Sewage sludge charcoal production by N2- and CO2-torrefaction

A.B. Hernández, F. Okonta, N. Freeman

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The production of sewage sludge charcoals under N2 and CO2 as torrefaction atmosphere and their subsequent combustion was compared in this work. The experiments were carried out in a Thermogravimetry-Infrared Spectrometry (TGA-FTIR) analyser and a laboratory scale furnace. High temperatures (230-480 °C) were considered in order to study the removal of N- and S-compounds, one of the main concerns for the thermal valorisation of sewage sludge. Torrefaction treatment at 330 °C under N2 produced a charcoal with a 34% reduction in weight. The release of SO2 during the combustion of this charcoal was negligible and the release of NH3 and COS was reduced by half (46% for NH3 and 52.5% for COS) compared with the combustion of raw sewage sludge. The pollutant removal improved with torrefaction temperature and the charcoal produced at 480 °C released a negligible amount of NH3, COS and SO2 during combustion. The CO2 used as torrefaction atmosphere exhibited a reactive behaviour in the FTIR-TGA analyser, increasing the weight loss rate and shifting the characteristic degradation peak to a temperature around 7 °C lower. Besides, the charcoals produced under CO2 exhibited a less reactive behaviour. Overall, the results here presented prove that the CO2 influences slightly the torrefaction mechanisms and the properties of the sewage sludge charcoals produced. © 2017 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)4406-4414
Number of pages9
JournalJournal of Environmental Chemical Engineering
Volume5
Issue number5
DOIs
Publication statusPublished - 2017

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Charcoal
Sewage sludge
charcoal
combustion
thermogravimetry
pollutant removal
atmosphere
Temperature
Spectrometry
spectrometry
Thermogravimetric analysis
sewage sludge
Furnaces
temperature
Infrared radiation
Degradation
degradation
experiment
Experiments

Cite this

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title = "Sewage sludge charcoal production by N2- and CO2-torrefaction",
abstract = "The production of sewage sludge charcoals under N2 and CO2 as torrefaction atmosphere and their subsequent combustion was compared in this work. The experiments were carried out in a Thermogravimetry-Infrared Spectrometry (TGA-FTIR) analyser and a laboratory scale furnace. High temperatures (230-480 °C) were considered in order to study the removal of N- and S-compounds, one of the main concerns for the thermal valorisation of sewage sludge. Torrefaction treatment at 330 °C under N2 produced a charcoal with a 34{\%} reduction in weight. The release of SO2 during the combustion of this charcoal was negligible and the release of NH3 and COS was reduced by half (46{\%} for NH3 and 52.5{\%} for COS) compared with the combustion of raw sewage sludge. The pollutant removal improved with torrefaction temperature and the charcoal produced at 480 °C released a negligible amount of NH3, COS and SO2 during combustion. The CO2 used as torrefaction atmosphere exhibited a reactive behaviour in the FTIR-TGA analyser, increasing the weight loss rate and shifting the characteristic degradation peak to a temperature around 7 °C lower. Besides, the charcoals produced under CO2 exhibited a less reactive behaviour. Overall, the results here presented prove that the CO2 influences slightly the torrefaction mechanisms and the properties of the sewage sludge charcoals produced. {\circledC} 2017 Elsevier Ltd. All rights reserved.",
author = "A.B. Hern{\'a}ndez and F. Okonta and N. Freeman",
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Sewage sludge charcoal production by N2- and CO2-torrefaction. / Hernández, A.B.; Okonta, F.; Freeman, N.

In: Journal of Environmental Chemical Engineering, Vol. 5, No. 5, 2017, p. 4406-4414.

Research output: Contribution to journalArticle

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AB - The production of sewage sludge charcoals under N2 and CO2 as torrefaction atmosphere and their subsequent combustion was compared in this work. The experiments were carried out in a Thermogravimetry-Infrared Spectrometry (TGA-FTIR) analyser and a laboratory scale furnace. High temperatures (230-480 °C) were considered in order to study the removal of N- and S-compounds, one of the main concerns for the thermal valorisation of sewage sludge. Torrefaction treatment at 330 °C under N2 produced a charcoal with a 34% reduction in weight. The release of SO2 during the combustion of this charcoal was negligible and the release of NH3 and COS was reduced by half (46% for NH3 and 52.5% for COS) compared with the combustion of raw sewage sludge. The pollutant removal improved with torrefaction temperature and the charcoal produced at 480 °C released a negligible amount of NH3, COS and SO2 during combustion. The CO2 used as torrefaction atmosphere exhibited a reactive behaviour in the FTIR-TGA analyser, increasing the weight loss rate and shifting the characteristic degradation peak to a temperature around 7 °C lower. Besides, the charcoals produced under CO2 exhibited a less reactive behaviour. Overall, the results here presented prove that the CO2 influences slightly the torrefaction mechanisms and the properties of the sewage sludge charcoals produced. © 2017 Elsevier Ltd. All rights reserved.

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