The Water Chemical Characteristics Of Groundwater And The Simulation Of Nitrogen Migration In The Irrigation Area Of Reclaimed Water

With the rapid development of the city and the improvement of the treatment technology of urban sewage treatment,the scale of recycling of urban sewage in our country has been gradually increased.It is important to understand the process of hydrogeochemical during the underground storage of reclaimed water.Through the model,we can define the hydrogeochemical change process,and get the important parameters,provide threshold for injection water quality,better ensure the safety of reclaimed water during the underground storage.Base on"the projects of the quality regulation and control for the reclaimed water underground storage",this research choose a typical section,research thechange ofthe related components concentration and the"three nitrogen"transformation mechanism,and then establish a multicomponent reactions migration model,simulation the process of the"three nitrogen"migration transformation during the underground storage of reclaimed water,get key parameters,predict the trend of evolution,and combining thebackground valueof the research area groundwater,put forward thethreshold concentrationof nitrogen in the process of the reclaimed water safety storage.Through data analysis and simulation,we can draw the following conclusion:（1）Reclaimed water injection make 30 meters aquifer water chemical type changed,30 m aquifer water chemical types is HCO₃-Ca-Mg before injection,and after inject reclaimed water,the aquifer water chemical types is Cl-HCO₃-Ca-Mg.（2）Simulation result shows,along the horizontal flow,the concentration of total nitrogen and ammonia nitrogen in the groundwater changes is go up and then reduce,and nitrate and nitrite nitrogen concentration is stay low.Along the vertical flow changes are basically the same with the horizontal flow.（3）Simulation results of multi-component response migration model are shownisthat the effects of ammonia adsorption and denitrification occurred in the research area.The adsorption of ammonia nitrogen reduces the concentration of ammonia nitrogen in the prophase,and the denitrification effect causes the nitrate nitrogen to be consumed and the concentration of the nitrogen remains low.The denitrification rate constant is between 0.05-0.08（1/day）.