Ressearch On The Migration And Transformation Mechanism Of 1,2,4-Trichlorobenzene In The Waste Contaminated Groundwater And Its Simulation And Forecast

Due to the landfill of Luhuagang in the southern suburbs of Kaifeng was built without the linning and seepage facilitied. The water and soil surrounding was serously polluted by the landfill leachate. and the pollution plume will be expand to downstream over time if the leachate continue leaking.This paper was based on the project of " the migration and transformation mechanism and control measures of groundwater contaminant at the southern suburbs landfill of Kaifeng ". and the southern suburbs landfill of Kaifeng was taken as the study area. Inorganic and organic hydrochemical features along with risk assessment results of orgnic pollution.we choose 1,2,4-trichlorobenzene as the typical leachate pollutant and carry out laborary experiments to study transformation mechanism of it, model the migration and transformation of it in aquifers and predict its variation tendency. These study show that:(1)The main hydrochemical types of groundwater are HCO3-Ca·Mg·Na,HCO3-Ca·Mg and HCO3-Ca·Na·Mg. The water quality in the study area is poor. which was classified to be class IV. The main factors exceeding standard limit are TDS, chloride,NO2-, Fe,Mn,and fluoride.(2)Previous results show that the shallow groundwater is lightly polluted by halogenated hydrocarbon and halogenated aromatics. The detection rate of polycyclic aromatic is high, but the degree of pollution caused by it is light. Near the landfill polycyclic aromatic hydrocarbons and total DDT are potentially harmful to human health and environment, which mainly came from benzo (a) pyrene. With the exception of HCB, halogenated hydrocarbons and halogenated aromatic hydrocarbons in addition to HCB did not have serious threat to human health and environment.The concentrations of 1,2-dichlorobenzene,1,2,4-trichlorobenzene and 1,2,3 trichlorobenzene in the groundwater are mostly light pollution; the concentrations of 1,2,4-Trichlorobenzene and 1,2,3-trichlorobenzene of the part sampling points are heavy pollution levels near the village; the concentration of naphthalene in G7 is high, and groundwater samples taken from other sampling points are lightly polluted. The potential hazards to human health and the environment of polycyclic aromatic hydrocarbons and halogenated aromatic hydrocarbons are not serious.The impact to environment caused by 1.2.4-trichlorobenzene is the most serious one. and it has the potential hazards on human health and environment.(3) Results of experiments on the absorption kinetics of 1.2.4-trichlorobenzene show that absorption processes of silt, fine sand, medium sand to the 1.2.4 trichlorobenzene fit the standard second order kinetic model. Absotption rate of 1.2.4-trichlorobenzene on these three kinds of media is sequenced:silt fine sand medium sand.Resuls of experiments on the adsorption thermodynamics of 1.2.4 trichlorobenzene show that its rule of absorption thermodynamic is correspond with the Freundlich model, the order of the adsorption capacity of the 1.2.4 trichlorobenzene in the three kinds of media is:silt> fine sand> medium sand.Biodegradation experiments show that biological degradation of 1,2,4 trichlorobenzene in silt, fine sand, medium sand can be describe on first-order decay kinetics equation and the Monod kinetic equation. The order of decay rate of the 1.2.4-trichlorobenzene in the three kinds of media is silt> fine sand> medium sand. Attenuation of 1.2.4-trichlorobenzene in silt is the fastest, attenuation rate in the medium sand is the slowest. The biodegradation rate of 1.2.4-trichlorobenzene of the non-sterilizated medium is higher than the sterilizated medium.With the concentration of 1,2.4-trichlorobenzene initial gradually hoist, the biological degradation rate gradually accelerate. (4) 1-D simulation results of migration column experiments of 1,2,4 trichlorobenzene show that the migration of the 1,2,4-trichlorobenzene in sand and fine sand can be affcted by retardation. The concentration of 1,2,4-trichlorobenzene in the sample hole decreased accordingly from the inlet to the outlet peak over time, and 1,2,4-trichlorobenzene is more easily migrated in medium sand than fine sand.(5)Through establishing the analysis model to predict migration and transformation of 1.2.4-trichlorobenzen. it shows that 5 years should be taken to remove the 1.2.4-trichlorobenzene in groundwater through the natural attenuation. Therefore, it is suggested that some measurments should be taken for controlling the leakage of of the landfill leachate. so the further pollution will be avoided firsth,and MNA technologies should be carried out to remedy contaminated groundwater combined with PRB and AS technology.