Batch Supercritical Water Oxidation

Batch supercritical water oxidation (SCWO) High-temperature technology still at the R D stage that is potentially applicable to destruction of neat agent and CAIS vials... 

The use of batch supercritical water oxidation (batch SCWO) to treat liquid secondary waste streams of the EDS was reviewed in a previous report by this committee (NRC, 2001b). 

TACOM TBA TCLP THC TNB TNBA TNT TOC TRBP TW-SCWO Tank-Automotive and Armaments Command tributylamine toxicity characteristic leaching procedure total hydrocarbons trinitrobenzene trinitrobenzoic acid trinitrotoluene (an energetic material) total organic carbon thermal reduction batch processor transpiring-wall supercritical water oxidation... 

The performance of the new analytical method was adequate to ensure that measured GB concentrations in the hydrolysate were low enough for secondary treatment using supercritical water oxidation (SCWO). Method detection limit (MDL) values in hydrolysate were 2.2 pg/L (2.2 ppb) with 68 percent recovery and were calculated in accordance with standard U.S. Environmental Protection Agency (EPA) methods (40 CFR Part 136, Appendix B). This value is well below the release criteria of 75 ppb for GB in the hydrolysate. A more significant performance parameter is the target action limit (TAL), which is the concentration for which 95 percent of the measurements will be below the release criteria (Malloy et al., 2007). In an analysis of GB performed on hydrolysate generated from two batch reactor studies conducted at Battelle, the TAL values were calculated at 57 ppb and 52 ppb. 

Gas-phase chemical reduction Supercritical water oxidation (continuous) Supercritical water oxidation (batch) Persulfate oxidation Electrochemical oxidation... 

Supercritical water oxidation (batch) Sandia National Laboratories/ Livermore, Calif. H neutralent simulant, GB neutralent simulant, vials of CHClj... 

Supercritical water oxidation (SCWO) is a hydrothermal process for the oxidative destruction of organic wastes. An oxidant and the wastes to be disposed are fed to a reactor in the presence of high concentrations of water heated above the critical temperature and pressure of pure water (374°C, 3,204 psia). These wastes can be fed continuously into the SCWO reactor (continuous SCWO) or, in an alternative design, a small volume of waste is mixed with water and an oxidizer (H2O2) in a pressure vessel, heated to reaction temperature above the critical point of water, and then cooled (batch SCWO). The committee evaluated continuous SCWO in its previons report (NRC, 2001a), but did not evaluate batch SCWO, which was still at a very early stage of development. 

Supercritical water oxidation (SCWO) Strong oxidizing capability pollution prevention High temperatures and pressures make system complex and prone to failures corrosion and plugging due to precipitated salts are problems Batch SCWO could address problems of continuous SCWO but requires significant further develc jment... 

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). ... 

To summarize, the committee recommends that available R D resources be focused on development of chemical oxidation, wet-air oxidation, and supercritical water oxidation (batch mode). Similarly, it recommends that no further resources be spent on development of electrochemical oxidation, supercritical water oxidation (continuous mode), GPCR, biotreatment, or SET for this purpose. 

Initial studies of phenol SCWO Involved in extensive SCWO study Investigated the unique features of supercritical water in terms of density, dielectric constant, viscosity, diffusivity, electric conductance, and solvating ability Treatment of hazardous organic compounds Application of SCWO to the decomposition of sludges Found that sludge readily decomposes at near-critical water conditions with 02 or H202 as an oxidant in a batch or continuous flow reactor Treatment of sludges... 

Example 3.3. The rate coefficients k in the adjacent table were calculated by Savage and Smith [56] from six independent measurements of the oxidation of acetic acid in supercritical water at 440°C in a batch microreactor. The mean value of k and its 95% confidence interval are obtained as follows. 

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