Anaerobic digestion of municipal solid waste and sewage sludge under mesophilic and thermophilic conditions: A thermal study in DSC associated to infrared spectroscopy

• Published in: Journal of thermal analysis and calorimetry 2013-03, Vol.111 (3), p.1861-1870
• Main Authors: Provenzano, Maria Rosaria, Daniela Malerba, A., Buscaroli, Alessandro, Zannoni, Denis, Senesi, Nicola
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Applied sciences; Calorimetry; Chemistry; Chemistry and Materials Science; Exact sciences and technology; General treatment and storage processes; Infrared spectroscopy; Inorganic Chemistry; Invisibility; Measurement Science and Instrumentation; Physical Chemistry; Pollution; Polymer Sciences; Refuse and refuse disposal; Sludge; Thermodynamics; Toy industry; Wastes
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-012-2598-6

In this study, thermal analysis in differential scanning calorimetry associated to Fourier self-deconvolution (FSD) of infrared spectra was applied to the study of anaerobic digestion of the organic fraction of domestic solid waste and sewage sludge mixed in 1:1 ratio under mesophilic and thermophilic conditions. Curves showed an exothermic peak in the high-temperature range and a number of endothermic and/or exothermic peaks in the low- and medium-temperature range. The high-temperature exotherm was a common feature on curves of all samples. Digestates evidenced a shift of this exotherm toward higher temperature with respect to both substrates and feed-in materials as a result of a greater chemical complexity attained by organic matter (OM) during the process. A further shift toward higher temperature values was observed on digestates obtained under thermophilic conditions with respect to digestates obtained under mesophilic conditions. This result was associated to a higher recalcitrance of digestates produced under more drastic conditions. Based on evidence obtained by FSD spectra, the exotherm in the medium-temperature range was assigned to combustion of carbohydrates and to loss of aliphatic structures and carboxylic groups. Enthalpy data associated to the high-temperature exotherm were used to differentiate feed-in materials and their corresponding digestates and to distinguish digestates obtained under different operative conditions.