Temperature effect on diffusion and non-linear adsorption of ammonium through geosynthetic clay liner and in-situ clayey soil in Hanoi, Vietnam

Abstract

High concentration of ammonium was detected in groundwater in southern Hanoi, Vietnam while municipal solid waste (MSW) landfills were known to generate large amounts of NH4+. Thus, bottom barrier with well performance should be required in Hanoi MSW landfills to minimize NH4+ migration. Hanoi is expected to experience temperature increase, which enables to reduce hydraulic-barrier performance. Hence, study on temperature effect on NH4+ adsorption and diffusion through landfill barriers plays a key role in prevention of NH4+ contaminated aquifers. The objective is to evaluate effect of three kinds of temperature (20oC, 35oC and 50oC) on NH4+ adsorption and diffusion through GCL and in-situ clayey soil sampled in Hanoi (HN clay). The results show that GCL possesses higher non-linear partitioning coefficient (Kd*) and lower diffusion coefficient (De) than HN clay in all cases of temperature. Both GCL and HN clay experienced an increase of Kd* and De in the temperature range of 20oC and 35oC. When temperature rises to 50oC, Kd* tends to decrease but De keep increasing. Hence, the study indicates a more dominant effect of diffusion coefficient than non-linear partitioning coefficient in promotion of ammonium mass transport through HN clay.