Physicochemical Characterization of the Rejected Waste From the Mechanical and Biological Treatment of Municipal Solid Waste

Mechanical and Biological Treatment units (MBT), are a key element in the management of municipal solid waste as they are the preferred route for minimization of the amount of waste delivered to landfills. However, taking into account the waste received by the MBT’s, it is observed that a significant part is sent to controlled landfills without any kind of valorization. Within this framework, a characterization of the rejected waste produced in one of these facilities was carried out in order to assess their potential for energy recovery. The rejected waste is composed by different fractions, namely paper, textiles, plastic films, hard plastics, glass, metal, organic matter and undifferentiated waste. In the present work the rejected waste from a MTB unit is sorted into different classes and each one is fully characterized and assessed as an energy source. For the physicochemical characterization of different residues the following tests were performed: weight loss at 105 °C, elemental analysis, the determination of the heating value, thermogravimetric analysis and FTIR spectroscopy. Considering the potential for energetic recovery of the different fractions, only paper, textiles, hard plastics and plastic films were characterized because of the high moisture content of organic material. According to the results, there is a great variability of the physical-chemical properties within the various samples, both in composition and moisture. Most notably the polymer based residues (hard plastics and plastic films) show a heating value that compares favorably with both traditional biomasses and fossil fuels. Therefore, providing their acceptance in terms of toxicity, they can provide a valuable source of energy and contribute to the reduction of waste delivered to landfills.