Study On The Effect Of Monitored Natural Attenuation Repairing Technology For Groundwater At Informal Landfill

With the rapid development of social economy and the rapid progress of science and technology, groundwater pollution is becoming more and more serious. Groundwater pollution has the characteristics of concealment, that is to say, groundwater is not easy to be found after polluted, so the problems associated with the groundwater become more and more prominent. The groundwater pollution problem is very serious in our country. According to an uncompleted statistic, slight pollution in all areas accounted for only 1/3, and the heavily pollution in all cities areas are up to 2/3. Therefore, the management of groundwater pollution has no time to delay.There are many factors that cause the pollution of groundwater in our country. Among them, the most serious one is that the leachate from the urban informal landfill site gets into the groundwater system. The underground water pollution caused by the informal landfill site has great harm to the social ecological environment and the human production and life. The process of polluted groundwater remediation is also extremely complex and slow, and the effect is not obvious. Compared with other active groundwater remediation techniques, monitoring natural attenuation can reduce the concentration of groundwater contaminants to a specific target value in a relatively short period of time. Therefore, it is of great significance to study and evaluate the monitoring natural attenuation remediation technology in the informal landfill site.This paper summarizes the mechanism of monitoring natural attenuation, influencing factors and the attenuation ability of characteristic pollutants. This paper also introduces the basic theory of groundwater numerical simulation. The research object of an informal landfill site is located in Beijing City. Combined with the basic information of the site and the monitoring results of groundwater quality, that natural attenuation can occur in the study area is confirmed preliminarily. The trend of PH, dissolved oxygen, sulfate, ammonia nitrogen and nitrate nitrogen in groundwater was analyzed. Ammonia nitrogen pollutions are selected for numerical simulation of groundwater. The numerical simulation software of VISUAL MODFLOW is used to establish numerical model, and the numerical includes dispersion, adsorption and volatilization. Then the data of characteristic pollutant concentration already acquired are used to correct the model. The change trend of ammonia nitrogen pollutant is forecasted in informal site.The results predicted by the model show that the concentration of ammonia nitrogen in the study area can be reduced to 0.5mg/L in 15 years, which reached the V kinds of groundwater standards. The concentration of ammonia nitrogen in the study area can be reduced to 0.2g/L in 20 years, which reached the V kinds of groundwater standards. It indicates that groundwater ammonia nitrogen pollution remediation effect is obvious under the influence of natural attenuation in the site. So it is feasible to repair groundwater pollution by monitoring natural attenuation technology in this research area.