Thermal desorption and pyrolysis of oil contaminated drill cuttings by microwave heating

Oil contaminated drill cuttings were treated in a single mode microwave cavity, and it was found that certain conditions promote pyrolysis of the oil whereas others caused thermal desorption only. This is particularly interesting since most microwave-induced pyrolysis occurs only when microwave-absorbing materials such as activated carbon are added to the process materials, however the drill cuttings used in this study contain just water as the microwave-absorbing phase. It is shown that higher microwave power and electric field strength are the major factors which appear to determine the mechanism of oil removal, although a number of explanations are suggested as to why pyrolysis occurs. These include poor heat and mass transfer inherent in granular materials, and also the potential effects of bound water. This study demonstrates the volumetric heating potential of granular materials and mixed solids, and has potential applications in the pyrolysis of a range of waste materials from contaminated soils to domestic wastes.