- Wet oxidation
Wet oxidation is a form of hydrothermal treatment. It is the
oxidationof dissolved or suspended components in waterusing oxygenas the oxidizer. It is referred to as "Wet Air Oxidation" (WAO) when airis used. The oxidation reactions occur in superheated waterat a temperatureabove the normal boiling pointof water (100 °C), but below the critical point (374 °C).
The system must be maintained under pressure to avoid excessive
evaporationof water. This is done to control energy consumption due to the latent heat of vaporization. It is also done because liquid water is necessary for most of the oxidation reactions to occur. Compoundsoxidize under wet oxidation conditions that would not oxidize under dryconditions at the same temperature and pressure.
Wet oxidation has been used commercially for around 60 years. It is used predominately for treating
wastewater. It is often referred to as the [http://www.water.siemens.com/en/Product_Lines/Zimpro_Products/Zimpro_Products/Pages/Zimpro_Wet_Air_Oxidation.aspx | Zimpro] process; after Fred T. Zimmermannwho commercializedit in the mid 20th century.
Commercial systems typically use a bubble column reactor, where air is bubbled through a vertical column that is liquid full of the hot and pressurized wastewater. Fresh wastewater enters the bottom of the column and oxidized wastewater exits the top. The heat released during the oxidation is used to maintain the operating temperature.
The majority of commercial wet oxidation systems are used to treat industrial wastewaters, such as
sulfideladen spent causticstreams. Almost as many systems are also used for treating biosolids, in order to pasteurizeand to decrease volume of material to dispose of.
Supercritical water oxidation
*Zimmermann, F. "Waste Disposal", US Patent 2665249, 1950.
*Mishra, V.; Mahajani, V.; Joshi, J. "Wet Air Oxidation", "Ind. Eng. Chem. Res.", 34, 2-48, 1995.
*Maugans C.; Ellis, C. "Wet Air Oxidation: A Review of Commercial Sub-Critical Hydrothermal Treatment", Twenty First Annual International Conference on Incineration and Thermal Treatment Technologies, New Orleans, May 13-17, 2002. [http://www.usfilter.com/NR/rdonlyres/BA897F25-AC3B-4CF9-8009-F6BAF92DDB03/0/IT32002WAOhistorypaper.pdf|WAO History Paper]
*Patria, L.; Maugans, C.; Ellis, C.; Belkhodja, M.; Cretenot, D.; Luck, F.; Copa, B. "Wet Air Oxidation Processes", "Advanced Oxidation Processes for Water and Wastewater Treatment", S. Parsons Editor, pp 247-274. 2004, IWA Publishing.
*Giudici, D.; Maugans, C. "Improvement of Industrial Synthesis of Methyl Methacrylate Application of a Wet Air Oxidation Process (WAO)", [http://www.usfilter.com/SiteCollectionDocuments/Product_Lines/Zimpro/Brochures/Improvement%20of%20Industrial%20Sysnthesis%20by%20Methly%20Methacrylate.pdf|USFilter Technical Report No. 428.]
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