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Supercritical water oxidation (SCWO) could offer a viable treatment alternative to destroy the organic structure of ion-exchange resins (IER) that are radioactive process wastes and which contain radioactivity. The GC/MS technique was used successfully to identify the low-concentration degradation compounds that are present in the cold liquid effluent after SCWO of polystyrenic IER at 380 °C (25.5 MPa). The study of the behavior of these IER in supercritical water enhances the role of temperature and the role of supercritical water in the degradation process. With the exception of acetic acid, the identified compounds are aromatic. The functional groups are released during the heating time, and they do not interfere in the degradation process. The oxidation involves a complex set of reaction pathways. A mechanism including parallel and competitive reactions is proposed.

A syntrophic consortium was enriched in a basal medium containing cinnamate as the carbon and energy source. It was found to consist of three morphologically distinct microbes, viz., a short, rod-shaped, non-motile bacterium with distinctly pointed ends, Papillibacter cinnamivorans; a rod-shaped, motile bacterium with rounded ends, Syntrophus sp.; and a methanoarchaeon, Methanobacterium sp. This methanogen was then replaced by a collection strain of Methanobacterium formicicum. A syntrophic interdependency of the three partners of the consortium was observed during growth on cinnamate. In the presence of bromoethanesulfonic acid (BESA), cinnamate was transformed to benzoate, whereas under methanogenic conditions without BESA, cinnamate was first transformed to benzoate via beta-oxidation and subsequently completely degraded into acetate, CH(4), and CO(2). Papillibacter cinnamivorans was responsible for benzoate production from cinnamate, whereas a syntrophic association between Syntrophus sp. and the methanogen degraded benzoate to acetate, CH(4), and CO(2). A new anaerobic degradation pathway of cinnamate into benzoate via beta-oxidation by a pure culture of P. cinnamivorans is proposed.

In this paper, we examine the wet-air oxidation (WAO) of four nuclear-fuel-chelating compounds [diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and thenoyltrifluoroacetone (TTA)]. The study focuses on the kinetics and mechanism of the degradation process. Identification of the free-radical intermediates was performed via the spin-trapping technique. The reaction of each compound studied was found to occur in two steps, with a partial order of one with respect to TOC for both steps. Among the compounds studied, TTA shows the most difficulty when degrading. Hydroxyl, hydroxycarbonyl, and nitrogenous radicals are some of those formed during the degradation process. Schematic reaction pathways, which can explain the formation of some mineral byproducts, are proposed on the basis of these radicals.

Abstract. The Wet Air Oxidation of four organic complexants was studied. This study focuses on the determination of the main by-products formed and the optimization of the degradation yield in a defined area according to four parameters, which are reaction temperature, initial substrate concentration, reaction time and oxygen partial pressure. This optimization is followed by a classic Doehlert matrix.

-When fine and cohesive particles are the subject of study, fluid beds are of concern of due to the formation of channeling. This work presents a study that was carried out on the drying of fine particles, in this case a crystalline organic acid, in a mechanically stirred fluidized bed. The drying kinetics curves were determined by evaluating the influences of initial moisture content and temperature of the drying gas at the entrance of the bed. This study shows the suitability of the stirred fluidized bed for the drying of solids of low-quality fluidization.

The oxidation of meat-and-bone meal (MBM) and two different raw animal byproducts (before and after rendering) has been studied by wet air oxidation (WAO) and catalytic wet air oxidation (CWAO), which represents an alternative way of animal byproduct disposal. The degradation of organic compounds was monitored by dissolved organic carbon (DOC) analysis following the subcritical conditions (230−280 °C, 9.9−18.6 MPa), which has led to the degradation of up to 90% of the initial total organic carbon (TOC) and reached 99% within the presence of platinum as a catalyst for the oxidation of a raw non-defatted sample. The oxidation of organic compounds has been studied as a function of pressure and temperature and showed that the TOC removal increased at higher temperature and higher pressure favoring the mass transfer of oxygen and organic compound into the liquid phase. The byproducts of the oxidation were identified; acetic acid was the main refractory organic compounds representing approximately 50% of the final residual TOC. The major inorganic byproduct was identified as ammonia, which was quantitatively removed (98.9%) in presence of platinum catalyst supported over alumina in basic medium.