The Study On Remediation Of Contaminated Groundwater Environmental Of Red Bed By Landfill Leachate

In the past,simple landfill was the main method of disposal of rural garbage,but because of its low degree of garbage classification,the field area without corresponding anti-seepage measures and the collection and treatment facilities of leachate,the simple landfill also became the main pollution source of the environment,especially the influence for the groundwater environment from infiltration of leachate.In the red layer area of Sichuan Province,groundwater is an important drinking water source,and its safety is seriously affected by the surrounding simple landfill.With the increase of environmental protection,the simple landfill is required to be banned and closed.But because of the aquifers in the red layer have low permeability,which makes the diffusion of pollutants slow,and the groundwater system contaminated by landfill leachate is difficult to rely on natural restoring force in a short time,and it needs to take artificial repair measures to accelerate the process of restore.In view of this,this paper takes the low permeability medium of Sichuan red layer as the research object.Aiming at the characteristics of the groundwater contaminated by the landfill leachate,which is the high content of ammonia nitrogen and the difficult degradation organic matter,poor biodegradability,the physical model of the simulated red layer groundwater environment restoration is constructed.The remediation of the groundwater is repaired by the combined repair method of chemical-oxidation and aeration.In this paper,the effect of oxidant dose and aeration mode on the removal efficiency and mechanism of organic and NH₃-N were investigated by single factor test in polluted water.The applicability of the combined repair method in the process of water environment remediation in red layer polluted by landfill leachate was verified under the best conditions.The piper mainly explores the removal efficiency and mechanism of organic compounds and NH₃-N in the groundwater with different doses of PS under the condition of sufficient amount of ZVI by the chemical oxidation experiment.6 groups of working-conditions were designed in the experiment.The test results show that the PS/ZVI system in the low permeability medium of the red layer has obvious removal effect on COD,and there is a positive correlation between the COD removal rate and the amount of adding in the incremental phase of 0³.0g/L.The oxidation efficiency of the oxidant is inhibited when it exceeds 3.0g/L,the growth rate of COD removal rate is reduced.And considering the economy and efficiency,the optimum dosage of PS was 3.0g/L,and the removal rate of COD was 66.74%.At the same time,the UV₂₅₄ and fluorescence peaks of fulvic acids and eutrophic acid in the 3D-EEM decreased with time,indicating that the refractory organic compounds?such as humic acids and aromatic substances?in the reaction system were removed,and the biodegradability was improved.Therefore,the system of PS/ZVI can effectively remove organic matter from groundwater.The aeration experiment mainly studies the removal characteristics of pollutants in groundwater under the natural environment,aerobic environment and alternation of aerobic-anaerobic environment.The experiment has designed 5 groups of working conditions.The results show that the content of COD and humic acids is negatively correlated with the duration of pulse-aeration in the aeration process,but the decrease is limited;the process of aeration has obvious removal effect on NH₃-N,and it may be effectively removed by blowing and biological oxidation at the early stage of aeration.The removal rate of blow-off may be weakened due to the decrease of NH₃-N concentration,and the removal rate of NH₃-N is reduced by only microorganism,and the removal efficiency of NH₃-N in pulse-aeration is higher than continuous-aeration,and it has a positive correlation with the pulse length.The removal rate of NH₃-N of pulse 12h is the highest?79.52%?,also the best way of aeration.Based on the optimum dosage of PS and the best aeration mode,and under the premise of enlarging the scale of the experiment.The pilot test is one simulation experiment that groundwater environment is restored by the combined method of the chemical oxidation an aeration.The results show that the method has good repair effect on red bed groundwater,in which the comprehensive removal efficiency of COD and NH3-N is 71.3%and 94.59%respectively.At the same time,the chemical oxidation process and aeration can cause a certain degree secondary pollution to the groundwater environment in the process of the remediation of groundwater in the red layer.The most important pollution is the excess of sulfate concentration and the air pollution caused by ammonia gas,but they can be removed by suitable methods of the subsequent remediation of groundwater.The pH of the water has not been seriously reduced after oxidation,but it is still alkaline because of the effect of the buffer substance.Fe²⁺/Fe³⁺is easy to form precipitate under alkaline environment,so the content of Fe²⁺/Fe³⁺remains relatively stable in water.From the point of view of cost,repair effect and effect of two-pollution,the combined repair method of chemical oxidation and aeration has certain applicability in leachate-contaminated groundwater remediation of the red layer,and it has a certain application prospect in engineering examples.