The Influence Of Submerged Plant On The Purification Of Nitrogen In River Water

Excessive input of nitrogen result in the eutrophication of rivers,oceans and lakes.It is harmful to aquatic animals and also do harm to the safety of drinking.In recent years,the ecological water purification technologies with submerged plant plays an important role in water purification and water environmental management.this paper based on monitoring the water quality of typical secondary river in Tianjin,the purification effect of water nitrogen by submerged plant was studied under the condition of laboratory,and the the data was used to matching the submerged plant water ecological dynamic model,the main conclusions are as follows:The long term observation data of river water indicate that,in the dry seasons,the water quality of Jizhuangzi river and Sihua river is relatively consistent,and both of them are priority with total dissolved nitrogen and total dissolved phosphorus(proportion dissolved nitrogen and dissolved phosphorus were 93.8-95.7%and 39.7-54.9%,74.13%-84.13%and 42.28%-84.13%);In the rainy seasons,it has large variations of water quality in both of two rivers(the proportion of grain nitrogen were 16.83%-85.81%,12.34%-72.10%).Water quality of the two rivers improved during the April 24 to October 23,total nitrogen,ammonia nitrogen,total phosphorus,CODcr,DO became ?,?,?,?,? and ?,?,?,?,? from bad ?,?,bad ?,?,bad ? and?,?,?,?,?,the TP of JiZhuangZi river increases maximum.An indoor simulation system was developed to investigate the removal of external nitrogen from the system Potamogeton crispus L.under the condition of constant inflow rate,compared with unplanted treatment,the removal efficiencies of total nitrogen,ammonia nitrogen and nitrate nitrogen in planted treatment was 7.2%,31.6%and 6.6%respectively,while plant group was 21.9%,56.6%and 28.2%and increased by 14.7%,25.0%and 21.6%,respectively,when the system was stable.Both plant uptake and plant-promoted biodenitrification were the main processes promoting denitrification in the system by P.crispus.During the experiment,the proportion of transferable nitrogen in planted treatment decreased in general,and the decrement was 1.9 times as much as that in unplanted treatment;It can be concluded that Potamogeton crispus L.could not only accelerate the removal of external nitrogen from the system,but also reduce the risk of internal nitrogen releasing from sediment.Established a submerged plant nitrogen migration channel model,and verified with laboratory simulation data.The result showed that the model can match the monitoring data for ammonia nitrogen and nitrate nitrogen,and the correlation coefficient between the model predicted and the measured values were 0.86 and 0.96;but for organic nitrogen,the correlation coefficients is only 0.69.Organic nitrogen,ammonia nitrogen and nitrate nitrogen are sensitive to water nitrification rate,net ammonia nitrogen mass transfer rate between water and sediment,the mortality of plant,the concentration of organic nitrogen inputs.In addition,organic nitrogen is sensitive to net nitrate nitrogen mass transfer rate between water and sediment.ammonia nitrogen is sensitive to organic nitrogen ammonification rate,ammonia nitrogen nitrification rate,net nitrate nitrogen mass transfer rate between water and sediment.