• KSBB Journal
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• v.23 no.3
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• pp.245-250
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• 2008

The treatment of a model wastewater containing quinoline in an integrated wet oxidation-aerobic biological treatment was investigated. Partial wet oxidation under mild operating conditions was capable of converting the original quinoline to biodegradable organic acids such as nicotinic, formic and acetic acid, the solution of which was subjected to the subsequent aerobic biological treatment. The wet oxidation was carried out at 250$^{\circ}C$ and the initial pH of 7.0, and led to effluents of which nicotinic acid was oxidized through 6-hydroxynicotinic acid by a Bacillus species in the subsequent aerobic biological treatment. Either homogeneous catalyst of $CuSO_4$ or phenol, which is more degradable in the wet oxidation compared to quinoline, was also used for increasing the oxidation rate in the wet oxidation of quinoline at 200$^{\circ}C$. The oxidation of quinoline in the catalytic wet oxidation and the wet co-oxidation with phenol resulted in effluents of which nicotinic acid was biodegradable earlier in the aerobic biological treatment compared to those out of the non-catalytic wet oxidation at 250$^{\circ}C$. However, the lag phase in the biodegradation of nicotinic acid formed out of the wet oxidation at 250$^{\circ}C$ was considerably shortened after the adaptation of Bacillus species used in the aerobic biological treatment with the effluents of the quinoline wet oxidation.

• KSBB Journal
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• v.22 no.4
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• pp.244-248
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• 2007

The treatment of a model wastewater containing high concentration, 10 $g/{\ell}$, of phenol in an integrated wet oxidation-aerobic biological treatment was investigated. Partial wet oxidation under mild operating conditions was capable of converting the original phenol to biodegradable organic acids such as maleic acid, formic acid and acetic acid, the solution of which was subjected to the subsequent aerobic biological treatment. The wet oxidation was carried out at 150$^{\circ}C$ and 200$^{\circ}C$ and the initial pH of 1 to 12. The high temperature of 200$^{\circ}C$ and the acidic initial condition in the wet oxidation led to effluents of which biodegradability was higher in the subsequent biological oxidation process, as assessed by chemical oxygen demand (COD) removal. Homogeneous catalyst of $CuSO_4$ was also used for increasing the oxidation rate in the wet oxidation at 150$^{\circ}C$ and initial pH of 3.0. However, the pretreatment with the catalytic wet oxidation resulted in effluents which were less biodegradable in the aerobic biological process compared to those out of the non-catalytic wet oxidation at the same operating conditions.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.292-302
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• 2009

The wet oxidation of phenol has been investigated at temperatures from 150 to $250^{\circ}C$ and oxygen partial pressures from 25.8 to 75.0 bar with initial pH of 1.0 to 12.0 and initial phenol concentration of 10 g/l. Chemical Oxygen Demand COD has bee measured to estimate the oxidation rate. Reaction intermediates have been identified and their concentration profiles have been determined using liquid chromatography. The destruction rate of phenol have shown the first-order kinetics with respect to phenol and the changes in COD during wet oxidation have been described well with the lumped model. The impact of various homogeneous catalysts, such as $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Co^{2+}$ and $Ce^{3+}$ ions, on the destruction rate of phenol and COD has also been studied. The homogeneous catalyst of $CuSO_4$ has been found to be the most effective for the destruction of phenol and COD during wet oxidations. The destruction rate of formic acid formed during wet oxidations of phenol have increased as increasing temperature and $CuSO_4$ concentration. The final concentrations of acetic acid which has been formed during wet oxidations and difficult to oxidize have increased with reaction temperature and with decrease in the catalyst load.

• Journal of Energy Engineering
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• v.9 no.2
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• pp.123-129
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• 2000

Mg(OH)$_2$를 흡수제로 이용한 습식탈황에서 페슬러리에 대한 산화반응 특성을 고려하였다. SO3-2 전환율 (MgSO3 폐슬러리의 산화반응 전환율) 과 산소의 물질전달특성을 고찰하기 위해 회분식 및 연속식 실험을 수행하였따. 3리터 용량을 갖는 직사각형모양의 아크릴 반응기에서 공기/슬러리 공급비(20-60) , 수리학적 체류시간(HRT)(1-3hr), SO3-2 유입농도(1000-3000ppm)등의 변화조건에서 실험이 행하여졌다. 실험결과 SO3-2 전환율은 공기공급량과 체류시간에 비례하여 증가하였다. 또한 슬러리 공급에 대한 최적공기공급비 0.02ι/(ι.ppm)에서 MgSO3 폐슬러리는 90%이상 산화되었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.805-805
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• 1995

핵연료저장시설의 화재 등 극단적인 사고조건하에서 $UO_2$ 소결펠렛의 습식산화와 건식산화에 대한 연구를 수행하였다. 손상된 지르칼로이 피복관 속의 $UO_2$ 소결펠렛을 산성분위기의 습윤조건하에서 산화시킬 때의 $UO_2$ 펠렛의 산화속도는 IDR(mg/$\textrm{cm}^2$.min) = 1.55 [H$^{+}$]$^{1.21}$ 로 나타났다. 또한 습윤조건하에서 $UO_2$ 분말에 알카리 및 알카리 토금속 산화물, 그리고 백금족 및 회토류 산화물 등과 같은 불순물들이 존재할 때의 산화속도를 조사하였으며 이들에 대한 영향도 관찰하였다. 핵연료저장시설의 가상화재를 바탕으로 한 400~$700^{\circ}C$의 온도범위에서, 피복관이 씌워진 $UO_2$ 소결펠렛의 건식산화반응을 조사한 바 $UO_2$ 소결펠렛은 산화초기에 U$_4$O$_{9}$ 또는 U$_3$O$_{7}$ 등의 중간상 형성에 따른 3-4%의 부피축소에 의해 결정립계 균열이 일어나고, $600^{\circ}C$ 이하에서는 온도증가에 따라 중간상에서 U$_3$O$_{8}$ 상으로의 상변화에 의한 부피팽창으로 피복관의 변형과 함께 산화속도의 가속을 발견할 수 있었고, $600^{\circ}C$ 이상에서는 핵연료소자의 소성변형으로 인한 산화속도의 지연을 발견할 수 있었다. 또한 $UO_2$ 펠렛의 건식산화거동은 기체-고체 반응시의 전형적인 형태인 shrinking core model에 잘 적용될 것으로 판단되었다.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.2077-2083
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• 2000

For the application of wet air oxidation(WAO) process reactive dyes, remazol blacks has been selected as the subject for this study. The rate of decomposition relating to the reaction temperature and catalyst has been summarized during the catalytic wet air oxidation reaction. When 1.5 gram per liter of platinum is added titanium-dioxide and the partial pressure is adjusted to 6 atmosphere at the reaction temperature exceeding $200^{\circ}C$, more than 95% of the remazol blacks dyes were decomposed. When the reaction temperature was raised to $200^{\circ}C$, $220^{\circ}C$ and $250^{\circ}C$, respectively, for 240 minutes after adding the catalyst, the remaining rate of ultraviolet absorbance had dropped significantly to 18%, 12%, and 4%. At the reaction temperature of $250^{\circ}C$, color removal efficiency was approximately 95% or more after 120 minutes from the beginning of the reaction.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.486-492
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• 2009

Wet oxidations (WO) of quinoline in aqueous solution were carried out at $225^{\circ}C$ and $250^{\circ}C$. In the WO at $250^{\circ}C$, quinoline was degraded completely within 30 min and the reduction in total organic carbon (TOC) of 63% was achieved during 120 min. However, the rate of the reduction in TOC was only 13% within 240 min during the WO at $225^{\circ}C$. Nicotinic and acetic acid were found to be main intermediates formed during the oxidation of quinoline. With the addition of the homogeneous catalyst $CuSO_4$ or more easily oxidizable phenol, WOs of quinoline were also carried out under moderate conditions at $200^{\circ}C$. The catalytic WO with $CuSO_4$ of 0.20 g/L showed the destruction rates of quinoline and TOC comparable to those in the WO at $250^{\circ}C$. The WOs of quinoline-phenol mixture exhibited induction periods to degrade quinoline and phenol during which free radicals were produced to initiate WOs. With increasing initial concentrations of phenol at a given initial concentration of quinoline, the induction periods in the destructions of quinoline and phenol became shorter and the reduction in TOC increased from 60% to 75% during 180 min of the WOs. The reduction rate of an induction period decreased as increasing the initial concentration ratio of phenol to quinoline. On the other hand, phenol degradation in the WOs of quinoline-phenol mixtures required a longer induction period and proceeded slower compared to the case of the WO of phenol.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.259-267
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• 2010

The catalytic wet oxidations of the wastewater containing azo dye Reactive Black 5(RB5) with heterogeneous catalyst of CuO have been carried out to investigate the effects of temperature($190{\sim}230^{\circ}C$) and catalyst concentration(0.00~0.20 g/l) on the removals of colour and total organic carbon TOC. The wastewater colour was measured with spectrophotometer, and the oxidation rate was estimated with TOC. About 90% of colour was removed during 120 min in thermal degradation of the RB5 wastewater at $230^{\circ}C$, while TOC was not removed at all. As increasing reaction temperature and catalyst concentration, the removal rates of colour and TOC increased in the catalytic wet oxidations of RB5 wastewater. The effects of catalyst were already considerable even at 0.01 g CuO/l, while the removal rates of colour and TOC increased negligibly with increasing the catalyst concentration above 0.05 g CuO/l. The initial destruction rates of the wastewater colour have shown the first-order kinetics with respect to the wastewater colour. TOC changes during catalytic wet oxidations have been well described with the global model, in which the easily degradable TOC was distinguished from non-degradable TOC of the wastewater. The impacts of reaction temperature on the destruction rate of the wastewater colour and TOC could be described with Arrhenius relationship. Activation energies of the colour removal reaction in thermal degradation, wet oxidation, and catalytic wet oxidation(0.20 g CuO/l) of the RB5 wastewater were 108.4, 78.3 and 74.1 kJ/mol, respectively. The selectivity of wastewater TOC into the non-degradable intermediates relative to the end products in the catalytic wet oxidations of RB5 wastewater was higher compared to that in phenol wet oxidations.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.248-254
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• 2016

Efficacious wastewater treatment is essential for increasing sewage sludge volume and implementing strict environmental regulations. The operation cost of sludge treatment amounts up to 50% of the total costs for wastewater treatment plants, therefore, an economical sludge destruction method is crucially needed. Amid several destruction methods, wet air oxidation (WAO) can efficiently treat wastewater containing organic pollutants. It can be used not only for sludge destruction but also for useful by-product production. Volatile fatty acids (VFAs), one of many byproducts, is considered to be an important precursor of biofuel and chemical materials. Its high reaction condition has instituted the study of gravity pressure reactor (GPR) for an economical process of WAO to reduce operation cost. Simulation of subcritical condition was conducted using Aspen Plus with predictive Soave-Redlich-Kwong (PSRK) equation of state. Conjointly, simulation analysis for GPR depth, oxidizer type, sludge flow rate and oxidizer injection position was carried out. At GPR depth of 1000m and flow rate of 2 ton/h, the conversion and yield of VFAs were 92.02% and 0.17g/g, respectively.

• The KSFM Journal of Fluid Machinery
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• v.19 no.3
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• pp.10-13
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• 2016

The wet-air oxidation in gravity pressure reactor is effective for organic waste treatment with energy saving under high pressure and high temperature. But its oxidation control is difficulty because its multi-phase flow characteristics is very complicated. The flow characteristics of an oxidizer feed section in the gravity pressure reactor were investigated using numerical method which are verified by comparison with experimental results. In this study, the results showed that the flow rate of oxidizer have an effect on the generation of bubble around feed section.