• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.415-422
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• 1996

Tritium removal from tritiated heavy water in a PHWR is the most effective way in reducing workers' internal dose and radioactivity emissions from Wolsong NPP. The optimum design of the Wolsong TRF (Tritium Removal Facility) was carried out using an approximate short-cut method with an assumption that the TRF, designed to extract 8 MCi per year of elemental tritium from a heavy oater feedstream, uses Liquid Phase Catalytic Exchange (LPCE) front-end process and Cryogenic Distillation (CD) process.

• Membrane and Water Treatment
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• v.11 no.4
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• pp.303-312
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• 2020

This study aims to investigate at a laboratory scale fluorides removal from an industrial wastewater having excessive F^- concentration through a hybrid process combining neutralization and membrane separation. For the membrane separation operation, both Reverse Osmosis (RO) and Nanofiltration (NF) were investigated and confronted. The optimized neutralization step with hydrated lime allowed reaching fluoride removal rates of 99.1± 0.4 %. To simulate continuous process, consecutive batch treatments with full recirculation of membrane process brines were conducted. Despite the relatively high super saturations with respect to CaF₂, no membrane cloaking was observed. The RO polishing treatment allowed decreasing the permeate fluoride concentration to 0.9± 0.3 mg/L with a fluoride rejection rate of 93± 2% at the optimal transmembrane pressure of around 100 psi. When NF membrane was used to treat neutralization filtrate, the permeate fluoride concentration dropped to 1.1± 0.4 mg/L with a fluoride rejection rate of 88± 5% at the optimal pressure of around 80 psi. Thus, with respect to RO, NF allowed roughly 20% decrease of the driving pressure at the expense of only 5% drop of rejection rate. Both NF and RO permeates at optimal operating transmembrane pressures respect environmental regulations for reject streams discharge into the environment.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.109-117
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• 2010

In the present study, the degradation characteristics of Lindane by Advanced Oxidation Processes(UV/$H_2O_2$, Photo-Fenton process) were studied. The degradation efficiency of Lindane in aqueous solution was investigated at various initial pH values, Fenton's reagent concentrations and initial concentrations of Lindane. GC-ECD was used to analyze lindane. Lindane has not been degraded without application of AOPs over two hours. But, approximately 5% of lindane was degraded with UV or $H_2O_2$ alone. Lindane with UV/$H_2O_2$ process showed approximately 7% higher removal efficiency than $H_2O_2$ process. In the UV/$H_2O_2$ process, the pH values did not affect the removal efficiency. The optimal mole ratio of $H_2O_2/Fe^{2+}$ for lindane degradation is about 1.0 in Photo-Fenton process. Also, the experimental results showed that lindane removal efficiency increased with the decrease of initial concentration of lindane. Under the same conditions, the order lindane of removal efficiency is as following : Photo-Fenton process > UV/$H_2O_2$ process > $H_2O_2$ process. In addition, intermediate products were identified by GC-MS techniques. Than PCCH(Pentachlorocyclohexene) was identified as a reaction intermediate of the Photo-Fenton process.

• Journal of Korean Society on Water Environment
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• v.29 no.1
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• pp.74-80
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• 2013

The aim of this study is to evaluate color removal from leather-dyeing wastewater using $O_3$ and $O_3/H_2O_2$ unit processes and a serial process for $O_3$, followed by the $O_3/H_2O_2$ process. The color removal rate of the $O_3$ alone process was only 65% effective, and the color increased when an applied $O_3$ dose of more than 40 ~ 50 mg/L was applied. On the other hand, the color was completely removed without increments of color by the $O_3/H_2O_2$ process with $H_2O_2$ injection ratio of 0.2 and 0.3 (wt. $H_2O_2$/wt. $O_3$). Even though the injection of $H_2O_2$ had an effect on color removal, the color removal rates from $O_3$ alone and from $O_3/H_2O_2$ were similar up to the initial $O_3$-demand stage with an application of 0 ~ 40 mg/L $O_3$. In conclusion, it was found that the $O_3$ followed by the $O_3/H_2O_2$ serial process, the method injecting $H_2O_2$ after ozonation with $O_3$-demand (30 ~ 40 mg/L) in the first stage, is the most appropriate process for effective color removal from leather-dyeing wastewater.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.23-28
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• 1999

Phosphate removal through adsorbent, such as activated alumina, powdered aluminum oxide, flyash, blasted furnace slag and other materials, is commonly and widely practiced. The purpose of this study was to improve the removal efficiency of phosphorus in waste sludge earned at seafood processing factories. To investigate the utility and the feasibility of this sludge disposal process, experiment was carried out with a batch process. As a result, phosphate removal appears to increase with increasing adsorbent does, but shows no changes at an adsorbent does over 5g/l. With increasing ratios of initial phosphate concentration to adsorbent does, the amount of removed phosphate is increased while phosphate removal(%) is decreased. Wasted sludge, treated with zinc chloride chemically, represented a better efficiency than the untreated activated sludge and zinc chloride itself, when they reacted with phosphate solution.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.689-695
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• 2004

Electrocoagulation has been suggested as a promising alternative to conventional coagulation. The process is characterized by reduced sludge production, no requirement for chemical use, and ease of operation. However, this coagulation has scarcely been studied in water purifying process. This study was performed several batch experiments to compare turbidity removal between electrocoagulation and chemical coagulation. In addition, characteristics of floe were evaluated with zeta potential and particle size distributions. Electrocoagulation showed a relatively higher removal of turbidity (approximately 5%) with the same aluminum amount than conventional chemical coagulation. In addition, turbidity removal by electrocoagulation was less sensitive to pH and was greater for more extensive pH range than chemical coagulation. The results of zeta potential and floc size distributions illustrated that electrocoagulation provided the preferable conditions for coagulation such as zeta potential close to zero millivolt and increased portions of particles in the range of 40 and $100{\mu}m$.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.309-315
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• 2018

The applicability of the ultrafiltration process for color removal from dye-containing water has been examined in this study. The optimization of major process variables, such as dye concentration, chitosan concentration and transmembrane pressure on permeate flux and color removal efficiency was investigated. To find the most appropriate results for the experiment, the Box-Wilson experimental design method was employed. The results were correlated by a response function and the coefficients were determined by regression analysis. Permeate flux variation and color removal efficiency determined from the response functions were in good agreement with the experimental results. The optimum conditions of chitosan concentration, dye concentration and pressure were 50 mg/l, 50 mg/l and 3 bars, respectively for the highest permeate flux. On the other hand, optimum conditions for color removal efficiency were determined as 50 mg/l of dye concentration, 50 mg/l of chitosan concentration and 1 bar of pressure.

• Membrane and Water Treatment
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• v.7 no.2
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• pp.143-154
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• 2016

Acetic acid can be removed from wastewater by esterification in a membrane reactor. Pervaporation membrane reactor (PVMR) is an alternative process to conventional separation processes. It is an environmentally friendly process. The main advantages of the PVMR are simultaneous water removal and production of an ester economically. In this study, the synthetic wastewater has been used. Esterification reaction of acetic acid with isopropanol has been studied in the presence of tungstosilicic acid hydrate as a catalyst in a batch reactor and in a PVMR. The effects of important operating parameters such as reaction temperature, initial molar ratio of isopropanol to acetic acid and catalyst concentration has been examined. Removal of acetic acid (conversion of acetic acid) was obtained as 85% using a PVMR by removal of water from the reaction mixture.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.155-160
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• 2007

This study was conducted to find out the chlorine removal characteristics of waste plastic mixture by pyrolysis process with thermogravimetric analysis(TGA) and a lab-scale pyrolyzer. The material used as plastic wastes were PE (Poly-ethylene), PP (Poly-prophylene), and PVC (Poly Vinyl Chloride). Experimental procedure were composed of three steps; 1st step: TGA of PVC, PP and PE, 2nd step: chlorine removal rate of PVC in a lab-scale pyrolyzer, 3rd step: chlorine removal rate of PVC-PE and PVC-PP mixture in a pyrolyzer. Through the results of TGA, we can estimate the basic pyrolysis characteristics of each plastic, and then we can also derive the design parameters and operating conditions of the lab-scale pyrolyzer. The results can be used as primary data for designing a system to produce RPF (Refuse Plastic Fuel), a waste incinerator and a pyrolysis/gasification process.

• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.41-48
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• 2000

In this study, we have investigated the effect of the various operating conditions on the removal fluorine in the rinsed water for the semiconductor industry by using electrolysis process. The removal efficiency of fluorine was irrelevant to initial pH, and carbon anode was high-level treatment in the effect of various electrodes. Fluorine included in the wastewater is treated by the addition of a Ca(OH)2, removal efficiency of electrolysis was increased about 40%. Besides the removal efficiency of fluorine was increased as the current density was increased and this treatment system could reduce both the total sludge and running costs. The feasibility of the electrochemical treatment to the fluorine containing wastewater was verified from this study.