Papers by Author: Jong Oh Kim

Abstract: We evaluated the treatment efficiency of humic acid using Ti and anodized TiO₂ metal plate with/without Fe-doping. Variation of humic acid concentration after 60 minutes of UV irradiation in the case of Ti only, Fe-Ti, TiO₂ only and Fe-TiO₂ was about 3.0%, 5.5%, 9.8% and 9.2%, respectively. . It is found that hypochromic effect was revealed in all cases with respect to doping time. Fe doping method is considered to be effective for humic acid degradation in spite of relatively low surface area of Ti and anodized TiO₂ metal plate.

Abstract: This study aims to show the catalyst effect for the removal of low molecular weight organics in semiconductor wastewater. To investigate and compare the removal efficiency, experiments were conducted to change in mixing ratio of catalyst with activated carbon. As a result, optimal condition for the removal of acetone and IPA of the catalyst ratio was (Cu+Fe) = 8:2 and (Fe+Al)=9:1 with activated carbon at pH 3. Acetone was removed above 70% and isopropyl alcohol (IPA) was almost removed 100% in the pH 3, pH 4 except for pH 7 condition, the remaining acetone concentration was 51.4 ppb in IPA solution, these results is attributed that IPA transformed to acetone after the reaction. Solid-advanced oxidation processes was believed to be an effective method to treat the low adsorbability of organics contained in electric wastewater.

Abstract: This study was conducted to investigate the effect of operational parameters in anodized photocatalytic metal membrane reactor (PMMR) for the removal of Isopropyl alcohol in electric wastewater. The effect of UV light type, the strength of UV light, the injection of TiO2 powder and air flowrate was investigated. About 70% of removal of IPA under the condition of UV irradiation (UV-C, 64W) in combination with an anodized TiO₂ metal membrane was achieved within 180 minutes treatment, indicating that the UV/anodized photocatalytic TiO₂ metal membrane process is a promising treatment technology for treating IPA in electric wastewater.

Abstract: A laboratory, jar-test type study was conducted to investigate the effect of operational parameters on coagulation efficiency when PACl and ferric chloride are used. Under the same dosages, TP removal by ferric chloride was more effective than that of PACl with municipal fresh sewage, while PACl was superior to ferric chloride in case filtered municipal fresh sewage was used as feed. Zeta potential is believed to be a feasible parameter for the determining of appropriate coagulant dosage. Optimal pH for TOC removal was about 6.0, which is slightly lower than that for turbidity and color removal. There are no significant difference in the removal of TOC, turbidity and color over the range of GT values 12,780~112,800.

Abstract: This study focused on the adsorption characteristics of hazardous heavy metals using reactive inorganic agents in synthetic wastewater. Basic properties of five reactive agents were analyzed by zeta potential, particle size, XRF and SEM. Zeta potential of five adsorbents was 45, 7, 14, -2 and 45 mV, respectively. Average particle size was in the range of 1.4 to 9㎛. By XRF analysis, main components were Na, Al, Si, S and Fe in reactive agents and no great differences in Mg, K, Ca and Ti components. As, Zn, Ni, Cu, Cr, Cd and Pb were used as target heavy metals. Adsorption capacity of Pb and Cu was in the order: TN 315Ny-T3>TN820L>TN315NY.

Abstract: An anodized TiO2 membrane has enhanced photocatalytic properties of anatase phase and small crystal size. From the photocatalytic results, the prepared anodized nano-structured TiO2 membrane had an effective organics decomposition capacity and high water permeability. This anodization method enabled the prepared nano-structured TiO2 membrane to have high photocatalytic activity and desired pore structure.

Abstract: The amount of food waste has been increasing every year. Food waste takes relativity high portion of domestic waste and we have much difficulty in treating it. Most of food wastes are landfilled or incinerated after drying for the reduction of water content. The operation cost of the landfill and the incineration are very high. To solve the landfill and the incineration problems in recent years, the recycling of food waste was used by the methods of turning food waste into animal food and fertilizer. Food wastes are compatible to be used as feedstock of the fermentation because they contain valuable nutrients. Among these situations, organic acids, which are effectively used in a variety of industrial processes, can be considered to be a high cost value-added products. The purpose of this study is to evaluate the possibility of organic acid concentration using a MF/RO system. A MF/RO system was believed to be an effective one for the concentration of organic acid from food waste. Water quality of fermentation broth, MF permeate and RO retentate in terms of conductivity, pH, electric conductivity, TS (Total solids), TDS (Total dissolved solids), CODcr concentration, chloride ion concentration was examined as analytic items. pH of fermentation broth was higher than that of MF permeate and RO retentate due to the concentration of organic acid. pH of RO retentate was about 4. Conductivity, TDS, CODCr and chloride ion of RO retentate were about 1.3, 1.3, 2.9, 4.5 times higher than that of fermentation broth, respectively and TS reduced about 0.8 times. This may be ascribed to separate effectively the solid-liquid separation by MF and RO rejection. Consequently, a MF/RO system is believed to be applicable for the concentration of organic acid from fermentation broth of food waste.

Abstract: This study was conducted to evaluate the treatment performance of the system using peroxy radical/ozone reaction for refractory organic compounds removal in aqueous solution. The effect of initial humic acid concentration was conducted under the conditions of humic acid concentration 10 mg/L, 30 mg/L, 50 mg/L and 100 mg/L. Reaction rate constant (k) in 30 mg/L of humic acid concentration was higher than that of humic acid concentration 10 mg/L, 50 mg/L amd 100 mg/L. However, it decreased over the range of 30 mg/L of humic acid concentration due to the action of internal filter of humic acid itself. Reaction rate constant (k) in the initial 20 minute of reaction time was accelerated by decreasing hydraulic retention time (HRT). This may be ascribed to increase the reaction time between peroxy radical and ozone. pH is a key for both ozone stability and TiO2 surface property in aqueous solution. Reaction rate constant (k) of acid solution on pH variation was smaller compared to that of neutral or basic circumstances because ozone decomposes easily into hydroxyl radicals in neutral or basic solution. At reaction rate constant (k) for humic acid degradation in each unit process, peroxy radical/ozone combined system was higher than that of ozone only due to the effective production of hydroxyl radical. An obvious difference between ozone and peroxy radical/ozone is the consequence of hydroxyl radical produced by the reaction of ozone molecules and peroxy radicals.

Abstract: This study was conducted to evaluate the effect of a photocatalysis/oxidant system for the treatment of humic acid and heavy metals in aqueous solutions. Hydrogen peroxide, ozone and potassium peroxodisulfate were tested as oxidants. The effect of the oxidant concentration was conducted with a pH of 7, a UV intensity of 64 W and a TiO2 dosage of 0.3 g/L. The addition of oxidants over the amounts of H2O2 50 mg/L, O3 20 g/m3 and K2S2O8 50 mg/L inhibits the system efficiency. The negative effect of the high concentration of oxidants likely results from OH radical quenching caused by the excess oxidant. Therefore, the optimal dosages for the oxidants such as a hydrogen peroxide, ozone and potassium peroxodisulfate were found to be 50 mg/L, 20 g/m3 and 50 mg/L, respectively. The addition of an oxidant in the UV/TiO2 system enhanced the degradation efficiency of humic acid and heavy metals compared to no addition of an oxidant. The degradation efficiency of humic acid and heavy metals was much greater for the UV/TiO2/H2O2 system.

Abstract: The objective of this study is to evaluate the performance of photocatalysis/hydrogen peroxide/metal membrane system. Metal membrane for the separation of TiO2 particles was used in an experiment and nominal pore size is 0.5 μm. Hydrogen peroxide was tested as oxidants. The removal efficiency of CODCr and color for initial hydrogen peroxide concentration increases rapidly with an increase in the hydrogen peroxide concentration up to 50 mg/L. The removal efficiency of of CODCr and color for 50 mg/L of initial hydrogen peroxide concentration was about 95 % and 98 %, respectively. However, the addition of hydrogen peroxide over 50 mg/L inhibits the system efficiency. The addition of hydrogen peroxide in UV/TiO2 system enhanced removal efficiency of CODCr and color compared to no addition of hydrogen peroxide. This may be ascribed to capture the electrons ejected from TiO2 and to produce OH radicals. The application of metal membrane in UV/ TiO2/H2O2 system enhanced removal efficiency of CODCr and color due to the adsorption of metal membrane surface as well as the production of OH radical. In application of metal membrane with nominal pore size 0.5 μm, TiO2 particles were effectively separated from the treated water by metal membrane rejection. Photocatalytic metal membrane was much smaller resistance than these of humic acid, TiO2 and humic acid/ TiO2 due to humic acid degradation of photocatalytic reaction.