Hydrothermal carbonization of dry toilet residues as an added-value strategy – Investigation of process parameters

Wüst, Dominik; Correa, Catalina Rodríguez; Suwelack, Kay; Köhler, Hermann; Kruse, Andrea

doi:10.1016/j.jenvman.2019.01.005

Cited by 23 publications

(13 citation statements)

References 58 publications

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“…In comparison with the carbon content of 87.9 wt% in the pyrochar, the steam-activated pyrochar contains 86.9 wt% (Table 2). This agrees with the findings of Wüst et al [38], who reported that heat treatment of biomass increases the carbon content of the pyrochar produced. This also results in improved electrochemistry through structural reorganization of the carbon network toward graphitic structures [39].…”

Section: Composition Of the Corncob Pyrocharssupporting

confidence: 93%

Electricity generation in microbial fuel cell from wet torrefaction wastewater and locally developed corncob electrodes

et al. 2021

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Corncob pyrochar activated with steam (CCA) and nonactivated corncob pyrochar (NCC) were produced and characterized. The performance of the best material was tested in a dual-chambered microbial fuel cell (MFC) as an electrode for bioelectricity generation using wet torrefaction wastewater as substrate. Pyrolysis of 80.3 g of dried corncobs was carried out at 600 • C under a constant N 2 flow of 3 L min −1 for 30 min and the resulting pyrochar was activated using steam also at 600 • C. Voltage and current outputs from the MFC were recorded daily for 18 days. The proximate and Brunauer-Emmett-Teller (BET) surface area analyses revealed that CCA had the highest fixed carbon content of 71.9 % and higher surface area of 104.0 m 2 g −1 respectively. A larger pore diameter of 1.9 × 10 −3 µm was also recorded with the CCA than 1.2 × 10 −3 µm for NCC. The MFC produced a maximum power output of 21.5 mW. The physicochemical analyses of the wastewater effluent revealed an increased electrical conductivity from 1724 to 3460 µS cm −1 with a significant decrease by 91.9% in the total organic carbon (TOC) from 3700 to 298 mg L −1 . Steam activation increases the surface area, porosity, stability and redox reversibility of the corncob pyrochar. Therefore, steam-activated corncob pyrochar performed well in MFCs due to the high power output observed. K E Y W O R D Sbiobased corncob pyrochar, electrodes in MFC, power output of MFC, steam activation, wastewater This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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Section: Composition Of the Corncob Pyrocharssupporting

confidence: 93%

Electricity generation in microbial fuel cell from wet torrefaction wastewater and locally developed corncob electrodes

et al. 2021

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“…Another possibility for the lower VM content of hydrochar is, that, during the HTC, the degradation of hemicellulose and cellulose occurs at lower temperatures (160-180 • C) than during the pyrolysis because of the presence of subcritical water [32,33]. Such a reduction in the VM content increases the FC associated to the carbonization process [16,34,35]. The FC found in the produced chars is similar due to being three times bigger than in raw SSL (Table 2).…”

Section: Proximate and Ultimate Analysesmentioning

confidence: 99%

Combustion Characteristics of Hydrochar and Pyrochar Derived from Digested Sewage Sludge

et al. 2020

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In this paper, hydrochars and pyrochars were produced at 260 °C under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. Moreover, the combustion kinetics of raw SSL and the derived pyrochars and hydrochars without coal blending were determined at two different air flows (20 and 90 mL/min) and compared. In the same conditions, the yield of hydrochar was significantly lower than that of pyrochar, confirming the different reaction pathways followed in each process. The results showed hydrochars have lower carbon recovery and energy yield than pyrochars, making the latter more suitable for energy purposes. The thermogravimetric combustion study showed that both thermochemical treatments increased the ignition temperature but decreased the burnout temperature, which results in higher stability during handling and storage. However, raw SSL is better for combustion than hydrochar according to the combustibility index. In addition, the kinetic study showed that the activation energy of the combustion of biochars, especially pyrochar, is lower than that of raw SSL, which is advantageous for their combustion.

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“…It operates in presence of water, at comparatively mild temperatures (180-300 • C) and a corresponding saturation pressure [6][7][8][9][10][11]. The resulting solid product, usually called hydrochar (HC), is more stable and has higher carbon content than the starting substrate and improved (higher) heating value with respect to the char resulting from slow-pyrolysis or conventional carbonization at the same temperature [12][13][14]. In addition to the hydrochar, HTC gives rise to a high organic load aqueous stream [15,16], and a gas consisting mainly of CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Low-Cost Activated Grape Seed-Derived Hydrochar through Hydrothermal Carbonization and Chemical Activation for Sulfamethoxazole Adsorption

et al. 2019

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Activated carbons were prepared by chemical activation with KOH, FeCl3 and H3PO4 of the chars obtained via hydrothermal carbonization of grape seeds. The hydrochars prepared at temperatures higher than 200 °C yielded quite similar proximate and ultimate analyses. However, heating value (24.5–31.4 MJ·kg−1) and energy density (1.04–1.33) significantly increased with carbonization temperatures between 180 and 300 °C. All the hydrochars showed negligible BET surface areas, while values between 100 and 845 m2·g−1 were measured by CO2 adsorption at 273 K. Activation of the hydrochars with KOH (activating agent to hydrochar ratio of 3:1 and 750 °C) led to highly porous carbons with around 2200 m2·g−1 BET surface area. Significantly lower values were obtained with FeCl3 (321–417 m2·g−1) and H3PO4 (590–654 m2·g−1), showing these last activated carbons important contributors to mesopores. The resulting materials were tested in the adsorption of sulfamethoxazole from aqueous solution. The adsorption capacity was determined by the porous texture rather than by the surface composition, and analyzed by FTIR and TPD. The adsorption equilibrium data (20 °C) fitted the Langmuir equation well. The KOH-activated carbons yielded fairly high saturation capacity reaching up to 650 mg·g−1.

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Hydrothermal carbonization of dry toilet residues as an added-value strategy – Investigation of process parameters

Cited by 23 publications

References 58 publications

Electricity generation in microbial fuel cell from wet torrefaction wastewater and locally developed corncob electrodes

Electricity generation in microbial fuel cell from wet torrefaction wastewater and locally developed corncob electrodes

Combustion Characteristics of Hydrochar and Pyrochar Derived from Digested Sewage Sludge

Low-Cost Activated Grape Seed-Derived Hydrochar through Hydrothermal Carbonization and Chemical Activation for Sulfamethoxazole Adsorption

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