Experimental Study On Removal Of Vinyl Chloride Pollutants In Groundwater By Zero Valent Iron/Activated Carbon Process

This paper studies how to remove the vinyl chloride pollutants in groundwater more economically and efficiently.More and more people pay more attention to this kind of pollutants,such as halogenated hydrocarbons,which appear more and more in natural water.Among them,perchloroethylene(PCE)and trichloroethylene(TCE)are widely used as organic solvents in industrial production.Zero valent iron(ZVI)has been widely used in the remediation of contaminated groundwater because of its high efficiency and low cost.Among them,the permeable reactive barrier(PRB)technology with zero valent iron as the reaction medium has been applied in some practical applications.However,it is also found that zero valent iron is easily oxidized,and humic acid and calcium ions in groundwater may affect the reaction system.In the pilot scale experiment,the zero valent iron showed higher removal efficiency for trichloroethylene and perchloroethylene,and the reaction was in accordance with the pseudo first order kinetic equation.Humic acid did not show the reduction of perchloroethylene alone.Humic acid has a significant inhibitory effect on the removal of perchloroethylene in the presence of calcium ions.The inhibitory effect was more obvious when the calcium ions existed in the solution.The removal process of zero valent iron(ZVI)column,zero valent iron(ZVI)activated carbon(AC)layered column and ZVI and AC mixed column was studied by using perchloroethylene(PCE)as the target pollutant.In this paper,the removal rate of PCE initial concentration,the removal rate of ZVI column and mixed column and the influence of long time operation on the removal rate were analyzed.The results showed that in different initial concentration of PCE(19.9-107.4 g L-1),the sameEmpty Bed Contact Time(60 min)and a period of time(1-528h),ZVI and AC layered column can effectively remove PCE in water(35%-98%).Reducing hydraulic load can Improve removal rate.ZVI-AC layered column system is more efficient for the removal of perchloroethylene.When the zero valent iron / activated carbon hybrid system is used in the actual production,the main factors that affect the total investment scale are the cost of infrastructure and the ratio of iron to carbon.The combination of zero valent iron and activated carbon can effectively reduce the total cost and increase the removal efficiency of chlorinated hydrocarbons.