• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.381-386
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• 2006

Many different types of bleaching chemicals and processes have been globally used for deinked pulp. Besides chlorine-free bleaching chemicals, hydrogen peroxide, and sodium dithionite that could be used without restriction for almost all types of fibers, chlorine-containing chemicals such as chlorine dioxide and sodium hypochlorite have also used throughout the world. Even though hydrogen peroxide is commonly used in newsprint, it could not effectively increase brightness. Experimental evaluation on the possibility of using formamidine sulfinic acid (FAS), a reducing agent, for bleaching a wood-containing deinked pulp has been carried out in this study. The effect of bleaching efficiency for FAS on operational conditions and chemical concentrations compaired to hydrogen peroxide in one and two stages was studied. FAS bleaching showed higher brightness at high temperature and low consistency, and vice versa for peroxide one. Bleaching with sodium silicate and DTPA in FAS and peroxide stage showed better results than cases without them. Sodium silicate and chelant seemed minimize the influence of transition metal ions, including manganese and iron ions, which induce both bleaching agents to decompose. As a result, FAS as a reducing agent seems more effective than hydrogen peroxide for increasing brightness and reducing yellowness. FAS and FAS sequence seemed more efficient than the other two stages of bleaching sequences with regard to the best brightness level obtained. When bleaching was conducted with FAS, COD load was just about one-third compared to peroxide, and brightness stability of the bleached pulp appeared better than peroxide after UV light irradiation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.1
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• pp.138-145
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• 2010

The combined effect of 50 ppm aqueous chlorine dioxide ($ClO_2$) or 0.5% fumaric acid with $5 kJ/m^2$ ultraviolet-C (UV-C) on the postharvest quality of "Flamengo" strawberries was examined. After non-thermal treatment, the samples were stored at $4\pm1^{\circ}C$ for 12 days. The combined treatment of fumaric acid/UV-C reduced the initial populations of total aerobic bacteria and yeast and molds in the strawberries by 2.09 and 2.02 log CFU/g, respectively, compared to those of the control. In addition, after 12 days of storage the yeast and molds population in the combined treatment was 1.72 log CFU/g, compared to 5.10 log CFU/g for the control, resulting in a significant decrease of 3.38 log CFU/g. Postharvest treatments used in this study caused negligible changes in the color of the strawberries. Sensory evaluation results indicated that the combined postharvest treatment provided better sensory scores than did the control. In particular, the overall acceptability scores were higher for the combined treatment groups after 5 days of storage. These results suggest that combined treatment of either 50 ppm $ClO_2$ or 0.5% fumaric acid with $5 kJ/m^2$ UV-C can be useful for maintaining the quality of strawberries.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.15-21
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• 2000

In chlorine dioxide delignification and bleaching the formation of chlorate is undesirable because it does not react with lignin and is harmful to the environment. Chlorate is mainly formed from the in-situ generated hypochlorus acid which is also the main reason for AOX formation. In previous literature scavengers of hypochlorous acid such as sulfamic aicd, DMSO, and hydrogen peroxide have been added to bleaching stages to reduce AOX formation but less attention has been paid to chlorate reduction. This paper thus focuses on the reduction of chlorate content caused by the following additives, sulfamic acid, DMSO, hydrogen peroxide, and oxalic acid. The results show that only sulfamic acid and DMSO reduce chlorate formation under our chlorine dioxide prebleaching conditions. Results by UV spectroscopy and pH adjustment show that scavengers react with hypochlorous acid much faster than with chlorine. Hydrogen peroxide and oxalic acid react with HClO/$Cl_2$much slower than DMSO and sulfamic acid do. The reason for the ineffectiveness of hydrogen peroxide and oxalic acid is ascribed to their slow reaction rates with HClO compared to that of chlorate formation. The fact that only 30-35% of the chlorate can be reduced by sulfamic acid and DMSO when charged in same mole ratio to chlorine dioxide, suggested that the reaction rate of DMSO and sulfamic acid with hypochlorous aicd are of the same magnitude as that of chlorate formation.

• Journal of the Korean Chemical Society
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• v.58 no.5
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• pp.490-495
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• 2014

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1105-1113
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• 2004

Disinfection of a waterborne pathogenic protozoa, Giardia lamblia, by the conventional chlorine method has been known to be difficult. An alternative disinfection has been carried out by using a UV -light illuminating optical­fiber photoreactor. Light intensity diffused from one piece of a clad-removed optical-fiber was $1- 1.5{\mu}Em^{-2}s^{-1}$. Disinfection capability in a UV -light irradiated optical-fiber reactor suspended with 0.01 g $TiO_{2}\;dm^{-3}$ was 1.4 times that in the same reactor without $TiO_{2}$ photocatalysts. To resolve the absorption and scattering of UV light by the particles themselves as well as the difficulty of recycling particles in the slurry­type reactor, $TiO_{2}$ which was obtained by a hydrothermal method, was immobilized on clad-removed optical fibers. Such pretreatment of fiber surface resulted in an excellent transparency, which enhanced the UV light to diffuse laterally from a fiber surface. Coating time of the prepared solution by the hydrothermal method was not effective after more than two times. Disinfection capability in the $TiO_{2}$-immobilized optical-fiber reactor was $83\%$ in 1 h at $40^{\circ}C$, which was slightly higher than $76\%$ at $22^{\circ}C$ and $68\%$ at $10^{\circ}C$. Disinfection capability at $22^{\circ}C$ increased from $74\%$ at an initial pH of 3.4, through $76\%$ at pH 6.5, to $87\%$ at an initial pH of 10. Oxygen supply with air-flow rate of 5 $cm^3\;min^{-1}$ did not seem to increase the disinfection capability with UV /immobilized $TiO_2$.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.57-62
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• 2006

Six organophosphorus, one organochlorine, and three synthetic pyrethroid pesticides were analyzed for their residues during washing and hot-air drying of red peppers conducted in the production of powder. The residue ratio in organophosphorus pesticides was 33% in chlorpyrifos, 31 % in diazinon, 50% in methidathion, 80% in EPN, 28% in fenitrothion, and 60% in profenofos. The ratio in pyrethroids was 109% in cypermethrin, 102% in deltamethrin, and 106% in fenvalerate. That in organochlorine was 56% in ${\alpha}$-endosulfan and 90% in ${\beta}$-endosulfan. The results were greatly different between organophosphorus and pyrethroid pesticides. UV irradiation along with hot-air drying brought about a remarkable reduction of the residues, up to 70% as compared with hot-air drying only. The removal effect was most remarkable in pyrethroids, which are hardly removed by hot-air drying. The color of the pepper was not changed during UV irradiation. The use of oxidizing agents such as hydrogen peroxide or chlorine dioxide during washing did not show a remarkable removal of residues. The residue ratio was not affected whether the pesticide is contaminated artificially or naturally.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.126-132
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• 1997

Trihalomethanes (THMs) are formed during the chlorination of waters containing precusors compounds, most commonly humic substances, changes in pH, TOC, temperature, precusor source and concentration chlorine dosage, bromide level and reaction time directly influence trihalomethane formation potential (THMFP) and kinetics. A standard THMFP experiment was conducted for each water under the following conditions ; $20^{\circ}C$, pH 7.4, reaction time of 48hr, TOC 5.7mgC/L. A series of kinetic experiments was conducted for each water to provide THM formation under varying conditions of reaction time, pH, temperature and TOC, chlorine dosage. The resultant mutiple parameter powre function predicts a THM which allows direct calculation of THM, is $[THM]=0.00039(pH-2.81)[TOC][Cl_2]^{0.321}\;t^{0.266}\;T^{0.286}$ Characteristics of raw water in advanced drinking water treatment pilot plant were, TOC levels ran from 4.42~6.84mgC/L, pH 7.2~7.8, temperature $7.0{\sim}18.4^{\circ}C$, UV-254 absorbance $0.057{\sim}0.85cm^{-1}$, THM levels ranged from 0.031~0.049mgC/L.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.2059-2065
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• 2000

The purpose of this study is to improve coagulation efficiency by pre-treatment of high pH water using sulfuric acid. The common reason of pH increasing at down stream of Nakdong river is water blooming. The pH go above 9.0 during water blooming periods. The higher pH water demands more coagulant and pre-chlorine dosage than lower pH water for better coagulation condition. The DOC, THMFP, UV-254 after coagulation with the same coagulant dosage by pre-treatment from pH 9.2 down to 8.1 with sulfuric acid are 1.84mg/L, $51{\mu}g/L$ and $0.032cm^{-1}$, by pretreatment of chlorine are 2.09mg/L, $78{\mu}g/L$ and $0.030cm^{-1}$, by pre-treatment of sulfuric acid and chlorine are 2.14mg/L, $72{\mu}g/L$ and $0.031cm^{-1}$ respectively. Pretreatment with sulfuric acid can improve water quality and reduce coagulant demand.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1632-1638
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• 2012

The effects of combined treatment of aqueous $ClO_2$ and UV-C or electron beam irradiation on microbial growth and quality in chicon during storage at $4^{\circ}C$ were investigated. Samples were treated separately with 50 ppm of $ClO_2$, 5 kJ/$m^2$ of UV-C, 2, 5, 7, and 10 kGy of electron beam irradiation, as well as a combination of $ClO_2$ and UV-C or 2 kGy of electron beam irradiation. The populations of total aerobic bacteria as well as yeast and molds in the chicon samples were determined following each treatment. The populations of total aerobic bacteria in the chicon samples decreased by 1.49~2.92 log CFU/g following combined treatment of $ClO_2$ and UV-C irradiation compared to the control, whereas the populations of yeast and molds decreased by 1.63~1.78 log CFU/g. On the contrary, following combined treatment of $ClO_2$ and electron beam irradiation, the populations of total aerobic bacteria as well as yeast and molds in the chicon samples were undetectable during storage. Color measurements indicated that Hunter $L^*$, $a^*$, and $b^*$ values were not significantly different among the treatments during storage. These results suggest that combined treatment of $ClO_2$ and electron beam irradiation can be useful for improving microbiological safety in chicon during storage.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.17-23
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• 2009

Interest in application of ultraviolet light technology for primary disinfection of potable water in drinking water treatment plants has increased significantly in recent years. The efficacy of disinfection processes in water purification systems is governed by several key factors, including reactor hydraulics, disinfectant chemistry, and microbial inactivation kinetics. The objective of this work was to develop a computational fluid dynamics(CFD) model to predict velocity fields, mass transport, chlorine decay, and microbial inactivation in a continuous flow reactor. The CFD model was also used to evaluate disinfection efficiency in alternative reactor designs. In a typical operation, water enters the inlet of a UV lamp and flows through the annular space between the quartz sleeve and the outside chamber wall. The irradiated water leaves through the outlet nozzle. In this paper, it describe the how to design optimal ultraviolet disinfection device for ground water and rainwater. To search the optimal design method, it was performed computer simulation with 3D-CFD discrete ordinates model and manufactured prototype. Using proposed design method, performed simulation and proved satisfied performance.