Migration and methanogens: A review of current landfill gas field research at ANL

Landfill gas recovery research at Argonne National Laboratory is focusing on a project studying gas movement through landfill cover materials and a pilot investigation of microbial populations in landfills. Vertical gas pressure and concentration gradients between the top of refuse and the landfill cover are being examined. In particular, changes in the vertical gradients indicative of changes in magnitude and direction of pressure or diffusional flow with time are being monitored. This study emphasizes changes in vertical pressure and concentration gradients related to barometric pressure and other meteorological variables, soil moisture changes, and pumping rates at simulated recovery wells. Preliminary results suggest that changes in soil-gas pressures in the landfill cover and top of refuse closely follow changes in barometric pressure. Measurable concentration gradients exist between the top of refuse and the cover materials indicating that diffusion is a major mechanism for gas movement, particularly during dry weather when pressure gradients are negligible. A pilot investigation has begun on microbial populations in sanitary landfills. First, a series of leachate samples from various depths at the Blackwell Forest Preserve Landfill were evaluated for microbial populations, selected chemical constituents, and methane production. Diverse motile populations of fluorescing organisms were found in selectedmore » samples. 19 refs., 6 figs., 3 tabs.« less