A prototype system for the hydrothermal oxidation of feces
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Author (Corporation)
Publication date
14.11.2022
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Type
01A - Journal article
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Parent work
Water Research: X
Special issue
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Volume
17
Issue / Number
Pages / Duration
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Publisher / Publishing institution
Elsevier
Place of publication / Event location
Amsterdam
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Abstract
To ensure access to safe sanitation facilities in rural communities, cheap off-grid technologies need to be
developed to substitute pit latrines and open defecation. In this study, we present a prototype system based on
hydrothermal oxidation, which, under optimal conditions, converts a fecal sludge simulant almost completely to
CO2 and water, leaving behind only a carbon-poor aqueous phase with the minerals. The prototype has been
designed to process the feces from two households. This technology does not only enable a fast and complete
conversion, but is potentially also very energy efficient, as the feed does not require any pre-treatment or drying.
The system was found to effectively remove 97–99% of the total organic carbon within a reaction time of 600 s
under an external energy demand of roughly 4 kWh per kilogram of wet feces by using the oxygen in air as an
oxidant. A total of ten experiments with varying injection pressure, total solids content of the feed, and residence
time in the reactor were performed to find experimental settings with high conversion. Only when the residence
time was decreased from 600 to 300 s did the conversion fall significantly below 97%. To reach a target value of
99.9% TOC conversion, the reactor temperature and/or the residence time must be increased further. To achieve
a system applicable in regions with no connection to the energy grid, the thermal loss of the reactor insulation
needs to be lowered further to achieve an overall thermally self-sustaining operation.
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ISBN
ISSN
2589-9147
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Zero Emission
Publication status
Published
Review
Peer review of the complete publication
Open access category
Gold
License
Citation
Affolter, J., Brunner, T., Hagger, N., & Vogel, F. (2022). A prototype system for the hydrothermal oxidation of feces. Water Research: X, 17. https://doi.org/10.1016/j.wroa.2022.100160