Bio-Crude Production through Aqueous Phase Recycling of Hydrothermal Liquefaction of Sewage Sludge

Ayaz A. Shah, Saqib S. Toor, Tahir H. Seehar, Rasmus S. Nielsen, Asbjørn H. Nielsen, Thomas H. Pedersen and Lasse A. Rosendahl
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Ayaz A. Shah: Department of Energy Technology, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg, Denmark
Saqib S. Toor: Department of Energy Technology, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg, Denmark
Tahir H. Seehar: Department of Energy Technology, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg, Denmark
Rasmus S. Nielsen: Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark
Asbjørn H. Nielsen: Department of Civil Engineering, Aalborg University, Thomas Manns Vej 23, 9220 Aalborg, Denmark
Thomas H. Pedersen: Department of Energy Technology, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg, Denmark
Lasse A. Rosendahl: Department of Energy Technology, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg, Denmark

Energies, 2020, vol. 13, issue 2, 1-18

Abstract: Hydrothermal liquefaction (HTL) is a promising technology for the production of bio-crude. However, some unresolved issues still exist within HTL, which need to be resolved before its promotion on a commercial scale. The management of the aqueous phase is one of the leading challenges related to HTL. In this study, the sewage sludge has been liquefied at 350 °C with and without catalyst (K 2 CO 3 ). Subsequently, aqueous phase recycling was applied to investigate the effect of recycling on bio-crude properties. Obtained results showed that the energy recovery in the form of bio-crude increased by 50% via aqueous phase recirculation, whereas nitrogen content in the bio-crude was approximately doubled after eight rounds of recycling. GCMS characterization of the aqueous phase indicated acetic acid as a major water-soluble compound, which employed as a catalyst (0.56 M), and resulted in a negligible increase in bio-crude yield. ICP-AES highlighted that the majority of the inorganics were transferred to the solid phase, while the higher accumulation of potassium and sodium was found in the aqueous phase via successive rounds of recycling.

Keywords: aqueous phase recycling; sewage sludge; hydrothermal liquefaction; bio-crude (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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