Unravelling the Role of Biochemical Compounds within the Hydrothermal Liquefaction Process of Real Sludge Mixtures

Marco Balsamo, Francesca Di Lauro (), Maria Laura Alfieri, Paola Manini, Piero Salatino, Fabio Montagnaro () and Roberto Solimene
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Marco Balsamo: Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant’Angelo, 80126 Napoli, Italy
Francesca Di Lauro: Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant’Angelo, 80126 Napoli, Italy
Maria Laura Alfieri: Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant’Angelo, 80126 Napoli, Italy
Paola Manini: Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant’Angelo, 80126 Napoli, Italy
Piero Salatino: Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale V. Tecchio 80, 80125 Napoli, Italy
Fabio Montagnaro: Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant’Angelo, 80126 Napoli, Italy
Roberto Solimene: Institute of Sciences and Technologies for Sustainable Energy and Mobility, National Research Council, Piazzale V. Tecchio 80, 80125 Napoli, Italy

Sustainability, 2024, vol. 16, issue 5, 1-18

Abstract: This paper aims to provide a contribution to understanding the role of sludge macro-components (lipids, proteins and carbohydrates) on the yield/quality of bio-crude obtained via hydrothermal liquefaction (HTL). This was pursued by analysing the HTL process of real sludges and the mixtures thereof at different compositions, a topic that has been explored in a very limited way in the pertinent literature. The HTL experiments were run with municipal sludge, tannery sludge and a mixture of them in 25:75, 50:50 and 75:25 weight ratios in a batch reactor at 350 °C and for different residence times. The outcomes for a single sludge showed a greater bio-crude yield for the municipal one (42.5% at 10 min), which is linked to its significant carbohydrate content. The results obtained from the sludge mixtures suggested that a carbohydrate-to-protein mass ratio of 2:1 would maximise the bio-crude yield (average value of about 38%). Moreover, LC-MS and NMR analyses highlighted that the mixed sludges contributed to the formation of a higher number of compounds after the HTL treatment, with respect to the pure municipal or tannery sludge, with an increase in amine, alcohols and aromatic compounds.

Keywords: hydrothermal liquefaction; tannery sludge; sludge mixtures; Maillard reactions; bio-crude; biochemical interaction; energetic valorisation; waste biomass; NMR and mass spectrometry; Amadori compound (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
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