Combined acid pretreatment and co-hydrothermal carbonization to enhance energy recovery from food waste digestate

Xiefei Zhu; Mingjing He; Zibo Xu; Zejun Luo; Bin Gao; Roger Ruan; Chi Hwa Wang; Ka Hing Wong; Daniel C.W. Tsang

doi:10.1016/j.enconman.2022.115855

Combined acid pretreatment and co-hydrothermal carbonization to enhance energy recovery from food waste digestate

Xiefei Zhu, Mingjing He, Zibo Xu, Zejun Luo, Bin Gao, Roger Ruan, Chi Hwa Wang, Ka Hing Wong, Daniel C.W. Tsang

Bioproducts and Biosystems Engineering

Research output: Contribution to journal › Article › peer-review

51 Scopus citations

Abstract

To achieve clean and efficient utilization of food waste digestate (FWD), a novel strategy of combining acid pretreatment and co-hydrothermal carbonization was developed to prepare value-added hydrochar from food waste digestate. The acid pretreatment of FWD was carried out with 1 M HCl for 8 h at a solid-to-liquid ratio of 1:5. In addition to the characterization of physicochemical properties including proximate analysis, elemental content, heating value, and thermal stability of the hydrochar, TG-FTIR-MS and TG-DSC were used to evaluate the pyrolysis gaseous products and combustion performance of hydrochar. The results showed that the combination strategy enhanced the fuel properties of the hydrochar. In particular, the ash content of hydrochar was reduced to a minimum of 6.3%, thereby increasing the heating value by nearly two folds. The acid pretreatment and the addition of wood waste increased the H/C and O/C ratios of hydrochar while enhancing the thermal stability of hydrochar. The peak types of the infrared spectrum and mass spectrum of the pyrolysis gaseous products remained largely unchanged. Based on the comprehensive combustion index and combustion stability index, blending with wood waste could obtain a comparable combustion performance of the hydrochar with multiple cycles of acid pretreatment. The apparent activation energy of hydrochar was 102.0 and 90.4 kJ mol⁻¹ by FWO and KAS methods, respectively. The strategy advocated here presents a new ‘green’ perspective for the large-scale energy recovery from food waste digestate that is currently under-utilized.

Original language	English (US)
Article number	115855
Journal	Energy Conversion and Management
Volume	266
DOIs	https://doi.org/10.1016/j.enconman.2022.115855
State	Published - Aug 15 2022

Bibliographical note

Funding Information:
This work was supported by the Fundamental Research Funds for the Central Universities (WK2090000037) and Hong Kong Environment and Conservation Fund (Project 101/2020). The authors appreciate the feedstock provision from the Hong Kong Environmental Protection Department. X.Z. thanks the funding of the Hong Kong Scholar Program (XJ2020022).

Funding Information:
This work was supported by the Fundamental Research Funds for the Central Universities ( WK2090000037 ) and Hong Kong Environment and Conservation Fund (Project 101/2020 ). The authors appreciate the feedstock provision from the Hong Kong Environmental Protection Department. X.Z. thanks the funding of the Hong Kong Scholar Program ( XJ2020022 ).

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

Biochar/hydrochar stability
Energy potential
Food waste recycling
Gaseous products
Solid fuel
Sustainable waste management

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.enconman.2022.115855

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title = "Combined acid pretreatment and co-hydrothermal carbonization to enhance energy recovery from food waste digestate",

abstract = "To achieve clean and efficient utilization of food waste digestate (FWD), a novel strategy of combining acid pretreatment and co-hydrothermal carbonization was developed to prepare value-added hydrochar from food waste digestate. The acid pretreatment of FWD was carried out with 1 M HCl for 8 h at a solid-to-liquid ratio of 1:5. In addition to the characterization of physicochemical properties including proximate analysis, elemental content, heating value, and thermal stability of the hydrochar, TG-FTIR-MS and TG-DSC were used to evaluate the pyrolysis gaseous products and combustion performance of hydrochar. The results showed that the combination strategy enhanced the fuel properties of the hydrochar. In particular, the ash content of hydrochar was reduced to a minimum of 6.3%, thereby increasing the heating value by nearly two folds. The acid pretreatment and the addition of wood waste increased the H/C and O/C ratios of hydrochar while enhancing the thermal stability of hydrochar. The peak types of the infrared spectrum and mass spectrum of the pyrolysis gaseous products remained largely unchanged. Based on the comprehensive combustion index and combustion stability index, blending with wood waste could obtain a comparable combustion performance of the hydrochar with multiple cycles of acid pretreatment. The apparent activation energy of hydrochar was 102.0 and 90.4 kJ mol−1 by FWO and KAS methods, respectively. The strategy advocated here presents a new {\textquoteleft}green{\textquoteright} perspective for the large-scale energy recovery from food waste digestate that is currently under-utilized.",

keywords = "Biochar/hydrochar stability, Energy potential, Food waste recycling, Gaseous products, Solid fuel, Sustainable waste management",

author = "Xiefei Zhu and Mingjing He and Zibo Xu and Zejun Luo and Bin Gao and Roger Ruan and Wang, {Chi Hwa} and Wong, {Ka Hing} and Tsang, {Daniel C.W.}",

note = "Funding Information: This work was supported by the Fundamental Research Funds for the Central Universities (WK2090000037) and Hong Kong Environment and Conservation Fund (Project 101/2020). The authors appreciate the feedstock provision from the Hong Kong Environmental Protection Department. X.Z. thanks the funding of the Hong Kong Scholar Program (XJ2020022). Funding Information: This work was supported by the Fundamental Research Funds for the Central Universities ( WK2090000037 ) and Hong Kong Environment and Conservation Fund (Project 101/2020 ). The authors appreciate the feedstock provision from the Hong Kong Environmental Protection Department. X.Z. thanks the funding of the Hong Kong Scholar Program ( XJ2020022 ). Publisher Copyright: {\textcopyright} 2022 Elsevier Ltd",

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doi = "10.1016/j.enconman.2022.115855",

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T1 - Combined acid pretreatment and co-hydrothermal carbonization to enhance energy recovery from food waste digestate

AU - Zhu, Xiefei

AU - He, Mingjing

AU - Xu, Zibo

AU - Luo, Zejun

AU - Gao, Bin

AU - Ruan, Roger

AU - Wang, Chi Hwa

AU - Wong, Ka Hing

AU - Tsang, Daniel C.W.

N1 - Funding Information: This work was supported by the Fundamental Research Funds for the Central Universities (WK2090000037) and Hong Kong Environment and Conservation Fund (Project 101/2020). The authors appreciate the feedstock provision from the Hong Kong Environmental Protection Department. X.Z. thanks the funding of the Hong Kong Scholar Program (XJ2020022). Funding Information: This work was supported by the Fundamental Research Funds for the Central Universities ( WK2090000037 ) and Hong Kong Environment and Conservation Fund (Project 101/2020 ). The authors appreciate the feedstock provision from the Hong Kong Environmental Protection Department. X.Z. thanks the funding of the Hong Kong Scholar Program ( XJ2020022 ). Publisher Copyright: © 2022 Elsevier Ltd

PY - 2022/8/15

Y1 - 2022/8/15

N2 - To achieve clean and efficient utilization of food waste digestate (FWD), a novel strategy of combining acid pretreatment and co-hydrothermal carbonization was developed to prepare value-added hydrochar from food waste digestate. The acid pretreatment of FWD was carried out with 1 M HCl for 8 h at a solid-to-liquid ratio of 1:5. In addition to the characterization of physicochemical properties including proximate analysis, elemental content, heating value, and thermal stability of the hydrochar, TG-FTIR-MS and TG-DSC were used to evaluate the pyrolysis gaseous products and combustion performance of hydrochar. The results showed that the combination strategy enhanced the fuel properties of the hydrochar. In particular, the ash content of hydrochar was reduced to a minimum of 6.3%, thereby increasing the heating value by nearly two folds. The acid pretreatment and the addition of wood waste increased the H/C and O/C ratios of hydrochar while enhancing the thermal stability of hydrochar. The peak types of the infrared spectrum and mass spectrum of the pyrolysis gaseous products remained largely unchanged. Based on the comprehensive combustion index and combustion stability index, blending with wood waste could obtain a comparable combustion performance of the hydrochar with multiple cycles of acid pretreatment. The apparent activation energy of hydrochar was 102.0 and 90.4 kJ mol−1 by FWO and KAS methods, respectively. The strategy advocated here presents a new ‘green’ perspective for the large-scale energy recovery from food waste digestate that is currently under-utilized.

AB - To achieve clean and efficient utilization of food waste digestate (FWD), a novel strategy of combining acid pretreatment and co-hydrothermal carbonization was developed to prepare value-added hydrochar from food waste digestate. The acid pretreatment of FWD was carried out with 1 M HCl for 8 h at a solid-to-liquid ratio of 1:5. In addition to the characterization of physicochemical properties including proximate analysis, elemental content, heating value, and thermal stability of the hydrochar, TG-FTIR-MS and TG-DSC were used to evaluate the pyrolysis gaseous products and combustion performance of hydrochar. The results showed that the combination strategy enhanced the fuel properties of the hydrochar. In particular, the ash content of hydrochar was reduced to a minimum of 6.3%, thereby increasing the heating value by nearly two folds. The acid pretreatment and the addition of wood waste increased the H/C and O/C ratios of hydrochar while enhancing the thermal stability of hydrochar. The peak types of the infrared spectrum and mass spectrum of the pyrolysis gaseous products remained largely unchanged. Based on the comprehensive combustion index and combustion stability index, blending with wood waste could obtain a comparable combustion performance of the hydrochar with multiple cycles of acid pretreatment. The apparent activation energy of hydrochar was 102.0 and 90.4 kJ mol−1 by FWO and KAS methods, respectively. The strategy advocated here presents a new ‘green’ perspective for the large-scale energy recovery from food waste digestate that is currently under-utilized.

KW - Biochar/hydrochar stability

KW - Energy potential

KW - Food waste recycling

KW - Gaseous products

KW - Solid fuel

KW - Sustainable waste management

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ER -

Combined acid pretreatment and co-hydrothermal carbonization to enhance energy recovery from food waste digestate

Abstract

Bibliographical note

Keywords

UN SDGs

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