Study On Sediments Adsorbing And Releasing Phosphorus And Phosphorus Prediction

Based on the previous studies, it points out that it is very important to research the sediment adsorbing and releasing the pollutants. We choose the sediment in the Three-Gorge Reservoir area and the Yangtze River raw water for the studied object, and then analyze the total phosphorus adsorption capacity of the sediment under the conditions of different concentration or different initial concentration of water-phase phosphorus; And identify the capacity of the sediment releasing the total phosphorus under the conditions of the of different pH of water bodies, different electrical conductivity and different sediment particle size. Based on experimental analysis of the Three-Gorges reservoir,total phosphorus content was predicted.In this paper, the results of research are in the following areas:(1) Using filtered natural river water from Yangtze River as experiment water, some experiments are designed to study the adsorption kinetics of phosphorous. The results show that the amount of phosphorous is in dynamic equilibrium in water phase and sediment phase. They reach equilibrium in 10 hours. With the same initial concentration of phosphorous in water phase, the equilibrium time increases with the concentration of sediment. But it has not an obvious law under the condition of different initial concentration of phosphorous in water phase.(2) The isothermal adsorption of phosphorous by suspended sediment is studied by some isothermal adsorption experiments. Some conclusions are drawn: In water body with the same concentration of sediment, the amount of phosphorous adsorbed by suspended sediment increases with its initial concentration in water phase. But the value induces in reverse increment increases lightly when the initial concentration of phosphorous reaches up to a certain value. With the same condition of the initial phosphorous concentration, its adsorption amount decreases with the concentration of sediment. This phenomenon also appears in heavy metals adsorption experiments and is named by"sediment adsorption effect". The results also show that the adsorption content increase with the concentration of sediment. This property will contribute to the self-purification and environment capacity.(3) The data of isothermal adsorption experiments are analyzed by isothermal adsorption equations. The analyzed results indicate that the adsorption of phosphorous by suspended sediment is in agreement with Langmuir equation and Freundlich equation. Additionally, the concentration of sediment has insignificant effect on the parameters of isothermal adsorption equation. But the smaller is the sediment size, the more is the extreme adsorption amount of phosphorous.(4) Through the different total phosphorus releasing test under the conditions of different electrical conductivity, different pH, different size sediment of the, we know that while the conductivity is between 475μm/cm and 1949μm/cm, TP releasing rate declines as the conductivity rises, but do not drop. While the particle size is in the 20-200, with the particle size decreasing, sediment releasing phosphorus also decrease; while the pH of aqueous solution is in range 4.10-10.63, pH is low, TP is no change in emissions, pH releasing in 10.63 increased dramatically.(5) Through Analyze the Three-Gorge Reservoir's unique terrain, hydrological characteristics, as well as the migration and transformation law of the controlling eutrophication nutrients - phosphorus, total phosphorus concentration of the Three Gorges reservoir can be predicted. And it is in order to provide a scientific basis for governance to the Three-Gorge water environment.