Laboratory-Scale Aerobic Landfill Bioreactor: A Precursor to Modeling and Full-Scale Investigation

Accelerated stabilization of municipal solid waste (MSW) through the recirculation of leachate and/or addition of water and air has been investigated intensely over the past several years. In general there are many benefits to this approach of enhancing the rate of waste biodegradation including increased settlement and valuable air space, reduced leachate toxicity and treatment costs, and lessened post-closure concerns. Aerobic operation maximizes these benefits while also raising other concerns. In particular, the addition of oxygen into a heterogeneous matrix wherein pockets of methane may exist could exacerbate combustion potential. Moreover, addition of water and/or leachate increases the unit weight and may reduce effective stresses. As such, it is vital that the appropriate amount of air and moisture be distributed throughout the waste without an excessive use of wells or trenches that pose financial or logistical obstacles. Soil vapor extraction studies have shown that simultaneous injection and extraction can move fluid through porous media with greater efficiency than one or the other individually. This paper describes aspects of the largest reported (approx. 10 m³) laboratory-scale bioreactor designed to simulate the aerobic decomposition of MSW under controlled air injection and vapor extraction. One of the objectives of this laboratory effort is to investigate and model the flow of water, leachate and air as related to system performance. Data generated from this work are intended to provide a basis for model verification as well as insight into field application.