Hydrothermal conversion of toilet waste: effect of processing conditions on gas phase emissions

Autor: Gerty J.H.P. Gielen, John P. Andrews, Christine M. Karbiwnyk, Mark J.C. Riddell, Sean W. Husheer, Daniel J. Gapes
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Heliyon, Vol 8, Iss 6, Pp e09708- (2022)
Druh dokumentu: article
ISSN: 2405-8440
DOI: 10.1016/j.heliyon.2022.e09708
Popis: Globally, many populations suffer from a lack of access to basic sanitation facilities. This is partly caused by a combination of water resource shortages and the high cost of conventional centralised treatment systems. A novel decentralised treatment technology based on sub-critical hydrothermal processing of organic wastes at toilet-scale, contributes to addressing these economic and resource limitations. To be effective, this technology needs to satisfy a broad range of environmental and safety considerations, including the nature and quantity of formed gas products. We investigated the impact of four process parameters (temperature; O2: COD ratio (λ); time; feed solids content) on off-gas composition by quantifying volatile organic compounds (VOCs), CO, H2 and CO2 in factorial experiments. Temperature and λ influenced VOCs generation greatly. The lowest VOC emissions occurred at 200% λ and 300 °C. Aldehydes and ketones were mostly generated at 200% λ and intermediate temperatures, sulphur compounds in the absence of oxygen, and aromatics, furans, and pyrroles at intermediate oxygen levels and elevated temperatures. Most CO was created at 300 °C but its concentration decreased at longer processing times. Processing conditions have complex impacts and require careful consideration when designing for real world deployment.
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