Biologically Reactive Multispecies Transport in Sanitary Landfill

This study proposes a numerical model for gas- and water-phase solute transport describing the change in leachate quality and gas production by microbial activities in a sanitary landfill. The proposed model includes gas and water flows, multispecies transport of gas and water phases, interphase mass transfer of solids and water-phase solutes, microbial growth and death, and aerobic and anaerobic biodegradation. In simulations of gas-phase flow and transport, the influence of gas temperature and composition on flow and transport phenomena area incorporated by changing the gas viscosity and diffusivity. Simulation results using the proposed model are very close to the results of the BIOF&T model and analytical solutions on test problems. Finally, the model is applied to simulate the leachate quality and three gas compositions of a waste decomposition experiment using a lysimeter. The results of the simulation explain the dynamic fluctuation of gas composition with time and match the leachate quality and three gas compositions measured in a limited time span.