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Title: The treatment of a toxic nitrgenous-containing organic compound by supercritical water oxidation and wet air oxidation processess [i.e. processes] : operating conditions and reaction kinetics
Author: Ashraf-Ball, Nur Hezlin.
ISNI:       0000 0001 3430 4764
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2005
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Hydrothermal. oxidation processes at high pressure and temperature can be operated at conditions below or above the critical point of water (374.2'C and 221 bar). The former, is known as Wet Air Oxidation (WAO) and the latter is often referred to as Supercritical Water Oxidation (SCWO). The researchp resentedin this thesisa imed at investigatingt he viability of SCWO and WAO in treating 1,8- diazabicyclo [5.4.0] undec-7-ene (DBU)-containing wastewaterp roducedf rom pharmaceuticaal pplications.D BU was selecteda s a recalcitrant nitrogenous compound of industrial interest, which is difficult to treat by conventional treatmentm ethodso f industrial wastewatersI.n principle, the two processesc an be regarded to a certaine xtenta s the samep rocessw ith the main differenceb eing the conditionso f water. Among many other implications( will be discussedin the thesis),t his resultsi n the existence of two phasesin the subcriticalr angew hile it is monophasica t the supercriticalr ange. In SCWO, a laboratory scale system consisting of a plug-reactor was employed for acquisition of novel kinetic data in the supercritical region by investigating the effect of several operating parameters namely temperature, pressure, oxidant-to-organic ratio, organic concentration and residence time. The possible reactions by-products were also investigated by following the fates of carbon and nitrogen at various reaction conditions. A laboratorys cales emi-batchs ystemc onsistingo f a stirredt ank reactorw as employedf or the WAO studies to obtain novel kinetic data of the destruction of DBU in the subcritical region. The investigation was focused on the effect of reaction temperature, pressure, organic concentration and the speed of impeller. No studies on oxidant-to-organic ratio were undertakena s the systemo peratedin vast excesso f oxidant. The kinetic data acquired in both sub- and supercritical systems were consequently incorporatedin the semi-batcha nd continuousr eactore quationsfo r WAO and SCWO system respectively to develop kinetic rate expressions for both processes. It was found that the global rate expressions uccessfullyd escribedt he kinetics of SCWO in a plug flow continuous reactor, while the WAO semi-batch process was modelled by the pseudo-first order expression. Complete organic carbon removal was achieved in the SCWO system, but incomplete removal was observed in the WAO system even at extreme operation conditions. Significant proportion of nitrogen component from the waste was converted to ammonia rather than nitrogen gas.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available