Supercritical water oxidation (SCWO) is an advanced technology, best applied for the destruction of unrecyclable, stable, hazardous wastes of diverse composition. With the escalating problem of hazardous waste worldwide, SCWO offers an excellent alternative to incineration and landfills, which are the current techniques for unrecyclable waste disposal. The aim of this work is to link water chemistry to operational behaviour and its impact on process design. This chapter relates the intermolecular structure and thermophysical properties of supercritical water (SCW) to its operational behaviour, leading up to the main design considerations of the SCWO process. Starting with a conceptual process description, it highlights the roles of the feedstock nature, reactor design and energy integration scenarios and their effects on the process performance. Corrosion and salt formation are discussed as the current issues that have hindered commercialisation. Furthermore, it illustrates two approaches to enhance the SCWO process: multi-port oxidant injection, and addition of a co-fuel (isopropyl alcohol (IPA) in this case) to improve the ammonia removal as a recalcitrant N intermediate. Theoretically, kinetics investigations in the presence and absence of IPA are shown to highlight its influence on the rate expression. Finally, three case studies demonstrate the experimental work on N-containing and real wastes.
|Title of host publication||Supercritical and Other High-pressure Solvent Systems: For Extraction, Reaction and Material Processing|
|Editors||Andrew Hunt, Thomas Attard|
|Place of Publication||London|
|Publisher||Royal Society of Chemistry|
|Number of pages||36|
|Publication status||Published - 28 Aug 2018|