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Luo X, Pei X, Zhang X, Du H, Ju L, Li S, Chen L, Zhang J. Advancing hydrothermal carbonization: Assessing hydrochar's role and challenges in carbon sequestration. ENVIRONMENTAL RESEARCH 2025; 270:121023. [PMID: 39914712 DOI: 10.1016/j.envres.2025.121023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2024] [Revised: 01/31/2025] [Accepted: 02/01/2025] [Indexed: 02/14/2025]
Abstract
The increasing urgency to reduce atmospheric CO2 emissions has driven research into sustainable carbon sequestration technologies, with hydrochar (HC) emerging as a promising material. HC is derived from hydrothermal carbonization (HTC), a thermochemical process that converts biomass into a carbon-rich solid at moderate temperatures and self-generated pressure in an aqueous environment. Due to its unique reaction pathways, HC differs significantly from biochar (BC) derived from pyrolysis in terms of application, performance, and structural characteristics. Despite HC's potential for long-term carbon storage, critical gaps remain in understanding its sequestration mechanisms, influencing factors, and optimization strategies-hindering its effective application. This review critically evaluates HC's carbon sequestration capacity, focusing on overlooked complexities that influence its performance. Key parameters, including feedstock composition, reaction temperature, pH, and residence time, are systematically examined to elucidate their impact on HC's structural integrity and carbon stability. Special attention is given to the role of lignin in enhancing stability and thermal resilience, as well as the concept of carbon-ash recalcitrance, where mineral embedding enhances carbon stability. To assess HC's long-term sequestration effectiveness, this study analyzes key indicators such as thermal stability, chemical resilience, aromaticity, and dissolved organic carbon (DOC) leaching.Besides, this review explores innovative strategies for improving HC's sequestration performance, including HTC liquid recycling, chemical modification, and salinity control. By integrating expert-driven insights and identifying research gaps, this synthesis advances theoretical understanding while outlining future directions for optimizing HC as a sustainable carbon sink. Ultimately, this work establishes HC as a critical material in global carbon management efforts and climate change mitigation.
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Affiliation(s)
- Xin Luo
- State Key Laboratory of Geological Disaster Prevention and Geological Environment Protection, Chengdu University of Technology, 610059, China; Tianfu Yongxing Laboratory, Chengdu, 610200, China
| | - Xiangjun Pei
- State Key Laboratory of Geological Disaster Prevention and Geological Environment Protection, Chengdu University of Technology, 610059, China; Tianfu Yongxing Laboratory, Chengdu, 610200, China
| | - Xiaochao Zhang
- State Key Laboratory of Geological Disaster Prevention and Geological Environment Protection, Chengdu University of Technology, 610059, China; Tianfu Yongxing Laboratory, Chengdu, 610200, China.
| | - Haiying Du
- Key Laboratory of Coordinated Control and Joint Remediation of Water and Soil Pollution for National Environmental Protection, College of Ecological Environment, Chengdu University of Technology, Chengdu, 610059, China.
| | - Linxue Ju
- Geological Institute of China Chemical Geology and Mine Bureau, Beijing, 100101, China
| | - Shengwei Li
- Chengdu Center of China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu, 610218, China
| | - Lei Chen
- Tianjin Normal University, Tianjin, 300387, China
| | - Junji Zhang
- Chengdu Center of China Geological Survey (Geosciences Innovation Center of Southwest China), Chengdu, 610218, China
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Lang Q, Guo X, Wang C, Li L, Li Y, Xu J, Zhao X, Li J, Liu B, Sun Q, Zou G. Characteristics and phytotoxicity of hydrochar-derived dissolved organic matter: Effects of feedstock type and hydrothermal temperature. J Environ Sci (China) 2025; 149:139-148. [PMID: 39181629 DOI: 10.1016/j.jes.2023.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 08/27/2024]
Abstract
The dissolved organic matter (DOM) with high mobility and reactivity plays a crucial role in soil. In this study, the characteristics and phytotoxicity of DOM released from the hydrochars prepared from different feedstocks (cow manure, corn stalk and Myriophyllum aquaticum) under three hydrothermal carbonization (HTC) temperatures (180, 200 and 220°C) were evaluated. The results showed that the hydrochars had high dissolved organic carbon content (20.15 to 37.65 mg/g) and its content showed a gradual reduction as HTC temperature increased. Three fluorescent components including mixed substance of fulvic acid-like and humic acid-like substances (C1, 30.92%-58.32%), UVA humic acid-like substance (C2, 25.27%-29.94%) and protein-like substance (C3, 11.74%-41.92%) were identified in hydrochar DOM by excitation emission matrix spectra coupled with parallel factor analysis. High HTC temperature increased the relative proportion of aromatic substances (C1+C2) and humification degree of hydrochar DOM from cow manure, while it presented adverse effects on the hydrochar DOM from corn stalk and Myriophyllum. aquaticum. The principal component analysis suggested that feedstock type and HTC temperature posed significant effects on the characteristics of hydrochar DOM. Additionally, seed germination test of all hydrochar DOM demonstrated that the root length was reduced by 8.88%-26.43% in contrast with control, and the germination index values were 73.57%-91.12%. These findings provided new insights into the potential environmental effects for hydrochar application in soil.
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Affiliation(s)
- Qianqian Lang
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Xuan Guo
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Chao Wang
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Lingyao Li
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Yufei Li
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Junxiang Xu
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Xiang Zhao
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Jijin Li
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Bensheng Liu
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Qinping Sun
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
| | - Guoyuan Zou
- Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
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Lima ETG, Sales ÉDS, Saraiva RDA, Rachide Nunes R. Study on the auxin-like activity of organic compounds extracted from corn waste hydrochar prepared by hydrothermal carbonization. ENVIRONMENTAL TECHNOLOGY 2024; 45:5558-5567. [PMID: 38190259 DOI: 10.1080/09593330.2023.2298663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 12/15/2023] [Indexed: 01/10/2024]
Abstract
This work studied the auxin-like activity of liquid and solid hydrochar from aboveground corn biomass prepared using hydrothermal carbonization (HTC). Understanding the action of organic compounds in regulating plant metabolism is important to develop strategies to improve plant growth and production. Bioassays were performed by testing liquid hydrochar concentrations in the range of 0.0557-5570.0 mg carbon L-1; and solid hydrochar (via extracted dissolved organic matter, DOM) in the range of 0.026-2600.0 mg carbon L-1, using seeds of Lactuca sativa. SEM, ATR-FTIR, and Py-GC/MS were applied to assess the effect of HTC on hydrochar production/composition. Liquid hydrochar presented an intense bioactivity, completely inhibiting the germination of testing seeds at higher concentrations. Liquid hydrochar also was considerably more bioactive. Py-GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids (linear and aromatic) and amino acids. The concentration of more bioactive molecules, rather than their simple presence in the hydrochar fraction, determined the bio-stimulating effect, besides an excellent linear regression between the auxin-like effect and the concentration of active molecules.
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Affiliation(s)
| | | | | | - Ramom Rachide Nunes
- Department of Chemistry, Federal Rural University of Pernambuco, Recife, Brazil
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Yang C, Xia P, Zhao L, Wang K, Wang B, Huang R, Yang H, Yao Y. Hydrothermal carbonization of woody waste: Changes in the physicochemical properties and the structural evolution mechanisms of hydrochar during this process. CHEMOSPHERE 2024; 366:143524. [PMID: 39395478 DOI: 10.1016/j.chemosphere.2024.143524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 09/16/2024] [Accepted: 10/09/2024] [Indexed: 10/14/2024]
Abstract
The Chinese medicine residue (CMR) is composed of wet woody waste, including licorice and ephedra, so using hydrothermal carbonization (HTC) to recover renewable energy from the CMR is a suitable treatment method. An in-depth analysis of the physicochemical properties and structural evolution mechanism of hydrochars is helpful in fundamentally promoting the energy utilization of traditional Chinese medicine waste residue. Therefore, this study analyzed the physicochemical properties and morphological structure of hydrochar produced under varying HTC conditions using multiple testing methods. The evolution of the hydrochar's structural characteristics can be categorized into three stages: component decomposition, structural rearrangement, and carbonization. During the component decomposition and carbonization stages, numerous nanoscale micropores form within the hydrochar. These micropores' specific surface area and pore volume can reach up to 113.420 m2/g and 0.01913 cm3/g, respectively. The highest fractal dimension values for D1 and D2 are 2.6354 and 2.5565, while the maximum values for the microcrystalline stacking height (Lc) and the average number of crystalline layers (Nave) are 0.3354 and 1.9968, respectively. Consequently, the hydrochar produced during these stages exhibits a rougher pore surface and a more complex structure, making it more suitable for adsorbing heavy metals from soil and sequestering CO2. During the structural rearrangement stage, the hydrochar exhibits higher contents of fixed carbon (FC), MgO, P2O5, and a higher C/N atomic ratio, with maximum values of 38.51%, 0.99%, 1.12%, and 28.49, respectively. Thus, the hydrochar produced during this stage is more suitable for soil remediation and nutrient recovery.
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Affiliation(s)
- Cong Yang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Peng Xia
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment Ministry of Education, Guizhou University, Guiyang, 550025, China.
| | - Lingyun Zhao
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Key Laboratory of Unconventional Natural Gas Evaluation and Development in Complex Tectonic Areas, Ministry of Natural Resources, Guiyang, 550081, China; Guizhou Academy of Petroleum Exploration and Development Engineering, Guiyang, 550081, China
| | - Ke Wang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Bing Wang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Rui Huang
- College of Electrical Engineering, Guizhou University, Guiyang, 550025, China
| | - Huan Yang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Yuanzhu Yao
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
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Luo X, Du H, Du J, Zhang X, Xiao W, Qin L. The influence of biomass type on hydrothermal carbonization: Role of calcium oxalate in enhancing carbon sequestration of hydrochar. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 349:119586. [PMID: 37984272 DOI: 10.1016/j.jenvman.2023.119586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/22/2023] [Accepted: 11/04/2023] [Indexed: 11/22/2023]
Abstract
Addressing climate change through effective carbon sequestration strategies is critical. This study presents an investigation into the hydrothermal carbonization (HTC) and co-hydrothermal carbonization (Co-HTC) of invasive plants (IPs) to produce hydrochars to unveil the significant impact of biomass type and unique mineral on the stability of hydrochars. Nine hydrochars were produced from six IPs, utilizing both single and mixed biomass. A key finding is the observable that calcium oxalate forms as a surface mineral during HTC through different characterization techniques, the presence of which notably influenced the stability of hydrochars, resulting in enhanced thermal (highest R50 = 0.81) and chemical (lowest carbon loss rate = 4.02%) stability of hydrochars, possibly acting as a protective layer. Besides, a positive correlation was established between the yield of hydrochars and the lignin content of the original biomass. It is also observed that Co-HTC of plant materials rich in Ca2+ can enhance the formation of calcium oxalate minerals. This is likely due to their synergistic role in the HTC process, promoting the release of more C2O42- and Ca2+. Our results signify the crucial role of biomass composition in the HTC process and spotlight the potential of calcium oxalate in augmenting hydrochar stability. This study offers valuable insights that bolster the theoretical framework for employing hydrochar derived from IPs as a potent material for carbon sequestration.
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Affiliation(s)
- Xin Luo
- Key Laboratory of Coordinated Control and Joint Remediation of Water and Soil Pollution for National Environmental Protection, College of Ecological Environment, Chengdu University of Technology, Chengdu, 610059, China
| | - Haiying Du
- Key Laboratory of Coordinated Control and Joint Remediation of Water and Soil Pollution for National Environmental Protection, College of Ecological Environment, Chengdu University of Technology, Chengdu, 610059, China
| | - Jie Du
- Jiuzhaigou Administration, Aba, 623400, China
| | - Xiaochao Zhang
- Key Laboratory of Coordinated Control and Joint Remediation of Water and Soil Pollution for National Environmental Protection, College of Ecological Environment, Chengdu University of Technology, Chengdu, 610059, China; State Key Laboratory of Geological Disaster Prevention and Geological Environment Protection, Chengdu University of Technology, 610059, China.
| | | | - Liang Qin
- Sichuan Huadi Construction Engineering Co., Ltd, Chengdu, 610036, China
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Zhang Y, Zhao Y, Ji J, Zhang W, Wei W, Li J, Liu Y, Tao H, Zhang H. Reduction and valorization of dairy manure by organic chelating acid-assisted hydrothermal process: Dewatering performance, energy recovery, and effluent toxicity. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 163:134-143. [PMID: 37011561 DOI: 10.1016/j.wasman.2023.03.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/07/2023] [Accepted: 03/28/2023] [Indexed: 06/19/2023]
Abstract
Livestock manure with high moisture content is a challenge for management and further disposal. In this study, the organic chelating acid(EDTA)-assisted hydrothermal (EAHT) process was used to achieve dewatering, dry mass minimization, and volume reduction of dairy manure (DM). The hydrophobic modification of DM resulted in a 55% reduction in dry mass, and the specific resistance to filtration (SRF) showed a shift in dewatering performance from unfilterable to highly filterable. An investigation of the reaction mechanisms suggests that proteins and polysaccharides were released from the damaged extracellular polymeric substances (EPS) of the DM into effluent. The surface functional groups of the hydrochar were changed from hydrophilic to hydrophobic, which promotes the transformation of bound water to free water in the DM with enhanced dewatering performance. The obtained hydrochar at 17.5 mg/g EDTA dosage exhibited the highest calorific value (HHVdaf = 29.25 MJ/kg). The HHVdry of samples have little difference and approach that of anthracite coal (19.2-21.1 MJ/kg)After EAHT, the combustion safety of the hydrochar was improved, which is highly significant for its use as biofuel. The by-product effluent showed lower biological toxicity after EAHT than after HT. The findings of this study demonstrated that EAHT can be efficient in achieving DM reduction and energy recovery, which provides widespread agricultural and environmental application prospects.
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Affiliation(s)
- Yihang Zhang
- School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Yuqing Zhao
- School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Jie Ji
- School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Weitao Zhang
- Hebei Animal Husbandry Station, 19 Changjiang Avenue, Shijiazhuang, Hebei Province 050035, China
| | - Wei Wei
- Hebei Animal Husbandry Station, 19 Changjiang Avenue, Shijiazhuang, Hebei Province 050035, China
| | - Jia Li
- Hebei Animal Husbandry Station, 19 Changjiang Avenue, Shijiazhuang, Hebei Province 050035, China
| | - Yue Liu
- Hebei Institute of animal husbandry and veterinary medicine, 428 Dongguan street, Baodin, Hebei Province 071000, China
| | - Hong Tao
- School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - He Zhang
- School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China.
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Cavali M, Libardi Junior N, de Sena JD, Woiciechowski AL, Soccol CR, Belli Filho P, Bayard R, Benbelkacem H, de Castilhos Junior AB. A review on hydrothermal carbonization of potential biomass wastes, characterization and environmental applications of hydrochar, and biorefinery perspectives of the process. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159627. [PMID: 36280070 DOI: 10.1016/j.scitotenv.2022.159627] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/17/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
It is imperative to search for appropriate processes to convert wastes into energy, chemicals, and materials to establish a circular bio-economy toward sustainable development. Concerning waste biomass valorization, hydrothermal carbonization (HTC) is a promising route given its advantages over other thermochemical processes. From that perspective, this article reviewed the HTC of potential biomass wastes, the characterization and environmental utilization of hydrochar, and the biorefinery potential of this process. Crop and forestry residues and sewage sludge are two categories of biomass wastes (lignocellulosic and non-lignocellulosic, respectively) readily available for HTC or even co-hydrothermal carbonization (Co-HTC). The temperature, reaction time, and solid-to-liquid ratio utilized in HTC/Co-HTC of those biomass wastes were reported to range from 140 to 370 °C, 0.05 to 48 h, and 1/47 to 1/1, respectively, providing hydrochar yields of up to 94 % according to the process conditions. Hydrochar characterization by different techniques to determine its physicochemical properties is crucial to defining the best applications for this material. In the environmental field, hydrochar might be suitable for removing pollutants from aqueous systems, ameliorating soils, adsorbing atmospheric pollutants, working as an energy carrier, and performing carbon sequestration. But this material could also be employed in other areas (e.g., catalysis). Regarding the effluent from HTC/Co-HTC, this byproduct has the potential for serving as feedstock in other processes, such as anaerobic digestion and microalgae cultivation. These opportunities have aroused the industry interest in HTC since 2010, and the number of industrial-scale HTC plants and patent document applications has increased. The hydrochar patents are concentrated in China (77.6 %), the United States (10.6 %), the Republic of Korea (3.5 %), and Germany (3.5 %). Therefore, considering the possibilities of converting their product (hydrochar) and byproduct (effluent) into energy, chemicals, and materials, HTC or Co-HTC could work as the first step of a biorefinery. And this approach would completely agree with circular bioeconomy principles.
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Affiliation(s)
- Matheus Cavali
- Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, 88040-970 Florianópolis, Santa Catarina, Brazil.
| | - Nelson Libardi Junior
- Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, 88040-970 Florianópolis, Santa Catarina, Brazil
| | - Julia Dutra de Sena
- Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, 88040-970 Florianópolis, Santa Catarina, Brazil
| | - Adenise Lorenci Woiciechowski
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, 81531-908 Curitiba, Paraná, Brazil
| | - Carlos Ricardo Soccol
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, 81531-908 Curitiba, Paraná, Brazil
| | - Paulo Belli Filho
- Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, 88040-970 Florianópolis, Santa Catarina, Brazil
| | - Rémy Bayard
- DEEP (Déchets Eaux Environnement Pollutions) Laboratory, National Institute of Applied Sciences of Lyon, 69100 Villeurbanne, France
| | - Hassen Benbelkacem
- DEEP (Déchets Eaux Environnement Pollutions) Laboratory, National Institute of Applied Sciences of Lyon, 69100 Villeurbanne, France
| | - Armando Borges de Castilhos Junior
- Department of Sanitary and Environmental Engineering, Federal University of Santa Catarina, 88040-970 Florianópolis, Santa Catarina, Brazil
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Zhang X, Qin Q, Sun X, Wang W. Hydrothermal treatment: An efficient food waste disposal technology. Front Nutr 2022; 9:986705. [PMID: 36172524 PMCID: PMC9512071 DOI: 10.3389/fnut.2022.986705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
The quantities of food waste (FW) are increasing yearly. Proper disposal of FW is essential for reusing value-added products, environmental protection, and human health. Based on the typical characteristics of high moisture content and high organic content of FW, hydrothermal treatment (HTT), as a novel thermochemical treatment technology, plays unique effects in the disposal and utilization of FW. The HTT of FW has attracted more and more attention in recent years, however, there are few conclusive reviews about the progress of the HTT of FW. HTT is an excellent approach to converting energy-rich materials into energy-dense fuels and valuable chemicals. This process can handle biomass with relatively high moisture content and allows efficient heat integration. This mini-review presents the current knowledge of recent advances in HTT of FW. The effects of HTT temperature and duration on organic nutritional compositions (including carbohydrates, starch, lipids, protein, cellulose, hemicellulose, lignin, etc.) and physicochemical properties (including pH, elemental composition, functional groups, fuel properties, etc.) and structural properties of FW are evaluated. The compositions of FW can degrade during HTT so that the physical and chemical properties of FW can be changed. The application and economic analyses of HTT in FW are summarized. Finally, the analyses of challenges and future perspectives on HTT of FW have shown that industrial reactors should be built effectively, and techno-economic analysis, overall energy balance, and life cycle assessment of the HTT process are necessary. The mini-review offers new approaches and perspectives for the efficient reuse of food waste.
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Affiliation(s)
- Xinyan Zhang
- National Engineering Laboratory for Reducing Emissions from Coal Combustion, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong University, Jinan, China
- *Correspondence: Xinyan Zhang
| | - Qingyu Qin
- Laboratory of Biomass and Bioprocessing Engineering, College of Engineering, China Agricultural University, Beijing, China
| | - Xun Sun
- Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan, China
- Xun Sun
| | - Wenlong Wang
- National Engineering Laboratory for Reducing Emissions from Coal Combustion, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong University, Jinan, China
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Hydrothermal Carbonization of Spent Coffee Grounds for Producing Solid Fuel. SUSTAINABILITY 2022. [DOI: 10.3390/su14148818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Spent coffee grounds (SCG) are industrial biowaste resulting from the coffee-brewing process, and they are often underutilized and end up in landfills, thereby leading to the emission of toxic gases and environmental damage. Hydrothermal carbonization (HTC) is an attractive approach to valorize wet biomass such as SCG to valuable bioproducts (i.e., hydrochar). Thus, in this work, the HTC of SCG was carried out in a 500 L stainless steel vessel at 150, 170, 190, 210, and 230 °C for 30 min, 60 min, 90 min, and 120 min and a feedstock to water weight ratio of 1:5, 1:10, and 1:15, and the use of the resulting hydrochar as a solid fuel was evaluated. The results showed that a high energy recovery (83.93%) and HHV (23.54 MJ/kg) of hydrochar was obtained at moderate conditions (150 °C, 30 min, and feedstock to water weight ratio of 1:5) when compared with conventional approaches such as torrefaction. Following this, the surface morphology, functionality, and combustion behavior of this hydrochar were characterized by SEM, FTIR, and TGA, respectively. In short, it can be concluded that HTC is an effective approach for producing solid fuel from SCG and the resulting hydrochar has the potential to be applied either in domestic heating or large-scale co-firing plants.
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