Effect Of Fine Sediment Flocculation On Phosphorus Transfer And Transformation

At present,the research on the migration and transformation of phosphorus mainly focuses on the effect of sediment interface on the migration and transformation of phosphorus in water.It is often neglected that in the case of disturbance,the fine-grained sediment in the suspended state will flocculate.It affects the phosphorus content in the aqueous phase and the solid phase and the process of morphological migration and transformation.In fact,the disturbance generated in the natural environment can flocculate the fine-grained sediment in the lateral or longitudinal direction,thus affecting the migration,transformation and distribution characteristics of phosphorus,thereby changing the distribution of phosphorus in the water body,resulting in eutrophication of the water body.In this paper,the indoor experimental simulation method is used to study the fine particle sediment and its phosphorus content in the flocculation phenomenon.The particle size of different sediment particles and different sediment concentration,water pH,speed and temperature are investigated.The effect of flocculation on the characteristics of sediment adsorption and desorption of phosphorus under the influence of environmental factors,the flocculation degree is quantitatively characterized by sediment flocculation process,and the effect of fine-grained sediment flocculation on phosphorus distribution and migration and transformation process is analyzed..The main findings are as follows:The adsorption and desorption test results of phosphorus floes from suspended sediments under different conditions can be realized that in the water-sand environment system,the sediment particle size is the same under the initial concentration of aqueous phosphorus.Factors such as concentration,water pH,rotation speed and temperature can significantly affect the process of adsorption and desorption of phosphorus by sediment flocs and sediment.Among them,the increase of sediment concentration will lead to the increase of phosphorus adsorption by fine-grained sediment and the increase of desorbed phosphorus;the acidic and alkaline waters are beneficial to the adsorption and desorption of phosphorus by sediment flocs;The adsorption/desorption amount of phosphorus in granular sediment increases with the increase of temperature;when the rotation speed is 120r/min~150r/min,fine particle sediment can form a relatively stable flocculation process.If the rotation speed is too large,it will produce The shearingforce of the water flow will destroy the sediment flocculation group,resulting in a decrease in the flocculation degree,thereby affecting the desorption/adsorption amount of phosphorus by the sediment.The equilibrium adsorption kinetics test of phosphorus floes formed from suspended sediments shows that at the same temperature,the equilibrium adsorption of phosphorus to the initial concentration of phosphorus in the same particle size group increases with the initial concentration of aqueous phosphorus.The increase and the amount of sediment per unit mass increase with the initial concentration of phosphorus in the same aqueous phase.Under the different temperature conditions,the equilibrium adsorption amount of sediment to phosphorus increased with the increase of temperature.The results of the isothermal equilibrium adsorption test data using Langmuir and Freundlich isotherms show that the Langmuir and Freundlich isotherms can be used to fit the adsorption kinetics of fine-grained sediment to phosphorus,but Langmuir isotherm fitting Better results.In the process of adsorption and desorption of phosphorus from sediment flocs formed by suspended sediment,the research focused on the change of phosphorus content and its distribution characteristics and flocculation degree in sediment.The experiment basically follows: the higher the flocculation degree,the phosphorus The larger the amount of migration and transformation,the pH value and temperature of the water are the migration and transformation of the phosphorus form in the fine-grained sediment mainly affecting the environmental factors;Fe/Al-P(iron-aluminum-phosphorus)And Ca-P(calcium phosphate)is the main component of phosphorus in fine-grained sediment,followed by OP(organo phosphorus).The dominant phosphorus forms in the process of phosphorus migration and transformation are Fe/Al-P morphology and Ca-P morphology.