| Many proposals suggest that air injection into bioreactor landfills enhance waste composition; several potential benefits of air addition have been hypothesized, yet little has been proven about the overall performance of aerobic landfills compared with current anaerobic landfills. Utilizing research conducted with six-foot tall stainless steel simulated landfill lysimeters, complete with fabricated wastes, this Ph.D. dissertation compares aerobic and anaerobic landfills with respect to gas and leachate quality, fate of metals, settlement behavior and biodegradation of lignocellulosic materials.; Through air injection, a large enhancement of waste decomposition was observed. More than 90% of the maximum chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total organic carbon (TOC) concentrations decreased within 100 days. During the methanogenic phase in the anaerobic condition, concentrations of ammonia increased by an amount four times greater than the initial concentrations. A large change of ammonia was not observed from the aerobic lysimeters.; The fate of metals leached from the various metal sources including cathode ray tube (CRT) monitor glass and ground CCA-treated wood were explored. Metal leaching trends observed varied from anaerobic to aerobic lysimeters; the average concentrations of As, Fe, Mn, and Zn in the anaerobic lysimeters proved significantly greater in concentration than observed in the anaerobic lysimeters. Furthermore, significantly greater concentrations of Al, Cu, Cr, and Pb were detected in the aerobic lysimeters as compared to the anaerobic lysimeters.; Using leachate and gas measurements, mass losses from the aerobic and anaerobic lysimeters were estimated. Mass removed from the wastes was primarily converted into gas; after the water was removed from the lysimeters, the mass of waste excavated from each lysimeter was compared with the estimated loss mass. For wood waste, no great influence on air addition was observed through cellulose/lignin analysis. Methane potential of lignocellulosic materials other than wood waste resulted in great differences of biodegradation between aerobic and anaerobic lysimeters.; The landfill settlement behavior occurring in aerobic and anaerobic simulated landfills was mathematically analyzed. The logarithm of mass loss was linearly correlated with the percentage of settlement. With this relationship, the secondary settlement of bioreactor landfills could be mathematically modeled using the first-order exponential function. |
