Study On Monitoring And Early Warning Technology Applied To Groundwater Contamination In Waste Landfills

Leachate is produced by rain scouring in landfills.Once leachate leaks into groundwater and enters the food chain,it will pose a serious threat to human health.Therefore,the monitoring and early warning of groundwater pollution in landfills is an important means and measures to prevent the pollution from the source.At present,the research of groundwater pollution monitoring and early warning at home and abroad is mainly focused on regional hydrogeological units and drinking water sources,and the monitoring and warning functions are separated.The research on online monitoring and early warning of groundwater pollution in landfills as a typical site needs to be further developed.Based on the existing monitoring and early warning methods around the world,a set of monitoring and warning methods suitable for groundwater pollution in landfills are designed through optimization and integration,and the methods are verified and demonstrated in practical sites.The real-time monitoring and early warning of groundwater pollution are realized.The main steps of the method are as follows:1)investigation and risk assessment of site environmental pollution.Through hydrogeological exploration and multi-index comprehensive evaluation,the hydrogeological conditions and groundwater pollution risk of landfills are determined.According to the risk grade,the frequency of monitoring and warning is determined and the monitoring and warning system of groundwater pollution is constructed.2)The hardware system of on-line monitoring of groundwater environment and software data analysis and warning platform are established to realize on-line transmission of on-line monitoring data,intelligent automatic well washing and sample collection.The online analysis of monitoring data and the dynamic display of early warning results are three main functions.Finally,the corresponding pollution prevention measures are put forward.The groundwater pollution monitoring and warning method designed in this study was verified in an informal landfill in Tianjin.The landfill site is located in the sea plain area,the groundwater depth is relatively shallow(average 3.5 m),the velocity of flow is 0.043 cm/d,the main pollutants(chloride ion,ammonia nitrogen,nitrate and organic matter)are mainly distributed in the southern region of the landfill site,and the risk level of groundwater pollution is relatively high.The on-line monitoring index(conductivity)is significantly related to the concentration of characteristic pollutants,and the best correlation is to chlorine ion(R~2=0.864).According to the site environmental characteristics,the hardware system and software platform for monitoring and warning of groundwater pollution are constructed.It has the characteristics of automatic and rapid well washing sampling,real-time on-line transmission of monitoring data,accurate and reliable warning results,scientific and reasonable pollution prevention measures,simple and convenient operation flow and so on.The system operation results show that,the warning level of groundwater pollution in this landfill is red,and the pollution tends to spread.The method of monitoring and early warning proposed in this study provides a theoretical basis for monitoring and early warning of groundwater pollution in landfills,and the monitoring and warning system can be applied to practical sites.It provides a reference for the monitoring and early warning of groundwater pollution in landfill.