Research On The Laws Of Groundwater Pollution In A Coking Plant InTangshan

Coking wastewater has the characteristics of large discharge amount,complex composition,difficult to degrade and so on,is a kind of high concentration wastewater with toxic and harmful.Coking wastewater once leaked into the aquifer,it will cause pollution of groundwater,this pollution can last for decades,even hundreds of years.Groundwater pollution is hidden and difficult to reverse,it seriously restricts the coordination and sustainable development of groundwater environment,resulting in varying degrees of economic losses,and even harm the health of residents.This paper takes a coking plant in Tangshan as the research object.According to the survey,the coking wastewater has caused pollution to the surrounding aeration zone,groundwater environment and so on.Therefore,the study of groundwater pollution is very necessary,it is of great practical significance to find out the pollution source,pollution path and pollutant migration rule in the groundwater,and to provide effective and effective method for the groundwater pollution control and treatment in the coking plant.Through data collection and combined with field geological environment exploration,hydrogeological test,water level monitoring and other research methods,the geological and hydrogeological conditions in the study area are analyzed comprehensively.12 groundwater monitoring wells in the study area were sampled and analyzed,and the groundwater quality was evaluated.The results show that: 75% of the monitoring wells appear excessive phenomenon of different factors.There are 14 indicators exceeding Grade ? standard in groundwater,among which JC12# monitoring well has 11 components exceeding the standard,the exceeding standard component is the most.In order to further analyze the pollution level of groundwater in the study area,the pollution index was used to evaluate the pollution status.The results show that the groundwater is polluted in different degrees,with light pollution and heavy pollution,of which 5 monitoring wells appear heavy pollution.Mainly concentrated in the southeast of the factory,the most serious pollution component is cyanide and volatile phenols.On this basis,the aquifer of the study area is generalized into a three-dimensional unconfined flow aquifer.and the corresponding mathematical model of groundwater pollution is established.According to the results of water quality evaluation,the cyanide with the characteristic of high exponent and hazard in pollutants of coking plant were selected as simulated migration factor.The spatial and temporal distribution of cyanide concentration in groundwater in the study area under different scenarios was numerically simulated by Visual MODFLOW.Based on the analysis of the simulation results,the migration rule of cyanide in shallow groundwater was preliminarily analyzed.Finally,the prevention and control measures of groundwater pollution problem in the study area are put forward.The simulation results show that convection and dispersion are the main causes of cyanide migration during groundwater migration.The cyanide migrated mainly in the downstream direction of the pollution source.The pollution area on the two sides of the pollution source are basically symmetrical,and the pollution halo shows the different migration distance in the horizontal and vertical directions.Therefore,the pollution halo is mostly the shape of the plume or similar elliptical distribution.When cyanide is continuously fed into the aquifer,the cyanide concentration in the groundwater below the source is the highest.with the diffusion to the periphery,the concentration value is gradually decreased in the two-axis direction.The pollution degree of cyanide to groundwater is related to the distance from the pollution source,and the closer to the pollution source,the higher the pollution degree of groundwater.When the pollution source is effectively removed,over time,the center of gravity of the pollution is gradually moving downstream from the pollution source,and the highest concentration of pollution halo showed a decreasing tendency.