Title:
Challenges and Strategies of Hydrothermal Liquefaction of Sewage Sludge
Author(s):
Fan, Y., Hornung, U., Dahmen, N.
Document(s):
Paper
Slide presentation
Abstract:
During the last decade, hydrothermal liquefaction (HTL) has been suggested as a cost-effective and eco-friendly solution for the valorization of SS, as it is able to convert high-moisture feedstocks to an energy-dense liquid biocrude, which could be further refined into transportation fuels. However, SS is a protein-rich feedstocks, leading to an inevitable presence of N-containing compounds in the formed biocrude, thus failing fuel standards and preventing the integration into refineries for further processing. Developing economic potential for SS-derived biocrude requires an in-depth investigation of the fate of nitrogen during liquefaction, to find out suitable strategies for utilization. Results show that Maillard reactions (MRs) occurring between proteins and carbohydrates significantly affect the mechanistic reaction in biocrude formation. On the one hand, MRs take place during the heat-up period and improve the biocrude yield by inhibiting carbonization and transferring more carbon into the oil phase. On the other hand, they compete with amidation reactions, producing N-containing heterocycles instead of fatty acid amides. In order to avoid or suppress amidation during HTL and to maximize energy valorization of SS, an innovative integration of lipid extraction of sewage sludge and consecutive HTL of the extracted sewage sludge (LESS) is explored. The extracted lipid can be applied as high quality of biodiesel, the extracted residual can be treated by HTL to produce biocrude. The HTL of LESS show promising yields above 350 °C and, therefore, energy recovery reached values of 85.4 % for hydrothermal liquefaction of sewage sludge alone and 98.3 % for integrated approach considering the whole range of biofuel products. However, a suitable energy consumption rate is depending on the method of extraction.
Keywords:
sewage sludge, nitrogen, hydrothernal liquefaction
Topic:
Biomass Conversion to Intermediate Bioenergy Carriers, Sustainable Biofuels and Bio-Based Products
Subtopic:
Hydrothermal Processing
Event:
29th European Biomass Conference and Exhibition
Session:
3CO.15.4
Pages:
773 - 780
ISBN:
978-88-89407-21-9
Paper DOI:
10.5071/29thEUBCE2021-3CO.15.4
Price:
FREE
