Waste materials such as waste oil, plastic, and biomass waste are being generated every year around the world. Some of these wastes are effectively collected and recovered for use as an energy source or chemical feedstock, while some are simply discarded or burned in ways that can pollute the environment. The improper disposal of these waste materials (e.g., used engine oil, PVC, and municipal solid wastes) may constitute an environmental hazard due to the presence of undesirable species such as metals, soot and polycyclic aromatic hydrocarbons (PAHs). For example, studies have reported that the high concentrations of PAHs in sewage effluents and urban runoffs are due to their contamination by waste oil [1]. Due to the difficulties associated with the contaminants in these waste 222materials, a large portion of the wastes are simply disposed of by landfilling. This method presents no recovery of the potential value of the waste but leads to potential environmental pollution due to considerably long decomposition times and the risk of contaminants leaking out to the surrounding environment. As such, the treatment and disposal of these wastes represents a significant challenge in the real world.