The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar

Poultry litter was converted to biochar by torrefaction and to hydrochar by hydrothermal carbonisation. Many parameters were measured for the resulting chars, to investigate the effects of the production method and production temperature. SEM showed the presence of large quantities of crystalline ma...

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Main Authors: Joyce Clarke, Maria Olea
Format: Article
Language:English
Published: MDPI AG 2024-06-01
Series:Reactions
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Online Access:https://www.mdpi.com/2624-781X/5/3/20
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author Joyce Clarke
Maria Olea
author_facet Joyce Clarke
Maria Olea
author_sort Joyce Clarke
collection DOAJ
description Poultry litter was converted to biochar by torrefaction and to hydrochar by hydrothermal carbonisation. Many parameters were measured for the resulting chars, to investigate the effects of the production method and production temperature. SEM showed the presence of large quantities of crystalline material on the surface of the biochars. The elemental composition of some crystals was determined as 35% K and 31% Cl. This was confirmed as sylvite (KCl) crystals, which explains the high levels of water-extractable potassium in the biochar and may also be important in germination inhibition. Biochars almost totally inhibited germination, whilst hydrochars decreased germination. Although germination occurred on hydrochar, root growth was severely inhibited. Consequently, the germination index may be better to determine total phytotoxicity as it measures both effects and could be used as a bioassay for chars used as soil amendments. Washing removed germination inhibition in a low-temperature char (350 °C), possibly by removing KCl; however, root toxicity remained. There were very low levels of heavy metals, suggesting they are not the source of toxicity. In biochars, pore mean size decreased with temperature from 350 °C to 600 °C, due to changes in pore size distribution. The mean pore size was measured directly using SEM. The merits of this method are discussed. Low-temperature biochars seem best suited for fuel as they have a high calorific value, high hydrophobicity, a low ash content and a high yield. Higher temperatures are better for soil amendment and sequestration applications with a smaller mean pore size, higher surface area, and higher pH.
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spelling doaj-art-0ee6b8b5057c4fa8a2afb0773fd00dc82025-08-20T01:55:49ZengMDPI AGReactions2624-781X2024-06-015337941810.3390/reactions5030020The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter BiocharJoyce Clarke0Maria Olea1Unaffiliated, Middlesbrough TS5 7HQ, UKInstitute of Continuing Education (ICE), University of Cambridge, Madingley Hall, Cambridge CB23 8AQ, UKPoultry litter was converted to biochar by torrefaction and to hydrochar by hydrothermal carbonisation. Many parameters were measured for the resulting chars, to investigate the effects of the production method and production temperature. SEM showed the presence of large quantities of crystalline material on the surface of the biochars. The elemental composition of some crystals was determined as 35% K and 31% Cl. This was confirmed as sylvite (KCl) crystals, which explains the high levels of water-extractable potassium in the biochar and may also be important in germination inhibition. Biochars almost totally inhibited germination, whilst hydrochars decreased germination. Although germination occurred on hydrochar, root growth was severely inhibited. Consequently, the germination index may be better to determine total phytotoxicity as it measures both effects and could be used as a bioassay for chars used as soil amendments. Washing removed germination inhibition in a low-temperature char (350 °C), possibly by removing KCl; however, root toxicity remained. There were very low levels of heavy metals, suggesting they are not the source of toxicity. In biochars, pore mean size decreased with temperature from 350 °C to 600 °C, due to changes in pore size distribution. The mean pore size was measured directly using SEM. The merits of this method are discussed. Low-temperature biochars seem best suited for fuel as they have a high calorific value, high hydrophobicity, a low ash content and a high yield. Higher temperatures are better for soil amendment and sequestration applications with a smaller mean pore size, higher surface area, and higher pH.https://www.mdpi.com/2624-781X/5/3/20poultry littertorrefactionhydrothermal carbonisationbiocharhydrochargermination
spellingShingle Joyce Clarke
Maria Olea
The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
Reactions
poultry litter
torrefaction
hydrothermal carbonisation
biochar
hydrochar
germination
title The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
title_full The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
title_fullStr The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
title_full_unstemmed The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
title_short The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
title_sort effect of temperature and treatment regime on the physical chemical and biological properties of poultry litter biochar
topic poultry litter
torrefaction
hydrothermal carbonisation
biochar
hydrochar
germination
url https://www.mdpi.com/2624-781X/5/3/20
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