Modeling Leachates at Landfill Boundaries

Abstract

The performance of a fixed bed slag desorption (leaching) column was investigated and a mathematical model describing the desorption process was developed by considering intraparticle and external film diffusion resistances as rate controlling mechanisms. A linear equilibrium relationship between leachate metals in the liquid, and on the slag phase was developed. Four grades of GFETC “Lurgi‐type” fixed bed slagging coal gasification solid waste particles with diameters of 20‐40, 40‐60, 60‐100 and 100‐200 mesh were used for application of the developed model. Slags were derived from the gasification of North Dakota lignite coals. The model used a finite‐difference technique (implicit method) for solution and for generation of effluent concentration profiles. Calibration of the model was done using column studies. The effect of intraparticle diffusion and external film diffusion resistances were evaluated by conducting experiments with different slag particle sizes keeping fluid velocity constant and with different fluid velocities keeping particle size constant.