• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.541-548
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• 2017

Uranium metal used for fabrication of fuel for research reactors in India is generally produced by magnesio-thermic reduction of $UF_4$. Performance of magnesio-thermic reaction and recovery and quality of uranium largely depends on properties of $UF_4$. As ammonium diuranate (ADU) is first product in powder form in the process flow-sheet, properties of $UF_4$ depend on properties of ADU. ADU is generally produced from uranyl nitrate solution (UNS) for natural uranium metal production and from uranyl fluoride solution (UFS) for low enriched uranium metal production. In present paper, ADU has been produced via both the routes. Variation of uranium recovery and crystal structure and composition of ADU with progress in precipitation reaction has been studied with special attention on first appearance of the precipitate Further, ADU produced by two routes have been calcined to $UO_3$, then reduced to $UO_2$ and hydroflorinated to $UF_4$. Effect of two different process routes of ADU precipitation on the characteristics of ADU, $UO_3$, $UO_2$ and $UF_4$ were studied here.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.753-761
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• 2005

In this study, pretreatment of organic matters with $MIEX^{(R)}$ was evaluated using bench-scale experimental procedures on four organic matters to determine its effect on subsequent UF membrane filtration. For comparison, coagulation process was also used as a pretreatment of UF membrane filtration. Moreover, the membrane fouling potential was identified using different fractions and molecular weights of organic matters. From the removal property of MW organic matters by coagulation process for the sample water NOM and AOM, the removal efficiency of high MW organic matters were much higher than those of low MW organic matters. It was shown that the removal efficiency of high MW organic matter more than 10 kDa was lower than that of low MW organic matter for $MIEX^{(R)}$ process. For the change of permeate flux by the pretreatment process, $MIEX^{(R)}$+UF process showed high removal efficiency of organic matter as compared with coagulation-UF processes, but high reduction rate of permeate flux was presented through the reduction of removal efficiency of high MW organic matter. From sequential filtration test results in order to examine the effect of MW of organic matter on membrane fouling, it was found that the membrane foulant was occurred by high MW organic matter, and the DOC of organic matter less than 0.5 mg/L was working as the membrane foulant. In the case of sample water composed of low MW organic matter less than 10 kDa, since the low MW organic matter less than 10 kDa has high removal efficiency by $MIEX^{(R)}$, low reduction rate of permeate flux is obtained as compared with coagulation-UF processes. In summary, it is required to conduct the research on physical/chemical characteristic of original water before pretreatment process of membrane process is selected, and a pertinent pre-treatment process should be employed based on the physical/chemical characteristic of original water.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.10
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• pp.678-683
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• 2012

One of alternatives to solve the global water shortages is the reuse of wastewater. The aim of this study was to evaluate whether it can be reused for industrial water from wastewater in "A" City with ultrafiltration (UF) and reverse osmosis (RO) process. The results obtained in this study were that the inorganics such as Na, Mg, Cl, Ca, Mn, $PO_4$, $SO_4$, etc. were removed with high treatment efficiency (more than 97%), respectively. However, the removal of $NH_4$-N, TN, $NO_3$-N, BOD was found to be 35.71%, 85.21%, 87.05% and 56%, respectively. The removal efficiency of nutrients was relatively low compared to other metal ions. Despite low nutrients removal, the treated wastewater is recommended to reuse, because the nutrient contents in influent from the secondary wastewater treatment plant were small amount. In addition, all other metrics in the wastewater were found to be lower amount than wastewater reuse criteria. Therefore, the wastewater treated by UF-RO could be sufficient to reuse for industrial waster.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.7
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• pp.495-502
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• 2013

This work was performed to investigate proper condition of coagulation treatment as UF process pretreatment that consider UF permeate flux and residual Al concentration. The coagulant used an alum as $Al_2(SO_4)_3{\cdot}16H_2O$ and PACl (r = 1.5) made this study. The experiment was tested in adjusting conditions such as alum dose, flocculation time and coagulation pH of seawater. Consequently, higher coagulant dose lead to elevation of UF permeate flux while residual aluminium also increased in condition of pH 8.0. The most suitable condition which has a good permeate flux and low residual aluminium, in this works, was coagulant dose of 0.7 mg/L (as Al, alum) and 1.2 mg/L (as Al, PACl) and coagulation pH 6.5. In addition, applying the flocculation time with 1.2 mg/L of PACI reduced. The flocculation time reduced UF permeate flux in using alum.

• Natural Product Sciences
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• v.20 no.1
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• pp.58-64
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• 2014

In this study, edible protopanaxadiol saponin enriched fraction were prepared by ultrafiltration (UF). Ginseng extract was prepared from mixtures of ginseng main root and rootlet (root: rootlet = 4 : 6). UF system was used the four-piston Diaphragm pump equipped with 5 kDa pore size Hydrosart Cassette made by regenerated cellulose acetate (CA) or 3 kDa pore size Hollow Fiber cartridge made by polyethersulfone (PES). Total ginsenoside contents of concentrated fraction by UF system was found to higher, compared to before those of untreated method. Especially, processing of UF showed the increase of PPD-type ginsenoside, while PPT-type ginsenoside was gradually decreased by both 3 kDa and 5 kDa membrane. After removal of 80% water by the 5 kDa Hydrosart Cassette and by 3 kDa Hollow Fiber cartridge, ginsenoside Rb1 content was higher 37.2 mg/g and 25.3 mg/g than 20.8 mg/g in untreated process. The ratio of Rb1 to Rg1 (Rb1/Rg1) and PPD- to PPT- type ginsenoside (PPD/PPT) were higher in inner fluid of ginseng extract after UF by 3 kDa cartridge (47.1 and 23.5, respectively) and 5 kDa Cassette (25.3 and 11.9, respectively) than those of before UF (5.7 and 3.7, respectively). PPD-type ginsenoside enriched fraction by UF system could be developed as a new ginseng material in food and cosmetic industrials.

• Membrane and Water Treatment
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• v.8 no.3
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• pp.279-292
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• 2017

This study was aimed at ultrafiltration (UF) as a pretreatment before reverse osmosis (RO) within the scheme of hybrid reverse osmosis-multistage flush (RO-MSF) desalination. Seawater at elevated temperature (after MSF heat-exchangers) was used as a feed in this process. The pretreatment system was represented as a set of functionally-linked technological segments such as: UF filtration, backwashing, chemical- enhanced backwashing, cleaning, waste disposal, etc. The process represents the sequences of operating cycles. The cycle, in turn, consists of the following unit operations: filtration, backwashing and chemical-enhanced backwashing (CEB). Quantitative assessment was based on the following indicators: normalized permeability, transmembrane pressure, specific energy and water consumption, specific waste generation. UF pre-treatment is accompanied by the following waste streams: $W1=1.19{\times}10$ power of $-2m^3$ (disposed NaOCl with 0.0044% wt.)/$m^3$ (filtrate); $W2=5.95{\times}10$ power of $-3m^3$ (disposed $H_2SO_4$ with 0.052% wt.)/$m^3$(filtrate); $W3=7.26{\times}10$ power of $-2m^3$ (disposed sea water)/$m^3$ (filtrate). Specific energy consumption is $1.11{\times}10$ power of $-1kWh/m^3$ (filtrate). The indicators evaluated over the cycles with conventional (non-chemical) backwashing were compared with the cycles accompanied by CEB. A positive impact of CEB on performance indicators was demonstrated namely: normalized UF resistance remains unchanged within the regime accompanied by CEB, whereas the lack of CEB results in 30% of its growth. Those quantitative indicators can be incorporated into the target function for solving different optimization problems. They can be used in the software for optimisation of operating regimes or in the synthesis of optimal flow- diagram. The cycle characteristics, process parameters and water quality data are attached.

• Nutrition Research and Practice
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• v.9 no.4
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• pp.364-369
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• 2015

BACKGROUND/OBJECTIVES: Inflammation is associated with various types of acute and chronic alcohol liver diseases. In this study, we examined whether umbelliferone (7-hydroxycoumarin, UF) ameliorates chronic alcohol-induced liver damage by modulating inflammatory response and the antioxidant system. METHODS: Rats were fed a Liber-Decarli liquid diet containing 5% alcohol with or without UF (0.05 g/L) for 8 weeks, while normal rats received an isocaloric carbohydrate liquid diet. RESULTS: Chronic alcohol intake significantly increased serum tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and interleukin 6 levels and decreased interleukin 10 level; however, UF supplementation reversed the cytokines related to liver damage. UF significantly suppressed hepatic lipopolysaccharide binding protein, toll-like receptor 4 (TLR4), nuclear factor kappa B, and TNF-${\alpha}$ gene expression increases in response to chronic alcohol intake. Masson's trichrome staining revealed that UF improved mild hepatic fibrosis caused by alcohol, and UF also significantly increased the mRNA expressions and activities of superoxide dismutase and catalase in liver, and thus, decreased lipid peroxide and mitochondrial hydrogen peroxide levels. CONCLUSIONS: The findings of this study indicate that UF protects against alcohol-induced liver damage by inhibiting the TLR4 signaling pathway and activating the antioxidant system.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.31-36
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• 2006

This study was conducted to improve the bond strength of plywood bonded with F/U molar ratio urea-formaldehyde (UF) resins modified with the selected FGMDI prepolymer contents for various purposes. The amount of FGMDI was mixed with liquid UF resin at 0 wt% (as control), 2 wt%, 5 wt%, 10 wt%, 25 wt%, and 50 wt% based on the resin solids. As results, in bonding strength, plywood with F/U molar ratio of 1.4 showed the highest value in Type 2 test and all molar ratio UF resins modified with over 25 wt% of the FGMDI showed more than $11kgf/cm^2$, which was satisfied the minimum requirement of KS standard, $7.5kgf/cm^2$, after Type1.5 testing. As F/U molar ratio was increased and the FGMDI addition in the UF resin was increased, average reduction rate of Type 1.5 bonding strength compared with Type 2 was significantly decreased.

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.787-796
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• 2017

A low dimensional stability and poor bending strength properties were main problems in particleboard manufacturing. The objective of this research was to evaluate the effect of mixed wood species and urea-formaldehyde (UF) or urea-melamine-formaldehyde (UMF) resins on the physical and mechanical properties of three-layer particleboards. The ratio of face/core/back layer was 1 : 2 : 1. The resin content of 12% for both UF resins and UMF resins (UF/MF = 70/30% w/w) was used. The results of this study showed that the utilization of S.mahagony shaving using both UF and UMF resins caused a decrease in the thickness swelling and water absorption of the boards. Thickness swellings of particleboard made of Sengon/Sengon/Sengon (SSS), Mahogany/Mahogany/Mahogany (MMM), Sengon/Mahogany/Sengon (SMS), and Mahogany/Sengon/Mahogany (MSM) were in the range of 23%, 12~16%, 14~16%, and 13~21%, respectively. The board bonded with UMF resin demonstrated better dimensional stability than that bonded with UF resin alone. Modulus of elasticity (MOE) and modulus of rupture (MOR) of particleboards made of S. mahagony shaving in the surface layer in both MMM and MSM boards were better than those of the SSS and SMS. MOE of MMM and MSM board was in the ranges of 24,000 to $26,000kg.cm^{-2}$ and 18,000 to $21,000kg.cm^{-2}$ respectively. Meanwhile, the MOR of board was in the ranges of 200 to $240kg.cm^{-2}$ and 190 to $228kg.cm^{-2}$, respectively.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.639-645
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• 2008

The objectives of this research are to (1) observe changes in particle size distribution due to formation of microflocs during coagulation process (2) identify the membrane fouling potential on cross flow system (3) investigate the mechanism of membrane fouling. The rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. The pretreatment of the raw water significantly reduced the fouling of the UF membrane. Also, the rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane. That is, during the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation not only improved dissolved organics removal efficiency but also flux recovery efficiency.