Study On The Nitrogen And Phosphorus Deposition Regulation In Sediment And Protecting Strategy Of Water Quality In Recycle Wastewater Landscape River In Tianjin Economical And Technology Development Area (TEDA)

This paper was one part of subsidiary topic of "water environment quality improvement and integrate exemplify in Tianjin economical and technology development area(TEDA)". The paper focused on the study for the mechanism of nitrogen and phosphorus removing and transformation which effected by many physical and chemical factors and the interaction of solution and sediment by experiment, then further revealed nitrogen and phosphorus deposition regulation in saline-alkali soil in recycle wastewater landscape river in TEDA. Based on the research achievements, the paper proposed the water quality protection strategy which were feasible and effective was brought up in this paper. The method and result would further enrich and supplement contents in thefield of nutrition deposition-release, thus provide theory and project experience for landscape river construction and eutrophication prevention in other similar city. Though dynamic monitoring river water quality about six months and sediment chemical composition, the conclusion was obtained as following: firstly, the total dissoluble nitrogen content in water ranged between 12.77 and 36.64mg/l, in which the nitrate quantity nearly accounted for fifty percent, but ammonium content was much low; The dissoluble phosphorous content mainly made up of phosphate in water ranged between 1.22 and 4.87mg/l. And the percentage of phosphate was 98%. The salt quantity in water fluctuated between 3560 and 11546mg/l, thus the range was much wide. Secondly, ammonium quantity among the dissoluble nitrogen in sediment accounted for eighty-nine percent. But nitrate quantity was much low in sediment. In sediment, phosphorous mainly comprised phosphate which about accounted for eighty-six. The sediment which was slightly acid was mainly made up of sodium compound. Based on the analysis of the factors which effected the phosphorous and nitrogen removing and transformation, a series of static and compared experiments in which the gravity rate of the water and sediment was 1/4 were adopted to study the phosphorous and nitrogen disposition regulation. The result showed that the quantity of the nitrogen and phosphorus deposition and removal was related to the original content of nitrogen and phosphorus in water ,the diameter of the sediment particle ,the conductivity of water,temperature and pH of water, and the conclusion indicated individually as following: (1)the quantity of the phosphorous deposition was related linearly to the original content of phosphorus. And the equation between them was y=3.5373x+0.8654,so their relations were noticeable(R2=0.9976). But the rate of the deposition was decreased with a rise of original phosphorous content;Although C / Q= 1/(Qmax KL )+C/Qmax transformed from Langmuir adsorption equation didn't fit phosphorus adsorption in the sediment, 1 /Q = (1/KL Qmax )(1/C)+1/Qmax another equation transformed from Langmuir adsorption equation and log Q = nlogC+logKF transformed from Freundlich adsorption equation fit phosphorus adsorption in the sediment. Simulated result manifested that adsorption isotherms curves were fitted to Langmuir equation as well as Freundlich equation,moreover, the relations of both of adsorption isotherms curves were noticeable. The maximum of adsorptive capacity of sediment was 52.910mg/kg. But the nitrate content in water showed a variation of increasing at earlier stage and decreasing at later stage in experimental course nitrogen in water were taken down in different series experiment of original nitrogen content; The ammonia content was released from sediment when the original content of ammonia was ranged from 2.841mg/l to 4.04mg/l because the ammonia content in water was increased. Reversely, the equilibrium content of ammonia in water was decreased when the original content of ammonia was ranged from 7.932mg/l to11.33mg/l.(2)the deposition quantity and velocity of phosphorus in sediment were rised as well as the quantity of ammonia in water was decreased when the diameter of the sediment particle was decreased in different series sediment particle experiments; On the whole the disposition quantity was more at the first 24 hours than the other time. And the phosphorus disposition nearly came to equilibrium after 24 hours. The quantity of the phosphorous deposition was related logarithmically to the diameter of the sediment particle. The following was the equation between them y=0.9361Ln(x)+7.3034, and the related coefficient R2=0.8705.Though the total dissolved nitrogen and nitrate contents in every series sediment particle experiment decreased, the quantity variation of total dissolved nitrogen and nitrate wasn't related to the diameter of the sediment particle(.3)higher was the water conductivity, the more was the deposition quantity of phosphorus. The relationship between the deposition quantity and the water conductivity was y=0.0173x2-0.1282x+10.098(R2=0.8587); Moreover, the total dissolved nitrogen content was decreased in different series water conductivity experiments. And the total dissolved nitrogen content in water raised with the increasing of the water conductivity by contrast. Furthermore the ammonia was released from the sediment, and the released quantity of ammonia raised with a rise in water conductivity;The nitrate content was decreased in different series water conductivity experiments, which had...