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Article

Sequential Hydrothermal Processing of Sewage Sludge to Produce Low Nitrogen Biocrude

Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Academic Editor: Gianni Andreottola
Processes 2021, 9(3), 491; https://doi.org/10.3390/pr9030491
Received: 29 January 2021 / Revised: 23 February 2021 / Accepted: 28 February 2021 / Published: 9 March 2021
(This article belongs to the Special Issue Process Design of Biomass Thermochemical Conversion)
A hydrothermal pre-treatment has been developed to improve sewage sludge quality or to produce low nitrogen biocrude via hydrothermal liquefaction (HTL) in a subsequent step. The mild hydrothermal pre-treatment (150 °C) step was performed with deionized water, sulfuric acid (0.5 M), or citric acid (0.5 M) to solubilize nitrogen containing compounds in the aqueous supernatant. Downstream, the residual solid material was liquefied with the addition of sodium carbonate via hydrothermal liquefaction (350 °C). The pre-treatment with citric acid transferred up to 66.7 wt. % of nitrogen into the aqueous supernatant, while 62.0 wt. % of carbon was recovered in the solid. Due to the pre-treatment lipids retained in the sewage sludge solid, which increased the favored biocrude yield up to 42.9 wt. % and the quality evaluating value H/Ceff ratio significantly to 1.48. Multi-method characterization of the resulted biocrude samples showed a lower concentration of N-heterocycles, while long-chain aliphatics and free fatty acid are increased. View Full-Text
Keywords: hydrothermal hydrolysis; nitrogen extraction; sequential hydrothermal liquefaction; sewage sludge; pre-treatment hydrothermal hydrolysis; nitrogen extraction; sequential hydrothermal liquefaction; sewage sludge; pre-treatment
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MDPI and ACS Style

Zimmermann, J.; Raffelt, K.; Dahmen, N. Sequential Hydrothermal Processing of Sewage Sludge to Produce Low Nitrogen Biocrude. Processes 2021, 9, 491. https://doi.org/10.3390/pr9030491

AMA Style

Zimmermann J, Raffelt K, Dahmen N. Sequential Hydrothermal Processing of Sewage Sludge to Produce Low Nitrogen Biocrude. Processes. 2021; 9(3):491. https://doi.org/10.3390/pr9030491

Chicago/Turabian Style

Zimmermann, Joscha, Klaus Raffelt, and Nicolaus Dahmen. 2021. "Sequential Hydrothermal Processing of Sewage Sludge to Produce Low Nitrogen Biocrude" Processes 9, no. 3: 491. https://doi.org/10.3390/pr9030491

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