Study On Removal Of Chlorinated Hydrocarbons From Groundwater Source By Aeration Stripping Technology

There are many types of chlorinated hydrocarbons in groundwater,which are harmful and have been a serious threat to groundwater safety and human health.In this paper,I chose four kinds of chlorinated hydrocarbons,namely,carbon tetrachloride,trichloromethane,trichlorethylene and tetrachlorethylene,which are the most abundant in groundwater,how to removal chlorinated hydrocarbons by aeration stripping was studied.This paper investigated the main influencing factors of removal chlorinated hydrocarbons used aeration stripping,including the gas-fiow rate of unit area,initial concentration of chlorinated hydrocarbons and temperature,and explored the effect of other chlorinated hydrocarbon coexistence on the removal rate.Finally,the mathematical model of dechlorination of chlorinated hydrocarbons was established,and the effect of chlorinated alkanes and chlorinated olefins in different gas-water ratio was predicted respectively,then further discussed the relationship between molecular connection index and aeratin rate.It will provide the basis for practical application of this technology.The concrete conclusions are as follows:?1?The experimental results showed that aeration stripping technology can quickly and effectively remove the chlorinated hydrocarbons in groundwater.Higher gas-fiow rate of unit area,higher initial concentration of chlorinated hydrocarbons and higher temperature will lead shorter time to meet the emission standards.However,increasing unit area of aeration will enhance the energy consumption.Therefore,the best condition for removing 5 mg/L of chlorinated hydrocarbons by aeration stripping technique is that the aeration rate per unit area is between 0.421 and 0.631m3/?m2·min?,and the temperature is higher than 20?.?2?Under the same experimental conditions,the removal rate of the four chlorinated hydrocarbons was carbon tetrachloride> tetrachlorethylene>trichlorethylene> trichloromethane.The coexistence of multiple chlorinated hydrocarbons can increase the removal rate of each chlorinated hydrocarbon.?3?The mathematical model of dechlorination of chlorinated hydrocarbons can be expressed as C/C₀= exp?-G · q?,the stripping coefficient G has related to theHenry's constant H,and q is the gas-water ratio.The model was used to simulate the effect of chlorinated alkanes and chlorinated olefins in different gas-water ratio.For20? water in the zone,a 50%,70% and 90% removal rate for the four contaminates corresponds to a gas-water ratio is about: carbon tetrachloride is 6.48,11.25,21.52;chloroform is 17.33,30.10,57.56;trichloroethylene is 13.59,23.61,45.15 and tetrachloroethylene is 9.90,17.20,32.89?Which can be used as the basis of aeration stripping technology to remove chlorinated hydrocarbons about gas-water ratio.?4?Under the condition of temperature 25?,initial concentration was 5 mg/L and unit area aeration rate of 0.526 m3/?m2·min?,the quasi-first order reaction rate constant k has a good correlation with zero order molecular connected index 0?.The equation is k=0.1457×0?-0.4066,and the correlation index R² = 0.8401.