Browsing by Subject "hydrothermal carbonization"

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Access status: Open Access ,
Fuel properties characterization of hydrochars derived from agricultural digestate
(2025) Mikusińska, Joanna ; Szkadłubowicz, Klaudia ; Prus, Zuzanna ; Kuźnia, Monika; Gajek, Marcin; Wilk, Małgorzata
Wydział Inżynierii Metali i Informatyki Przemysłowej
Agricultural digestate is a by–product of biogas plant processes. Its composition is variable and depends on the type of raw feedstock used. Due to its high moisture content the digestate is suitable for hydrothermal carbonization (HTC). The HTC process is performed in a reactor where the feedstock is heated to a high temperature in an aqueous environment. As a result of the reaction, a solid product, process water and a gaseous product are generated. The gaseous product is obtained in trace amounts unlike the process water where the amount is significant. The rich in carbon solid product of the HTC process is hydrochar. Hydrochars can be used as an alternative to non–renewable fossil fuels. The aim of this paper was to investigate and characterize hydrochars derived from agricultural digestate at 190 ◦C, 200 ◦C and 210 ◦C and residence times of: 0.5, 1, 1.5, and 2 h. In addition, the fuel properties and combustion performance supported by an activation energy determination were evaluated. In brief, it was found that a higher temperature and longer residence time produced a more carbonaceous biofuel.
Access status: Open Access ,
Hydrothermal carbonization of digestate produced in the biogas production process
(2023) Mikusińska, Joanna; Kuźnia, Monika; Czerwińska, Klaudia; Wilk, Małgorzata
Wydział Inżynierii Metali i Informatyki Przemysłowej
In agricultural biogas plants, besides biogas, the by-product digestate is also produced. Due to its high moisture content and organic origin, it can successfully be applied in the hydrothermal carbonization process to avoid the fate of landfilling. This paper reviews the properties of agricultural digestate and its hydrothermal conversion (HTC) into hydrochar and process water. The type of feedstock and the parameters of the HTC process, such as temperature, pressure and residence time, affects the physical and chemical characteristics of hydrochar. Therefore, its possible application might be as a biofuel, fertilizer, soil improver, adsorber, or catalyst. In this paper, the properties of hydrochar derived from agricultural digestate are widely discussed.
Access status: Open Access ,
The effect of an acid catalyst on the hydrothermal carbonization of sewage sludge
(2023) Wilk, Małgorzata; Śliz, Maciej; Czerwińska, Klaudia; Śledź, Małgorzata
This research is focused on the addition of a catalyst, sulphuric acid (VI), to sewage sludge, and its effect on solid and liquid products resulting from the hydrothermal carbonization process. Consequently, for hydrochars, proximate and ultimate analyses, higher heating value and specific surface area were determined. Additionally, Fourier-transform infrared spectrophotometric and thermogravimetric analyses were conducted. The heavy metal contents in the ash composition of hydrochars were identified by X-ray fluorescence spectrometry. It was confirmed that the catalyst addition changed the structure as well as the physical and chemical properties of hydrochars and their ashes. Regarding post-processing water, both pH value and conductivity were determined and the element composition, including heavy metals, was conducted by the inductively coupled plasma optical emission and mass spectrometry analyses. It was found that the addition of the catalyst caused a decrease in heavy metal contents and an increase of phosphorus compound in filtrates.
Access status: Open Access ,
The treatment of post-processing liquid from the hydrothermal carbonization of sewage sludge
(2023) Czerwińska, Klaudia; Marszałek, Anna; Kudlek, Edyta; Śliz, Maciej; Dudziak, Mariusz; Wilk, Małgorzata
Wydział Inżynierii Metali i Informatyki Przemysłowej
The liquid phase, being amajor product of the hydrothermal carbonization of sewage sludge, is highly problematic due to numerous toxic compounds that make it impossible to dispose of without adequate purification. Therefore, this study is focused on the two groups of selected advanced methods of post-processing water derived from the hydrothermal carbonization process of sewage sludge. The first group included membrane processes, namely ultrafiltration, nanofiltration and double nanofiltration. The second included coagulation, ultrasonication and chlorination. Chemical and physical indicators were determined to confirm the validity of these treatment methods. The highest reduction values were found for double nanofiltration, which showed a spectacular decrease in the Chemical Oxygen Demand by 84.9 %, specific conductivity by 71.3%, nitrate nitrogen by 92.4%, phosphate phosphorus by 97.1%, total organic carbon by 83.3 %, total carbon by 83.6 %, and inorganic carbon by 88.5 %, as compared to the liquid phase after hydrothermal carbonization. In the second group, for the largest number of parameters, the greatest reduction was achieved when $10 cm^{3}/L$ of iron coagulant was added to the permeate from ultrafiltration. Additionally, COD decreased by 41 %, P-PO3-4 content by 78 %, phenol content by 34 %, TOC content by 97 %, TC content by 95 % and IC content by 40 %.