink into the bottom of the river become a part of sediment, and the other part mixed with water fully, and have a series of physical and chemical and biological reaction with the river flow. High concentration of ammonia nitrogen in the sediment interstitial water can released into the overlying water directly, and a large number of organic nitrogen of the sediment can also be decomposed into ammonia nitrogen into the overlying water under a certain conditions, result in higher concentration of ammonia nitrogen in the overlying water, so the solid pollutants from the shore is an important factor to cause excess nitrogen of the water. Based on the drainage pipe sediment from the coast of Ding shan river as the research object, using the commonly research methods of the sediment nitrogen releasing characteristics-laboratory simulation methods, survey the impact of the temperature, p H, soil and water ratio, agitation conditions on the drainage pipe sediment nitrogen release characteristics and changes of endogenous nitrogen, explore the transformation regular between different nitrogen species, expanding the knowledge of nitrogen release process of drainage pipe sediment, in order to provide based data to the prevention and control of the risk of drain-pipeline sediment nitrogen pollution. The results show that:The effects of soil and water ratio, p H, temperature and rotation on the nitrogen transformation of sediment in drainage pipeline were investigated in this study. The experimental results for the four impact factors indicated that ammonia nitrogen was main existing form for nitrogen release from the sediment to the overlying water, the concentration of ammonia nitrogen was uptrend, get the maximum in the four to six days, and it went down till to the end of experiments. While the variation tend of nitrate nitrogen concentration was opposite to that of ammonia nitrogen. The factor of p H influenced most in the release of ammonia nitrogen among the four factors, then the disturbance, and the temperature has a minimal impact. The release of ammonia nitrogen followed the descending order of p H 6.3>p H 8.0>p H 9.6, and the maximum concentration was 54.0, 30.9 and 26.7 mg·L-1 respectively. The higher soil and water ratio and the longer agitation time under the same agitation speed, the higher ammonia nitrogen concentration can be obtained. An increase in temperature promote the conversion of ammonia nitrogen to the nitrate nitrogen, and speed up the decrease of total nitrogen in the overlying water.The process of cultivating drainage pipeline sediment under different environmental factors, determinate the concentration of total nitrogen in overlying water and sediment interstitial water as well as the sediment at the same time, the experimental results show that the integral change trend of total nitrogen in overlying water and sediment pore water between different environmental factors were the same, the total nitrogen in the overlying water was rise firstly then went down till to the end of experiments, while the total nitrogen in the pore water drop dramatically and a small rise or to be stable at the end of experiment, the total nitrogen concentration in overlying water and pore water approaching, there are a certain difference of the close degree and the level of stability under different environment conditions. While the total nitrogen in the sediment in the experiment have a change trend of descent-rise- descent again, the change range of total nitrogen in the sediment is different under different environmental conditions.