Combustion Characteristics of Hydrochar and Pyrochar Derived from Digested Sewage Sludge

Arauzo, Pablo J.; Atienza-Martínez, María; Ábrego, Javier; Olszewski, Maciej P.; Cao, Zebin; Kruse, Andrea

doi:10.3390/en13164164

Cited by 44 publications

(17 citation statements)

References 58 publications

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“…The biochar yield was highest for pyrolysis of digestates (44.8% for B-D1 and 45.5% for B-D2), lower for SS (32.5%), and lowest for TLP pyrolysis (25.6%). Biochar yields and higher heating values listed in Table 6 are comparable with the data for SS [95], and other bio-waste [50] given in the literature. The ash content in the biochars increased compared to the feedstocks.…”

Section: Chemical Characteristics Of Biocharssupporting

confidence: 85%

Pyrolysis of Solid Digestate from Sewage Sludge and Lignocellulosic Biomass: Kinetic and Thermodynamic Analysis, Characterization of Biochar

Petrović

Vohl

Predikaka³

et al. 2021

Sustainability

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This study investigates the pyrolysis behavior and reaction kinetics of two different types of solid digestates from: (i) sewage sludge and (ii) a mixture of sewage sludge and lignocellulosic biomass—Typha latifolia plant. Thermogravimetric data in the temperature range 25–800 °C were analyzed using Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose kinetic methods, and the thermodynamic parameters (ΔH, ΔG, and ΔS) were also determined. Biochars were characterized using different chemical methods (FTIR, SEM–EDS, XRD, heavy metal, and nutrient analysis) and tested as soil enhancers using a germination test. Finally, their potential for biosorption of NH4+, PO43−, Cu2+, and Cd2+ ions was studied. Kinetic and thermodynamic parameters revealed a complex degradation mechanism of digestates, as they showed higher activation energies than undigested materials. Values for sewage sludge digestate were between 57 and 351 kJ/mol, and for digestate composed of sewage sludge and T. latifolia between 62 and 401 kJ/mol. Characterizations of biochars revealed high nutrient content and promising potential for further use. The advantage of biochar obtained from a digestate mixture of sewage sludge and lignocellulosic biomass is the lower content of heavy metals. Biosorption tests showed low biosorption capacity of digestate-derived biochars and their modifications for NH4+ and PO43− ions, but high biosorption capacity for Cu2+ and Cd2+ ions. Modification with KOH was more efficient than modification with HCl. The digestate-derived biochars exhibited excellent performance in germination tests, especially at concentrations between 6 and 10 wt.%.

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Section: Chemical Characteristics Of Biocharssupporting

confidence: 85%

Pyrolysis of Solid Digestate from Sewage Sludge and Lignocellulosic Biomass: Kinetic and Thermodynamic Analysis, Characterization of Biochar

Petrović

Vohl

Predikaka³

et al. 2021

Sustainability

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“…[28] Although the yield of hydrochar at high temperatures is relatively low, the proportion of carbon in hydrochar is high, indicating that a significant amount of carbon is retained in the solid. [142][143]…”

Section: Elemental Compositionmentioning

confidence: 99%

Towards Negative Emissions: Hydrothermal Carbonization of Biomass for Sustainable Carbon Materials

Yu,

He,

Zhang

et al. 2024

Advanced Materials

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The contemporary production of carbon materials heavily relies on fossil fuels, contributing significantly to the greenhouse effect. Biomass is a carbon‐neutral resource whose organic carbon is formed from atmospheric CO2. Employing biomass as a precursor for synthetic carbon materials can fix atmospheric CO2 into solid materials, achieving negative carbon emissions. Hydrothermal carbonization (HTC) presents an attractive method for converting biomass into carbon materials, by which biomass can be transformed into materials with favorable properties in a distinct hydrothermal environment, and these carbon materials have made extensive progress in many fields. However, the HTC of biomass is a complex and interdisciplinary problem, involving simultaneously the physical properties of the underlying biomass and sub/supercritical water, the chemical mechanisms of hydrothermal synthesis, diverse applications of resulting carbon materials, and the sustainability of the entire technological routes. This review starts with the analysis of biomass composition and distinctive characteristics of the hydrothermal environment. Then, the factors influencing the HTC of biomass, the reaction mechanism, and the properties of resulting carbon materials are discussed in depth, especially the different formation mechanisms of primary and secondary hydrochars. Furthermore, the application and sustainability of biomass‐derived carbon materials are summarized, and some insights into future directions are provided.This article is protected by copyright. All rights reserved

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“…However, this strategy does not account for benefits regarding the production of hydrochar and positive effects associated with its application as it would be the use of char as a supplement in the same digestion process for producing active fertilizers. Arauzo et al [73] studied the combustion characteristics of digested material and the pyrochar and hydrochar obtained from the thermal processing of digestate, and reported better combustion characteristics for digestate and pyrochar, whereas hydrochar presented a poor combustion scenario.…”

Section: Scenariomentioning

confidence: 99%

Feasibility of Coupling Anaerobic Digestion and Hydrothermal Carbonization: Analyzing Thermal Demand

et al. 2021

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Anaerobic digestion is a biological process with wide application for the treatment of high organic-containing streams. The production of biogas and the lack of oxygen requirements are the main energetic advantages of this process. However, the digested stream may not readily find a final disposal outlet under certain circumstances. The present manuscript analyzed the feasibility of valorizing digestate by the hydrothermal carbonization (HTC) process. A hypothetical plant treating cattle manure and cheese whey as co-substrate (25% v/w, wet weight) was studied. The global performance was evaluated using available data reported in the literature. The best configuration was digestion as a first stage with the subsequent treatment of digestate in an HTC unit. The treatment of manure as sole substrate reported a value of 752 m3/d of biogas which could be increased to 1076 m3/d (43% increase) when coupling an HTC unit for digestate post-treatment and the introduction of the co-substrate. However, the high energy demand of the combined configurations indicated, as the best alternative, the valorization of just a fraction (15%) of digestate to provide the benefits of enhancing biogas production. This configuration presented a much better energy performance than the thermal hydrolysis pre-treatment of manure. The increase in biogas production does not compensate for the high energy demand of the pre-treatment unit. However, several technical factors still need further research to make this alternative a reality, as it is the handling and pumping of high solid slurries that significantly affects the energy demand of the thermal treatment units and the possible toxicity of hydrochar when used in a biological process.

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Combustion Characteristics of Hydrochar and Pyrochar Derived from Digested Sewage Sludge

Cited by 44 publications

References 58 publications

Pyrolysis of Solid Digestate from Sewage Sludge and Lignocellulosic Biomass: Kinetic and Thermodynamic Analysis, Characterization of Biochar

Pyrolysis of Solid Digestate from Sewage Sludge and Lignocellulosic Biomass: Kinetic and Thermodynamic Analysis, Characterization of Biochar

Towards Negative Emissions: Hydrothermal Carbonization of Biomass for Sustainable Carbon Materials

Feasibility of Coupling Anaerobic Digestion and Hydrothermal Carbonization: Analyzing Thermal Demand

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