Laboratory Test On The Effect Of The Suspended Particle On The Seepage Migration Of Heavy Metal Ions

The effect of suspended particles on the seepage migration of heavy metal ions in porous media has important significance in sewage treatment,artificial recharge of ground water,heavy metal pollutant treatment,exploration of groundwater,chemical industry and landfill disposal.Through laboratory experiments in this research,many factors such as seepage velocity,concentration and the size of suspended particles are discussed and the affecting mechanism of suspended particles on the migration of heavy metal ions are studied.The main contents are as follows:(1)Experiments were conducted to investigate the effects of particle size,particle concentration,hydrodynamic force on the transport and deposition of single particle under neutral(pH=7)and acidic(pH=5.5)conditions in saturated porous media.Three different sizes and four different concentrations experimental series were performed,including three different seepage velocities experiment.The studies show that,the effect of seepage velocity and particle size on the the transport and deposition of single particle are the same under two conditions.The peak concentration of effluent increases with the increasing seepage velocity for the same particle size.The peak concentration of effluent is reduced with the increasing particle size for the same seepage velocity.In the course of the change of seepage velocity,the migration of particles is the result of two factors:particle size and hydrodynamic force.But the effect of particle concentration on the the transport and deposition of single particle are different under two conditions.In the case of small particle size,the peak relative concentration of effluent increases with the increasing injection concentration,but the increase in acidity is slowed down.For large particle size,there exists a critical injection concentration for particles under neutral conditions.Under acidic conditions,the relative concentration of the effluent decreases with the increase of the injection concentration,and there is no critical injection concentration.In addition,the presence of H+ in acidic conditions inhibits the seepage migration of particles,which shows a decrease in the relative concentration of the effluent.With the increase of particle size,the inhibition effect is more obvious.(2)Experiments were conducted to investigate the effects of concentration,hydrodynamic force on the migration of single heavy metal ions.Three different seepage velocities and five different concentration experimental series were performed.The results show,the charge of seepage velocity does not affect the relative concentration of lead ions in the effluent under the same concentration,and its corresponding pore volume is the same.For the same seepage velocity,the peak relative concentration of effluent increases with the increasing injection concentration and the increase is not affected by the seepage velocity.In addition,the injection solution contains a small amount of sodium ions,which does not affect the seepage migration process of lead ions.(3)To study the effecting mechanism of suspend particles on the migration of heavy metal lead ions,The coupling migration experiments of suspended particles and heavy metal lead ions were carried out under three different seepage velocities and three different particle sizes.The studies show that,the suspended particles promote the migration of heavy meal lead ions.When the particle size of suspended particles increases,the promoting effect is more obvious,and when the particles size increases to a certain extent,the promoting effect is weakend.Compared with the heavy metal lead ions,the pore volume corresponding to the peak concentration of the particles is relatively small,and the migration of the particles is accelerated.Besides,the presence of heavy metal lead ions inhibits the migration of particles.When the particle size increases,the inhibitory effect is more obvious,and when the particle size increases to a certain extent,the inhibitory effect is weakened.The promoting effect of suspended particles on lead ions and the inhibitory effect of lead ions on suspended particles are corresponding to each other.In summary,the coupling migration process of suspended particles and heavy metal lead ions is interrelated and interacting with each other.