Supercritical water oxidation economics

Aki SNVK, Abraham MA. An economical evaluation of catalytic supercritical water oxidation comparison with alternative waste treatment technologies. Environ Prog 1998 17(4) 246-255. 

Styrene ion-exchange resins, which are used in the nuclear industry [29]. It is argued that the destruction of pulp mill sludges from paper manufacture by supercritical water oxidation is now an economic proposition [12]. These sludges contain dioxins and furans and therefore have high land-fill costs. 

It is evident that such a demanding and expensive technology will be Umited to special apphcations where efficiency is favoured over economic issues. Supercritical water oxidation as a waste treatment technology will most likely be used for waste streams that are hard to dispose of in other ways. A possible solution is the use of catalysts to lower the process temperature and to soften the requirements for construction materials and energy consumption. Consequently, attempts to apply hydrothermally stable catalysts in SCWO plants have been reported (see below). 

Another important bulk chemical that could be derived from glycerol is acrylic acid (Craciun et al., 2005 Shima and Takahashi, 2006 Dubois et al., 2006). Shima and Takahashi (2006) reported a complete process for acrylic acid production involving the steps of glycerol dehydration in a gas phase followed by the application of a gas phase oxidation reaction to a gaseous reaction product formed by the dehydration reaction. Dehydration of glycerol could lead to commercially viable production of acrolein, which is an important and versatile intermediate for the production of acrylic acid esters, superabsorber polymers or detergents (Ott et al., 2006). Sub- and supercritical water have been applied by Ott et al. (2006) as the reaction media for glycerol dehydration, but the conversion and acrolein selectivities that have been achieved so far are not satisfactory for an economical process. 

Solid materials, such as sewage sludge, have been oxidised successfully in supercritical water [24]. The economical destruction of biomass waste is now only a possibility in the longer term. The same is true of plastic waste, although special cases exist, for example when the waste is radioactive. The latter was the motivation of a study of the oxidation of poly-... 

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