• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.241-249
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• 2000

In this study, UV-catalyzed $H_2O_2$ oxidation and $H_2O_2$ oxidation to remove contaminants from photo processing chemicals were investigated at various conditions. Photo processing chemicals contains high concentrations of organic compounds and has very low biodegradability. Hydrogen peroxide is subjected to gradual decomposition as metastable substance. In the process, short-lived and highly reactive hydroxyl radicals are formed. The decomposition can be significantly accelerated by use of appropriate catalyst, such as ultraviolet radiation. The experiments were conducted in a UV-free reflecting reactor in batch and a high-pressure mercury lamp was used as UV source. Mixing, cooling and ventilation of the reactor were operated during experiments. In $UV/H_2O_2$ oxidation and $H_2O_2$ oxidation, the removal efficiencies of $COD_{Cr}$, TOC and chromaticity increased with the increase of $H_2O_2$ dosage and were higher in the controlled pH condition of 3 than in original pH condition of 8. In $UV/H_2O_2$ oxidation under the optimum condition of pH 8 and 1.3 stoichiometric $H_2O_2$ dosage, the removal efficiencies of $COD_{Cr}$, TOC and chromaticity were 47.5%, 75.0% and 91.5% respectively and $BOD/COD_{Cr}$ ratio was significantly increased from 0.04 to 0.21.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.289-296
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• 2007

Porous media for sewage treatment were developed through a pyrolysis process of food wastes with loess in the study. This work was carried out in two consecutive stages; in the first stage, new porous media were prepared through a high temperature pyrolysis process, and then the resultant media were applied to a simple lab-scale sewage treatment process in the second stage. To determine the optimum operating conditions of pyrolysis and mixing ratio of materials, physical properties such as specific surface area, porosity and compressive strength of final products were analyzed. The removal efficiencies of TOC and COD were measured to evaluate the effectiveness of resultant porous media. As a result of the experiment, we found that the best mixing ratio of food wastes to loess was 1 : 1 at $1,100^{\circ}C$. Average porosity of the developed media was 37.0%, in which pore size ranged from 1 to $20{\mu}m$, showing quite vigorous microbial activation. After immersing the media into a reactor for sewage treatment for eight days, removal efficiencies of TOC and COD were 87.3% and 85.0%, respectively.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.204-211
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• 2013

In this study, the deriving optimum conditions for decolorization of Acid Orange II solution was carried using $TiO_2$ advanced oxidation process. After that, on base of the deriving results, the range of dye concentration was estimated. In addition, acute toxicity test was also carried to assess toxicity unit according to decolorization and TOC removal. In case of the blockage of light, 20 mg/L of dye solution, and 0.5 g $TiO_2$, the effect of decolorization at pH 3 was larger than at pH 6 and 10, so it was shown that decolorization is dependent on pH. The use of 5 g $TiO_2$ showed best performance of decolorization, but that of 3 g $TiO_2$ was chosen to optimum condition in considering of economical aspects. Four light sources, sun, fluorescent lamp, BLB lamp, and UV-B lamp, were used and decolorization was 99.4% and 100% at 50 mg/L, 98.6% and 99.7% at 100 mg/L for sun and UV-B lamp, respectively. In spite of the optimum condition of decolorization at pH 3, the evaluation of acute toxicity test showed highly toxic. In conclusion, although the optimum treatment of dye solution is performed, water ecology can be polluted in discharging it into water system. Therefore, it is needed to study of water ecological system with dye water treatment, and it takes all the circumstances into consideration.

• Journal of Animal Science and Technology
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• v.45 no.4
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• pp.641-648
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• 2003

In a batch mode treatment process, which electrolyzes the wastewater after derivation of N-P crystal formation and recovery, the characteristics of pollutant removal induced with the changes of loading rate and hydraulic retention time were studied. $MgCl_2$ was used as Mg source for the formation of struvite and the molar ratio of $MgCl_2$ to $PO_4^{3-}$ in influent was 1.3. When analyzing the average treatment efficiencies and removal characteristics obtained from four separate operations (Run I, II, III, IV), removal efficiencies of PO43- was not function of its loading rate. Under a condition of sufficient aeration and Mg source provided, over 88% of $PO_4^{3-}$ was eliminated by the formation of MAP without any pH adjustment, in spite of loading rate variation. An optimum-loading rate of NH4-N to achieve high removal efficiency was approximately $100g/m^3/d$. Below that loading rate, the removal of NH4-N was proportional to the loading rate into the system, and hence stable and high removal efficiency, over 90%, was achieved. However, when the loading rate increased over that rate, removal efficiency began to drop and fluctuate. Removal efficiency of TOCs was dependant upon the hydraulic retention time ($r^2$=0.97), not upon the loading rate. Stable and high color removal (94%) was obtained with 2 days of HRT in electrolysis reactor.

• Textile Coloration and Finishing
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• v.17 no.2 s.81
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• pp.31-39
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• 2005

This study was conducted to remove the dyes in dye wastewater by the chemical precipitation or biological treatment which are one of the main pollutants in dye wastewater. In order to remove the disperse dyes effectively in aqueous solution by chemical precipitation process, coagulation and flocculation tests were carried out using several coagulants on various reaction conditions. It was found that the Ferrous sulfate was the most effective coagulant for the removal of disperse dye(DB79), and we could get the best result for the removal of disperse dye(DB56) in the aspects of TOC removal efficiency and sludge yield. When the Ferrous sulfate dosage was 800mg/l, the sludge settling velocity was very fast$(SV_{30}=4\%)$, and the color was effectively removed in the disperse dye(DB79) solution. Although the color removal was ineffective when the Alum was used as a coagulant, the sludge yield decreased in comparison with the Ferrous sulfate or the Ferric sulfate being used in the disperse dye(DB56) solution. In order to decolorize disperse dye(DR17) by using biological treatment process, a strain which has potential ability to degrade disperse dyes was isolated from natural system. The optimal culture conditions of temperature and pH were found to be $40^{\circ}C\;and\;8.5\~9$, respectively. When yeast extract was mixed with polypeptone at the mixing ratio of 1:1 as a nitrogen source, decolorization efficiency was highest$(93\%)$ among the nitrogen sources. The strain screened was excellent to adjust to pH, and it seems to have ability to control pH needed to growth. The optimal culture conditions in concentration of $MgSO_{4.}\cdot7H_2O\;and\;KH_2PO_4$ were $0.1\%(w/v)\;and\;0.2\%(w/v)$, respectively. Strains degrading and decolorizing reactive dyes, RB198 and RR141 which were isolated from water system, are named RBK1 and RRK. And the cell growth characteristics of RBK1 and RRK were investigated. The optimal culture conditions of temperature and pH were found to be 30t' and 7.0, respectively. Optimum nitrogen source was peptone, and it was found that decolorization efficiencies by strains RBK1 and RRK, were $85\%\;and\;62\%$, respectively, with introduction of 4,000mg/l of peptone. In the case of RBK1, color removal efficiencies were very high below 400mg/l. Decolorization efficiency was over $90\%$ at 20hours of culture time. The Color degradation ability of RRK was lower than that of RBK1.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.429-437
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• 2006

To establish the efficient treatment technology of chemical cleaning wastewater from power plant, several AOPs($UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation) were investigated. Treatment efficiencies and the electrical energy requirements based on the EE/O parameter(the electrical energy, required per order of pollutant removal in $1m^3$ wastewater) were evaluated. TOC removal efficiencies of $UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation at the optimum conditions were 95.5%, 92.3%, 91.5%, respectively. The electrical energy requirements of $UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation were $11.26kWh/m^3,\;3.85kWh/m^3,\;0.799kWh/m^3$, respectively. From these results, it could be concluded that all of the three oxidation processes were effective for the degradation of citric acid. Considering the treatment efficiency and economical aspect, photo-Fenton oxidation was the most efficient treatment process among the three processes tested.