Supercritical water oxidation commercialization

Supercritical Water Oxidation Meeting. Achievements and Challengers in Commercial Applications. Aug 14-15, 2001, Arlington, VA. 

Most research work on the use of supercritical water has been conducted batchwise and involved non-analytical determinative applications. Thus, supercritical water oxidation (SCWO) was proposed as an alternative treatment for hazardous waste disposal [191] and also as a commercial tool for decomposing trichloroethylene, dimethyl sulphoxide and isopropyl alcohol on a pilot plant scale [192]. Current commercially available equipment (the aqua Critox" system) is usable with industrial and municipal sludge, mixed (radioactive and organic, liquid and solid) waste and military waste. This commercially available treatment has a number of advantages, namely (a) because it uses an on-site treatment method, it avoids the need to transport hazardous materials (b) it ensures complete destruction of organic wastes and allows reuse of the effluent as process water with results that meet the regulations for drinking water and (c) no licence for effluent or air emissions is needed. 

A variety of chemical and biological reactions involving supercritical fluid technology are being explored and developed. They include polymerization reactions, biomass conversion, hydrogen production, applications of supercritical water oxidation, self-assembly applications, synthesis of specialty chemicals, manufacture of materials with tailored properties, and much more. These developments and new ones are expected to mature and be commercially deployed in years to come. 

Marrone, P.A. Hodes, M. Smith, K.A. Tester, J.W. Salt precipitation and scale control in supercritical water oxidation—part B commercial/ full-scale applications. J. Supercrit. Fluids 2004, 29 (3), 289-312. 

R. N. McBrayer, J. W. Griffith and A. Gidner, Operation of the First Commercial Supercritical Water Oxidation Industrial Waste Facility, Proceedings of International Conference on Oxidation Technologies for Water and Wastewater Treatment, 1996. 

L. Stenmark, Aqua Critox , the Chematur AB Concept for SCWO, in Supercritical Water Oxidation—Achievements and Challenges in Commercial Applications, A. Nazeri, R. W. Shaw and P. A. Marrone (eds.). Proceedings of Workshop held August 14-15, 2001, in Arlington, Virginia, Strategic Analysis, Inc., 2001. 

P. A. Man-one, M. Hodes, K. A. Smith and J. W. Tester, Salt Precipitation and Scale Control in Supercritical Water Oxidation—Part B Commercial/Full-scale Applications, ... 

J. W. Griffith and D. H. Raymond, The First Commercial Supercritical Water Oxidation Sludge Processing Plant, Proceedings of the International Conference on Incineration and Thermal Treatment Technologies, Philadelphia, PA, May 2001. 

T. Oe, A. Suzuki, H. Suzugaki and S. Kawasaki, "Commercialization of the First Supercritical Water Oxidation Facility for Semiconductor Manufacturing Wastes, Proceedings of 1998 Semiconductor Pure Water and Chemicals Conference, 399-407, 1998. 

The same equipment can be used as in PLE, but for temperatures above 200°C, there is no commercial equipment available and specially designed or home-built insmiments are therefore used. Chematur in Sweden manufactures industrial-scale supercritical water oxidation plants operating at temperatures above 400°C (Aqua Critox ). It is possible that such equipment can be modified to subcritical water extraction processes. Uhde in Germany probably also has industrial-scale solutions for PHWE. 

Supercritical or.near-critical water has found technical applications for hydrothermal syntheses, as discussed in detail in Chapter 4.1. Another more recent industrid application of chemical reactions in SCFs is the oxidative destruction of chemical wastes in SCH2O (SCWO, supercritical water oxidation). A detailed coverage of the large and prolific field of SCWO is outside the scope of this book on chemical synthesis. The extensive pilot plant activity, primarily by MODAR (now General Atomics) and Eco Waste Technologies, has recently been sununarized by Schmieder [171]. The first commercial plant was opened by Huntsman Chemical in collaboration with Eco Waste. 

The committee also believes that commercially available hazardous waste incinerators should be suitable for final treatment of neutralents, although test burns may be necessary. Some neutralents are high in sodium, which tends to shorten the life of the refractory brick used to line incinerators, but wastes of similar composition have been treated satisfactorily. Commercial hazardous waste facilities are available that offer other technologies that might be better for aqueous wastes. These technologies include biological treatment, supercritical fluid extraction (not to be confused with supercritical water oxidation, discussed later in this chapter) followed by incineration of the smaller volume of extracted organics, and chemically based proprietary processes. 

If neither the ACWA nor the commercially mature technologies can be used as is—if, for example, substantial process or permit modifications would be needed to dispose of nonstockpile neutralents—then the committee recommends that NSCMP should invest R D resources first in further improvements in chemical oxidation and wet-air/02 oxidation. Only if these technologies cannot be adapted easily does the committee recommend that the Army consider investing resources in supercritical water oxidation (batch mode). ... 

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. 

Building on the results of these initial studies, Modell began adding oxygen in order to explore the effect of the supercritical water environment on oxidation reactions of organic species. In 1980, he started MODAR as the first company established to develop and commercialize the SCWO process. Many of the characteristic attributes that are commonly associated with SCWO were first discovered and described by personnel at MODAR, and they established an... 

This commercial process requires pressurization and a relatively high temperature. Oxygen is the oxidizing agent, and acetic acid (CH3COOH) is the solvent. An alternative route employs supercritical water as the solvent and hydrogen peroxide as the oxidant. This alternative process has several potential advantages, most particularly the elimination of acetic acid as solvent. 

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