• Advances in environmental research
• /
• v.9 no.3
• /
• pp.191-214
• /
• 2020

The rise in population and industrialization accounts for the generation of a huge amount of wastewaters. The treatment of this wastewater is obligatory to safeguard the environment and various life forms. Conventional methods for high strength wastewater treatment coming out to be ineffective. Advanced oxidation processes (AOPs) for such wastewater treatment proved to be very effective particularly for the removal of various refractory compounds present in the wastewater. Ozone based AOPs with its high oxidizing power and excellent disinfectant properties is considered to be an attractive choice for the elimination of a large spectrum of refractory compounds. Furthermore, it enhances the biodegradability of wastewaters after treatment which favors subsequent biological treatments. In this review, a detailed overview of the AOPs (like the Fenton process, photocatalysis, Electrochemical oxidation, wet air oxidation, and Supercritical water oxidation process) has been discussed explicitly focusing on ozone-based AOPs (like O₃, O₃/H₂O₂, O₃/UV, Ozone/Activated carbon process, Ozone/Ultrasound process, O₃/UV/H₂O₂ process). This review also comprises the involved mechanisms and applications of various ozone-based AOPs for effective municipal/industrial wastewaters and landfill leachate treatment. Process limitations and rough economical analysis were also introduced. The conclusive remarks with future research directions also underlined. It was found that ozonation in combination with other effective AOPs and biological methods enhances treatment efficacies. This review will serve as a reference document for the researchers working in the AOPs field particularly focusing on ozone-based AOPs for wastewater treatment and management systems.

• Journal of Soil and Groundwater Environment
• /
• v.22 no.2
• /
• pp.17-25
• /
• 2017

The efficiency and mechanism of electrochemical phenol oxidation using persulfate (PS) and nanosized zero-valent iron (NZVI) were investigated. The pseudo-first-order rate constant for phenol removal by the electrochemical/PS/NZVI ($1mA^*cm^{-2}/12$ mM/6 mM) process was $0.81h^{-1}$, which was higher than those of the electrochemical/PS and PS/NZVI processes. The electrochemical/PS/NZVI system removed 1.5 mM phenol while consuming 6.6 mM PS, giving the highest stoichiometric efficiency (0.23) among the tested systems. The enhanced phenol removal rates and efficiencies observed for the electrochemical/PS/NZVI process were attributed to the interactions involving the three components, in which the electric current stimulated PS activation, NZVI depassivation, phenol oxidation, and PS regeneration by anodic or cathodic reactions. The electrochemical/PS/NZVI process effectively removed phenol oxidation products such as hydroquinone and 1,4-benzoquinone. Since the electric current enhances the reactivities of PS and NZVI, process performance can be optimized by effectively manipulating the current.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.8
• /
• pp.829-836
• /
• 2005

In this study, the characteristics of atrazine decompositon with photo-chemical oxidation process was investigated by the oxidation products analysis. The main products of the process were OIET(2-hydroxy-4-ethylamino-6-isopropylamino s-triazine), OIAT(2-hydroxy-4-amino-6-isopropylamino s-triazine) and OAAT(2-hydroxy-4,6-diamino-s-triazine), resulting i n dechlorination or hydroxylation as the main mechanism of the photo-chemical oxidation process. Through the material balance analysis of TOC and chloride ion in the aqueous solution, it was concluded that mineralization of the atrazine was not occurred but the dechlorination of atrazine had been completed.

• Journal of Environmental Science International
• /
• v.29 no.12
• /
• pp.1205-1211
• /
• 2020

In this study, the applicability of reduction-oxidation-linked treatment was evaluated for nitrobenzene and a by-product by analyzing the reaction kinetics. Nitrobenzene showed very low reactivity to persulfate that was activated using various methods. Nitrobenzene effectively reacted through the reduction process using Zero-Valent Iron (ZVI). However, aniline, a toxic substance, was produced as a by-product. Reduction-oxidation-linked treatment is a method that can allow the oxidative degradation of aniline after reducing nitrobenzene to aniline. The experimental results show improved reactivity and complete decomposition of the by-product. Improved reactivity and decomposition of the by-product were observed even under conditions in which the reduction-oxidation reaction was induced simultaneously. No activator was injected for persulfate activation in the process of reducing oxidant linkage, and the activation reaction was induced by ferrous iron eluted from the ZVI. This indicates that this method can be implemented relatively simply.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.5
• /
• pp.1157-1162
• /
• 2013

We proposed AlGaN/GaN high-electron-mobility transistors (HEMTs) using thermal oxidation for NiOx passivation. Auger electron spectroscopy, secondary ion mass spectroscopy, and pulsed I-V were used to study oxidation features. The oxidation process diffused Ni and O into the AlGaN barrier and formed NiOx on the surface. The breakdown voltage of the proposed device was 1520 V while that of the conventional device was 300 V. The gate leakage current of the proposed device was 3.5 ${\mu}A/mm$ and that of the conventional device was 1116.7 ${\mu}A/mm$. The conventional device exhibited similar current in the gate-and-drain-pulsed I-V and its drain-pulsed counterpart. The gate-and-drain-pulsed current of the proposed device was about 56 % of the drain-pulsed current. This indicated that the oxidation process may form deep states having a low emission current, which then suppresses the leakage current. Our results suggest that the proposed process is suitable for achieving high breakdown voltages in the GaN-based devices.

• Journal of environmental and Sanitary engineering
• /
• v.18 no.1
• /
• pp.23-29
• /
• 2003

The effect of ozone oxidation on bio-degradability of leachate was studied. Ozone oxidation process was used as pre-treatment process to enhance performance of biological process in treating landfill leachate. Optimum ozone injection rate and contact time in this experiment was $160{\;}mg{\;}O_/{\ell}{\cdot}hr$ and 45 minutes, respectively. Bio-degradability was enhanced 5.08% by ozone oxidation. The ratio of ozone demand/DOC concentration was $0.049~0.091{\;}mg{\;}O_3/mg{\;}DOC$. The increase of bio-degradability depending on ozone injection rate(D) and contact time(T) can be expressed as follows ; The rate of bio-degradation of DOC was increased proportionally with the increase of ozone injection rate and contact time irrespective of landfill site age. The increase of bio-degradability by ozone addition was not satisfactory. It is hard to expect significant increase in bio-degradability by ozone treatment only. Thus, it is evaluated that ozone oxidation can not increase biodegradability significantly in concentrated wastewater composed of complex organic compound such as leachate.

• Journal of Korean Society on Water Environment
• /
• v.21 no.1
• /
• pp.1-6
• /
• 2005

The effect of ozone oxidation on biodegradability of leachate was studied. Ozone oxidation process was used as pre-treatment process to enhance performance of biological process in treating landfill leachate. Optimum ozone dosing rate and contact time in this experiment was $160mg\;O_3/L$ hr and 45 minutes, respectively. Biodegradability was enhanced 5.08% by ozone oxidation. The ratio of ozone demand/DOC concentration was $0.049{\sim}0.091mg\;O_3/mg$ DOC. The increase of biodegradability depending on ozone dosing rate(D) and contact time(T) can be expressed as follows ; ${\Delta}E=0.00479{\cdot}D^{0.773}{\cdot}T^{0.800}$ The biodegradation rate of DOC was increased proportionally with the increase of ozone dosing rate and contact time irrespective of landfill site age. The increase of biodegradability by ozone addition was not satisfactory. It is hard to expect significant increase in biodegradability by ozone treatment only. Thus, it is evaluated that ozone oxidation can not increase biodegradability significantly in concentrated wastewater composed of complex organic compound such as leachate.

• Journal of Preventive Veterinary Medicine
• /
• v.43 no.4
• /
• pp.194-200
• /
• 2019

This study was conducted to investigate the mechanism of the oxidation process of meat. In the instrumental color, redness, yellowness, and chroma showed significant differences during storage period (P<0.05), whereas hue angle increased (P<0.05), but no significant difference in lightness(P>0.05). The results of TBARS increased significantly during storage period (P<0.05). The thiol and carbonyl contents increased significantly during storage period(P<0.05). Metabolites analysis showed that lactic acid, proline, phenylalanine, mannose, talose, lysine, and tyrosine were significantly different with the storage periods (P<0.05). All the samples used in the experiment were able to confirm that sample went through normal oxidation process with indicators and components were increased or decreased. Further research is needed to study the correlation between metabolite materials.

• Applied Chemistry for Engineering
• /
• v.28 no.3
• /
• pp.318-325
• /
• 2017

Wastewater including ethanolamine used in the second generation of nuclear power plants is filtered out in the ion exchange resin of the condensate polishing plant. In the regeneration process of ion exchange resin, a strong acidic wastewater containing ethanolamine and a lager amount of ionic substances are released. In this study, the process involving UV oxidation part with or without absorbents was developed for treating wastewater released from the ionic exchange resin. The effect of adsorbents on the wastewater treatment was investigated by using UV oxidation system developed by us. As a result, the COD removal efficiency of UV/GAC process with the granular activated carbon (GAC) as an adsorbent was 71.3% at pH 12.8. The removal efficiency was 21.8% higher than that of the wastewater treated using UV oxidation process without any adsorbents at the same condition. The removal of T-N was 88.6% at pH 12.8 when using UV oxidation with the GAC absorbent, which was 18.0% higher than that of using the UV oxidation process without any absorbents. It is thought that ethanolamine adsorbed on the absorbent improved the efficiency of UV oxidation process. Therefore, the UV/GAC adsorption oxidation process can be more effective in treating wastewater containing ethanolamine than that of using the process without any absorbents.

• Journal of the Korean Applied Science and Technology
• /
• v.22 no.3
• /
• pp.250-256
• /
• 2005

This study was aimed to investigate treatment feasibility of leachate from D landfill that is located in gyr대ungbuk. From the analytical results of leachate, organic and nonbiodegradable matters were contained in high concentration. Thus chemical treatment was introduced to degrade nonbiodegradable matters in pre or post biological process. Two types of Fenton oxidation were adapted in this study. The first one is pre treatment process before biological treatment. The second one is post treatment process after biological treatment. The optimal conditions of both treatment methods were investigated as follows. In case of pre treatment process, the optimal conditions appeared in $Fe^{+2}/H_2O_2$(mmol/mmol): 0.1, $H_2O_2/CODcr$(mg/mg): 27.0, pH: 3 and reaction time: 2hrs. On the other hand, in case of post treatment process, the optimal conditions appeared in $Fe^{2+}$(mmol/mmol): 0.14, $H_2O_2/COD_{cr}$(mg/mg): 57.4, pH: 3 and reaction time: 1.25hrs. In the above optimal conditions, high COD removal was obtained in pre and post treatment process. Also it can expect that Fenton oxidation converted nonbiodegradable matters into biodegradable matters.