The Anti-Seepage Performance Study Of The Improved Landfill Liner

In a solid waste containment facility, volatile organic contaminants(VOCs) can diffuse through the geomembrane and have a potential to pollute the underlying soil and groundwater. The liner system is the important part of the landfill. A compacted clay liner(CCL) is frequently adopted as a barrier to the pollution plume. However,the traditional landfill liner is easy to crack, and the seepage control performance is poor. Therefore, the research improving the performance of the landfill site of clay liner and reducing the secondary pollution of leachate on the surrounding environment, has important practical significance and application value.Based on clay liner as the research object, the research is to improve the anti-seepage effect. The first method uses the surfactant to modify the bentonite-sand.The pressure plate apparatus and saturator were used to research on the permeability of unsaturated state of modified bentonite-sand. The second method is trying to introduce mutually disconnected bubbles into liner to stop the VOCs penetration. The main conclusions are summarized as follows:(1) Collect and summarize previous research, discussing different methods and different physical and mechanical properties of adding sand, bentonite modified agent.The result shows that the impermeable performance of the modified bentonite has become worse. The experimental study of bentonite-the permeability of sand after cationic surfactant treatment. The water, and permeability properties of bentonite-sand after modified with surfactant(CTMAB) become worse. Therefore, the solutions using organic modifier modified bentonite-sand to improve the anti-seepage effect need to be taken seriously.(2) The present model couples the consolidation of the liner due to waste emplacement and the solute transport of the VOCs. The numerical results suggest that the gas partitioning between the aqueous phase and a trapped gas phase can greatly reduce the rates of transport of hydrophobic VOCs in the CCL. But the numerical simulations demonstrate that unsaturation and vapor adsorption cannot impede break of typical VOCs through clay liner at municipal waste landfill.(3) The research studied on the typical transmission and transformation of VOCsconsidering the oxygen contributed to the inherent biodegradation based on the original model. The numerical simulations demonstrate that unsaturation and vapor adsorption can impede break of typical VOCs through clay liner to some extent. The significant intrinsic biodegradation of VOCs is experienced at the presence of oxygen in gas bubbles and the thickness of bubbles wall layer is relatively thin and on the magnitude of cm. The method has a very good application foreground.In this paper, in the modification and two kinds of new type of clay base with bubbles landfill liner indoor experiment and numerical simulation, the study found that landfill liner with organic modified bentonite- sand should be cautious and avoid excessive permeability, not conforming to the design standard. The research found that oxygen bubbles of the clay liner under the condition of low permeability can effectively block the migration of volatile organic pollutants. The method has a very good application foreground. The corresponding results provide a reference for the landfill design, construction in the future.