Study On Coupled Migration Characteristics Of Suspended Particles And Lead Ions When Changing The Seepage Velocity And Concentration

The influence of suspended particles on the migration characteristics of heavy metal ions has important research significance in the fields of metal mineral smelting,landfill,urban wastewater treatment and application of pesticides and fertilizers.Suspended particles,heavy metal lead ions and their coupling migration characteristics in saturated porous media was studied in this paper by indoor soil column penetration test under changing seepage velocity and injection concentration.The main research contents are as follows:(1)The migration characteristics of single silicon powder in saturated porous media were studied under the change of seepage velocity and injection concentration,and the penetration tests with three particle sizes were carried out under four kinds of seepage velocity changes and two kinds of silicon powder concentration changes,the results show that the concentration of the silicon powder in the effluent changes at the same time when the seepage velocity is changed.As the seepage velocity increases,the increase in concentration of silicon powder in the effluent decreases.When the seepage velocity is larger,the pore volume corresponding to the peak concentration of silicon powder in the effluent is smaller,the peak concentration difference of silicon powder between different particle sizes is larger,and the peak concentration difference of silicon powder between different concentrations is larger.What's more,when the silicon powder injection concentration is changed,the silicon powder concentration in the effluent lags behind.When the concentration of silicon powder is increased,the increase in concentration of the small particle size silicon powder decreases,and the increase in concentration of the large particle size silicon powder increases.When the concentration of silicon powder is reduced,the decrease in the concentration of silicon powder decreases.Moreover,the larger particle size of the silicon powder,the greater concentration in the effluent.The greater injection concentration,the greater effect of the seepage velocity on the migration of silicon powder.For silicon powders with different particle sizes,the corresponding pore volume is the same when the concentration of silicon powders changes and peak concentration is reached again.(2)The migration characteristics of single lead ions in saturated porous media were studied under changing seepage velocity and lead ion injection concentration,and the penetration tests were carried out under two kinds of seepage velocity changes and two kinds of lead ion injection concentration changes.The results show that seepage velocity does not affect the concentration of lead ions in the effluent and the pore volume corresponding to the peak concentration.When the concentration of injected lead ions increases,the concentration of lead ions in the effluent increases,and the pore volume corresponding to the peak concentration remains substantially unchanged.(3)The coupled migration characteristics of suspended particles and lead ions in saturated porous media were studied under changing seepage velocity and lead ion injection concentration.The penetration tests were carried out under two kinds of seepage velocity changes,two kinds of lead ion concentration changes,three kinds of silicon powder particle size and two kinds of silicon powder concentration,the results show that the presence of lead ions during coupling migration inhibits the migration of small particle size silicon powder,but accelerate the migration of silicon powder.When the concentration of silicon powder is large,as the concentration of lead ions increases,the decrease in concentration of silicon powder in the effluent decreases if the seepage velocity is small,and the decrease in concentration of silicon powder in the effluent increases if the seepage velocity is large.What's more,as the concentration of lead ions increases,the decrease in concentration of silicon powder in the effluent decreases when the concentration of silicon powder is large.On the contrary,the presence of silicon powder during the coupling migration process promotes the migration of low-concentration lead ions.The greater the percolation velocity,the more obvious the effect of promotion.However,the presence of silicon powder inhibits the migration of high-concentrations lead ions.The greater the seepage velocity,the less obvious the effect of inhibition.As the particle size of the silicon powder increases,the peak concentration of lead ions in the effluent decreases if the concentration of the silicon powder is small,and the peak concentration of lead ions in the effluent increases if the concentration of the silicon powder is large.The higher the concentration of silicon powder,the smaller the concentration of lead ions in the effluent and the smaller effect of speed and concentration changes when the particle size of the silicon powder is smaller,and the larger concentration of lead ions in the effluent and the larger effect of speed and concentration changes when larger particle size.Besides,the migration of lead ions lags behind that of silicon powder.